Muscle
Palmaris longus
Variable tendon to the palmar fascia
High-yield
Its tendon lies medial to flexor carpi radialis near the wrist and usually passes superficial to the carpal tunnel roof. Congenital absence is a normal variant.
Overview
When present, this small superficial forearm muscle sends a long tendon over the flexor retinaculum into the palmar aponeurosis. It tightens that sheet of fascia and makes a modest contribution to wrist flexion.
Reference facts
- Origin
- Common flexor origin at the medial epicondyle of the humerus
- Insertion
- Palmar aponeurosis and flexor retinaculum
- Action
- Tightens the palmar aponeurosis and weakly flexes the wrist
- Innervation
- Median nerve, usually described with C7-C8 contributions
- Blood supply
- Branches of the ulnar arterial system
Clinical correlation
Because its usual functional contribution is small, the tendon is often used as a graft. Its presence and anatomy must be checked first; absence rates differ across populations and cannot be summarized by one universal percentage.
Frequently asked questions
What does the palmaris longus do?
The palmaris longus tightens the palmar aponeurosis and weakly flexes the wrist.
What nerve innervates the palmaris longus?
The palmaris longus is innervated by the median nerve, usually described with C7-C8 contributions.
Where does the palmaris longus attach?
The palmaris longus originates from the common flexor origin at the medial epicondyle of the humerus and inserts on the palmar aponeurosis and flexor retinaculum.
What is the blood supply of the palmaris longus?
Branches of the ulnar arterial system.