Oberarm

The Oberarm, or upper arm, is the region of the upper limb between the shoulder and the elbow. It contains the humerus, the main skeletal element, as well as the muscles, nerves, and vessels that supply and move the arm. The upper arm forms a transition between the shoulder girdle and the forearm and serves as a lever system for elbow movements.

Anatomy and compartments: The humerus is the single long bone of the region, articulating proximally with the scapula at the shoulder joint and distally with the forearm bones at the elbow joint. The arm is divided by fascial septa into an anterior (flexor) compartment and a posterior (extensor) compartment. The anterior compartment houses the biceps brachii, brachialis, and coracobrachialis, while the posterior compartment contains the triceps brachii, which extends the elbow. Neurovascular structures run along the arm: the brachial artery and accompanying veins travel medially; the musculocutaneous nerve supplies the anterior compartment, the radial nerve travels in the posterior aspect and supplies the posterior arm, and the median and ulnar nerves follow more distal courses toward the forearm.

Function: The upper arm acts as a conduit and lever for forearm movements. Elbow flexion is primarily produced by the biceps brachii, brachialis, and associated muscles, while elbow extension is produced by the triceps brachii. The arm also provides attachment sites for shoulder and forearm muscles and contributes to the stability of the elbow and shoulder regions during activity.

Clinical notes: Common injuries include humeral shaft fractures and proximal humerus fractures; supracondylar fractures are frequent in children. Nerve or vascular injury can accompany fractures, particularly involving the radial nerve in midshaft injuries.