Superficial head of flexor pollicis brevis
Caput superficiale flexoris brevis pollicis
- Related terms: Superficial head; Flexor pollicis brevis: Superficial head
Definition
Superficial head of flexor pollicis brevis | |||
Origin | Flexor retinaculum, trapezium. | ||
Insertion | Base of the proximal phalanx (radial side). | ||
Innervation | Median nerve (recurrent branch) C8, T1 | ||
Action | Flexes the thumb | ||
Antagonist | Extensor pollicis longus muscle, Extensor pollicis brevis muscle | ||
The superficial head of flexor pollicis brevis is the more prominent and lateral of the two portions of this thenar muscle, playing a key role in thumb flexion.
Origin
This head originates from two specific structures: the flexor retinaculum and the tubercle of the trapezium bone.
Course
Its muscle belly extends along the radial (thumb) side of the flexor pollicis longus tendon.
Insertion
As it becomes tendinous, the superficial head inserts onto the radial side of the base of the first (proximal) phalanx of the thumb. Characteristically, a sesamoid bone is embedded within this insertion tendon. While it contributes to a common insertion tendon with the deep head onto the radial side of the proximal phalanx, its distinct origin and course define it.
Innervation
The superficial head of flexor pollicis brevis receives its nerve supply from the recurrent branch of the median nerve.
References
Okwumabua E, Sinkler MA, Bordoni B. Anatomy, Shoulder and Upper Limb, Hand Muscles. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537229/
Loss J, Li ZM. Biometry of thenar muscle origins on the flexor retinaculum. Clin Anat. 2020 Nov;33(8):1176-1180.
