Palmaris Longus
Forearm · Upper Limb
The Palmaris Longus is found among the Forearm muscles of the Upper Limb. Originating at Medial epicondyle of humerus (common flexor origin), it inserts at Flexor retinaculum and palmar aponeurosis. It is responsible for several movements: Flexion of wrist; tenses palmar aponeurosis. Its nerve supply is the Median nerve (C7, C8).
Origin, Insertion, Action & Nerve
Origin
Medial epicondyle of humerus (common flexor origin)
Insertion
Flexor retinaculum and palmar aponeurosis
Action
Flexion of wrist; tenses palmar aponeurosis
Nerve
Median nerve (C7, C8)
Attachments explained
The Palmaris Longus is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Medial epicondyle of humerus (common flexor origin)
Insertion
Flexor retinaculum and palmar aponeurosis
Action & function
When the Palmaris Longus contracts, it produces the following movements: Flexion of wrist; tenses palmar aponeurosis.
As part of the Forearm group of the Upper Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Palmaris Longus receives its nerve supply from the Median nerve (C7, C8). This nerve carries fibres from spinal segment(s) C7, C8.
Because a muscle can only contract when its nerve is intact, injury to the Median nerve or to its spinal roots (C7, C8) can weaken or paralyse the Palmaris Longus, impairing the movements it normally produces (flexion of wrist). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Palmaris Longus (the OIANS method)
OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Palmaris Longus, work through them in order: picture its origin, trace the muscle to its insertion, reason out the action that shortening between those two points must create, then add the nerve that drives it.
Most students remember the Palmaris Longus fastest by linking its action back to its attachments rather than memorising each fact in isolation. Once the origin and insertion make sense, the action usually follows logically.
Palmaris Longus quick facts
- Region
- Upper Limb
- Group
- Forearm
- Origin
- Medial epicondyle of humerus (common flexor origin)
- Insertion
- Flexor retinaculum and palmar aponeurosis
- Action
- Flexion of wrist; tenses palmar aponeurosis
- Nerve
- Median nerve (C7, C8)
- Spinal roots
- C7, C8
Frequently asked questions
Where is the Palmaris Longus located?
The Palmaris Longus is a muscle of the Forearm group, located in the Upper Limb.
What is the origin of the Palmaris Longus?
Medial epicondyle of humerus (common flexor origin)
What is the insertion of the Palmaris Longus?
Flexor retinaculum and palmar aponeurosis
What movements does the Palmaris Longus produce?
Flexion of wrist; tenses palmar aponeurosis
What nerve supplies the Palmaris Longus?
Median nerve (C7, C8)
Is the Palmaris Longus free to study in OIANS?
Yes. The Palmaris Longus is free in OIANS: its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory, and because it belongs to the Upper Limb it is also covered by the free Quiz and Flashcard decks. The other regions, the "All Muscles" deck, and the Progress and Explore tools are unlocked with a one-time Lifetime purchase.
Related muscles
Study the Palmaris Longus
Test yourself on Upper Limb muscles with interactive quizzes and flashcards in the free OIANS app.
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