Hand

Hand

EXTRINSIC FLEXOR MUSCLES: DIGITS 2-5

Flexor Digitorum Superficialis

• Origin: Common flexor tendon origin (medial humeral epicondyle) & midradius
• Insertion: Volar plate proximal interphalangeal (IP) joints & bases of middle phalanges digits 2-5
• Innervation: Median nerve
• Superficialis tendons split at bases of proximal phalanges into 2 tendon slips

Slips pass around flexor digitorum profundus (FDP) tendon before inserting into middle phalangeal bases

Flexor digitorum superficialis (FDS) forms “tunnel” for FDP
• Flexes metacarpophalangeal joints (aided by lumbricals & interossei) & proximal IP joints

Flexor Digitorum Profundus

• Origin: Proximal 1/2 of radius & interosseus membrane
• Insertion: Volar plates, distal IP joints, & bases of distal phalanges of digits 2-5
• Innervation: Ulnar & median nerves
• Flexes distal IP joints & proximal IP, metacarpophalangeal (aided by lumbricals & interossei) joints of digits 2-5

INTRINSIC MUSCLES: HYPOTHENAR AREA

Hypothenar Eminence

• Mirror image of thenar eminence
• Muscles (superficial to deep): Abductor digiti minimi (ADM), flexor digiti minimi (FDM), opponens digiti minimi (ODM)

Origin: ADM from pisiform; FDM & ODM from flexor retinaculum & hook of hamate

Insertion: ADM & FDM → conjoint insertion ulnar aspect base of proximal phalanx little finger

– ODM to proximal 2/3 metacarpal shaft little finger

Innervation: All by ulnar nerve

INTRINSIC MUSCLES: THENAR AREA

Thenar Eminence

• Muscles: Abductor pollicis brevis (APB), flexor pollicis brevis (FPB), opponens pollicis (OP)

Origin: Flexor retinaculum & tubercle of trapezium

Insertion: APB, FPB conjoint insertion at base of proximal phalanx radial aspect

– OP to volar aspect 1st metacarpal shaft
• Innervation: All by median nerve except FPB, which has also partially supplied by ulnar nerve

Adductor Pollicis Muscle

• Oblique (proximal) & transverse (distal) heads
• Origin: Capitate, trapezoid, 2nd & 3rd metacarpals
• Insertion: Ulnar aspect base of proximal phalanx of thumb, IP joint, volar plate of thumb

Also contributes fibers to extensor hood of thumb, which forms adductor aponeurosis
• Innervation: Ulnar nerve
• Actions: Adducts thumb toward 3rd digit & aids extension of IP joint
• Separated from thenar muscles by fascial plane & innervated by ulnar rather than median nerve

INTRINSIC MUSCLES: PALMAR AREA

Lumbricals

• Numbered 1-4 from radial to ulnar
• Origin: Radial aspect FDP tendon index to little fingers
• Insertion: Radial aspect extensor tendon expansion index to little fingers
• Innervation: Most radial 2 lumbricals by median nerve, most ulnar 2 lumbricals by ulnar nerve
• Actions: Flex metacarpophalangeal joints & extend IP joints

Palmar Interossei

• Numbered 1-3 from radial to ulnar
• Origin: Mesial palmar aspect diaphyses of 2nd, 4th, & 5th metacarpals
• Insertion: Mesial lateral bands & mesial aspect bases of proximal phalanges of same digit as origin
• Innervation: Ulnar nerve
• Actions: Adduct digits & assist lumbricals with flexion of metacarpophalangeal joints & extension of IP joints of digits 2, 4, & 5

Dorsal Interossei

• Numbered 1-4 from radial to ulnar
• Origin: FDP tendons just distal to carpal tunnel
• Insertion: Radial lateral bands of digits 2-5
• Innervation: Ulnar nerve
• Actions: Extends IP joints 2-5 & abducts digits 2-5

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Tags: Diagnostic Ultrasound Musculoskeletal

Apr 9, 2020 | Posted by admin in MUSCULOSKELETAL IMAGING | Comments Off

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