Human Resources

Anatomy Lesson

Different Manual Tasks

Spine Mechanics:

The human spine is comprised of 33 ring-like vertebrae. These bones encase and protect the spinal cord and spinal nerves. Each vertebral body is separated by jelly-like annulus discs cushioning the bones and allowing for movement. When we bend forward, twist or even carry heavy objects, the jelly discs become compressed. Repetitive activities such as these can eventually cause the disc to slip or rupture from between the vertebral bones and compress a spinal nerve or a spinal cord resulting in sharp pain, numbness or weakness. To prevent herniated discs, avoid repetitive lifting with the back (lift using the legs instead), avoid lifting loads exceeding 51 lbs, twisting with heavy loads, repetitive bending forward.


Sciatica is caused by a pinching or compression of the Sciatic nerve, the longest nerve in the body. Symptoms vary depending on where the nerve is pinched, but some include low back pain, numbness or weakness in the trunk, legs, or feet. Treatments for sciatic can involve medications, manual manipulation (chiropractic, massage, acupuncture), surgery, or prescribed exercises.

Sprains and Strains:

Strains are torn or twisted muscles or tendons. Tendons are the tough, fibrous bands of tissue that connect muscle to bone. Sprains involve the stretching or tearing of a ligament. Ligaments are the fibrous bands of tissue that connect two or more bones at a joint and prevent excessive movement of the joint. Symptoms of sprains and strains involve pain that worsens with movement, muscle spasms, decreased range of motion. To prevent strains and sprains, limber up before and after a heavy lift and engage in regular exercise to strengthen muscles.


Nerves are enclosed cable like bundles that relay information throughout the body. Afferent neurons (sensory neurons) relay information from muscles and organs to the brain, and efferent neurons, also called motor neurons, send information from the brain to the rest of the body.

Carpal Tunnel Syndrome:

The carpal tunnel is a sheath in the wrist that encloses flexor tendons and the median nerve. Repeated wrist flexion and extension causes friction between the contents of the tunnel and the sheath. The median nerve and flexor tendons become irritated and inflamed, causing pain, numbness or weakness in the thumb, index, middle and ring finger. To prevent the development of carpal tunnel syndrome, try using an ergonomic computer keyboard and mouse to induce neutral wrist postures, and stretching your wrist and fingers regularly. Treatment for carpal tunnel syndrome includes anti-inflammatory drugs, and possibly surgical release of the transverse carpal ligament.