Palmaris Longus

By Christy Cael
[Functional Anatomy]

The palmaris longus is a relatively slender, superficial muscle located centrally on the anterior forearm. It originates from the common flexor tendon on the medial epicondyle, forming a fusiform muscle belly between the flexor carpi radialis and flexor carpi ulnaris muscles.
The structure of the palmaris longus is highly variable, but most commonly lies superficial to the flexor retinaculum at the wrist. The distal tendon anchors to the flexor retinaculum before fanning out into its insertion on the palmar aponeurosis. Similar to the platysma in the anterior neck, the palmaris longus inserts into soft tissue rather than bone.
Because the palmaris longus is located centrally on the forearm, it does not abduct or adduct the wrist. The efforts of this muscle are focused on flexing the wrist and tensing the palmar fascia, a web of connective tissue that attaches to the base of the second to fifth metacarpals. This structure protects the underlying finger flexor tendons and secures the skin of the palm. When under tension, the palmar fascia helps close the hand. This function contributes to grasping and maintaining grip strength.
Because of its origin on the medial epicondyle of the humerus, the palmaris longus contributes to elbow flexion; however, it is weak in this action compared to the biceps brachii, brachialis, and brachioradialis. It may contribute to joint stability when the elbow is near full extension. This type of motion is utilized in a golf swing, throwing motion, and overhead hitting activities.
Dysfunction of the palmaris longus takes many forms. One such dysfunction is fibrosis of the palmar aponeurosis (Dupuytren’s contracture), which limits mobility when opening the hand and extending the fingers, particularly the fourth and fifth digits. Trigger points in this muscle present as a superficial, prickling sensation in the palm, sometimes extending to the base of the thumb, but not into the fingers. Clients may also report tenderness on the palm and lack of grip strength. Activities that involve grasping implements or applying pressure to the palm (such as walking with a cane) exacerbate these symptoms. Maintaining proper range of motion, tone, and circulation in the palmaris longus and minimizing adhesions in the palmar fascia and aponeurosis may prevent or relieve these issues.

Palpating the Palmaris Longus
Positioning: client supine with forearm supinated.
1. Passively flex the elbow and the wrist to slacken tissue.
2. Locate the medial epicondyle and flexor tendon with the thumb.
3. Move distally and medially onto the muscle belly of the palmaris longus.
4. Resist at the base of the fingers and thumb as the client strongly cups the palm and flexes the wrist to ensure proper location.

Client Homework: Wrist Flexor Stretch
1. Sit or stand with your arm out in front of you, palm up.
2. Keeping your elbow slightly bent, use your other hand to pull your hand and fingers down until you feel a slight stretch in your wrist and arm.
3. Increase the stretch by gradually straightening your elbow.
4. Hold until you feel a release in the arm, wrist, and hand.

Editor’s note: The Client Homework element in Functional Anatomy is intended as a take-home resource for clients experiencing issues with the profiled muscle. The stretches identified in Functional Anatomy should not be performed within massage sessions or progressed by massage therapists, in order to comply with state laws and maintain scope of practice.

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