clinically oriented anatomy of human spinal column

vertebral column anatomy

1. The anatomy of the vertebral column (thoracic & lumbar sections/segments of spinal column By Dr. Soran M Kareem

2. Lecture outline Vertebral column composition Normal spinal curvatures Features of typical vertebrae Atypical vertebrae Thoracic vertebrae Lumbar vertebrae Clinical notes

3. Further readings! Anatomical basis of dentistry ; by Bernard Liebgott 3 rd edition chapters , 4 pages; 37, 54 & 87 Figures; 2-2, 2-, 2-4 & 3-5 & 4-1

4. Functions Protects the spinal cord from any mechanical injury by enclosing the cerebrospinal fluid (CSF), spinal cord, and nerve roots. Besides, it also protects various vital internal organs, such as the heart and lungs. Serves as the attachment point for several muscles, tendons, and ligaments, which are essential for body movement. Acts as the body’s central axis, bearing the whole body’s weight. It also supports the head, shoulder, and chest and balances the body by distributing the upper body’s weight to the lower extremities. Allows the spine to twist and bend through the joints between the vertebrae, the intervertebral discs. As a result, the spine can flex (bend forward), extend (bend backward), bend sideways, and rotate to some extent.

5. Spinal Curves The spine in adults has multiple natural curves. With the  thoracic  and  sacrococcygeal curves  being the primary ones. There are two other minor curvatures, the  cervical,  and  lumbar curves , at the respective regions of the spine. These curves provide extra strength to the spine to support and distribute the body’s weight, absorb shock, and allow the spine to bend and move in different directions .

6. Articulations Intervertebral symphyses:   All the vertebral bodies, except C1-C2 and S2-S3, are joined via fibrocartilaginous joints by intervertebral fibrocartilage in the form of intervertebral discs.  Zygapophyseal joints:  Synovial joints formed between the adjacent vertebral arches’ superior and inferior articular facets. Atlanto -occipital joint:  Another synovial joint found between the atlas (C1) and the occipital bone.

7. 1. Cervical Vertebrae There are 7 cervical vertebrae named  C1 -C7, having thin intervertebral discs. The first two, C1 (atlas) and  C2  (axis), have unique anatomy and help in the rotation of the head. The other five vertebrae, C3-C7, share similar anatomical features. They all have a bifid spinous process, transverse foramina, anterior and posterior tubercles, and a triangular vertebral foramen. 2. Thoracic Vertebrae There are 12 medium-sized thoracic vertebrae (T1-T12) in the spine, with thicker intervertebral discs than cervical ones. The size of the individual vertebra increases gradually down the spine. Their job is to articulate with the bony ribs, forming the rib cage or thoracic cage. 3. Lumbar Vertebrae The spine has 5 lumbar vertebrae(L1-L5) supporting the body weight. They have large, kidney-shaped vertebral bodies, triangular vertebral foramen, and short spinous processes. Among all the vertebrae, the L5 lumbar vertebra is the largest. 4. Sacrum It looks like a single bony component composed of 5 fused vertebrae (S1-S5). It looks like an inverted triangle, with the apex pointing inferiorly . 5. Coccyx It is another component of the vertebral column, formed by 4 fused vertebrae (Co1-Co4). It articulates with the apex of the sacrum and is devoid of the vertebral canal.

8. Clinical Relevance: Abnormal Morphology of the Spine There are several clinical syndromes resulting from an abnormal curvature of the spine: Kyphosis  – excessive thoracic curvature, causing a hunchback deformity. Lordosis  – excessive lumbar curvature, causing a swayback deformity. Scoliosis  – lateral curvature of the spine, usually of unknown cause. Cervical spondylosis  – decrease in the size of the intervertebral foramina, usually due to degeneration of the joints of the spine. The smaller size of the intervertebral foramina puts pressure on the exiting nerves, causing pain.

9. Clinical Relevance: Intervertebral Disc Herniation The intervertebral disc is a  fibro-cartilaginous  cylinder that lies between the vertebrae, joining them together. They permit the flexibility of the spine, and act as shock absorbers. In the lumbar and thoracic regions, they are wedge – shaped – supporting the curvature of the spine. Each vertebral disc has  two parts:  the nucleus pulposus  and annulus fibrosus . The annulus fibrosus is tough and collagenous, and it surrounds the jelly-like nucleus pulposus . Herniation of an intervertebral disc occurs when the  nucleus pulposus  ruptures, breaking through the annulus fibrosus . The rupture usually occurs in a posterior-lateral direction, after which the nucleus pulposis can irritate nearby spinal nerves – resulting in a variety of neurological and muscular symptoms.