Page 77 - ASOP ROT Study Guide

The shoulder girdle is also partially suspended from the vertebrae of the dorsal spine. The scapula
is held against the ribs by muscles attached to the vertebrae. It is attached at the front, by means
of the clavicle, to the breast bone.

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The skull (also called the cranium) is a bony box composed of flat bones joined by very short and
rather convoluted fibrous joints. It has a large hole (the foramen magnum) at its base for the
spinal cord to pass out and down the tunnel formed in the middle of the vertebral column. The two
eye sockets (orbits) at the front have small holes to allow nerves to pass from the eye ball to the
brain. There are a small number of very small holes around the front of the foramen magnum to
let a few nerves pass through which supply structures around the face and mouth (cranial nerves).
Otherwise the bony box is closed. The result is a very robust container which accommodates and
protects the brain. This is fine for preventing damage from minor knocks and for providing a good
site for the eyes and nose. However if the brain bleeds, following a more serious accident, or
swells for similar reasons or because of a growth then there is little spare room. This means that
the brain is very susceptible to anything that takes up space and causes a rise in pressure within the
skull (rise in intra-cranial pressure). If this happens the blood supply cannot get through to the
brain cells, which are highly dependent on an oxygen supply. Minor reductions in oxygen result in
brain dysfunction such as confusion and eventually loss in consciousness. Severe lack of oxygen
(hypoxia) is rapidly fatal.

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