8. Anatomy of the hand Flashcards
Skeleton of hand
Carpals
Metacarpals
Phalanges
Carpal bone arrangement
2 rows: distal and proximal, form carpal arch
Carpal bones proximal row:
Proximal row: Pisiform - in FCU Triquetral - triangle shaped Lunate - moon shaped Scaphoid - largest
Carpal bones distal row
Trapezium - forms saddle joint for thumb
Trapezoid
Capitate - skull-looking
Hamate - looks like hammer. Has hook of hamate
Clinical aspect of carpal bones?
Fracture of scaphoid is common. Slow recovery, as poor blood supply to proximal part - avascular necrosis
Joints of hand
Wrist bones - radiocarpal joints
Micarpal/intercarpal - not a lot of movement
Carpometacarpal joints
saddle joint - thumb one
interphalangeal joint - in fingers themselves, 1 in thumb, 2 in rest
Wrist (radiocarpal joint)
Between radius/disc and first carpal row
Reinforced by ligaments
Ulnar and radial collateral ligaments
Ligaments on the palmar/dorsal surfaces
Ulnar and radial collateral ligaments
limits abduction/adduction
Ligaments on the palmar/dorsal surfaces
limits extension/flexion
Radial styloid process
limits range of abduction
Carpometacarpal joints
Plane joints - Limited movement
Except for the saddle joint (between trapezium and d1)
- Enables opposition
Movements of the thumb
Movements of the thumb: extension, flexion, abduction, adduction, opposition, reposition
Metacarpophalangeal joints
Condylar joints
Flexion/extension
Abduction/adduction
Deep transverse metacarpal ligaments unifies metacarpals, not between digit 1 and 2
Interphalangeal joints
Hinge joints
Flexion/extension
Proximal interphalangeal joints (PIPs)
and
Distal interphalangeal joints (DIPs)
palmar aponeurosis
Thickened deep fascia
Triangular
Continuous with palmaris longus
Clinical – Dupuytren’s contracture
Long flexor tendons to digits
From muscles in anterior forearm
Pass through carpal tunnel
Flexor digitorum superficialis
d2-d5
Flexor digitorum profundus
d2-d5
Flexor pollicis longus
d1
Flexor retinaculum
aka transverse carpal ligament
prevents bowing of tendons
Nerve passing through carpal tunnel
Median nerve
What surrounds the tendons?
synovial sheaths
Flexor tendon insertions
Flexor digitorum profundus To base of distal phalanx
Flexor digitorum superficialis
To base of middle phalanx
What are vinculae?
Attach tendons to phalanges
What surrounds the tendons?
Synovial sheath surrounded by fibrous digital sheath
Alternating fibrous annular (A1-A5 pulley’s) and cruciate ligaments
Long extensor tendons to digits
From muscles in posterior forearm
D2-D5:
Extensor digitorum
Extensor indicis
Extensor digit minimi
D1:
Extensor pollicis longus
Extensor pollicis brevis
Abductor pollicis longus
Anatomical snuffbox
Anterior: abductor policis longus Lateral: extensor policis brevis Medial: extensor policis longus Floor: scaphoid bone and trapezium Passing through anatomical space: radial artery
Extensor digitorum insertion
into both middle phalanx (middle band of extensor digitorum)
and distal phalanx (lateral band)
Extensor hoods
Lumbricals and interossei insert into the extensor hoods
Lumbricals
Link flexor to extensor tendons
- Extend interphalangeal joints and flex MCP joints
- Precision grip (hold pen / pinch)
Flexor digitorum profundus inserts into extensor hood
palmar interossei
Interossei sit between the metacarpals
3 Palmar interossei
Metacarpals -> Extensor hoods (d2, d4 ,d5)
Palmar adduct (PAD) MCP joints Relative to middle finger (D3)
No palmar interossei for D1 (performed by adductor pollicis muscle) or D3
Dorsal interossei
4 Dorsal interossei
Metacarpals -> Extensor hoods d2, d3 (x2) ,d4
Dorsal abduct (DAB) MCP joints Relative to middle finger (D3)
No dorsal interossei for D1 or D5 (performed by thenar and hypothenar muscles)
Thenar and hypothenar muscles
thenar muscles - fine movements of the thumb (d1)
hypothenar muscles - fine movements of the little finger (d5)
Thenar muscles
Three muscles:
- Opponens pollicis
(into first metacarpal)
- Abductor pollicis brevis
3. Flexor pollicis brevis
(both into proximal phalanx)
Hypothenar muscles
Three muscles:
- Opponens digiti minimi
into fifth metacarpal - Abductor digiti minimi
3. Flexor digiti minimi
both into proximal phalanx
Adduction of the thumb
Adductor pollicis
Oblique head
Base 2nd and 3rd metacarpal + carpal bones
Transverse head
3rd metacarpal
both into proximal phalanx
What forms a complex anastamosis in the hand?
radial artery
ulnar artery
form complex anastomosis in hand
(So that blood can reach all parts in all hand positions)
Where is the deep palmar arch
Below long flexor tendons
What does the deep palmar arch supply?
D1 and 1/2 D2
Branches of deep palmar arch
princeps pollicis artery to D1
Radialis indicis artery to 1/2 of D2
Where is superficial palmar arch?
above long flexor tendons
Branches of superficial palmar arch
3 common palmar digital arteries
proper palmer digital arteries
What does superficial palmar arch supply?
1/2 D2 to D5
Where does median nerve pass through?
Carpal tunnel
Branches of median nerve
Recurrent branch to thenar muscles
Digital nerves to lateral 2 lumbricals and sensory d1 to 1/2 d5
Clinical relevance of median nerve
Carpal tunnel syndrome
What does the ulnar nerve supply?
deep branch to hypothenar muscles, interossei, medial 2 lumbricals, adductor pollicis
superficial branch to sensory 1/2 d4 and d5
Clinical relevance of ulnar nerve
clawed hand
