Spine Anatomy
Cervical Spine Anatomy
Cervical Bones
The Cervical Spine, often referred to as the neck, is a seven-bone section of vertebral bodies, also called vertebrae, that begins at the skull and ends by the shoulders. Cervical spine bones are numbered 1-7 and in medical terms are designated with a “C” before the number for reference. The C-1 vertebrae is called the atlas bone because it holds the weight of the skull directly. Below the Atlas is the Axis, or C-2 vertebrae, which exists as the first bone in the cervical spine that can turn, allowing for head movement.
Cervical Discs
There is a disc for cushion between each vertebral bone. Each disc has a tough exterior and a jelly like filling that absorbs energy from movement to protect the bones from fracture. Over time these discs are susceptible to damage. As the discs are damaged the support of the bones can be compromised leading to muscle spasms and nerve interference. The jelly like interior of discs if ruptured out is highly inflammatory to nerves and can cause a myriad of orthopedic spine issues.
Cervical Nerves
Every level of vertebrae in the cervical spine has nerve innervations where the spinal cord sends off nerves into the rest of the body. These nerves travel through the foraminal canals to exit the protected layers the spinal cord is nestled in. The cervical nerves innervate into the upper extremities, and therefore spine conditions of the cervical spine may present as radiating pain, numbness, tingling, or weakness in the arms and hands. Bone spurs can form around the facet joints of the spine pushing on the nerves of spine as the innervate off to the rest of the body causing foraminal stenosis.
Thoracic Spine Anatomy
The thoracic spine is the twelve-bone section of the upper back. Above the thoracic spine is the cervical, and below the thoracic is the lumbar spine. The thoracic spine acts as an attachment point for the ribs. Each thoracic vertebra has a disc below and above it to insulate applied energy. Thoracic vertebrae are very protected and rarely break except in high energy impacts such as car wrecks. Nerve impingement of the Thoracic vertebrae is selected against due to it being highly lethal to disrupt key organs such as the heart and lungs, therefore thoracic defects are quite rare in modern populations as without modern medicine it would be unlikely to survive to reproductive age.
Lumbar Spine Anatomy
The lumbar spine is composed of 5 bones that begin after the lowest rib and end at the hip joint. Each level of the lumbar spine has a disc below and above it to help absorb impacts from movement. Nerves in the lumbar spine travel into the lower extremities. When there is disfunction of the lumbar spine weakness, tingling, numbness, searing pain, and loss of strength can appear in the buttock through the toes, depending on which level of the lumbar spine has the issue.
Sacral Spine and Coccyx Anatomy
The Sacral Spine is a fused portion of bones below the lumbar spine, where the spine becomes part of the pelvic girdle. There is a joint in the sacral spine called the S.I. Joint (Sacroiliac Joint) that can become inflamed or arthritic causing up to a third of all lower back pain cases. The Coccyx is often referred to as the tail bone. The sacrum and the coccyx help support the pelvic girdle, protect the lower organs, and support the bodies weight while sitting.
