Palmaris longus tendon !
The palmaris longus tendon is the thin central tendon at the front of the wrist; it is absent in some people and often used as a tendon graft.
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What it is
A thin tendon in the middle of the front of the wrist, seen when the thumb and little finger touch and the wrist bends; absent in some people.
What it does
A weak wrist flexor that tightens the palm; surgeons often borrow it as a graft.
Key facts
- Attaches
- Superficial to the flexor retinaculum, into the palmar aponeurosis; missing in roughly one person in seven (varies widely between populations)
- Function
- Weak wrist flexor; tenses the palmar aponeurosis; the median nerve lies just deep to it at the wrist; a common tendon graft
- Tight in
- Wrist extension
Relations
- Course
- A short belly in the upper forearm gives a long thin tendon that runs down the middle of the front of the forearm and crosses over the flexor retinaculum into the palmar aponeurosis
- Deep
- Median nerve, just deep and slightly radial at the wrist, then the FDS tendons
- Lateral
- FCR tendon
- Medial
- FDS tendons and, further ulnar, the ulnar artery, the ulnar nerve and the FCU tendon
- Superficial
- Skin and antebrachial fascia; the palmar cutaneous branch of the median nerve runs close beside it at the wrist crease
How to find it
It is the most superficial and central tendon at the front of the wrist, in the middle of the distal crease and on the ulnar side of the FCR. It stands out when the wrist is flexed with the thumb and little finger pinched together.
Examination
- Schaeffer test: the tips of the thumb and little finger are pressed together while the wrist is bent forward; a cord rising in the middle of the wrist shows the tendon is present, its absence suggests agenesis
- Thompson test: a fist is made, the wrist flexed and the thumb pressed over the fingers; a visible tendon confirms it before a graft is planned, but a thin tendon in heavy skin can be missed
On imaging
Ultrasound shows it as a thin superficial tendon in the midline of the wrist, superficial to the flexor retinaculum, with the median nerve just deep to it; it confirms the tendon is present before graft harvest. On axial MRI it sits in the same place. It is not seen on radiographs.
Common problems
- Rarely a problem itself; about 1 in 7 people don't have it.
- Often harvested as a tendon graft (for example for UCL reconstruction), with little loss of function.
How it is diagnosed
Seen by touching the thumb to the little finger and bending the wrist (Schaeffer's test); ultrasound if unsure.
Treatment
- Used as the graft in UCL ('Tommy John') reconstruction.
Clinical notes
- Graft harvest uses one or more small incisions at the wrist; checking that it is present beforehand avoids taking the median nerve instead
- Used as a graft in reconstruction of the elbow's ulnar collateral ligament and in thumb and flexor tendon reconstructions
- A reversed or extra muscle belly at the wrist can look like a soft-tissue mass or compress the median nerve
Anatomical variants
- Absent on one or both sides; one-sided absence is common
- Reversed (belly at the wrist, tendon above) or doubled forms occur
Test yourself
Think of the answer, then tap the question to see it.
What lies just deep to the palmaris longus tendon at the wrist?
The median nerve, just deep and slightly radial; it has been harvested by mistake when the tendon was absent.
How often is the palmaris longus tendon absent?
In roughly one person in seven, varying widely between populations.
Why is the palmaris longus tendon commonly harvested?
It is a common graft for small tendon and ligament reconstructions, such as the elbow's ulnar collateral ligament.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- tendo musculi palmaris longi TA2 2482
- Official Spanish (DeCS)
- Tendón del músculo palmar largo
- English (TA2)
- Palmaris longus tendon
Related
Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Hand Palmaris Tendon; Anatomy, Shoulder and Upper Limb, Forearm Compartments.
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Representative model, for educational purposes only.
