one bone with
another. The shaft of these bones is cylindrical and hollow, and in
structure, their exterior surface is hard and compact, while the
interior portion is of a reticulated character. The enlarged
extremities of the round bones are more porous than the main shaft.

96. The UPPER EXTREMITIES contain sixty-four bones--the _Scap'u-la_,
(shoulder-blade;) the _Clav'i-cle_, (collar-bone;) the _Hu'mer-us_,
(first bone of the arm;) the _Ul'na_ and _Ra'di-us_, (bones of the
fore-arm;) the _Car'pus_, (wrist;) the _Met-a-car'pus_, (palm of the
hand;) and the _Pha-lan'ges_, (fingers and thumb.)

97. The CLAVICLE is attached, at one extremity, to the sternum; at the
other, it is united to the scapula. It is shaped like the Italic
_[s]_. Its use is to keep the arms from sliding toward the breast.

98. The SCAPULA is situated upon the upper and back part of the chest.
It is flat, thin, and of a triangular form. This bone lies upon and is
retained in its position by muscles. By their contractions it may be
moved in different directions.

99. The HUMERUS is cylindrical, and is joined at the elbow with the
ulna of the fore-arm; at the scapular extremity, it is lodged in the
_glenoid_ cavity, where it is surrounded by a membranous bag, called
the _capsular ligament_.

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95-104. _Give the anatomy of the bones of the upper extremities._ 95.
Give the structure of the bones of the extremities. 96. How many bones
in the upper extremities? Name them. 97. Give the attachments of the
clavicle. What is its use? 98. Describe the scapula. How is it
retained in its position? 99. Describe the humerus.

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[Illustration: Fig. 13. 1, The shaft of the humerus. 2, The large, round
head that is placed in the glenoid cavity. 3, 4, Processes, to which
muscles are attached. 5, A process, called the external elbow. 6, A
process, called the internal elbow. 7, The articulating surface upon
which the ulna rolls.]

[Illustration: Fig. 14. 1, The body of the ulna. 2, The shaft of the
radius. 3, The upper articulation of the radius and ulna. 4, Articulating
cavity, in which the lower extremity of the humerus is placed. 5, Upper
extremity of the ulna, called the olecranon process, which forms the
point of the elbow. 6, Space between the radius and ulna, filled by the
intervening ligament. 7, Styloid process of the ulna. 8, Surface of the
radius and the ulna, where they articulate with the bones