Lecture 22 – The Vertebral Column (Atlas and Adontoid Process)

We have discussed the hyoid bone before.  It is unique in that is has no bony attachments and is only connected by muscles and ligaments.  It is a u-shaped bone in the anterior portion of the neck.  It is inferior to the mandible and superior to the larynx.  Some people may casually call it the Adam’s apple.

The vertebral column has 33 bones:

7          cervical (neck)

12        thoracic

5          lumbar

5          sacral – immovable

4          coccygeal – immovable  (The sacrum and coccyx are fused.)

From the posterior angle, the spine looks like a column, while laterally it looks like a curve.  From superior to inferior, the curves are as follows:

Cervical curve

Thoracic curve

Lumbar curve

Sacral curve (also called the pelvic curve)

Coccygeal curve

Thoracic vertebrae have processes called ribs.  Thoracic vertebrae also have large spines, which are longer than the adjacent vertebra.  The lumbar vertebrae have the largest bodies because they are weight-bearing.

During a laminectomy, a surgeon will cut through the lamina to perform a tumor.  The thoracic area is a common site for spinal tumors.

C1 – 1st cervical vertebra – also called the atlas.  (The globe holds the world, which is round.  Keep it light-hearted with a silly hint!)  Likewise, the altas holds the skull.  Atlas articulates with the occipital bone and C2.  The occipital bone is immediately superior to the atlas.  The 1st cervical vertebra is a just a ring with no body.  C2 looks slightly different because it has a tooth-like process.  (Adontoid process)  The body of the first is fused to the body of the second, and fits like a puzzle.  C1 and C2’s fusion allows us to turn our heads laterally.

Intervertebral discs or just ‘discs’, as commonly called, are between the vertebrae to cushion them.  The shape of a disc is similar to a donut.  They are composed of rings of fibrocartilage.  The exterior is called annulus fibrosis, and the interior is called nucleus pulposis.  The nucleus pulposis is a soft, gelatinous center.  As a kid, I used to think that a slipped disc actually slipped out of place, creating a bone on bone situation.  In reality, the nucleus of the disc is leaking.  It involves a lot more than the implication that the whole disc slipped out of place.  This condition is exceedingly painful because many nerves are involved.  With degenerative disc disease, the discs take turns slipping.

Now, brace yourself for some really silly business!  I insist on drawing and writing pieces of information the old-fashioned way.  In the next few lectures, I will upload some crude drawings from my many years of notes.  Believe it or not, these drawings still help me to remember the most minute details.  I am excited about providing you with a great laugh!

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Filed under Anatomy Notes, The Skeletal System

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