1. The artificial arm proper, which has the external shape of the natural limb.
2. The worker's arm, a terminal appliance in which outward appearance is not considered.
The considerations as to the arm socket and its attachment by a shoulder cap are the same for the two types of appliance.
Attachment and Arm Socket.—The surface over the acromion and clavicle is the only point from which support can be given to an appliance for an amputation through the arm; the attachment is made by means of a shoulder cap.
The general shape of this shoulder cap and its attachment by means of a strap passed under the opposite axilla are similar to those described for appliances for amputation through the forearm.
Fig. 201.
Fig. 202.
The larger the shoulder cap the more it extends forwards over the anterior wall of the axilla, upwards over the supra clavicular fossa, and backwards over the scapula, the more secure will be the support. The appliance is heavy and has no support other than the axillary strap. The latter has a tendency to ride upwards against the axilla where it exerts a pressure which may be uncomfortable. This may be relieved by attaching a vertical strap which is buttoned to the trouser belt.