You’ve probably heard of the muscles in your forearm but do you really know what they do? There are several types of forearm muscles, including the flexor digitorum profundus, teres major, and adductor pollicis longus. Listed below are their definitions and functions. Keep reading to learn about their unique abilities and their connections to the rest of the arm. Getting to know them will make your forearm stronger and more functional.
The teres major
While the teres major is a large muscle, it is rarely considered to be the main source of shoulder pain. It attaches the scapula to the upper arm. When it becomes short, it pulls the arm inward and internally rotates it. It is not part of the rotator cuff, but works in tandem with it. This condition can occur in athletes who lift their arms over their head for extended periods of time.
The adductor pollicis longus
The adductor pollicis longus (APL) is a large muscle in the forearm. It has two superficial parts, one originating from the ulna and the other from the deep fascia of the forearm and radius. Both parts are joined by a small band of connective tissue and terminate in a tendon attached to the first metacarpal. When the APL becomes thick, it is called DeQuervain’s syndrome. The pain increases with movement of the thumb.
The pronator quadratus
The pronator quadratus muscle inserts on the lateral border of the radius and ulna, and is part of the anterior forearm muscle group. It is a deep-seated muscle with parallel running fibers, and receives the final branch of the anterior interosseous nerve. Pronation of the forearm is a characteristic movement of the hand. The muscle is innervated by the median and anterior interosseous nerves.
The flexor digitorum profundus
The flexor digitorum profundis is a fusiform muscle that lies deep in the anterior forearm compartment, just below the flexor digitorum superficialis. Its tendons pass through the carpal tunnel and arise below the wrist joint. When contracted, it produces mass action movement of all four tendons, enabling the fingers to bend, rotate, and extend.
The flexor carpi ulnaris
The FCUM (flexor carpi ulnarius) is a group of superficial musculature of the forearm. Its origins are from the medial epicondyle of the humerus, the olecranon of the ulna, and the upper two-thirds of the dorsal border of the ulna. Its primary functions are wrist flexion and abduction. This muscle also forms the medial border of the cubital fossa, a triangle that surrounds the wrist joint.
The flexor pollicis longus
The flexor pollicis longus is a group of muscles in the anterior compartment of the forearm. They vary in their origin and insertion. The presence of an additional head may lead to anterior interosseous syndrome (AIS). The clinical significance of the abnormality is unclear, but it may result in damage to the surrounding muscles or nerves. Therefore, it is important to identify the cause of the pain before undergoing any treatment.