Upper limb
Adductor Pollicis, Transverse Head
Musculus adductor pollicis (caput transversum)
- Origin
- Palmar surface of the shaft of the 3rd metacarpal
- Insertion
- Ulnar side of the base of the proximal phalanx of the thumb, via a sesamoid bone
- Function
- Adduction of the thumb; acts as the horizontal, fan-shaped head beneath the oblique head
- Innervation
- Ulnar nerve, deep (motor) branch, C8-T1
- Movement & chain
- Essential agonist for transversal thumb compression against the index finger in key and power pinch.
- Palpation
- Triangular muscle belly easily palpated across the palmar aspect of the 1st web space overlying the 3rd metacarpal.
- Clinical
- Essential for key pinch and power grip between thumb and index finger; paralyzed in high or deep ulnar nerve lesions.
- Segmental innervation
- Ulnar nerve, C8-T1.
- In clinical practice
- Focus on hand function and edema prevention; ensure IV cannulas and splints maintain functional hand position to prevent joint contractures.
- Region in the model
- Upper limb