ulnáris

The ulnaris muscle, also known as the ulnar muscle, is a major forearm muscle located on the medial side of the forearm. It is one of the two muscles that make up the flexor digitorum profundus, the other being the flexor pollicis longus. The ulnaris muscle originates from the medial epicondyle of the humerus and the olecranon process of the ulna. It inserts into the fifth metacarpal bone and the base of the proximal phalanx of the little finger.

The primary action of the ulnaris muscle is to flex the hand at the wrist and to adduct the hand. It also assists in the flexion of the fingers at the metacarpophalangeal joints. The ulnaris muscle is innervated by the ulnar nerve, which arises from the lumbar plexus and the sacral plexus.

The ulnaris muscle is often involved in injuries and conditions such as ulnar nerve entrapment, known as cubital tunnel syndrome, and ulnar collateral ligament injuries. These conditions can lead to symptoms such as pain, weakness, and numbness in the hand and fingers.

In summary, the ulnaris muscle is a crucial muscle in the forearm that plays a significant role in hand and finger movement. Its innervation and function are essential for understanding and treating related injuries and conditions.