Appendicular Skeleton
The appendicular skeleton consists of the bones of
the upper and lower extremities.
UPPER EXTREMITY.—The upper extremity
consists of the bones of the shoulder, the arm, the
forearm, the wrist, and the hand (figs. 1-21 and 1-22).
The bones that form the framework for the upper
extremities are listed in table 1-1.
Clavicle.—The clavicle (commonly called the
collar bone) lies nearly horizontally above the first rib
and is shaped like a flat letter S. The clavicle is a thin
brace bone that fractures easily. Its inner end is round
and attached to the sternum; its outer end is flattened
and fixed to the scapula. The clavicle forms the
anterior portion of the pectoral girdle (fig. 1-21). The
pectoral girdle is composed of the two clavicles and
two scapulae (shoulder blades). It functions as a
support for the arms and serves as an attachment for
several muscles.
Scapula.—The scapula is a triangular bone that lies
in the upper part of the back on both sides, between the
second and seventh ribs, forming the posterior portion
of the pectoral girdle. Its lateral corner forms part of the
shoulder joint, articulating with the humerus.
Humerus.—The humerus is the longest bone of
the upper extremity and is often called the arm bone
(fig. 1-22). It articulates with the pectoral girdle to
form the shoulder joint, and with the bones of the
1-12
HM3F0120
THORACIC
VERTEBRA
MANUBRIUM
BODY
STERNUM
XIPHOID
PROCESS
RIBS
COSTAL
CARTILAGE
STERNAL
ANGLE
TRUE RIBS
(VERTEBROSTERNAL
RIBS)
FALSE
RIBS
FLOATING RIBS
(VERTEBRAL RIBS)
(VERTEBROCHONDRAL
RIBS)
1
2
3
4
5
6
7
8
9
10
11
12
Figure 1-20.¾Anterior view of thorax,
HM3F0121
STERNAL
END
CLAVICLE
HEAD OF
HUMERUS
STERNUM
COSTAL
CARTILAGE
RIB
SCAPULA
HUMERUS
ULNA
RADIUS
Figure 1-21.—Pectoral girdle.
BONE
COMMON
NAME
TOTAL
NUMBER
IN BODY
clavicle
collar bone
2
scapula
shoulder blade
2
humerus
arm bone
2
radius and ulna
forearm bones
4
carpals
wrist bones
16
metacarpals
bones of the palm
10
phalanges
finger bones
28
Table 1-1.—Bones of the Upper Extremities
