|Origin||Medial epicondyle of humerus (via common flexor tendon)|
|Insertion||Palmar aponeurosis and flexor retinaculum of hand|
|Action||Flexion at the wrist joint
Stabilizes palmar aponeurosis
|Nerve||Median nerve (C7-C8)|
Anterior branch of ulnar recurrent artery
Location & Overview
The palmaris longus muscle is located in the superficial anterior compartment of the forearm and is a narrow muscle which is wider in the middle and narrower at its ends (fusiform shaped). It is located between the flexor carpi radialis muscle and the flexor carpi ulnaris muscle. It is also superficial to the flexor digitorum superficialis and part of the palmaris longus muscle overlaps the median nerve .
The palmaris longus can have variations which differ between individuals. Examples of this are: fusion with another muscle, an additional muscle belly, multiple tendinous insertions, or being entirely absent from one of both arms. Exact amounts of the population missing this muscle vary between studies, but have it has been suggested to be somewhere within the range of 2.5% to 26%. The proportion of people missing this muscle also varies depending on the demographic of population studied (e.g ethnicity or gender)    .
Origin & Insertion
The palmaris longus muscle originates on the medial epicondyle of humerus via the common flexor tendon. The common flexor tendon also serves as an attachment point for the flexor carpi ulnaris, palmaris longus, flexor carpi radialis, pronator teres, and flexor digitorum superficialis. The palmaris longus then inserts at the palmar aponeurosis and flexor retinaculum of the hand. The flexor retinaculum contributes to forming the carpal tunnel  .
The actions of the palmaris longus are to flex the hand at the radiocarpal (wrist) joint and to stabilize the palmar aponeurosis (which can improve the stability of the overlying palmar skin). The contribution of this muscle to flexion is minimal and it is considered just an accessory muscle during wrist flexion .
Blood is supplied to the palmaris longus via the median artery and the anterior branch of ulnar recurrent artery .
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Palmaris Longus Flashcards
|↑1, ↑2, ↑7, ↑11||Olewnik Ł, Wysiadecki G, Polguj M, Podgórski M, Jezierski H, Topol M. Anatomical variations of the palmaris longus muscle including its relation to the median nerve – a proposal for a new classification. BMC Musculoskelet Disord. 2017;18(1):539. Published 2017 Dec 19. doi:10.1186/s12891-017-1901-x|
|↑3||Georgiev GP, Iliev AA, Dimitrova IN, Kotov GN, Malinova LG, Landzhov BV. Palmaris Longus Muscle Variations: Clinical Significance and Proposal of New Classifications. Folia Med (Plovdiv). 2017 Sep 1;59(3):289-297. doi: 10.1515/folmed-2017-0035. PMID: 28976893.|
|↑4, ↑6, ↑8, ↑10, ↑12||Cooper DW, Burns B. Anatomy, Shoulder and Upper Limb, Hand Palmaris Tendon. 2021 Sep 3. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 30137801.|
|↑5||Ioannis D, Anastasios K, Konstantinos N, Lazaros K, Georgios N. Palmaris Longus Muscle’s Prevalence in Different Nations and Interesting Anatomical Variations: Review of the Literature [published correction appears in J Clin Med Res. 2016 Jan;8(1):62]. J Clin Med Res. 2015;7(11):825-830. doi:10.14740/jocmr2243w|
|↑9||Moore KL, Agur AMR, Dalley AF. Clinically Oriented Anatomy. 8th ed. Philadelphia: Lippincot Williams & Wilkins; 2017.|