Anatomy_Gray

Anatomy_Gray. The pyramidal process projects posteriorly and fills the space between the inferior ends of the medial and lateral plates of the pterygoid process of the sphenoid bone. The pterygoid processes and spines of the sphenoid bone are associated with structures related to the soft palate, which forms part of the roof of the oral cavity (Fig. 8.248A). The pterygoid processes descend, one on each side, from the lateral aspect of the body of the sphenoid bone. Each process has a medial and a lateral plate. These two vertically oriented plates project from the posterior aspect of the process. The V-shaped gap that occurs inferiorly between the two plates is filled by the pyramidal process of the palatine bone.


Anatomy_Gray

Anatomy_Gray. Projecting posterolaterally from the inferior margin of the medial plate of the pterygoid process is an elongate hook-shaped structure (the pterygoid hamulus). This hamulus is immediately behind the alveolar arch and inferior to the posterior margin of the hard palate. It is: a “pulley” for one of the muscles (tensor veli palatini) of the soft palate, and the attachment site for the upper end of the pterygomandibular raphe, which is attached below to the mandible and joins together the superior constrictor of the pharynx and the buccinator muscle of the cheek. At the root of the medial plate of the pterygoid process on the base of the skull is a small canoe-shaped fossa (scaphoid fossa), which begins just medial to the foramen ovale and descends anteriorly and medially to the root of the medial plate of the pterygoid process (Fig. 8.248A). This fossa is for the attachment of one of the muscles of the soft palate (tensor veli palatini).


Anatomy_Gray

Anatomy_Gray. The spines of the sphenoid, one on each side, are vertical projections from the inferior surfaces of the greater wings of the sphenoid bone (Fig. 8.248A). Each spine is immediately posteromedial to the foramen spinosum. The medial aspect of the spine provides attachment for the most lateral part of the tensor veli palatini muscle of the soft palate. The styloid process and inferior aspect of the petrous part of the temporal bone provide attachment for muscles associated with the tongue and soft palate, respectively. The styloid process projects anteroinferiorly from the underside of the temporal bone. It can be as long as 1 inch (2.5 cm) and points toward the lesser horn of the hyoid bone to which it is attached by the stylohyoid ligament (Fig. 8.248B). The root of the styloid process is immediately anterior to the stylomastoid foramen and lateral to the jugular foramen. The styloglossus muscle of the tongue attaches to the anterolateral surface of the styloid process.


Anatomy_Gray

Anatomy_Gray. The inferior aspect of the temporal bone has a triangular roughened area immediately anteromedial to the opening of the carotid canal (Fig. 8.248A). The levator veli palatini muscle of the soft palate is attached here. Cartilaginous part of the pharyngotympanic tube The trumpet-shaped cartilaginous part of the pharyngotympanic tube is in a groove between the anterior margin of the petrous part of the temporal bone and the posterior margin of the greater wing of the sphenoid (Fig. 8.248A). The medial and lateral walls of the cartilaginous part of the pharyngotympanic tube are formed mainly of cartilage, whereas the more inferolateral wall is more fibrous and is known as the membranous lamina. The apex of the cartilaginous part of the pharyngotympanic tube connects laterally to the opening of the bony part in the temporal bone.


Anatomy_Gray

Anatomy_Gray. The apex of the cartilaginous part of the pharyngotympanic tube connects laterally to the opening of the bony part in the temporal bone. The expanded medial end of the cartilaginous part of the pharyngotympanic tube is immediately posterior to the upper margin of the medial plate of the pterygoid process and opens into the nasopharynx. The cartilaginous part of the pharyngotympanic tube is lateral to the attachment of the levator veli palatini muscle and medial to the spine of the sphenoid. The tensor veli palatini muscle is attached, in part, to the membranous lamina. The mandible is the bone of the lower jaw (Fig. 8.249). It consists of a body of right and left parts, which are fused anteriorly in the midline (mandibular symphysis), and two rami. The site of fusion is particularly visible on the external surface of the bone as a small vertical ridge in the midline.


Anatomy_Gray

Anatomy_Gray. The upper surface of the body of the mandible bears the alveolar arch (Fig. 8.249B), which anchors the lower teeth, and on its external surface on each side is a small mental foramen (Fig. 8.249B). Posterior to the mandibular symphysis on the internal surface of the mandible are two pairs of small spines, one pair immediately above the other pair. These are the superior and inferior mental spines (superior and inferior genial spines) (Fig. 8.249A,C), and are attachment sites for a pair of muscles that pass into the tongue and a pair of muscles that connect the mandible to the hyoid bone. Extending from the midline and originating inferior to the mental spines is a raised line or ridge (the mylohyoid line) (Fig. 8.249C), which runs posteriorly and superiorly along the internal surface of each side of the body of the mandible to end just below the level of the last molar tooth.


Anatomy_Gray

Anatomy_Gray. Above the anterior one-third of the mylohyoid line is a shallow depression (the sublingual fossa) (Fig. 8.249C), and below the posterior two-thirds of the mylohyoid line is another depression (the submandibular fossa) (Fig. 8.249C). Between the last molar tooth and the mylohyoid line is a shallow groove for the lingual nerve. Immediately posterior to the last molar tooth on the medial upper surface of the body of the mandible is a small triangular depression (retromolar triangle) (Fig. 8.249A,C). The pterygomandibular raphe attaches just medial to the apex of this triangle and extends from here to the tip of the pterygoid hamulus above. The ramus of the mandible, one on each side, is quadrangular shaped and oriented in the sagittal plane. On the medial surface of the ramus is a large mandibular foramen for transmission of the inferior alveolar nerve and vessels (Fig. 8.249C).


Anatomy_Gray

Anatomy_Gray. The hyoid bone is a small U-shaped bone in the neck between the larynx and the mandible. It has an anterior body of hyoid bone and two large greater horns, one on each side, which project posteriorly and superiorly from the body (Fig. 8.250). There are two small conical lesser horns on the superior surface where the greater horns join with the body. The stylohyoid ligaments attach to the apices of the lesser horns. The hyoid bone is a key bone in the neck because it connects the floor of the oral cavity in front with the pharynx behind and the larynx below. Walls: the cheeks The walls of the oral cavity are formed by the cheeks. Each cheek consists of fascia and a layer of skeletal muscle sandwiched between skin externally and oral mucosa internally. The thin layer of skeletal muscle within the cheeks is principally the buccinator muscle.


Anatomy_Gray

Anatomy_Gray. The buccinator muscle is one of the muscles of facial expression (Fig. 8.251). It is in the same plane as the superior constrictor muscle of the pharynx. In fact, the posterior margin of the buccinator muscle is joined to the anterior margin of the superior constrictor muscle by the pterygomandibular raphe, which runs between the tip of the pterygoid hamulus of the sphenoid bone above and a roughened area of bone immediately behind the last molar tooth on the mandible below. The buccinator and superior constrictor muscles therefore provide continuity between the walls of the oral and pharyngeal cavities. The buccinator muscle, in addition to originating from the pterygomandibular raphe, also originates directly from the alveolar part of the mandible and alveolar process of the maxilla.


Anatomy_Gray

Anatomy_Gray. The buccinator muscle, in addition to originating from the pterygomandibular raphe, also originates directly from the alveolar part of the mandible and alveolar process of the maxilla. From its three sites of origin, the muscle fibers of the buccinator run forward to blend with those of the orbicularis oris muscle and to insert into the modiolus, which is a small button-shaped nodule of connective tissue at the interface between the muscles of the lips and cheeks on each side. The buccinator muscle holds the cheeks against the alveolar arches and keeps food between the teeth when chewing. The buccinator is innervated by the buccal branch of the facial nerve [VII]. General sensation from the skin and oral mucosa of the cheeks is carried by the buccal branch of the mandibular nerve [V3].


Anatomy_Gray

Anatomy_Gray. The floor of the oral cavity proper is formed mainly by three structures: a muscular diaphragm, which fills the U-shaped gap between the left and right sides of the body of the mandible and is composed of the paired mylohyoid muscles; two cord-like geniohyoid muscles above the diaphragm, which run from the mandible in front to the hyoid bone behind; and the tongue, which is superior to the geniohyoid muscles. Also present in the floor of the oral cavity proper are salivary glands and their ducts. The largest of these glands, on each side, are the sublingual gland and the oral part of the submandibular gland. The two thin mylohyoid muscles (Table 8.20), one on each side, together form a muscular diaphragm that defines the inferior limit of the floor of the oral cavity (Fig. 8.252A). Each muscle is triangular in shape with its apex pointed forward.


Anatomy_Gray

Anatomy_Gray. The lateral margin of each triangular muscle is attached to the mylohyoid line on the medial side of the body of the mandible. From here, the muscle fibers run slightly downward to the medial margin at the midline where the fibers are joined together with those of their partner muscle on the other side by a raphe. The raphe extends from the posterior aspect of the mandibular symphysis in front to the body of the hyoid bone behind. The posterior margin of each mylohyoid muscle is free except for a small medial attachment to the hyoid bone. The mylohyoid muscles: contribute structural support to the floor of the oral cavity, participate in elevating and pulling forward the hyoid bone, and therefore the attached larynx, during the initial stages of swallowing, and when the hyoid bone is fixed in position, depress the mandible and open the mouth.


Anatomy_Gray

Anatomy_Gray. Like the muscles of mastication, the mylohyoid muscles are innervated by the mandibular nerve [V3]. The specific branch that innervates the mylohyoid muscles is the nerve to the mylohyoid from the inferior alveolar nerve. The geniohyoid muscles (Table 8.20) are paired cord-like muscles that run, one on either side of the midline, from the inferior mental spines on the posterior surface of the mandibular symphysis to the anterior surface of the body of the hyoid bone (Fig. 8.252B,C). They are immediately superior to the mylohyoid muscles in the floor of the mouth and inferior to the genioglossus muscles that form part of the root of the tongue. The geniohyoid muscles: mainly pull the hyoid bone, and therefore the attached larynx, up and forward during swallowing; and because they pass posteroinferiorly from the mandible to the hyoid bone, when the hyoid bone is fixed, they can act with the mylohyoid muscles to depress the mandible and open the mouth.


Anatomy_Gray

Anatomy_Gray. Unlike other muscles that move the mandible at the temporomandibular joint, the geniohyoid muscles are innervated by a branch of cervical nerve C1, which “hitchhikes” from the neck along the hypoglossal nerve [XII] into the floor of the oral cavity. Gateway into the floor of the oral cavity In addition to defining the lower limit of the floor of the oral cavity, the free posterior border of the mylohyoid muscle on each side forms one of the three margins of a large triangular aperture (oropharyngeal triangle), which is a major route by which structures in the upper neck and infratemporal fossa of the head pass to and from structures in the floor of the oral cavity (Fig. 8.253). The other two muscles that complete the margins of the aperture are the superior and middle constrictor muscles of the pharynx.


Anatomy_Gray

Anatomy_Gray. Most structures that pass through the aperture are associated with the tongue and include muscles (hyoglossus, styloglossus), vessels (lingual artery and vein), nerves (lingual, hypoglossal [XII], glossopharyngeal [IX]), and lymphatics. A large salivary gland (the submandibular gland) is “hooked” around the free posterior margin of the mylohyoid muscle and therefore also passes through the opening. The tongue is a muscular structure that forms part of the floor of the oral cavity and part of the anterior wall of the oropharynx (Fig. 8.254A). Its anterior part is in the oral cavity and is somewhat triangular in shape with a blunt apex of the tongue. The apex is directed anteriorly and sits immediately behind the incisor teeth. The root of the tongue is attached to the mandible and the hyoid bone. The superior surface of the oral or anterior two-thirds of the tongue is oriented in the horizontal plane.


Anatomy_Gray

Anatomy_Gray. The superior surface of the oral or anterior two-thirds of the tongue is oriented in the horizontal plane. The pharyngeal surface or posterior one-third of the tongue curves inferiorly and becomes oriented more in the vertical plane. The oral and pharyngeal surfaces are separated by a V-shaped terminal sulcus of the tongue. This terminal sulcus forms the inferior margin of the oropharyngeal isthmus between the oral and pharyngeal cavities. At the apex of the V-shaped sulcus is a small depression (the foramen cecum of the tongue), which marks the site in the embryo where the epithelium invaginated to form the thyroid gland. In some people a thyroglossal duct persists and connects the foramen cecum on the tongue with the thyroid gland in the neck. The superior surface of the oral part of the tongue is covered by hundreds of papillae (Fig. 8.254B): Filiform papillae are small cone-shaped projections of the mucosa that end in one or more points.


Anatomy_Gray

Anatomy_Gray. Filiform papillae are small cone-shaped projections of the mucosa that end in one or more points. Fungiform papillae are rounder in shape and larger than the filiform papillae, and tend to be concentrated along the margins of the tongue. The largest of the papillae are the vallate papillae, which are blunt-ended cylindrical papillae invaginations in the tongue’s surface—there are only about 8 to 12 vallate papillae in a single V-shaped line immediately anterior to the terminal sulcus of the tongue. Foliate papillae are linear folds of mucosa on the sides of the tongue near the terminal sulcus of tongue. The papillae in general increase the area of contact between the surface of the tongue and the contents of the oral cavity. All except the filiform papillae have taste buds on their surfaces. Inferior surface of tongue


Anatomy_Gray

Anatomy_Gray. Inferior surface of tongue The undersurface of the oral part of the tongue lacks papillae, but does have a number of linear mucosal folds (see Fig. 8.265). A single median fold (the frenulum of the tongue) is continuous with the mucosa covering the floor of the oral cavity, and overlies the lower margin of a midline sagittal septum, which internally separates the right and left sides of the tongue. On each side of the frenulum is a lingual vein, and lateral to each vein is a rough fimbriated fold. The mucosa covering the pharyngeal surface of the tongue is irregular in contour because of the many small nodules of lymphoid tissue in the submucosa. These nodules are collectively the lingual tonsil. There are no papillae on the pharyngeal surface. The bulk of the tongue is composed of muscle (Fig. 8.254 and Table 8.21).


Anatomy_Gray

Anatomy_Gray. There are no papillae on the pharyngeal surface. The bulk of the tongue is composed of muscle (Fig. 8.254 and Table 8.21). The tongue is completely divided into left and right halves by a median sagittal septum composed of connective tissue. This means that all muscles of the tongue are paired. There are intrinsic and extrinsic lingual muscles. Except for the palatoglossus, which is innervated by the vagus nerve [X], all muscles of the tongue are innervated by the hypoglossal nerve [XII]. The intrinsic muscles of the tongue (Fig. 8.255) originate and insert within the substance of the tongue. They are divided into superior longitudinal, inferior longitudinal, transverse, and vertical muscles, and they alter the shape of the tongue by: lengthening and shortening it, curling and uncurling its apex and edges, and flattening and rounding its surface.


Anatomy_Gray

Anatomy_Gray. Working in pairs or one side at a time the intrinsic muscles of the tongue contribute to precision movements of the tongue required for speech, eating, and swallowing. Extrinsic muscles of the tongue (Fig. 8.255 and Table 8.21) originate from structures outside the tongue and insert into the tongue. There are four major extrinsic muscles on each side, the genioglossus, hyoglossus, styloglossus, and palatoglossus. These muscles protrude, retract, depress, and elevate the tongue. The thick fan-shaped genioglossus muscles make a substantial contribution to the structure of the tongue. They occur on either side of the midline septum that separates left and right halves of the tongue.


Anatomy_Gray

Anatomy_Gray. The genioglossus muscles originate from the superior mental spines on the posterior surface of the mandibular symphysis immediately superior to the origin of the geniohyoid muscles from the inferior mental spines (Fig. 8.256). From this small site of origin, each muscle expands posteriorly and superiorly. The most inferior fibers attach to the hyoid bone. The remaining fibers spread out superiorly to blend with the intrinsic muscles along virtually the entire length of the tongue. The genioglossus muscles: depress the central part of the tongue, and protrude the anterior part of the tongue out of the oral fissure (i.e., stick the tongue out). Like most muscles of the tongue, the genioglossus muscles are innervated by the hypoglossal nerves [XII].


Anatomy_Gray

Anatomy_Gray. Like most muscles of the tongue, the genioglossus muscles are innervated by the hypoglossal nerves [XII]. Asking a patient to “stick your tongue out” can be used as a test for the hypoglossal nerves [XII]. If the nerves are functioning normally, the tongue should protrude evenly in the midline. If the nerve on one side is not fully functional, the tip of the tongue will point to that side. The hyoglossus muscles are thin quadrangular muscles lateral to the genioglossus muscles (Fig. 8.257).


Anatomy_Gray

Anatomy_Gray. The hyoglossus muscles are thin quadrangular muscles lateral to the genioglossus muscles (Fig. 8.257). Each hyoglossus muscle originates from the entire length of the greater horn and the adjacent part of the body of the hyoid bone. At its origin from the hyoid bone, the hyoglossus muscle is lateral to the attachment of the middle constrictor muscle of the pharynx. The muscle passes superiorly and anteriorly through the gap (oropharyngeal triangle) between the superior constrictor, middle constrictor, and mylohyoid to insert into the tongue lateral to the genioglossus and medial to the styloglossus. The hyoglossus muscle depresses the tongue and is innervated by the hypoglossal nerve [XII]. An important landmark. The hyoglossus muscle is an important landmark in the floor of the oral cavity: The lingual artery from the external carotid artery in the neck enters the tongue deep to the hyoglossus, between the hyoglossus and genioglossus.


Anatomy_Gray

Anatomy_Gray. The lingual artery from the external carotid artery in the neck enters the tongue deep to the hyoglossus, between the hyoglossus and genioglossus. The hypoglossal nerve [XII] and lingual nerve (branch of the mandibular nerve [V3]), from the neck and infratemporal fossa of the head, respectively, enter the tongue on the external surface of the hyoglossus. The styloglossus muscles originate from the anterior surface of the styloid processes of the temporal bones. From here, each muscle passes inferiorly and medially through the gap (oropharyngeal triangle) between the middle constrictor, superior constrictor, and mylohyoid muscles to enter the lateral surface of the tongue where they blend with the superior margin of the hyoglossus and with the intrinsic muscles (Fig. 8.258). The styloglossus muscles retract the tongue and pull the back of the tongue superiorly. They are innervated by the hypoglossal nerves [XII].


Anatomy_Gray

Anatomy_Gray. The styloglossus muscles retract the tongue and pull the back of the tongue superiorly. They are innervated by the hypoglossal nerves [XII]. The palatoglossus muscles are muscles of the soft palate and the tongue. Each originates from the undersurface of the palatine aponeurosis and passes anteroinferiorly to the lateral side of the tongue (Fig. 8.259). The palatoglossus muscles: elevate the back of the tongue, move the palatoglossal arches of mucosa toward the midline, and depress the soft palate. These movements facilitate closing of the oropharyngeal isthmus and as a result separate the oral cavity from the oropharynx. Unlike other muscles of the tongue, but similar to most other muscles of the soft palate, the palatoglossus muscles are innervated by the vagus nerves [X]. The major artery of the tongue is the lingual artery (Fig. 8.260).


Anatomy_Gray

Anatomy_Gray. The major artery of the tongue is the lingual artery (Fig. 8.260). On each side, the lingual artery originates from the external carotid artery in the neck adjacent to the tip of the greater horn of the hyoid bone. It forms an upward bend and then loops downward and forward to pass deep to the hyoglossus muscle, and accompanies the muscle through the aperture (oropharyngeal triangle) formed by the margins of the mylohyoid, superior constrictor, and middle constrictor muscles, and enters the floor of the oral cavity. The lingual artery then travels forward in the plane between the hyoglossus and genioglossus muscles to the apex of the tongue. In addition to the tongue, the lingual artery supplies the sublingual gland, gingiva, and oral mucosa in the floor of the oral cavity. The tongue is drained by dorsal lingual and deep lingual veins (Fig. 8.260).


Anatomy_Gray

Anatomy_Gray. The tongue is drained by dorsal lingual and deep lingual veins (Fig. 8.260). The deep lingual veins are visible through the mucosa on the undersurface of the tongue. Although they accompany the lingual arteries in anterior parts of the tongue, they become separated from the arteries posteriorly by the hyoglossus muscles. On each side, the deep lingual vein travels with the hypoglossal nerve [XII] on the external surface of the hyoglossus muscle and passes out of the floor of the oral cavity through the aperture (oropharyngeal triangle) formed by the margins of the mylohyoid, superior constrictor, and middle constrictor muscles. It joins the internal jugular vein in the neck. The dorsal lingual vein follows the lingual artery between the hyoglossus and genioglossus muscles and, like the deep lingual vein, drains into the internal jugular vein in the neck. Innervation of the tongue is complex and involves a number of nerves (Figs. 8.260 and 8.261).


Anatomy_Gray

Anatomy_Gray. Innervation of the tongue is complex and involves a number of nerves (Figs. 8.260 and 8.261). Taste (SA) and general sensation from the pharyngeal part of the tongue are carried by the glossopharyngeal nerve [IX]. The glossopharyngeal nerve [IX] leaves the skull through the jugular foramen and descends along the posterior surface of the stylopharyngeus muscle. It passes around the lateral surface of the stylopharyngeus and then slips through the posterior aspect of the gap (oropharyngeal triangle) between the superior constrictor, middle constrictor, and mylohyoid muscles. The nerve then passes forward on the oropharyngeal wall just below the inferior pole of the palatine tonsil and enters the pharyngeal part of the tongue deep to the styloglossus and hyoglossus muscles. In addition to taste and general sensation on the posterior one-third of the tongue, branches creep anterior to the terminal sulcus of the tongue to carry taste (SA) and general sensation from the vallate papillae.


Anatomy_Gray

Anatomy_Gray. General sensory innervation from the anterior two-thirds or oral part of the tongue is carried by the lingual nerve, which is a major branch of the mandibular nerve [V3]. It originates in the infratemporal fossa and passes anteriorly into the floor of the oral cavity by passing through the gap (oropharyngeal triangle) between the mylohyoid, superior constrictor, and middle constrictor muscles (Fig. 8.262). As it travels through the gap, it passes immediately inferior to the attachment of the superior constrictor to the mandible and continues forward on the medial surface of the mandible adjacent to the last molar tooth and deep to the gingiva. In this position, the nerve can be palpated against the bone by placing a finger into the oral cavity. The lingual nerve then continues anteromedially across the floor of the oral cavity, loops under the submandibular duct, and ascends into the tongue on the external and superior surface of the hyoglossus muscle.


Anatomy_Gray

Anatomy_Gray. In addition to general sensation from the oral part of the tongue, the lingual nerve also carries general sensation from the mucosa on the floor of the oral cavity and gingiva associated with the lower teeth. The lingual nerve also carries parasympathetic and taste fibers from the oral part of the tongue that are part of the facial nerve [VII]. Taste (SA) from the oral part of the tongue is carried into the central nervous system by the facial nerve [VII]. Special sensory (SA) fibers of the facial nerve [VII] leave the tongue and oral cavity as part of the lingual nerve. The fibers then enter the chorda tympani nerve, which is a branch of the facial nerve [VII] that joins the lingual nerve in the infratemporal fossa (Fig. 8.262; also see p. 976). All muscles of the tongue are innervated by the hypoglossal nerve [XII] except for the palatoglossus muscle, which is innervated by the vagus nerve [X].


Anatomy_Gray

Anatomy_Gray. All muscles of the tongue are innervated by the hypoglossal nerve [XII] except for the palatoglossus muscle, which is innervated by the vagus nerve [X]. The hypoglossal nerve [XII] leaves the skull through the hypoglossal canal and descends almost vertically in the neck to a level just below the angle of the mandible (Fig. 8.263). Here it angles sharply forward around the sternocleidomastoid branch of the occipital artery, crosses the external carotid artery, and continues forward, crossing the loop of the lingual artery, to reach the external surface of the lower one-third of the hyoglossus muscle. The hypoglossal nerve [XII] follows the hyoglossus muscle through the gap (oropharyngeal triangle) between the superior constrictor, middle constrictor, and mylohyoid muscles to reach the tongue.


Anatomy_Gray

Anatomy_Gray. The hypoglossal nerve [XII] follows the hyoglossus muscle through the gap (oropharyngeal triangle) between the superior constrictor, middle constrictor, and mylohyoid muscles to reach the tongue. In the upper neck, a branch from the anterior ramus of C1 joins the hypoglossal nerve [XII]. Most of these C1 fibers leave the hypoglossal nerve [XII] as the superior root of the ansa cervicalis (Fig. 8.263). Near the posterior border of the hyoglossus muscle, the remaining fibers leave the hypoglossal nerve [XII] and form two nerves: the thyrohyoid branch, which remains in the neck to innervate the thyrohyoid muscle, and the branch to the geniohyoid, which passes into the floor of the oral cavity to innervate the geniohyoid. All lymphatic vessels from the tongue ultimately drain into the deep cervical chain of nodes along the internal jugular vein:


Anatomy_Gray

Anatomy_Gray. All lymphatic vessels from the tongue ultimately drain into the deep cervical chain of nodes along the internal jugular vein: The pharyngeal part of the tongue drains through the pharyngeal wall directly into mainly the jugulodigastric node of the deep cervical chain. The oral part of the tongue drains both directly into the deep cervical nodes, and indirectly into these nodes by passing first through the mylohyoid muscle and into submental and submandibular nodes. The submental nodes are inferior to the mylohyoid muscles and between the digastric muscles, while the submandibular nodes are below the floor of the oral cavity along the inner aspect of the inferior margins of the mandible. The tip of the tongue drains through the mylohyoid muscle into the submental nodes and then into mainly the jugulo-omohyoid node of the deep cervical chain.


Anatomy_Gray

Anatomy_Gray. The tip of the tongue drains through the mylohyoid muscle into the submental nodes and then into mainly the jugulo-omohyoid node of the deep cervical chain. Salivary glands are glands that open or secrete into the oral cavity. Most are small glands in the submucosa or mucosa of the oral epithelium lining the tongue, palate, cheeks, and lips, and open into the oral cavity directly or via small ducts. In addition to these small glands are much larger glands, which include the paired parotid, submandibular, and sublingual glands. The parotid gland (see pp. 900–901) on each side is entirely outside the boundaries of the oral cavity in a shallow triangular-shaped trench (Fig. 8.264) formed by: the sternocleidomastoid muscle behind, the ramus of the mandible in front, and superiorly, the base of the trench is formed by the external acoustic meatus and the posterior aspect of the zygomatic arch.


Anatomy_Gray

Anatomy_Gray. The gland normally extends anteriorly over the masseter muscle, and inferiorly over the posterior belly of the digastric muscle. The parotid duct passes anteriorly across the external surface of the masseter muscle and then turns medially to penetrate the buccinator muscle of the cheek and open into the oral cavity adjacent to the crown of the second upper molar tooth. The parotid gland encloses the external carotid artery, the retromandibular vein, and the origin of the extracranial part of the facial nerve [VII]. The elongate submandibular glands are smaller than the parotid glands but larger than the sublingual glands. Each is hook shaped (Fig. 8.265A,B):


Anatomy_Gray

Anatomy_Gray. The elongate submandibular glands are smaller than the parotid glands but larger than the sublingual glands. Each is hook shaped (Fig. 8.265A,B): The larger arm of the hook is directed forward in the horizontal plane below the mylohyoid muscle and is therefore outside the boundaries of the oral cavity—this larger superficial part of the gland is directly against a shallow impression on the medial side of the mandible (submandibular fossa) inferior to the mylohyoid line. The smaller arm of the hook (or deep part) of the gland loops around the posterior margin of the mylohyoid muscle to enter and lie within the floor of the oral cavity where it is lateral to the root of the tongue on the lateral surface of the hyoglossus muscle. The submandibular duct emerges from the medial side of the deep part of the gland in the oral cavity and passes forward to open on the summit of a small sublingual caruncle (papilla) beside the base of the frenulum of the tongue (Fig. 8.265C,D).


Anatomy_Gray

Anatomy_Gray. The lingual nerve loops under the submandibular duct, crossing first the lateral side and then the medial side of the duct, as the nerve descends anteromedially through the floor of the oral cavity and then ascends into the tongue. The sublingual glands are the smallest of the three major paired salivary glands. Each is almond shaped and is immediately lateral to the submandibular duct and associated lingual nerve in the floor of the oral cavity (Fig. 8.265). Each sublingual gland lies directly against the medial surface of the mandible where it forms a shallow groove (sublingual fossa) superior to the anterior one-third of the mylohyoid line. The superior margin of the sublingual gland raises an elongate fold of mucosa (sublingual fold), which extends from the posterolateral aspect of the floor of the oral cavity to the sublingual papilla beside the base of the frenulum of the tongue at the midline anteriorly (Fig. 8.265D).


Anatomy_Gray

Anatomy_Gray. The sublingual gland drains into the oral cavity via numerous small ducts (minor sublingual ducts), which open onto the crest of the sublingual fold. Occasionally, the more anterior part of the gland is drained by a duct (major sublingual duct) that opens together with the submandibular duct on the sublingual caruncle. Vessels that supply the parotid gland originate from the external carotid artery and from its branches that are adjacent to the gland. The submandibular and sublingual glands are supplied by branches of the facial and lingual arteries. Veins from the parotid gland drain into the external jugular vein, and those from the submandibular and sublingual glands drain into lingual and facial veins. Lymphatic vessels from the parotid gland drain into nodes that are on or in the gland. These parotid nodes then drain into superficial and deep cervical nodes.


Anatomy_Gray

Anatomy_Gray. Lymphatic vessels from the parotid gland drain into nodes that are on or in the gland. These parotid nodes then drain into superficial and deep cervical nodes. Lymphatics from the submandibular and sublingual glands drain mainly into submandibular nodes and then into deep cervical nodes, particularly the jugulo-omohyoid node. Parasympathetic innervation to all salivary glands in the oral cavity is by branches of the facial nerve [VII], which join branches of the maxillary [V2] and mandibular [V3] nerves to reach their target destinations. The parotid gland, which is entirely outside the oral cavity, receives its parasympathetic innervation from fibers that initially traveled in the glossopharyngeal nerve [IX], which eventually join a branch of the mandibular nerve [V3] in the infratemporal fossa (Fig. 8.266).


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Anatomy_Gray. All salivary glands above the level of the oral fissure, as well as all mucus glands in the nose and the lacrimal gland in the orbit, are innervated by parasympathetic fibers carried in the greater petrosal branch of the facial nerve [VII] (Fig. 8.266). Preganglionic parasympathetic fibers carried in this nerve enter the pterygopalatine fossa and synapse with postganglionic parasympathetic fibers in the pterygopalatine ganglion formed around branches of the maxillary nerve [V2]. Postganglionic parasympathetic fibers join general sensory branches of the maxillary nerve, such as the palatine nerves, destined for the roof of the oral cavity, to reach their target glands. All glands below the level of the oral fissure, which include those small glands in the floor of the oral cavity, in the lower lip, and in the tongue, and the larger submandibular and sublingual glands, are innervated by parasympathetic fibers carried in the chorda tympani branch of the facial nerve [VII] (Fig. 8.266).


Anatomy_Gray

Anatomy_Gray. The chorda tympani joins the lingual branch of the mandibular nerve [V3] in the infratemporal fossa and passes with it into the oral cavity. On the external surface of the hyoglossus muscle, preganglionic parasympathetic fibers leave the inferior aspect of the lingual nerve to synapse with postganglionic parasympathetic fibers in the submandibular ganglion, which appears to hang off the lingual nerve (Fig. 8.267). Postganglionic parasympathetic fibers leave the ganglion and pass directly to the submandibular and sublingual glands while others hop back onto the lingual nerve and travel with branches of the lingual nerve to target glands. Sympathetic innervation to the salivary glands is from spinal cord level T1. Preganglionic sympathetic fibers enter the sympathetic trunk and ascend to synapse in the superior cervical sympathetic ganglion (Fig. 8.268). Postganglionic fibers hop onto adjacent blood vessels and nerves to reach the glands.


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Anatomy_Gray. The roof of the oral cavity consists of the palate, which has two parts—an anterior hard palate and a posterior soft palate (Fig. 8.269). The hard palate separates the oral cavity from the nasal cavities. It consists of a bony plate covered above and below by mucosa: Above, it is covered by respiratory mucosa and forms the floor of the nasal cavities. Below, it is covered by a tightly bound layer of oral mucosa and forms much of the roof of the oral cavity (Fig. 8.269). The palatine processes of the maxillae form the anterior three-quarters of the hard palate. The horizontal plates of the palatine bones form the posterior one-quarter. In the oral cavity, the upper alveolar arch borders the hard palate anteriorly and laterally. Posteriorly, the hard palate is continuous with the soft palate.


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Anatomy_Gray. The mucosa of the hard palate in the oral cavity possesses numerous transverse palatine folds (palatine rugae) and a median longitudinal ridge (palatine raphe), which ends anteriorly in a small oval elevation (incisive papilla). The incisive papilla (Fig. 8.269) overlies the incisive fossa formed between the horizontal plates of the maxillae immediately behind the incisor teeth. The soft palate (Fig. 8.269) continues posteriorly from the hard palate and acts as a valve that can be: depressed to help close the oropharyngeal isthmus, and elevated to separate the nasopharynx from the oropharynx. The soft palate is formed and moved by four muscles and is covered by mucosa that is continuous with the mucosa lining the pharynx and oral and nasal cavities. The small tear-shaped muscular projection that hangs from the posterior free margin of the soft palate is the uvula. Muscles of the soft palate


Anatomy_Gray

Anatomy_Gray. The small tear-shaped muscular projection that hangs from the posterior free margin of the soft palate is the uvula. Muscles of the soft palate Five muscles (Table 8.22) on each side contribute to the formation and movement of the soft palate. Two of these, the tensor veli palatini and levator veli palatini, descend into the palate from the base of the skull. Two others, the palatoglossus and palatopharyngeus, ascend into the palate from the tongue and pharynx, respectively. The last muscle, the musculus uvulae, is associated with the uvula. All muscles of the palate are innervated by the vagus nerve [X], except for the tensor veli palatini, which is innervated by the mandibular nerve [V3] (via the nerve to the medial pterygoid). Tensor veli palatini and the palatine aponeurosis The tensor veli palatini muscle is composed of two parts—a vertical muscular part and a more horizontal fibrous part, which forms the palatine aponeurosis (Fig. 8.270A).


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Anatomy_Gray. The tensor veli palatini muscle is composed of two parts—a vertical muscular part and a more horizontal fibrous part, which forms the palatine aponeurosis (Fig. 8.270A). The vertical part of the tensor veli palatini is thin and triangular in shape with its base attached to the skull and its apex pointed inferiorly. The base is attached along an oblique line that begins medially at the scaphoid fossa near the root of the pterygoid process of the sphenoid bone and continues laterally along the membranous part of the pharyngotympanic tube to the spine of the sphenoid bone. The tensor veli palatini descends vertically along the lateral surface of the medial plate of the pterygoid process and pharyngeal wall to the pterygoid hamulus where the fibers converge to form a small tendon (Fig. 8.270A).


Anatomy_Gray

Anatomy_Gray. The tendon loops 90° medially around the pterygoid hamulus, penetrating the origin of the buccinator muscle as it does, and expands like a fan to form the fibrous horizontal part of the muscle. This fibrous part is continuous across the midline with its partner on the other side to form the palatine aponeurosis. The palatine aponeurosis is attached anteriorly to the margin of the hard palate, but is unattached posteriorly where it ends in a free margin. This expansive aponeurosis is the major structural element of the soft palate to which the other muscles of the palate attach. The tensor veli palatini: tenses (makes firm) the soft palate so that the other muscles attached to the palate can work more effectively, and opens the pharyngotympanic tube when the palate moves during yawning and swallowing as a result of its attachment superiorly to the membranous part of the pharyngotympanic tube.


Anatomy_Gray

Anatomy_Gray. The tensor veli palatini is innervated by the nerve to the medial pterygoid from the mandibular nerve [V3]. The levator veli palatini muscle originates from the base of the skull and descends to the upper surface of the palatine aponeurosis (Fig. 8.270B). On the skull, it originates from a roughened area on the petrous part of the temporal bone immediately anterior to the opening of the carotid canal. Some fibers also originate from adjacent parts of the pharyngotympanic tube. The levator veli palatini passes anteroinferiorly through fascia of the pharyngeal wall, passes medial to the pharyngotympanic tube, and inserts onto the palatine aponeurosis (Fig. 8.270B). Its fibers interlace at the midline with those of the levator veli palatini on the other side.


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Anatomy_Gray. Unlike the tensor veli palatini muscles, the levator veli palatini muscles do not pass around each pterygoid hamulus, but course directly from the base of the skull to the upper surface of the palatine aponeurosis. Therefore, they are the only muscles that can elevate the palate above the neutral position and close the pharyngeal isthmus between the nasopharynx and oropharynx. The levator veli palatini is innervated by the vagus nerve [X] through the pharyngeal branch to the pharyngeal plexus. Clinically, the levator veli palatini can be tested by asking a patient to say “ah.” If the muscle on each side is functioning normally, the palate elevates evenly in the midline. If one side is not functioning, the palate deviates away from the abnormal side.


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Anatomy_Gray. The palatopharyngeus muscle originates from the superior surface of the palatine aponeurosis and passes posterolaterally over its margin to descend and become one of the longitudinal muscles of the pharyngeal wall (Fig. 8.270C). It is attached to the palatine aponeurosis by two flat lamellae separated by the levator veli palatini muscle. The more anterior and lateral of these two lamellae is attached to the posterior margin of the hard palate as well as to the palatine aponeurosis. The two palatopharyngeus muscles, one on each side, underlie the palatopharyngeal arches on the oropharyngeal wall. The palatopharyngeal arches lie posterior and medial to the palatoglossal arches when viewed anteriorly through the oral cavity (Fig. 8.271). On each side, the palatine tonsil is between the palatopharyngeal and palatoglossal arches on the lateral oropharyngeal wall (Fig. 8.271A).


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Anatomy_Gray. On each side, the palatine tonsil is between the palatopharyngeal and palatoglossal arches on the lateral oropharyngeal wall (Fig. 8.271A). The palatopharyngeus muscles: depress the palate and move the palatopharyngeal arches toward the midline like curtains—both these actions help close the oropharyngeal isthmus; and elevate the pharynx during swallowing. The palatopharyngeus is innervated by the vagus nerve [X] through the pharyngeal branch to the pharyngeal plexus. The palatoglossus muscle attaches to the inferior (oral) surface of the palatine aponeurosis and passes inferiorly and anteriorly into the lateral surface of the tongue (Fig. 8.272). The palatoglossus muscle underlies a fold of mucosa that arches from the soft palate to the tongue. These palatoglossal arches, one on each side, are lateral and anterior to the palatopharyngeal arches and define the lateral margins of the oropharyngeal isthmus (Fig. 8.271A).


Anatomy_Gray

Anatomy_Gray. The palatine tonsil is between the palatoglossal and palatopharyngeal arches on the lateral oropharyngeal wall (Figs. 8.271 and 8.272). The palatoglossus muscles depress the palate, move the palatoglossal arches toward the midline like curtains, and elevate the back of the tongue. These actions help close the oropharyngeal isthmus. The palatoglossus is innervated by the vagus nerve [X] through the pharyngeal branch to the pharyngeal plexus. The musculus uvulae originates from the posterior nasal spine on the posterior margin of the hard palate and passes directly posteriorly over the dorsal aspect of the palatine aponeurosis to insert into connective tissue underlying the mucosa of the uvula (Fig. 8.272). It passes between the two lamellae of the palatopharyngeus superior to the attachment of the levator veli palatini. Along the midline, the musculus uvulae blends with its partner on the other side.


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Anatomy_Gray. The musculus uvulae elevates and retracts the uvula. This action thickens the central part of the soft palate and helps the levator veli palatini muscles close the pharyngeal isthmus between the nasopharynx and oropharynx. The musculus uvulae is innervated by the vagus nerve [X] through the pharyngeal branch to the pharyngeal plexus. Arteries of the palate include the greater palatine branch of the maxillary artery, the ascending palatine branch of the facial artery, and the palatine branch of the ascending pharyngeal artery. The maxillary, facial, and ascending pharyngeal arteries are all branches that arise in the neck from the external carotid artery (Fig. 8.273).


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Anatomy_Gray. The ascending palatine artery of the facial artery ascends along the external surface of the pharynx. The palatine branch loops medially over the top of the superior constrictor muscle of the pharynx to penetrate the pharyngeal fascia with the levator veli palatini muscle and follow the levator veli palatini to the soft palate. The palatine branch of the ascending pharyngeal artery follows the same course as the palatine branch of the ascending palatine artery from the facial artery and may replace the vessel.


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Anatomy_Gray. The palatine branch of the ascending pharyngeal artery follows the same course as the palatine branch of the ascending palatine artery from the facial artery and may replace the vessel. The greater palatine artery originates from the maxillary artery in the pterygopalatine fossa. It descends into the palatine canal where it gives origin to a small lesser palatine branch, and then continues through the greater palatine foramen onto the inferior surface of the hard palate (Fig. 8.274). The greater palatine artery passes forward on the hard palate and then leaves the palate superiorly through the incisive canal to enter the medial wall of the nasal cavity where it terminates. The greater palatine artery is the major artery of the hard palate. It also supplies palatal gingiva. The lesser palatine branch passes through the lesser palatine foramen just posterior to the greater palatine foramen, and contributes to the vascular supply of the soft palate.


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Anatomy_Gray. Veins from the palate generally follow the arteries and ultimately drain into the pterygoid plexus of veins in the infratemporal fossa (Fig. 8.275; also see pp. 980–981), or into a network of veins associated with the palatine tonsil, which drain into the pharyngeal plexus of veins or directly into the facial vein. Lymphatic vessels from the palate drain into deep cervical nodes (Fig. 8.275). The palate is supplied by the greater and lesser palatine nerves and the nasopalatine nerve (Figs. 8.274 and 8.276). originate in the pterygopalatine fossa from the maxillary nerve [V2]. palate) fibers from a branch of the facial nerve [VII] join the nerves in the pterygopalatine fossa, as do the sympathetics (mainly to blood vessels) ultimately derived from the T1 spinal cord level. The greater and lesser palatine nerves descend through the pterygopalatine fossa and palatine canal to reach the palate (Fig. 8.276):


Anatomy_Gray

Anatomy_Gray. The greater and lesser palatine nerves descend through the pterygopalatine fossa and palatine canal to reach the palate (Fig. 8.276): The greater palatine nerve travels through the greater palatine foramen and turns anteriorly to supply the hard palate and gingiva as far as the first premolar. The lesser palatine nerve passes posteromedially to supply the soft palate. The nasopalatine nerve also originates in the pterygopalatine fossa, but passes medially into the nasal cavity. It continues medially over the roof of the nasal cavity to reach the medial wall, then anteriorly and obliquely down the wall to reach the incisive canal in the anterior floor, and descends through the incisive canal and fossa to reach the inferior surface of the hard palate (Fig. 8.276). The nasopalatine nerve supplies gingiva and mucosa adjacent to the incisors and canine.


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Anatomy_Gray. The nasopalatine nerve supplies gingiva and mucosa adjacent to the incisors and canine. The oral fissure is the slit-like opening between the lips that connects the oral vestibule to the outside (Fig. 8.277). It can be opened and closed, and altered in shape by the movements of the muscles of facial expression associated with the lips and surrounding regions, and by movements of the lower jaw (mandible). The lips are entirely composed of soft tissues (Fig. 8.277B). They are lined internally by oral mucosa and covered externally by skin. Externally, there is an area of transition from the thicker skin that covers the face to the thinner skin that overlies the margins of the lips and continues as oral mucosa onto the deep surfaces of the lips. Blood vessels are closer to the surface in areas where the skin is thin and as a consequence there is a vermilion border that covers the margins of the lips.


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Anatomy_Gray. Blood vessels are closer to the surface in areas where the skin is thin and as a consequence there is a vermilion border that covers the margins of the lips. The upper lip has a shallow vertical groove on its external surface (the philtrum) sandwiched between two elevated ridges of skin (Fig. 8.277A). The philtrum and ridges are formed embryologically by fusion of the medial nasal processes. On the inner surface of both lips, a fold of mucosa (the median labial frenulum) connects the lip to the adjacent gum. The lips enclose the orbicularis oris muscle, neurovascular tissues, and labial glands (Fig. 8.277B). The small pea-shaped labial glands are between the muscle tissue and the oral mucosa and open into the oral vestibule.


Anatomy_Gray

Anatomy_Gray. A number of muscles of facial expression control the shape and size of the oral fissure. The most important of these is the orbicularis oris muscle, which encircles the orifice and acts as a sphincter. A number of other muscles of facial expression blend into the orbicularis oris or other tissues of the lips and open or adjust the contours of the oral fissure. These include the buccinator, levator labii superioris, zygomaticus major and minor, levator anguli oris, depressor labii inferioris, depressor anguli oris, and platysma (see pp. 897–899). The oropharyngeal isthmus is the opening between the oral cavity and the oropharynx (see Fig. 8.271). It is formed: laterally by the palatoglossal arches; superiorly by the soft palate; and inferiorly by the sulcus terminalis of the tongue that divides the oral surface of the tongue (anterior two-thirds) from the pharyngeal surface (posterior one-third).


Anatomy_Gray

Anatomy_Gray. The oropharyngeal isthmus can be closed by elevation of the posterior aspect of the tongue, depression of the palate, and medial movement of the palatoglossal arches toward the midline. Medial movement of the palatopharyngeal arches medial and posterior to the palatoglossal arches is also involved in closing the oropharyngeal isthmus. By closing the oropharyngeal isthmus, food or liquid can be held in the oral cavity while breathing. The teeth are attached to sockets (alveoli) in two elevated arches of bone on the mandible below and the maxillae above (alveolar arches). If the teeth are removed, the alveolar bone is resorbed and the arches disappear. The gingivae (gums) are specialized regions of the oral mucosa that surround the teeth and cover adjacent regions of the alveolar bone. The different types of teeth are distinguished on the basis of morphology, position, and function (Fig. 8.278A).


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Anatomy_Gray. The different types of teeth are distinguished on the basis of morphology, position, and function (Fig. 8.278A). In adults, there are 32 teeth, 16 in the upper jaw and 16 in the lower jaw. On each side in both maxillary and mandibular arches are two incisor, one canine, two premolar, and three molar teeth. The incisor teeth are the “front teeth” and have one root and a chisel-shaped crown, which “cuts.” The canine teeth are posterior to the incisors, are the longest teeth, have a crown with a single pointed cusp, and “grasp.” The premolar teeth (bicuspids) have a crown with two pointed cusps, one on the buccal (cheek) side of the tooth and the other on the lingual (tongue) or palatal (palate) side, generally have one root (but the upper first premolar next to the canine may have two), and “grind.” The molar teeth are behind the premolar teeth, have three roots and crowns with three to five cusps, and “grind.”


Anatomy_Gray

Anatomy_Gray. The molar teeth are behind the premolar teeth, have three roots and crowns with three to five cusps, and “grind.” Two successive sets of teeth develop in humans, deciduous teeth (“baby” teeth) (Fig. 8.278B) and permanent teeth (“adult” teeth). The deciduous teeth emerge from the gingivae at between six months and two years of age. Permanent teeth begin to emerge and replace the deciduous teeth at around age six years, and can continue to emerge into adulthood. The 20 deciduous teeth consist of two incisor, one canine, and two molar teeth on each side of the upper and lower jaws. These teeth are replaced by the incisor, canine, and premolar teeth of the permanent teeth. The permanent molar teeth erupt posterior to the deciduous molars and require the jaws to elongate forward to accommodate them. All teeth are supplied by vessels that branch either directly or indirectly from the maxillary artery (Fig. 8.279).


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Anatomy_Gray. All teeth are supplied by vessels that branch either directly or indirectly from the maxillary artery (Fig. 8.279). All lower teeth are supplied by the inferior alveolar artery, which originates from the maxillary artery in the infratemporal fossa. The vessel enters the mandibular canal of the mandible, passes anteriorly in bone supplying vessels to the more posterior teeth, and divides opposite the first premolar into incisor and mental branches. The mental branch leaves the mental foramen to supply the chin, while the incisor branch continues in bone to supply the anterior teeth and adjacent structures. All upper teeth are supplied by anterior and posterior superior alveolar arteries.


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Anatomy_Gray. All upper teeth are supplied by anterior and posterior superior alveolar arteries. The posterior superior alveolar artery originates from the maxillary artery just after the maxillary artery enters the pterygopalatine fossa and it leaves the fossa through the pterygomaxillary fissure. It descends on the posterolateral surface of the maxilla, branches, and enters small canals in the bone to supply the molar and premolar teeth. The anterior superior alveolar artery originates from the infra-orbital artery, which arises from the maxillary artery in the pterygopalatine fossa. The infra-orbital artery leaves the pterygopalatine fossa through the inferior orbital fissure and enters the inferior orbital groove and canal in the floor of the orbit. The anterior superior alveolar artery originates from the infra-orbital artery in the infra-orbital canal. It passes through bone and branches to supply the incisor and canine teeth.


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Anatomy_Gray. The gingivae are supplied by multiple vessels and the source depends on which side of each tooth the gingiva is—the side facing the oral vestibule or cheek (vestibular or buccal side), or the side facing the tongue or palate (lingual or palatal side): Buccal gingiva of the lower teeth is supplied by branches from the inferior alveolar artery, whereas the lingual side is supplied by branches from the lingual artery of the tongue. Buccal gingiva of the upper teeth is supplied by branches of the anterior and posterior superior alveolar arteries. Palatal gingiva is supplied by branches from the nasopalatine (incisor and canine teeth) and greater palatine (premolar and molar teeth) arteries. Veins from the upper and lower teeth generally follow the arteries (Fig. 8.279).


Anatomy_Gray

Anatomy_Gray. Veins from the upper and lower teeth generally follow the arteries (Fig. 8.279). Inferior alveolar veins from the lower teeth, and superior alveolar veins from the upper teeth drain mainly into the pterygoid plexus of veins in the infratemporal fossa, although some drainage from the anterior teeth may be via tributaries of the facial vein. The pterygoid plexus drains mainly into the maxillary vein and ultimately into the retromandibular vein and jugular system of veins. In addition, small communicating vessels pass superiorly, from the plexus, and pass through small emissary foramina in the base of the skull to connect with the cavernous sinus in the cranial cavity. Infection originating in the teeth can track into the cranial cavity through these small emissary veins. Venous drainage from the teeth can also be via vessels that pass through the mental foramen to connect with the facial vein.


Anatomy_Gray

Anatomy_Gray. Venous drainage from the teeth can also be via vessels that pass through the mental foramen to connect with the facial vein. Veins from the gingivae also follow the arteries and ultimately drain into the facial vein or into the pterygoid plexus of veins. Lymphatic vessels from the teeth and gingivae drain mainly into submandibular, submental, and deep cervical nodes (Fig. 8.280). All nerves that innervate the teeth and gingivae are branches of the trigeminal nerve [V] (Figs. 8.281 and 8.282). The lower teeth are all innervated by branches from the inferior alveolar nerve, which originates in the infratemporal fossa from the mandibular nerve [V3] (Figs. 8.281 and 8.282). The inferior alveolar nerve and its accompanying vessels enter the mandibular foramen on the medial surface of the ramus of the mandible and travel anteriorly through the bone in the mandibular canal. Branches to the back teeth originate directly from the inferior alveolar nerve.


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Anatomy_Gray. Adjacent to the first premolar tooth, the inferior alveolar nerve divides into incisive and mental branches: The incisive branch innervates the first premolar, the canine, and the incisor teeth, together with the associated vestibular (buccal) gingiva. The mental nerve exits the mandible through the mental foramen and innervates the chin and lower lip. Anterior, middle, and posterior superior All upper teeth are innervated by the anterior, middle, and posterior superior alveolar nerves, which originate directly or indirectly from the maxillary nerve [V2] (Figs. 8.281 and 8.282).


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Anatomy_Gray. All upper teeth are innervated by the anterior, middle, and posterior superior alveolar nerves, which originate directly or indirectly from the maxillary nerve [V2] (Figs. 8.281 and 8.282). The posterior superior alveolar nerve originates directly from the maxillary nerve [V2] in the pterygopalatine fossa, exits the pterygopalatine fossa through the pterygomaxillary fissure, and descends on the posterolateral surface of the maxilla. It enters the maxilla through a small foramen approximately midway between the pterygomaxillary fissure and the last molar tooth, and passes through the bone in the wall of the maxillary sinus. The posterior superior alveolar nerve then innervates the molar teeth through the superior alveolar plexus formed by the posterior, middle, and anterior alveolar nerves. The middle and anterior superior alveolar nerves originate from the infra-orbital branch of the maxillary nerve [V2] in the floor of the orbit:


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Anatomy_Gray. The middle and anterior superior alveolar nerves originate from the infra-orbital branch of the maxillary nerve [V2] in the floor of the orbit: The middle superior alveolar nerve arises from the infra-orbital nerve in the infra-orbital groove, passes through the bone in the lateral wall of the maxillary sinus, and innervates the premolar teeth via the superior alveolar plexus. The anterior superior alveolar nerve originates from the infra-orbital nerve in the infra-orbital canal, passes through the maxilla in the anterior wall of the maxillary sinus, and via the superior alveolar plexus, supplies the canine and incisor teeth. Innervation of gingivae Like the teeth, the gingivae are innervated by nerves that ultimately originate from the trigeminal nerve [V] (Fig. 8.282): Gingiva associated with the upper teeth is innervated by branches derived from the maxillary nerve [V2]. Gingiva associated with the lower teeth is innervated by branches of the mandibular nerve [V3].


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Anatomy_Gray. Gingiva associated with the lower teeth is innervated by branches of the mandibular nerve [V3]. The gingiva on the buccal side of the upper teeth is innervated by the anterior, middle, and superior alveolar nerves, which also innervate the adjacent teeth. Gingiva on the palatal (lingual) side of the same teeth is innervated by the nasopalatine and the greater palatine nerves: The nasopalatine nerve innervates gingiva associated with the incisor and canine teeth. The greater palatine nerve supplies gingiva associated with the remaining teeth. The gingiva associated with the (buccal) side of the mandibular incisor, canine, and premolar teeth is innervated by the mental branch of the inferior alveolar nerve. Gingiva on the buccal side of the mandibular molar teeth is innervated by the buccal nerve, which originates in the infratemporal fossa from the mandibular nerve [V3]. Gingiva adjacent to the lingual surface of all lower teeth is innervated by the lingual nerve.


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Anatomy_Gray. Skeletal landmarks in the head and neck are used for locating major blood vessels, glands, and muscles, and for locating points of access to the airway. Neurological examination of the cranial and upper cervical nerves is carried out by assessing function in the head and neck. In addition, information about the general status of body health can often be obtained by evaluating surface features, the eye and the oral cavity, and the characteristics of speech. Anatomical position of the head The head is in the anatomical position when the inferior margins of the bony orbits and the superior margins of the external acoustic meatuses are in the same horizontal plane (Frankfort plane). In addition to the external acoustic meatus and the bony margin of the orbit, other features that are palpable include the head of the mandible, zygomatic arch, zygomatic bone, mastoid process, and external occipital protuberance (Fig. 8.283).


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Anatomy_Gray. The head of the mandible is anterior to the external ear and behind and inferior to the posterior end of the zygomatic arch. It is best found by opening and closing the jaw and palpating the head of the mandible as it moves forward onto the articular tubercle and then back into the mandibular fossa, respectively. The zygomatic arch extends forward from the region of the temporomandibular joint to the zygomatic bone, which forms a bony prominence lateral to the inferior margin of the anterior opening of the orbit. The mastoid process is a large bony protuberance that is easily palpable posterior to the inferior aspect of the external acoustic meatus. The superior end of the sternocleidomastoid muscle attaches to the mastoid process. The external occipital protuberance is palpable in the midline posteriorly where the contour of the skull curves sharply forward. This landmark marks the point superficially where the back of the neck joins the head.


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Anatomy_Gray. Another clinically useful feature of the head is the vertex. This is the highest point of the head in the anatomical position and marks the approximate point on the scalp where there is a transition from cervical to cranial innervation of the scalp. Anterior to the vertex, the scalp and face are innervated by the trigeminal nerve [V]. Posterior to the vertex, the scalp is innervated by branches from cervical spinal nerves. Visualizing structures at the CIII/CIV and CVI vertebral levels Two vertebral levels in the neck are associated with important anatomical features (Fig. 8.284). The intervertebral disc between the CIII and CIV vertebrae is in the same horizontal plane as the bifurcation of the common carotid artery into the internal and external carotid arteries. This level is approximately at the upper margin of the thyroid cartilage.


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Anatomy_Gray. Vertebral level CVI marks the transition from pharynx to esophagus and larynx to trachea. The CVI vertebral level therefore marks the superior ends of the esophagus and trachea and is approximately at the level of the inferior margin of the cricoid cartilage. How to outline the anterior and posterior triangles of the neck The boundaries of the anterior and posterior triangles on each side of the neck are easily established using readily visible bony and muscular landmarks (Fig. 8.285). The base of each anterior triangle is the inferior margin of the mandible, the anterior margin is the midline of the neck, and the posterior margin is the anterior border of the sternocleidomastoid muscle. The apex of each anterior triangle points inferiorly and is at the suprasternal notch.


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Anatomy_Gray. The anterior triangles are associated with structures such as the airway and digestive tract, and nerves and vessels that pass between the thorax and head. They are also associated with the thyroid and parathyroid glands. The base of each posterior triangle is the middle one-third of the clavicle. The medial margin is the posterior border of the sternocleidomastoid muscle, and the lateral margin is the anterior border of the trapezius muscle. The apex points superiorly and is immediately posteroinferior to the mastoid process. The posterior triangles are associated with nerves and vessels that pass into and out of the upper limbs. How to locate the cricothyroid ligament An important structure to locate in the neck is the median cricothyroid ligament (Fig. 8.286) because artificial penetration of this membrane in emergency situations can provide access to the lower airway when the upper airway above the level of the vocal folds is blocked.


Anatomy_Gray

Anatomy_Gray. The ligament can be easily found using palpable features of the larynx as landmarks. Using a finger to gently feel laryngeal structures in the midline, first find the thyroid notch in the superior margin of the thyroid cartilage and then move the finger inferiorly over the laryngeal prominence and down the anterior surface of the thyroid angle. As the finger crosses the inferior margin of the thyroid cartilage in the midline, a soft depression is felt before the finger slides onto the arch of the cricoid cartilage, which is hard. The soft depression between the lower margin of the thyroid cartilage and the arch of the cricoid is the position of the median cricothyroid ligament. A tube passed through the median cricothyroid ligament enters the airway just inferior to the position of the vocal folds of the larynx.


Anatomy_Gray

Anatomy_Gray. A tube passed through the median cricothyroid ligament enters the airway just inferior to the position of the vocal folds of the larynx. Structures that may occur in or cross the midline between the skin and the median cricothyroid ligament include the pyramidal lobe of the thyroid gland and small vessels, respectively. Inferior to the cricoid cartilage, the upper cartilage of the larynx can sometimes be palpated above the level of the isthmus of the thyroid gland that crosses the trachea anteriorly. The landmarks used for finding the cricothyroid ligament are similar in men and women; however, because the laminae of the thyroid cartilage meet at a more acute angle in men, the structures are more prominent in men than in women. How to find the thyroid gland


Anatomy_Gray

Anatomy_Gray. How to find the thyroid gland The left and right lobes of the thyroid gland are in the anterior triangles in the lower neck on either side of the airway and digestive tract inferior to the position of the oblique line of the thyroid cartilage (Fig. 8.287). In fact, the sternothyroid muscles, which attach superiorly to the oblique lines, lie anterior to the lobes of the thyroid gland and prevent the lobes from moving upward in the neck. The lobes of the thyroid gland can be most easily palpated by finding the thyroid prominence and arch of the cricoid cartilage and then feeling posterolateral to the larynx. The isthmus of the thyroid gland crosses anterior to the upper end of the trachea and can be easily palpated in the midline inferior to the arch of the cricoid.


Anatomy_Gray

Anatomy_Gray. The isthmus of the thyroid gland crosses anterior to the upper end of the trachea and can be easily palpated in the midline inferior to the arch of the cricoid. The presence of the isthmus of the thyroid gland makes palpating the tracheal cartilages difficult in the neck. Also, the presence of the isthmus of the thyroid gland and the associated vessels found in and crossing the midline makes it difficult to artificially enter the airway anteriorly through the trachea. This procedure, a tracheostomy, is a surgical procedure. Estimating the position of the middle The middle meningeal artery (Fig. 8.288) is a branch of the maxillary artery in the infratemporal fossa. It enters the skull through the foramen spinosum and is within the dura mater lining the cranial cavity. In lateral blows to the head the middle meningeal artery can be ruptured, leading to extradural hemorrhage and eventual death if not treated.


Anatomy_Gray

Anatomy_Gray. In lateral blows to the head the middle meningeal artery can be ruptured, leading to extradural hemorrhage and eventual death if not treated. The anterior branch of the middle meningeal artery is the part of the vessel most often torn. This branch is in the temple region of the head, approximately midway between the superior margin of the orbit and the upper part of the external ear in the pterion region. The pterion is a small circular area enclosing the region where the sphenoid, frontal, parietal, and temporal bones of the skull come together. Lateral blows to the head can fracture the internal table of bone of the skull and tear the middle meningeal artery in the outer layer of dura mater that is fused to the cranium. Blood under pulsatile arterial pressure leaks out of the vessel and gradually separates the dura from the bone, forming a progressively larger extradural hematoma. Major features of the face


Anatomy_Gray

Anatomy_Gray. Major features of the face The major features of the face are those related to the anterior openings of the orbit, the nasal cavities, and the oral cavity (Fig. 8.289). The palpebral fissures are between the upper and lower eyelids and can be opened and closed. The oral fissure is the gap between the upper and lower lips and can also be opened and closed. The sphincter muscles of the oral and palpebral fissures are the orbicularis oris and orbicularis oculi muscles, respectively. These muscles are innervated by the facial nerve [VII]. The nares are the anterior apertures of the nasal cavities and are continuously open. The vertical groove in the midline between the external nose and the upper lip is the philtrum.


Anatomy_Gray

Anatomy_Gray. The nares are the anterior apertures of the nasal cavities and are continuously open. The vertical groove in the midline between the external nose and the upper lip is the philtrum. Sensory innervation of the face is carried by the trigeminal nerve [V]. The three divisions of this nerve are represented on the face and can be tested by touching the forehead (the ophthalmic nerve [V1]), the anterior cheek (the maxillary nerve [V2]), and skin over the anterior body of the mandible (the mandibular nerve [V3]). The eye and lacrimal apparatus Major features of the eye include the sclera, cornea, iris, and pupil (Fig. 8.290). The cornea is continuous with the sclera and is the clear circular region of the external covering of the eye through which the pupil and iris are visible. The sclera is not transparent and is normally white.


Anatomy_Gray

Anatomy_Gray. The upper and lower eyelids of each eye enclose between them the palpebral fissure. The eyelids come together at the medial and lateral palpebral commissures on either side of each eye. At the medial side of the palpebral fissure and lateral to the medial palpebral commissure is a small triangular soft tissue structure (the lacrimal lake). The elevated mound of tissue on the medial side of the lacrimal lake is the lacrimal caruncle, and the lateral margin overlying the sclera is the lacrimal fold. The lacrimal apparatus consists of the lacrimal gland and the system of ducts and channels that collects the tears and drain them into the nasal cavity. Tears hydrate and maintain the transparency of the cornea.


Anatomy_Gray

Anatomy_Gray. The lacrimal gland is associated with the upper eyelid and is in a small depression in the lateral roof of the orbit just posterior to the orbital margin. The multiple small ducts of the gland open into the upper margin of the conjunctival sac, which is the thin gap between the deep surface of the eyelid and the cornea. Tears are swept medially over the eye by blinking and are collected in small openings (lacrimal puncta), one on each of the upper and lower eyelids near the lacrimal lake. Each punctum is on a small raised mound of tissue (a lacrimal papilla), and is the opening of a small canal (lacrimal canaliculus) that connects with the lacrimal sac. The lacrimal sac is in the lacrimal fossa on the medial side of the orbit. From the lacrimal sac, tears drain via the nasolacrimal duct into the nasal cavity.


Anatomy_Gray

Anatomy_Gray. The lacrimal sac is in the lacrimal fossa on the medial side of the orbit. From the lacrimal sac, tears drain via the nasolacrimal duct into the nasal cavity. The external ear (Fig. 8.291) consists of the auricle and the external acoustic meatus. The auricle is supported by cartilage and is covered by skin. The external acoustic meatus is near the anterior margin of the auricle. The auricle is characterized by a number of depressions, eminences, and folds. The folded outer margin of the auricle is the helix, which ends inferiorly as the lobule. A smaller fold (the antihelix) parallels the contour of the helix and is separated from it by a depression (the scaphoid fossa). The tragus is a small eminence anteroinferior to the external acoustic meatus. Opposite the tragus and at the end of the antihelix is another eminence (the antitragus). The depression between the tragus and antitragus is the intertragic incisure.


Anatomy_Gray

Anatomy_Gray. The deepest depression (the concha) is bracketed by the antihelix and leads into the external acoustic meatus. Other depressions include the triangular fossa and the cymba conchae. Arterial pulses can be felt at four locations in the head and neck (Fig. 8.292). Carotid pulse—the common or external carotid artery can be palpated in the anterior triangle of the neck. This is one of the strongest pulses in the body. The pulse can be obtained by palpating either the common carotid artery posterolateral to the larynx or the external carotid artery immediately lateral to the pharynx midway between the superior margin of the thyroid cartilage below and the greater horn of the hyoid bone above. Facial pulse—the facial artery can be palpated as it crosses the inferior border of the mandible immediately adjacent to the anterior margin of the masseter muscle.


Anatomy_Gray

Anatomy_Gray. Facial pulse—the facial artery can be palpated as it crosses the inferior border of the mandible immediately adjacent to the anterior margin of the masseter muscle. Temporal pulse—the superficial temporal artery can be palpated anterior to the ear and immediately posterosuperior to the position of the temporomandibular joint. Temporal pulse—the anterior branch of the superficial temporal artery can be palpated posterior to the zygomatic process of the frontal bone as it passes lateral to the temporal fascia and into anterolateral regions of the scalp. In some individuals pulsations of the superficial temporal artery can be seen through the skin. Fig. 8.1 Major compartments of the head and neck. Fig. 8.2 Areas of transition from one compartment of the head to another. Infratemporal fossaLateral plate ofpterygoid processMandibular nerve [V3]Pterygopalatine fossaMaxillary nerve [V2]Ramus of mandible Fig. 8.3 Muscles of the face. Fig. 8.4 Boundaries of the neck.


Anatomy_Gray

Anatomy_Gray. Infratemporal fossaLateral plate ofpterygoid processMandibular nerve [V3]Pterygopalatine fossaMaxillary nerve [V2]Ramus of mandible Fig. 8.3 Muscles of the face. Fig. 8.4 Boundaries of the neck. Vertebra CVIIMandibleMastoid processSuperior nuchal lineAcromionManubrium of sternumClavicle Fig. 8.5 Major compartments of the neck. Fig. 8.6 Specialized structures of the neck. A. Conceptual view. B. Anatomical view. Fig. 8.7 Skull. A. Bones. B. Sutures. C. Fontanelles and lambdoid suture. Fig. 8.8 Cervical vertebrae. A. Typical features. B. Atlas—vertebra CI (superior view). C. Axis—vertebra CII (anterior view). D. Atlas and axis (anterolateral view). E. Atlanto-occipital joint (posterior view).


Anatomy_Gray

Anatomy_Gray. Foramen transversariumAnterior tuberclePosterior tubercleArchSuperior articular facetBodyTransverse processSpinous processDensAnterior archArticular facetfor densLateral massSuperior articular surface (for occipital condyle)Posterior archBodyAtlas (CI)Axis (CII)Articular facetfor densABCDForamenmagnumOccipital condyleOccipital boneApical ligamentof densSuperior longitudinal bandof cruciform ligamentInferior longitudinal bandof cruciform ligamentTransverseligament of atlasAlar ligamentsETectorial membrane (upper partof posterior longitudinal ligament)Posteriorlongitudinalligament Fig. 8.9 Hyoid. A. Bone. B. Attachments. ABLesser hornGreater hornBody of hyoid boneFloor of mouth (mylohyoid muscle)Thyrohyoid membraneStylohyoid ligamentMiddle pharyngeal constrictor muscleInferior pharyngeal constrictor muscleEpiglottis Fig. 8.10 Soft palate. A. Position. B. Muscles. Fig. 8.11 Superior thoracic aperture and axillary inlets. Fig. 8.12 Important vertebral levels—CIII/CIV and CV/CVI.


Anatomy_Gray

Anatomy_Gray. Fig. 8.10 Soft palate. A. Position. B. Muscles. Fig. 8.11 Superior thoracic aperture and axillary inlets. Fig. 8.12 Important vertebral levels—CIII/CIV and CV/CVI. Fig. 8.13 Larynx and associated structures in the neck. Fig. 8.14 Cranial nerves and parasympathetic innervation. Fig. 8.15 Cervical nerves. A. Structure. B. Dermatomes. Phrenic nerveBrachial plexus(C5 to T1)Cervical plexus(C1 to C4)Cutaneous nervesAnsa cervicalis tostrap musclesAC3C4C2C2C3C4Ophthalmic nerve [V1]Trigeminal nerve [V]Maxillary nerve [V2]Mandibular nerve [V3]Anterior rami (C2 to C4) ClavicleAcromionPosterior rami (C2 to C4)External occipital protuberanceB Fig. 8.16 Larynx, soft palate, epiglottis, and oropharyngeal isthmus. A. Overall design. B. Normal breathing. C. Breathing with food or liquid in the oral cavity. D. Swallowing. E. In a newborn child.


Anatomy_Gray

Anatomy_Gray. B. Normal breathing. C. Breathing with food or liquid in the oral cavity. D. Swallowing. E. In a newborn child. Soft palate(opens and closesoropharyngeal isthmus)Cranial cavityEarsChoanaeNasopharynxCVI vertebral levelPharynxEsophagusScapulaAxillary inletClavicleSuperior thoracic aperture(thoracic inlet)Manubrium of sternumTracheaVocal folds(together with other soft tissuestructures open and closecavity of larynx)Epiglottis(opens and closes laryngeal inlet)Oropharyngeal isthmusOral cavityNasal cavitiesOrbitsARib IVertebra TIOropharynxLaryngopharynxLaryngeal inletLarynx Laryngeal inletand laryngealcavity openBack oftongue elevated,palate depressedOropharyngealisthmus closedLarynx andhyoid pulledup and forwardresulting in openingthe esophagusEpiglottisclosed overlaryngeal inletOropharyngealisthmus openOpening between nasal andoral parts of pharynx closedby soft palateSoft palatein neutral positionMilk pathwayTracheaNasal cavityEEsophagusSoft palateLaryngealinletBCD


Anatomy_Gray

Anatomy_Gray. Fig. 8.17 Anterior and posterior triangles of neck. Fig. 8.18 Anterior view of the skull. GlabellaNasal boneFrontal boneSuperciliary archSupra-orbital notch(foramen)Zygomatic process(of frontal bone)Zygomatic boneFrontal process (of maxilla)Infra-orbital foramenInferior nasal conchaMaxillaOblique lineMandibleMental foramenMental tubercleMental protuberanceAngle of mandibleAlveolar part of mandibleZygomatic process (of maxilla)NasionNasal crestPiriform apertureAlveolar processRamus of mandibleBody of mandibleAnterior nasal spine Fig. 8.19 Lateral view of the skull.


Anatomy_Gray

Anatomy_Gray. Fig. 8.19 Lateral view of the skull. Sphenoparietal sutureCoronal sutureFrontal bonePterionSphenosquamous sutureGreater wing(of sphenoid bone)ZygomaticofacialforamenZygomatic boneMaxillaMental foramenBody of mandibleTemporal process (of zygomatic bone)Alveolar part(of mandible)Condylar processAngleZygomatic process (of temporal bone)Coronoid process Ramus of mandibleStyloid processMastoid processTympanic part (of temporal bone)Mastoid part of temporal boneOccipitomastoidsutureOccipital boneAsterionLambdoidsutureParietomastoidsutureParietal boneSquamous sutureSquamous part (of temporal bone)Nasal boneLacrimal boneZygomaticotemporalforamen(on deep surface ofzygomatic bone) Fig. 8.20 Posterior view of the skull. Fig. 8.21 Superior view of the skull. Fig. 8.22 Calvaria. Fig. 8.23 Inferior view of the skull.


Anatomy_Gray

Anatomy_Gray. Fig. 8.20 Posterior view of the skull. Fig. 8.21 Superior view of the skull. Fig. 8.22 Calvaria. Fig. 8.23 Inferior view of the skull. Incisive fossaHard palate (maxilla)Hard palate (palatine bone)Greater palatine foramenHamulusLesser palatine foramenLateral plate of pterygoidprocessMedial plate of pterygoidprocessVomerBody of sphenoidArticular tubercleMandibular fossaForamen ovaleForamen spinosumPetrous part oftemporal boneSquamous part oftemporal boneStyloid processStylomastoid foramenJugular foramenCarotid canalInferior nuchal lineOccipital condyleExternal occipital protuberanceSuperior nuchal lineExternal occipital crestForamen magnumPharyngeal tubercleHypoglossal canalMastoid processMastoid notchBasilar part of occipital boneForamen lacerumGroove for auditory tubeOpening of pterygoid canalPterygoid processScaphoid fossaPterygoid fossaGreater wing (of sphenoid bone)Posterior nasal aperture (choana)Pyramidal process of palatine boneAlveolar archPosterior nasal spine


Anatomy_Gray

Anatomy_Gray. Fig. 8.24 Roof of the cranial cavity. Frontal boneFrontal crestGroove for superiorsagittal sinusBregmaGranular foveolaeSagittal sutureLambdoid sutureOccipital boneLambdaParietal boneGrooves for middlemeningeal arteryCoronal sutureGroove for anterior branch of middle meningeal artery Fig. 8.25 Anterior cranial fossa. Foramen cecumForamina of cribriform plateBody of (sphenoid)Frontal crestOrbital part (of frontal bone)Crista galliCribriform plate (of ethmoid bone)Lesser wing (of sphenoid)Anterior clinoid process Fig. 8.26 Middle cranial fossa. Optic canalSuperior orbital fissureGreater wing (of sphenoid)Foramen rotundumGroove for middlemeningeal arteryForamen ovaleForamen spinosumForamen lacerumTegmen tympaniDorsum sellaeMiddle clinoid processPrechiasmatic sulcusTuberculum sellaeHypophyseal fossaPosterior clinoid processGroove and hiatus for lesser petrosal nerveGroove and hiatus for greater petrosal nerveArcuate eminenceTrigeminal impressionOpening of carotid canal


Anatomy_Gray

Anatomy_Gray. Fig. 8.27 Posterior cranial fossa. Superior border of petrous part of temporal boneInternal acoustic meatusJugular foramenHypoglossal canalForamen magnumClivusJugular tubercleGroove for sigmoid sinusGroove for inferior petrosal sinusGroove for transverse sinusInternal occipital crestInternal occipital protuberance Fig. 8.28 Summary of foramina and fissures through which major structures enter and leave the cranial cavity. A. Floor of cranial cavity. Also indicated are the regions between which each foramen or fissure communicates. B. Inferior aspect of cranium.


Anatomy_Gray

Anatomy_Gray. Foramen ovale:• [V3] Mandibular division of [V] (trigeminal nerve)Jugular foramen:• [IX] Glossopharyngeal nerve• [X] Vagus nerve• [XI] Accessory nerve• Internal jugular veinForamen magnum:• Spinal cord• Vertebral arteries Roots of accessory nerve [XI] pass from upper region of spinal cord through the foramen magnum into the cranial cavity and then leave the cranial cavity through the jugular foramenForamen spinosum:• Middle meningeal arteryStylomastoid foramen:• [VII] Facial nerveCarotid canal:• Internal carotid arteryHypoglossal canal:• [XII] Hypoglossal nerveCribriform plate: (anterior cranial fossa/nasal cavity)• [I] Olfactory nerves Optic canal:(middle cranial fossa/orbit)• [II] Optic nerve• Ophthalmic arterySuperior orbital fissure:(middle cranial fossa/orbit)• [V1] Ophthalmic division of [V] (trigeminal nerve)• [III] Oculomotor nerve• [IV] Trochlear nerve• [VI] Abducent nerve• Superior ophthalmic veinForamen rotundum:(middle cranial fossa/pterygopalatine


Anatomy_Gray

Anatomy_Gray. [V1] Ophthalmic division of [V] (trigeminal nerve)• [III] Oculomotor nerve• [IV] Trochlear nerve• [VI] Abducent nerve• Superior ophthalmic veinForamen rotundum:(middle cranial fossa/pterygopalatine fossa)• [V2] Maxillary division of [V] (trigeminal nerve)Foramen ovale:(middle cranial fossa/infratemporal fossa)• [V3] Mandibular division of [V] (trigeminal nerve)Foramen lacerum(filled with cartilage in life)Jugular foramen:(posterior cranial fossa/neck)• [IX] Glossopharyngeal nerve• [X] Vagus nerve• [XI] Accessory nerve• Internal jugular veinABForamen magnum:(posterior cranial fossa/neck)• Spinal cord• Vertebral arteries Roots of accessory nerve [XI] pass from upper region of spinal cord through the foramen magnum into the cranial cavity and then leave the cranial cavity through the jugular foramen Foramen spinosum:(middle cranial fossa/infratemporal fossa)• Middle meningeal arteryCarotid canal:(middle cranial fossa/neck)• Internal carotid arteryHypoglossal


Anatomy_Gray

Anatomy_Gray. cavity through the jugular foramen Foramen spinosum:(middle cranial fossa/infratemporal fossa)• Middle meningeal arteryCarotid canal:(middle cranial fossa/neck)• Internal carotid arteryHypoglossal canal:(posterior cranial fossa/neck)• [XII] Hypoglossal nerveInternal acoustic meatus:(posterior cranial fossa/ear, and neckvia stylomastoid foramen)• [VII] Facial nerve• [VIII] Vestibulocochlear nerve Labyrnthine artery and vein


Anatomy_Gray

Anatomy_Gray. Fig. 8.29 Skull fracture seen on a skull radiograph (patient in supine position). Fig. 8.30 Ultrasound scans. A. Normal carotid bifurcation. B. Internal carotid artery stenosis. Fig. 8.31 Cranial meninges. A. Superior coronal view. B. Continuity with the spinal meninges. Intracranial venous structure(superior sagittal sinus)Outer periosteal layer of dura materInner meningeal layer of dura materArachnoid materPia materDural partition (falx cerebri)SkullDura materSubarachnoid spaceABMeningeal layer of dura materForamen magnumPeriosteal layer of dura materSkullPeriosteumSpinal dura materSpinal extradural spaceVertebra CI Fig. 8.32 Dural partitions. A. Diagram. B. Dissection. Fig. 8.33 Dural arterial supply.


Anatomy_Gray

Anatomy_Gray. Fig. 8.32 Dural partitions. A. Diagram. B. Dissection. Fig. 8.33 Dural arterial supply. Middle meningeal arteryPosition of pterionMeningeal branch(from occipital artery)Meningeal branch(from vertebral artery)Posterior meningeal artery(from ascendingpharyngeal artery)Meningeal branch(from ascendingpharyngeal artery)Middlemeningeal arteryOccipital arteryAscending pharyngeal arteryExternal carotid arteryMaxillary arteryAnterior meningeal arteries(from ethmoidal arteries) Fig. 8.34 Dural innervation. Ophthalmic divisionof trigeminal nerve[V1]Ophthalmic division of trigeminal nerve [V1](tentorium cerebelli)Maxillary division of trigeminal nerve [V2]Mandibular division of trigeminal nerve [V3]Cervical nervesOphthalmic division oftrigeminal nerve [V1](falx cerebri) Fig. 8.35 Arrangement of the meninges and spaces. Fig. 8.36 Lateral view of the brain. Fig. 8.37 Sagittal section of the brain.


Anatomy_Gray

Anatomy_Gray. Fig. 8.35 Arrangement of the meninges and spaces. Fig. 8.36 Lateral view of the brain. Fig. 8.37 Sagittal section of the brain. Fig. 8.38 Arterial supply to the brain. A. Diagram. B. Magnetic resonance angiogram showing normal carotid and vertebral arteries. C. Enhanced CT scan of carotid vessels. Fig. 8.39 Arteries on the base of the brain. Fig. 8.40 Different imaging modalities used to evaluate a stroke (arrows). A. CT scan. B. T2weighted CT. C. Diffusion-weighted image (DWI). D. Apparent diffusion coefficient image (ADC). Fig. 8.41 Basilar tip aneurysm. A. Three-dimensional cranial cutaway CT scan. B. Magnified view of aneurysm. Fig. 8.42 Anterior communicating aneurysm. A. Left carotid angiogram. B. Left carotid angiogram after embolization. Fig. 8.43 Dural venous sinuses. Fig. 8.44 Veins, meninges, and dural venous sinuses.


Anatomy_Gray

Anatomy_Gray. Fig. 8.43 Dural venous sinuses. Fig. 8.44 Veins, meninges, and dural venous sinuses. Sigmoid sinusInferior sagittal sinusSuperior petrosal sinusBasilar sinusSphenoparietal sinusIntercavernous sinusCavernous sinusOphthalmic veinPterygoid plexus of veinsSuperior petrosal sinusSigmoid sinusInferior petrosal sinusRight transverse sinusGreat cerebral veinConfluence of sinusesStraight sinusSuperior sagittal sinus Fig. 8.45 Cavernous sinuses. Pituitary glandInternal carotid arteryDura materAbducent nerve [VI]Maxillary division of trigeminal nerve [V2]Cavernous (venous) sinusesSphenoidal (paranasal) sinusesOphthalmic division of trigeminal nerve [V1]Trochlear nerve [IV]Oculomotor nerve [III]Diaphragma sellae Fig. 8.46 Lateral view of right cavernous sinus with meningeal layer of dura removed to show contents.


Anatomy_Gray

Anatomy_Gray. Fig. 8.46 Lateral view of right cavernous sinus with meningeal layer of dura removed to show contents. Trochlea nerve [IV]Abducent nerve [VI]Abducent nerve [VI]Oculomotor nerve [III]Oculomotor nerve [III]Infundibulum (stalk of pituitary gland)Anterior clinoid processPosterior clinoid processTentorium cerebelliCut edge of dura materMaxillary nerve [V2]Ophthalmic nerve [V1]Trigeminal ganglionMandibular nerve [V3]Internal carotid arteryOptic nerve [III]Trochlea nerve [IV]Trigeminal nerve [V] Fig. 8.47 Scalp and meninges.


Anatomy_Gray

Anatomy_Gray. Neurovascular bundleV1V2Connected togetheras a structural unitSkinAponeurosisPeriosteum1234BoneOutertableInnertableDiploëAnterior cerebral arteryInternal carotidarteryDiploic veinSuperior sagittal sinusCavernous sinusOptic tractsDuraPeriostial layerMeningeal layerArachnoidSubarachnoid spacePiaEmissary vein: can spread infection fromthe scalp into the cranial cavityConnective tissue:contains majornerves and vesselsof the scalpFractureLoose connective tissue (danger area)• In scalping injuries, this is the layer in which separation occurs.• Infection can easily spread in this layer.• Blunt trauma can result in hemorrhage in this layer (blood can spread forward into the face, resulting in “black eyes”).Rupture of the middle meningeal artery (branches) by fracture of the inner table of boneresults in extradural hematoma. Under pressure, the blood progressively separates dura from the bone.Aneurysm• Ruptured aneurysms of vessels of the cerebral arterial circle hemorrhage directly into


Anatomy_Gray

Anatomy_Gray. in extradural hematoma. Under pressure, the blood progressively separates dura from the bone.Aneurysm• Ruptured aneurysms of vessels of the cerebral arterial circle hemorrhage directly into the subarachnoid space and CSF.Tear to cerebral vein where it crosses dura to enter cranial venous sinus can result in subdural hematoma. The tearseparates a thin layer of meningeal dura from that which remains attached to the periosteal layer. As a result, thehematoma is covered by an inner limiting membrane derived from part of the meningeal dura. ExtraduralhematomaSubdural hematomaVIIVIII1234


Anatomy_Gray

Anatomy_Gray. Fig. 8.48 Extradural hematoma. Axial CT scan of brain. Shift of the falx cerebriExtradural hematoma Fig. 8.49 Chronic (low-density) subdural hematoma. Axial CT scan of brain. Fig. 8.50 Subarachnoid hemorrhage. Axial CT scan of brain. Fig. 8.51 MRI of the brain shows peripherally enhancing tuberculosis lesions in the left temporal lobe and cerebral peduncle. Fig. 8.52 MRI of the brain reveals an incidental Chiari I malformation with herniation of the the cerebellar tonsils through the foramen magnum, giving rise to a cone shape. Fig. 8.53 Cranial nerves exiting the cranial cavity. Fig. 8.54 Cranial nerves on the base of the brain. Fig. 8.56 Facial muscles. Fig. 8.57 Orbital group of facial muscles. Fig. 8.58 Nasal group of facial muscles. Fig. 8.59 Oral group of facial muscles. Fig. 8.60 Buccinator muscle. Fig. 8.61 Auricular muscles. Fig. 8.62 Parotid gland. A. Lateral view. B. Cross section. Fig. 8.63 Tumor in parotid gland. Axial CT scan.


Anatomy_Gray

Anatomy_Gray. Fig. 8.60 Buccinator muscle. Fig. 8.61 Auricular muscles. Fig. 8.62 Parotid gland. A. Lateral view. B. Cross section. Fig. 8.63 Tumor in parotid gland. Axial CT scan. Fig. 8.64 Trigeminal nerve [V] leaving the skull. Fig. 8.65 Cutaneous distribution of the trigeminal nerve [V]. Third occipital(from posterior ramus of C3)Lesser occipitaland great auricular(from cervical plexus)Great auricular nerve(from anterior ramusof C2 and C3)Lesser occipital nerveZygomaticotemporalnervesSupra-orbital nerveAuriculotemporalnerveGreater occipital(from posteriorramus of C2)Supratrochlear nerveOphthalmic nerve [V1]Maxillary nerve [V2]Mandibular nerve [V3]External nasalnerveInfratrochlear nerveZygomaticofacial nerveInfra-orbital nerveBuccal nerveMental nerveTransverse cervical(from anterior ramus of C2 and C3)Transverse cervical Fig. 8.66 Facial nerve [VII] on the face. A. Terminal branches. B. Branches before entering the parotid gland.


Anatomy_Gray

Anatomy_Gray. Fig. 8.66 Facial nerve [VII] on the face. A. Terminal branches. B. Branches before entering the parotid gland. Fig. 8.67 Vasculature of the face. A. Lateral view. B. Branches of the maxillary artery. Fig. 8.68 Intracranial venous connections. Fig. 8.69 Lymphatic drainage of the face. Fig. 8.70 SCALP. Fig. 8.71 Layers of the scalp. Fig. 8.72 Occipitofrontalis muscle. A. Frontal belly. B. Occipital belly. Fig. 8.73 Innervation of the scalp. Fig. 8.74 Vasculature of the scalp. Fig. 8.75 Lymphatic drainage of the scalp. Fig. 8.76 Bones of the orbit. Optic canalFrontal boneEthmoidal foraminaEthmoid boneLacrimalgrooveLacrimal bonePalatine boneMaxillaInferior orbital fissureZygomatic boneGreater wing of sphenoidSuperior orbital fissureLesser wing of sphenoid Fig. 8.77 Eyelids.


Anatomy_Gray

Anatomy_Gray. Fig. 8.77 Eyelids. PeriosteumLevator palpebraesuperioris muscleSuperior conjunctival fornixConjunctivaTarsusSebaceous glandof eyelashTarsal glandOrbital septumSuperior tarsal muscle(smooth muscle)Tendon of levator palpebrae superioris muscleOrbicularis oculimuscle Fig. 8.78 Orbicularis oculi muscle. Fig. 8.79 Orbital septum. PeriosteumOrbital septumOrbital septumPeriosteumTendon of levator palpebrae superioris muscle Fig. 8.80 Tarsal plates. Tendon of levatorpalpebrae superioris muscleSuperior tarsusAnterior lacrimal crestMedial palpebral ligamentInferior tarsusOrbital septumLateral palpebral ligamentOrbital septum Fig. 8.81 Vasculature of the eyelids. Fig. 8.82 Innervation of the eyelids. Fig. 8.83 Lacrimal gland, anterior view. MedialPunctaLacrimal sacNasolacrimal ductLacrimalcanaliculiLacrimal glandTendon of levator palpebrae superioris muscle Fig. 8.84 Lacrimal gland and levator palpebrae superioris.


Anatomy_Gray

Anatomy_Gray. MedialPunctaLacrimal sacNasolacrimal ductLacrimalcanaliculiLacrimal glandTendon of levator palpebrae superioris muscle Fig. 8.84 Lacrimal gland and levator palpebrae superioris. Orbital part of lacrimal glandLacrimal vessels and nervePalpebral part oflacrimal glandTendon oflevator palpebrae superiorisOrbital septum Fig. 8.85 The lacrimal sac. Fig. 8.86 Position of lacrimal sac. Medial palpebral ligamentLacrimal part of orbicularis oculi muscleOrbital septum Posterior lacrimal crestLacrimal sacAnterior lacrimal crestPeriosteumAnteriorPosteriorLateral Fig. 8.87 Innervation of the lacrimal gland.


Anatomy_Gray

Anatomy_Gray. Fig. 8.87 Innervation of the lacrimal gland. Lacrimal nerveLacrimal glandForamen rotundumMaxillary nerve [V2]Pterygoid canalGreater petrosal nerveDeep petrosal nerveNerve ofpterygoid canalSympathetic plexusInternal carotid arteryBranch of zygomaticotemporal nerveZygomatic nervePterygopalatine ganglionSensory fibersSympathetic postganglionic fibersParasympathetic preganglionic fibersParasympathetic postganglionic fibersZygomaticotemporal nerveZygomaticofacial nerve Fig. 8.88 Openings into the bony orbit. Nasolacrimal canalInferior orbital fissure Optic canalFrontal boneEthmoidal foraminaEthmoid boneLacrimal bonePalatine boneMaxillaInfra-orbital grooveZygomatic boneGreater wing of sphenoidSuperior orbital fissureLesser wing of sphenoid Fig. 8.89 Optic canal and superior orbital fissure.