28 ANTHROPOLOGY. 
projecting ridge on the articular surface of the rib, and is inserted into - 
cavity in the intervertebral substance into winel the head is Teceiveds 
separates the two synovial membranes. 
In respect to the attachments of the tubercle, the external or pees 
costo-transverse ligament (pl. 125, jig. 2”) arises Afri the posterior surface of 
the extremity of the transverse process; passes outwards and is inserted 
into the rough, non-articular portion of the tubercle of the corresponding 
rib. It exists on all the ribs. The middle costo-transverse ligament (fig. 2*) 
connects the back part of the rib with the front of the corresponding trans- 
verse process. T'he anterior or internal costo-transverse ligament (fig. 2°), 
wanting in the first and twelfth ribs, arises from the lower border of the 
transverse process, and is inserted into the crest on the upper edge of the 
rib beneath. 
The cartilages of the ribs at their costal ends are convex, and are very 
closely united to the concave surfaces in the extremities of the bones by a 
sort of gomphosis. The articular ends of the cartilages are attached to the 
sternum by radiating ligaments, known as anterior, posterior, superior, and 
inferior sterno-costal (pl. 124, fig. 14°, and pl. 125, fig. 3). 
5. SPECIAL ANATOMY OF THE SUPERIOR EXTREMITIES. 
A. Bones of the Superior Extremities, 
Each superior extremity consists of the skoulder, arm, forearm, wrist, 
and hand: the whole limb comprises thirty-two bones, the sesamoid not 
included. The shoulder is composed of the clavicle and scapula; the arm, 
of the humerus; the forearm, of the radius and ulna; the carpus, or wrist, 
of the eight small carpal bones; and the hand, of five metacarpal and four- 
teen phalangeal bones. | 
The clavicle, or collar bone (pl. 122, fig. 3"), is a long bone extending from 
the summit of the sternum obliquely across the first rib, upwards, back- 
wards, and outwards to the acromion process of the scapula. It is curved 
like an italic f, and presents two extremities and a body or shaft. The 
sternal end is a thick, triangular, articulating surface, with the circumference 
roughened for the attachment of hgaments. The body is rounded in the 
middle and flattened towards the extremities. The acromial end is rough 
above and below, and at its termination presents a small articulating sur- 
face for the acromion scapule. The clavicle serves to support the scapula, 
and to prevent it from falling too far forwards or inwards; it serves as a 
fixed point for certain muscles, and it protects the vessels and nerves of the 
upper extremity. 
The scapula, or shoulder blade ( figs. 4°, 10, 11, 12), is situated at the 
upper, lateral, and posterior part of the chest, and extends from the 
second to the seventh rib. It is irregularly flat and triangular, present- 
ing an internal and external surface, three edges, and three angles. The 
internal or anterior surface (jig. 11) is slightly concave, and divided by 
three or four prominent lines into several broad grooves filled by the fasci- 
734 
