Textbook Readings:
Wiley: 7.9
Open Stax: 7.3
Libretexts: 6.4
Composed of 33 vertebrae
Divided into 5 regions:
Cervical (C1-C7): 7 vertebrae
Thoracic (T1-T12): 12 vertebrae
Lumbar (L1-L5): 5 vertebrae
Sacral (S1-S5): 5 fused vertebrae
Coccygeal (Co1-Co4): 3–5 fused vertebrae
The spine is not perfectly straight; it has 4 distinct curves:
Cervical Lordosis: inward curve of the cervical spine.
Thoracic Kyphosis: outward curve in the thoracic region.
Lumbar Lordosis: inward curve of the lumbar spine.
Sacral Kyphosis: outward curve of the sacral area.
Primary Curvature (Kyphosis):
Thoracic (2)
Sacral (4)
Secondary Curvature (Lordosis):
Cervical (1): develops as the head is raised.
Lumbar (3): develops when a child begins to walk.
Characteristics:
Boney cage with great flexibility.
Several symphyses (cartilaginous joints) contribute to flexibility.
Contains 23 intervertebral discs.
Points of articulation facilitate movement.
Cervical (C1-C7):
Smaller vertebral body compared to lumbar and thoracic.
Transverse processes: small extensions with foramina for blood vessels.
Thoracic (T1-T12):
Larger and thicker than cervical but smaller than lumbar.
Long spinous processes that project inferiorly.
Articulates with ribs.
Lumbar (L1-L5):
Largest and thickest for vertical weight support.
Short, stubby spinous processes that project posteriorly.
Vertebral Body:
Cylindrical mass on the anterior side:
Cervical: Smallest of the three regions.
Thoracic: Larger than cervical but smaller than lumbar.
Lumbar: Largest to withstand heavier loads (including head & torso).
Vertebral Foramen:
Large triangular opening for spinal cord:
Cervical: Largest of all.
Thoracic: Smaller than cervical, larger than lumbar.
Lumbar: Smallest of the three.
Vertebral Arch:
Protects spinal cord and is formed by:
Pedicles and laminae from each vertebra.
Spinous process projects posteriorly.
Superior Articulating Facet:
Different orientations in each region:
Cervical: Posterosuperior facing, slightly concave.
Thoracic: Posterolateral, flattened surface.
Lumbar: Medial points, convex.
Inferior Articulating Facet:
Different orientations in each region:
Cervical: Anteroinferior facing, flattened surface.
Thoracic: Anteriomedial point.
Lumbar: Lateral facing, concave surface.
Vertebral Notches:
Formed on pedicles, important for spinal nerve passage.
Intervertebral Foramen:
Openings between adjacent vertebrae where spinal nerves exit.
Sacrum:
Composed of 5 fused vertebrae, forms part of the pelvic girdle.
Contains sacral canal, contains remnants of the cauda equina.