The Vertebral Column
The vertebral column together with the sternum & ribs constitutes the skeleton of the trunk of the body. It composes 2/5th of the height of the body and has an average length in a male of 71 c.m. and in female 61 c.m. The adult vertebral column contains 26 vertebras. Prior to the fusion of sacral & coccygeal vertebrae, the total number is 33. It is strong and flexible to either direction & rotated on itself. Encloses & protects the spinal cord, supports the head and serves as a point of attachment for the ribs & muscles of the back.
Figure 8- Vertebral Column
General Features of Vertebra
- Each vertebra consists of a body, an arch, and various processes.
- The weight-bearing portion of each vertebra is the body.
- The vertebral arch surrounds a large opening called the vertebral foramen.
- Each vertebral arch consists of two pedicles, which extend from the body to the transverse process of each vertebra.
- Each vertebral arch consists of two laminae (thin plates), which extend from the transverse processes to the spinous process.
- The transverse and spinous processes provide attachment sites for the muscles that move the vertebral column.
- A single spinous process projects dorsally from where the two laminae meet.
- Each vertebra has a superior and an inferior articular process where the vertebrae articulate with each other.
Table – Description and function of bones of the vertebral column
|Bones||Description and function|
|Cervical vertebrae (7)||First (atlas), second (axis), and seventh vertebrae are C1-C7 modified; third through sixth are typical; all contain transverse formina. Atlas supports head, permits “yes” motion of head at joint between skull and atlas; axis Permits “no” motion at joint between axis and atlas.|
|Thoracic vertebrae (12)||Bodies and transverse processes have facets that articulate T1-T12 with ribs; laminae are short, thick, and broad. Articulate with ribs; allow some movement of spine in thoracic area.|
|Lumbar vertebrae (5)||Largest, strongest vertebrae; adapted for attachment of back L1-L5 muscles. Support back muscles; allow forward and backward bending of spine.|
|Sacrum||Wedge-shaped, made up of five fused bodies united by four (5 fused bones) intervertebral disks. Support vertebral column; give strength and stability to pelvis.|
|Coccyx||Triangular tailbone, united with sacrum by intervertebral (3 to 5 fused bones) disk. Vestige of an embryonic tail.|