Cut U 1 represents a shoulder-joint amputation, leaving a muscle stump. Cut U 2 shows a shoulder-joint amputation with no stump, and Cut U 3 represents a congenital malformation, the clavicle turned upward at its extremity, affording a knob, or prominence, on which an artificial arm can be securely adjusted.

An artificial arm constructed on the plan of that represented in Cut U 5 is suitable for any of the above cases. The manner in which it is applied and held by body strap is shown in Cut U 4.

Artificial arms are quite necessary in shoulder amputations or malformations; they keep the shoulders in position, restore symmetry to the body, and provide a means for assisting the other arm. By a shrug of the shoulder, the artificial arm is thrown forward, the flexion strap is contracted, and the elbow bends.

Young persons become very dexterous in manipulating arms under these conditions; they have been known to operate them so skillfully that few persons ever suspect the arms to be artificial.

Artificial arms for shoulder-joint amputations are constructed essentially the same as those for amputations between the elbows and shoulders. In addition to the usual stump socket there is a pad that runs well above the top and over the shoulder, resting on the shoulder close to the neck. The stump is held in position by a strap passing around the body under the opposite arm. The elbow joint admits of flexion and extension, and is provided with a locking arrangement that will hold it at right angles.

The attachment can be released by pressure applied to a press-button immediately under the forearm. Cuts U 6 and U 7 represent the arm flexed at right and oblique angles.

Peg arms for shoulder-joint amputations are practically the same as those for above-elbow amputations, and are described in previous chapter.