The upper arm, located between the shoulder and elbow joints, primarily contains muscles, nerves, blood vessels, and connective tissues.
Major Muscles of the Upper Arm
The area houses four main muscles:
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Anterior Compartment: Three muscles reside in the front of the upper arm:
- Biceps brachii: A large muscle responsible for flexion (bending) of the elbow and supination (rotating the palm upwards).
- Brachialis: Located beneath the biceps, it's a key elbow flexor.
- Coracobrachialis: A smaller muscle assisting in elbow flexion and shoulder adduction (moving the arm towards the body).
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Posterior Compartment: One prominent muscle is found on the back of the upper arm:
- Triceps brachii: This extends the elbow (straightens the arm). It's easily visible just under the skin's surface.
Other Structures
Besides muscles, the upper arm includes:
- Nerves: These transmit signals to and from the muscles and skin. The ulnar nerve, for example, runs along the inner arm near the elbow, and striking it causes the familiar "funny bone" sensation.
- Blood Vessels: These supply the muscles and tissues with oxygen and nutrients, removing waste products.
- Connective Tissues: These include tendons (attaching muscles to bones) and ligaments (connecting bones to other bones).
The humerus, the long bone of the upper arm, forms the skeletal foundation of this region. Injuries, such as fractures, can occur along the humerus, affecting the muscles and other structures within the arm.
The specific arrangement and size of these structures vary among individuals, but this general description provides a comprehensive overview of the arm's composition between the shoulder and elbow.
