[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) › Palmaris longus [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # Palmaris longus The palmaris longus is a slender forearm muscle with a long tendon to the palm; it tightens the palm, weakly bends the wrist and is absent in some people. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=palmaris_longus&side=r) Opens in the Durgical app, no sign-up needed. ## What it is A small forearm muscle with a long thin tendon to the palm; missing in some people. ## What it does Tightens the palm and weakly bends the wrist. ## Key points - Absent on one or both sides in a sizeable minority (up to about a quarter in some series; figures vary by population), with little loss of function - First-choice donor tendon for grafts, for example in flexor tendon or elbow ulnar collateral ligament reconstruction - At the wrist its tendon runs superficial to the flexor retinaculum, right over the median nerve, which lies just deep and slightly lateral ## Key facts **Origin** Medial epicondyle **Insertion** Flexor retinaculum and [palmar aponeurosis](https://durgical.com/en/anatomy/palmar-aponeurosis/) **Action** Flexes the wrist; tenses the palmar aponeurosis **Nerve** Median nerve (C7–C8) **Blood supply** Ulnar artery ## Relations **Superficial** [Antebrachial fascia](https://durgical.com/en/anatomy/antebrachial-fascia/) and [skin](https://durgical.com/en/anatomy/skin/); at the wrist it crosses in front of the flexor retinaculum, with the [palmar cutaneous branch of the median nerve](https://durgical.com/en/anatomy/palmar-cutaneous-branch-of-the-median-nerve/) close to its radial side **Deep** [Flexor digitorum superficialis](https://durgical.com/en/anatomy/flexor-digitorum-superficialis/) (FDS) in the forearm; at the wrist, the [median nerve](https://durgical.com/en/anatomy/median-nerve/) **Lateral** [Flexor carpi radialis](https://durgical.com/en/anatomy/flexor-carpi-radialis/) **Medial** [Flexor carpi ulnaris](https://durgical.com/en/anatomy/flexor-carpi-ulnaris/), with the [ulnar artery](https://durgical.com/en/anatomy/ulnar-artery/) and nerve running under cover of it ## How to find it Touching the thumb tip to the little-finger tip while flexing the wrist slightly makes its thin tendon stand out in the middle of the front of the wrist; if no cord appears the muscle is probably absent. ## Examination - Schaeffer test (thumb-to-little-finger opposition with slight wrist flexion): a visible tendon shows the muscle is present; no tendon suggests it is absent, checked before planning a graft ## On imaging Ultrasound confirms whether it is present before it is taken as a tendon graft: in a transverse view at the wrist it is a thin, flat tendon superficial to the flexor retinaculum, just in front of the median nerve. Absence on one or both sides is a normal variant, not a finding. Radiographs do not show it; MRI shows it only incidentally. ## Clinical notes - Harvested through small transverse incisions; when it is absent, the median nerve has been taken by mistake, so the tendon is identified before it is cut - Camitz opponensplasty: the tendon, lengthened with a strip of palmar aponeurosis, is moved to the [abductor pollicis brevis](https://durgical.com/en/anatomy/abductor-pollicis-brevis/) (APB) insertion to restore thumb abduction in severe [carpal tunnel](https://durgical.com/en/anatomy/carpal-tunnel/) syndrome - Can be rerouted to the [extensor pollicis longus](https://durgical.com/en/anatomy/extensor-pollicis-longus/) (EPL) in [radial nerve](https://durgical.com/en/anatomy/radial-nerve/) palsy transfers ## Anatomical variants - One of the most variable muscles: absent, reversed (belly at the wrist, tendon above), duplicated or with a belly in the middle - A reversed or distal belly can present as a wrist mass or compress the median nerve ## Related conditions - [Medial epicondylitis (golfer's elbow)](https://durgical.com/en/conditions/medial-epicondylitis/) ## Test yourself Think of the answer, then tap the question to see it. ## How often is the palmaris longus absent, and what is the functional cost? In a sizeable minority, up to about a quarter in some series (it varies by population), with little loss of function. ## What is the Schaeffer test for the palmaris longus? Thumb-to-little-finger opposition with slight wrist flexion: a visible tendon shows the muscle is present; it is checked before planning a graft. ## Why must the palmaris longus tendon be identified before harvest? The median nerve lies just deep and slightly lateral to it; when the muscle is absent, the nerve has been taken by mistake. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/palmaris-longus/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** musculus palmaris longus TA2 2482 **Official Spanish (DeCS)** Músculo palmar largo **English (TA2)** Palmaris longus ## Related - [Median nerve](https://durgical.com/en/anatomy/median-nerve/) - [Ulnar artery](https://durgical.com/en/anatomy/ulnar-artery/) - [Palmaris longus tendon](https://durgical.com/en/anatomy/palmaris-longus-tendon/) - [Humerus](https://durgical.com/en/anatomy/humerus/) - [Common flexor tendon](https://durgical.com/en/anatomy/common-flexor-tendon/) Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb, Hand Palmaris Tendon](https://www.ncbi.nlm.nih.gov/books/NBK519516/); [Anatomy, Shoulder and Upper Limb, Forearm Compartments](https://www.ncbi.nlm.nih.gov/books/NBK539784/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/palmaris-longus/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/palmaris-longus/