Spine Anatomy Definition List

WORD DEFINITION
Annulus fibrosus Outer fibrous layers of the intervertebral disc consisting of overlapping collagen fibers. Also called ‘annulus’.
Anterior longitudinal ligament A strong ligament running along the front of the spine that binds the vertebrae and vertebral disks together into a columnar unit.
Articular process A bony projection, part of which has a small smooth surface known as a facet. In the spine there are 4 articular processes off the back of each vertebrae, two upper and two lower that comprise the facet joints.
Atlas First cervical vertebra of the spinal column, located just beneath the skull. Supports the head.
Axis Second cervical vertebra of the spinal column, located below the atlas vertebra. Allows rotation of the neck. Has a bony protrusion called the dens, or odontoid process, which projects upward and within the atlas.
Cervical Refers to the neck or cervical curve of the spine; the top most curve that includes the neck area.
Cervical vertebrae The upper 7 vertebral bones of the spinal column that form the neck, and provide and support rotation for the head and neck.
Coccyx The lowest 4 bones of the spinal column that are fused in the shape of a triangle.
Degenerative spondylolisthesis Forward displacement of a vertebra from the vertebra below due to degenerative changes in the facet joints.  A Frequent cause of low back and leg pain.
Dens An element of the “axis” vertebra which projects upward, articulating with the “atlas” vertebra. Also called the odontoid process
Dura mater The outer most and toughest membrane surrounding the brain and continuing as part of the sac surrounding the spinal cord.  Also called the dura.
Epidural injections Technique whereby a liquid mechanism (steroid, anesthetic) is injected clinically into the epidural space surrounding the spinal cord and spinal nerves.
Epidural space Space between the spinal cord and the walls of the vertebral canal, on or over the dura.
Erector spinae muscles The most important extensor muscle group of the back. Responsible for returning the back to an erect position following motion. The erector spinae muscles secondarily contribute to lateral bending, rotation of the spine, and movement of the head. Another name for this muscle group is the sacrospinal muscle group.
External oblique abdominal muscles One of the powerful rotator muscles of the spine whose fibers run obliquely to the long axis of the body. Contribute to spinal movement by compressing the stomach organs and flexing the spine.
Facet joint capsule Collagen membrane that encloses the facet joint.
Facet joints Joints of the spine that connect all of the vertebrae and allow coordinated movement of the vertebral column.
Fibrocartilage tissue A dense strong cartilage found in intervertebral discs, the knee joint, and at the attachments of tendons and ligaments to bone.
Herniated disc A condition where the center (nucleus pulposus) of the intervertebral disc is protruding through the outer fibrous layer (annulus fibrosus) of the disc. A frequent cause of low back and leg pain.  Distinguish from a disc bulge.
Iliocostalis muscle A division of the erector spinae muscle group which help to extend the spine (bend backwards).
Internal oblique abdominal muscles One of the rotator muscles of the spine whose fibers run obliquely to the long axis of the body. Contribute to spinal movement by compressing the stomach organs and flexing the spine.
Interspinous ligament Ligaments that run between adjacent vertebral spines, extending from along the top of one to along the underside of the spine above; posteriorly bind the vertebrae together and limit the movement of the vertebral column.
Intertransverse ligaments Ligaments which travel between the tips of the transverse processes on vertebrae, contribute to spinal stability.
Intervertebral disc joint The articulation between two vertebrae provided by a fibrocartilage disc; joint of the vertebral column.
Laminae Flat pieces of the vertebral arch extending from the vertebral pedicles that form the back wall of the spinal canal.
Latissimus dorsi muscle Muscles that participate in bending forward (flexion), shoulder or head movements, or arm movement.
Ligamenta flava Bands of elastic ligament that connect the laminae and fuse with the facet joint capsules.
Longissimus muscles A division of the erector spinae muscles which helps to extend the spine (bend backwards) and flex it to one side.
Lumbar Refers to the lower back and that area of the spinal column called the ‘lumbar curve’. Consists of 5 vertebrae.
Lumbar vertebrae Have facet joint positions that virtually prevent rotation in the lower back, but they allow for a large amount of forward and backward bending (flexion and extension).
Multifidus muscle A back muscle whose fibers extend to each region of the spine, from sacral to cervical. Contributes to extension and lateral rotation of the spine.
Nucleus pulposus The soft and gelatinous center of an intervertebral disc which has a high water content in younger persons.
Pedicles Short, thick bony structures which project backwards from each side of the vertebral body and are joined by the laminae to complete the back wall of the spinal canal.
Posterior longitudinal ligament A ligament that binds the vertebrae and vertebral disks together into a columnar unit.  Weaker than the anterior longitudinal ligament.
Quadratus lumborum muscle Contributes mainly to lateral bending of the lumbar spine and is well situated for that purpose, spanning from the pelvis and lower lumbar area to the ribs and upper lumbar vertebrae ). Participate in flexion of the vertebral column, shoulder or head movements, or arm movement.
Range of motion The area through which a joint can be freely moved, actively or passively.
Rectus abdominis muscle A muscle that contributes to spinal movement by compressing the stomach organs and flexing the spine.
Regional anesthesia Anesthesia for a select region of the body produced by the injection of anesthesia around the sensory nerves supplying that area.
Sacrum Lowermost portion of the spinal column consisting of 3-5 fused bones, collectively in the shape of a triangle.
Spinal canal The space that houses the spinal cord and spinal nerves throughout the length of the vertebral column. Provides openings for the exit of paired spinal nerves from the spinal cord.
Spinal motion segment A segmental model of spinal function consisting of two adjacent vertebrae, three joints (two posterior facet joints and the intervertebral disk joint), and the associated ligaments.
Spinalis muscles Division of the erector spinae muscles contributing to extension of the spine (bending backwards).
Spinous processes Bony projections directly off the back of the spine that provide attachments for spinal ligaments and muscles; shape varies according to spinal region and function.  Progressively larger towards the lower spine to support the increased weight from above.
Supraspinous ligaments Ligaments that connect the tips of spinous processes and contribute to spinal stability and integrity by limiting the degree of spinal motion during movement.
Thoracic region Pertaining to the chest or the midback region of the spine, known as the thoracic curve and consisting of 12 vertebrae; in-between the cervical and lumbar regions of the spine.
Thoracic vertebrae Twelve vertebrae of the midback that allow significant rotation of the spine. The long spinous processes of these vertebrae (in addition to the rib cage) act to limit the degree of motion in the midback.
Transverse processes Bilateral and broad flat lateral projections from each vertebral body that function as attachments for spinal ligaments and muscles.
Transversospinalis muscles Deep spinal muscles whose subgroups span nearby vertebrae to rotate the head, and also to extend and laterally rotate the spine.
Trapezius muscle Muscle of the upper shoulder that participates in flexion of the vertebral column, and draws the head back and to the side as well as braces the shoulder.
Vertebral arch A partial circle of bone that is connected to the back of the body; it is made up of the pedicles and laminae.
Vertebral body A thick columnar-shaped bone comprising the front of each vertebra.
Vertebral column Main central support of the body consisting of approximately 33 vertebrae, or separate bones connected by muscles, ligaments, and tendons.
Vertebral facet joints Joints of the spine that connect all of the vertebrae and allow coordinated movement of the vertebral column.