A Practical Physiology: A Text-Book for Higher Schools

by Albert F. Blaisdell

10. The tuberosities of the humerus form the convexity of the shoulder. When the arm is raised, the convexity disappears,—there is a slight depression in its place. The head of the bone can be felt by pressing the fingers high up in the axilla.

11. The humerus ends at the elbow in two bony prominences (internal and external condyles). The internal is more prominent. We can always feel the olecranon. Between this bony projection of the ulna and the internal condyle is a deep depression along which runs the ulna nerve (commonly called the “funny” or “crazy” bone).

12. Turn the hand over with the palm upwards, and the edge of the ulna can be felt from the olecranon to the prominent knob (styloid process) at the wrist. Turn the forearm over with the palm down, and the head of the ulna can be plainly felt and seen projecting at the back of the wrist.

13. The upper half of the radius cannot be felt because it is so covered by muscles; the lower half is more accessible to the touch.

14. The three rows of projections called the “knuckles” are formed by the proximal bones of the several joints. Thus the first row is formed by the ends of the metacarpals, the second by the ends of the first phalanges, and the third by the ends of the second phalanges. That is, in all cases the line of the joints is a little in advance of the knuckles and nearer the ends of the fingers.

II. Muscular Landmarks.

1. The position of the sterno-mastoid muscle as an important and interesting landmark of the neck has already been described (p. 70).

2. If the left arm be raised to a vertical position and dropped to a horizontal, somewhat vigorously, the tapering ends of the pectoralis major and the tendons of the biceps and deltoid may be felt by pressing the parts in the axilla between the fingers and thumb of the right hand.

3. The appearance of the biceps as a landmark of the arm has already been described (p. 70). The action of its antagonist, the triceps, may be studied in the same manner.

4. The sartorius is one of the fleshy landmarks of the thigh, as the biceps is of the arm, and the sterno-cleido-mastoid of the neck. Its direction and borders may be easily traced by raising the leg,—a movement which puts the muscle in action.