The palmaris longus is a muscle located in the superficial compartment of the anterior forearm. It is present in about 85% of the population, while the remainder of the population is absent of this muscle. The palmaris longus aids in providing wrist flexion, albeit weakly. This article will provide an overview of the anatomy, attachments, actions, innervation, and blood supply of the palmaris longus.
The palmaris longus is a slender, fusiform muscle and is a flexor in the anterior compartment of the forearm. It is usually considered to be the most medial muscle in the anterior compartment.
The palmaris longus muscle has two attachments, one proximal and one distal. The proximal attachment is the medial epicondyle of the humerus, which inserts into the flexor retinaculum of the wrist laterally.
The main action of the palmaris longus muscle is to provide weak flexion at the wrist. This flexion is usually not strong enough to provide significant movement, and so it is generally considered supplemental to the other muscles of the forearm.
The palmaris longus is innervated by the median nerve, which is a branch of the brachial plexus. The median nerve does go on to innervate other muscles of the forearm, such as the pronator teres, flexor carpi radialis, palmaris brevis, and the flexor digitorum superficialis.
The palmaris longus is supplied by two major arterial sources; the ulnar artery, which is a branch of the brachial artery, and the recurrent branch of the radial artery. Additionally, it is supplied by the anterior interosseous artery, which branches off from the ulnar artery.
The palmaris longus is important in clinical orthopedics. It has been used as a donor tendon for transplant purposes, such as when a patient needs to repair their anterior cruciate ligament (ACL). Since the palmaris longus is absent in some people, this must be taken into consideration when performing any operations in this region.
It is also of clinical significance when performing a diagnosis or assessment of wrist/forearm strength. In this case, the palmaris longus can be used as a reference point or marker. If it is present, it can indicate that the patient has no weakness in the wrist/forearm region; however, if it is absent, it can be an indication of anatomical variation or pathology.
The palmaris longus is a muscle located in the superficial compartment of the anterior forearm that aids in providing weak flexion at the wrist. It has attachments from the medial epicondyle of the humerus to the flexor retinaculum of the wrist, and is innervated by the median nerve. Furthermore, it is supplied by the ulnar artery, the recurrent branch of the radial artery, and the anterior interosseous artery. Clinically, the palmaris longus is important, as it can be used as a donor tendon for transplant purposes, and as a reference point or marker when doing diagnostic assessments of wrist/forearm strength.
