4-29. SKULL
The skull is the skeleton of the head region. It is located on the top of the vertical
vertebral column. It has two major functional subdivisions: the cranium and the facial
(visceral) skeleton.
a. Cranium. The cranium is a spherical container that protects the brain. At the
base of the cranium is a series of openings. Blood vessels and nerves enter and leave
the cranial cavity through these openings.
b. Facial Skeleton. The facial skeleton is also referred to as the visceral skull.
It is attached to the anterior and inferior surfaces of the cranium. It is the skeleton of the
entrances of the respiratory and digestive systems and the orbits containing the eyes.
4-30. NOTE ABOUT THE VERTEBRAL COLUMN
The vertebral column is a series of individual segments, the vertebrae, and one
on top of the other.
4-31. MOTIONS OF THE HEAD
The upper part of the vertebral column, the neck region, and associated muscles
provide the head with its various motions. The upper two vertebrae are specifically
constructed for head motions.
a. The articulation between the occipital base of the skull and the atlas (the first
cervical vertebra) is specially constructed for anterior-posterior motions of the head
("nodding").
b. Between the atlas (the first cervical vertebra) and the axis (the second
cervical vertebra) is a special pivotal-type joint. This joint facilitates rotary (turning)
motions of the head.
4-32. WEIGHT BEARING
a. The vertebral bodies and the associated intervertebral discs are the primary
mechanism for supporting the body weight.
b. In the lumbar and lumbosacral regions, the articular processes of the
vertebrae is also weight bearing. (A bony projection extends upward and another
extends downward from each right and left side of the neural arch of each of these
vertebrae.) These projections are the articular processes. Through them, as well as
through the vertebral bodies and discs, adjacent vertebrae are articulated with each
other.
MD0007
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