Thumb

Thenar eminence

· 3 short muscles

· originate from flexor retinaculum

Nerve supply

· from recurrent branch of median n

· very variable

· AbPB

· always from median n

· FPB

· often double (deep part usually from ulnar n)

· may be exclusively ulnar n

· OP

· may be double supply

Abductor pollicis brevis

· most radial

Origin

· flexor retinaculum and tubercle of scaphoid

Insertion

· radial side of base of P1

· radial side of tendon of EPL

Flexor pollicis brevis

· ulnar side of AbPB

Origin

· flexor retinaculum and trapezium

Insertion

· radial sesamoid of thumb

· thus into radial side of base of P1

Opponens pollicis

· deep to other 2

Origin

· flexor retinaculum and adjacent trapezium

Insertion

· radial border of MC

adductor pollicis

· not included as part of thenar eminence

Origin

· transverse head

· whole length of palmar border of 3rd MC

· oblique head

· base of 2nd MC and adjoining trapezoid

· base of 3rd MC and adjoining capitate

Path

· fan-shaped heads converve

Insertion

· transverse head

· ulnar sesamoid of thumb

· thus into ulnar side of base of P1

· symmetrical with FPB

· oblique head

· ulnar tendon of EPL

· symmetrical with AbPB

Nerve supply

· by deep branch of ulnar n

flexor tendon

Pulleys

A1

· narrow sheath over MCP jt

Oblique

· broad sheath over P1

A2

· narrow sheath over IP jt

Flexor pollicis longus

· inserts into distal phalanx

extensor tendons

· one for each joint

· EPL for IP jt (into P2)

· EPB for MCP jt (into P1)

· APL for CMC jt (into MC)

Extensor pollicis longus

· in 3rd extensor compartment

· changes direction at Lister’s tubercle

· reaches ulnar side of EPB

· inserted into base of P2

· no extensor expansion

· tendon stabilised by AbPB and AdP

· AbPB inserts into radial side of tendon

· AdP inserts into ulnar side of tendon

Extensor pollicis brevis

· in 1st extensor compartment

· passes on ulnar side of APL

· converges with and passes along radial side of EPL

· inserted into base of P1

Abductor pollicis longus

· in 1st extensor compartment

· passes with EPB

· inserted into base of MC

Little finger

hypothenar eminence

· similar to thenar eminence

Nerve supply

· from deep branch of ulnar n

Abductor digiti minimi

· most ulnar

Origin

· flexor retinaculum and pisiform

Insertion

· ulnar side of base of P1

· ulnar extensor expansion (lateral slip)

Flexor digiti minimi

Origin

· flexor retinaculum

Insertion

· base of P1

Oppenens digiti minimi

Origin

· flexor retinaculum

· hook of hamate

Insertion

· ulnar border of 5th MC