Upper arm

Arm
The left arm of a human
Details
Artery	Axillary artery
Vein	Axillary vein
Nerve	Brachial plexus
Identifiers
Latin	Brachium
MeSH	D001132
TA	A01.1.00.022
Anatomical terminology []

In human anatomy, the arm is the upper limb of the body, comprising regions between the glenohumeral joint (shoulder joint) and the elbow joint. In common usage the arm extends to the hand. It can be divided into the upper arm, which extends from the shoulder to the elbow, the forearm which extends from the elbow to the hand, and the hand. Anatomically the shoulder girdle with bones and corresponding muscles is by definition a part of the arm. The Latin term brachium may refer to both the arm as a whole or to the upper arm on its own.

The humerus is one of the three long bones of the arm. It joins with the scapula at the shoulder joint and with the other long bones of the arm, the ulna and radius at the elbow joint. The elbow is the hinge joint between the end of the humerus and the ends of the radius and ulna. The humerus cannot be broken easily. Its strength allows it to handle loading up to 300 pounds (140 kg).

The arm is divided by a fascial layer (known as lateral and medial intermuscular septa) separating the muscles into two osteofascial compartments: the anterior and the posterior compartments of the arm. The fascia merges with the periosteum (outer bone layer) of the humerus. The compartments contain muscles which are innervated by the same nerve and perform the same action.

Two other muscles are considered to be partially in the arm: