Thenar Muscles

Description

Schematic drawings of the right hand, palmar view, with the thenar muscles shown in two layers Only bony attachments are shown. Left) Overview of the thenar muscles as visible after skinning the hand. Both heads of the flexor pollicis brevis are covered by the abductor pollicis. Right) Abductor pollicis and opponens pollicis are completely removed. The deep head of Cruveilhier (orange; a.k.a. the deep head of the flexor pollicis brevis) is shown with two heads attaching onto the ulnar and radial side at the base of the proximal phalanx of the thumb. The superficial head of the flexor pollicis brevis (dark orange) has a single head that inserts ulnarward onto the proximal phalanx of the thumb.

Drawing depicting the innervation of the thenar muscles (A: abductor pollicis brevis innervated by the median nerve; B1: flexor pollicis brevis (FPB) muscle superficial head innervated by the median nerve; B2: FPB muscle deep head innervated by the ulnar nerve). * Recurrent motor branch of the median nerve. ** Motor branch from the ulnar nerve to the deep head of the FPB muscle. Ulnar N: ulnar nerve. Median N: median nerve.

Names

• Thenar Muscles
• Thenar Eminence
• Thenar Muscle Group
• Thenar Eminence Muscles
• Intrinsic Thumb Muscles

Muscles

• Abductor pollicis brevis
• Flexor pollicis brevis
• Opponens pollicis
• Adductor pollicis

Actions

• Abduction of thumb
• Flexion of thumb
• Medial rotation of thumb
• Opposition of thumb

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Clinical signficance

• Atrophy of thenar eminence can be a sign of
  • Carpal Tunnel Syndrome
  • Median Nerve Injury

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See also

• Physical Exam Hand
• Hand And Wrist Anatomy
• Hand Pain (Main)
• Wrist Pain (Main)

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