The spine consists of seven cervical vertebrae (neck), 12 thoracic vertebrae (upper back), five lumbar vertebrae (lower back) and the sacral region. Nerves from the spinal column consist of eight cervical, 12 thoracic, five lumbar and five sacral. Identification of spinal nerves are C1 through C5 for cervical, T1 through T12 for thoracic, L1 through L5 for lumbar and S1 through S5 for sacral.
Numbness
Direct pressure on a nerve because of a herniated disc causes an interruption of the nerve signal to the brain. The Laser Spine Institute states that for cervical nerve involvement, the numbness manifests in the shoulder from the C5 nerve, down the arm to the thumb from the C6 nerve, down the arm to the middle finger from the C7 nerve, and on the outside of the hand from the C8 nerve Numbness from S1 in the lower region affects the outer side of the foot.
Pain
Pain from a herniated disc is a symptom that the associated nerve is pinched. Since the lower back carries the majority of the body's weight and movement, the sciatic nerve is the most common location for pain from a herniated disc. Symptoms include sharp pain in the hip, buttocks or leg, usually on just one side of the body. Expect sciatic pain to increase after sitting or standing and when walking a distance of only a few yards. Pain from a cervical herniated disc includes shoulder pain, neck pain and radiating pain to the forearm and upper arm.
Muscle Weakness
Symptoms of a pinched nerve from a herniated disc include weakness in the affected area. C5 compression symptoms include a weakness in the deltoid muscles. C6 compression affects the strength of the biceps and wrist muscles. Compression from a herniated disc in the lower back presents symptoms of weakness in the leg and/or foot. A pinched nerve at S1 causes weakness in the large muscle in the back of the calf. An L5 pinched nerve can cause ankle weakness.
Cauda Equina Syndrome
The American Academy of Orthopaedic Surgeons states that Cauda equina syndrome is a rare disorder of the bundle of nerve roots at the lower lumbar region of the spine. This area of the spinal column contains nerve roots that control the lower extremities and pelvic organs. Nerve compression from a herniated disc in the lower lumbar region can result in loss of bowel and bladder control, paralysis and loss of sexual sensation. Cauda equina syndrome is a surgical emergency requiring intervention at the onset of symptoms in order to prevent permanent impairment.
