(1) The bones of the cranium form a spherical case around the brain. With
age, the sutures between the cranial bones become more solid. The cranium has a
base with several openings for the passage of blood vessels and nerves. The vault (or
calvaria) is made up of flat bones arching over and covering the brain.
(2) The facial skeleton consists of bones which surround the nose and the
mouth. These are mainly flat and irregular bones. Bones of the facial skeleton also
form part of the orbit of each eye.
(3) Certain bones of the skull have air-filled spaces called the paranasal
(4) The upper jaw (maxilla) and the lower jaw (mandible) are parts of the
facial skeleton which surround the mouth.
(5) The hyoid bone is located at the junction between the head and the neck.
It is not articulated directly with the other bones. It is held in place--and moved
around--by groups of muscles above and below. The root of the tongue is attached to
its upper anterior surface. The larynx is suspended from its inferior surface. These
three structures, together, form the hyoid complex. This complex is a functional unit for
4-14. THE APPENDICULAR SKELETON
a. The appendicular skeleton is made up of the skeletal elements of the upper
and lower members (often incorrectly referred to as the "extremities"). These members
are appended (attached) to the axial skeleton.
b. The general pattern of construction of the upper and lower members is the
same as follows:
(1) Girdle. The girdle is the actual attaching part. It attaches (appends) the
limb (the member less the girdle) to the axial skeleton.
(2) Proximal limb segment. The proximal segment of the limb has a single
(3) Middle limb segment. The middle segment of the limb has two long
bones parallel with each other.
(4) Distal limb segment. The distal segment of the limb is made up of many
long and short bones. These bones are arranged into a five-rayed pattern--the digits.
c. See table 4-2 for the main bones of the upper and lower members.
Figures 4-7 through 4-13 give the main characteristics and details of the bones of the