L8 Anatomy of the hand Flashcards
Hand - bone groups
- Carpals
- Metacarpals
- Phalanges
Carpal bones
- Scaphoid
- Lunate
- Triquetral/triquetrium
- Pisiform
- Trapezium
- Trapezoid
- Capitate
- Hamate
Joints of the hand
- Wrist (radiocarpal)
- Midcarpal/intercarpal
- Carpometacarpal (saddle joint)
- Metacarpophalangreal
- Interphalangeal
Wrist(radiocarpal) joint
- Between radius/disc and first carpal row
- Reinforced by ligaments
Ligaments that reinforce the wrist(radiocarpal) joint
- Ulnar and radial collateral ligaments (limits abduction/adduction)
- Ligaments on the palmar/dorsal surfaces (limits extension/flexion)
Purpose of radial styloid process
- Limits range of abduction
What does the wrist joint allow for
- Flexion/extension
- Abduction/adduction
- Circumduction
Carpometacarpal joints
- Plane joints (limited movement)
- Except for the saddle joint(between trapezium and d1) - enables opposition
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 and distal interphalangeal joints
Palmar aponeurosis
- Thickened deep fascia
- Triangular
- Continuous with palmaris longus
- Consists of longitudinal and transverse fibres
Clinical relevance of palmar aponeurosis
- Dupuytren’s contracture
Long flexor tendons to digits
- From muscles in anterior forearm
- Pass through carpal tunnel
Flexor retinaculum
- Transverse carpal ligament
- Prevents bowing of tendons
Long flexor tendons associated with each digit
- Flexor digitorum superficialis (d2-5)
- Flexor digitorum profundus (d2-5)
- Flexor pollicis longus (d1)
Flexor tendon insertions
- Alternating fibrous annular (A1-A5 pulley’s) and cruciate ligaments
Where does flexor digitorum profundus insert
- To base of distal phalanx
Where does flexor digitorum superficialis insert
- To base of middle phalanx
- Note the vinculae (attach tendons to phalanges)
Long extensor tendons to digits
From muscles in posterior forearm
Extensor digitorum, indicis and digit minimi –> d2-5
Extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus –> d1
Extensor tendons that go through the anatomical snuff box
Abductor pollicis longus - to base of 1st metacarpal
Extensor pollicis brevis - to base of proximal phalanx
Extensor pollicis longus - to base of distal phalanx
Which artery goes through the anatomical snuff box
- Radial artery
Extensor digitorum insertion
- Medial band (into middle phalanx)
- Lateral band(into distal phalanx)
Muscles that insert into the 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)
Palmar interossei
Interossei sit between the metacarpals
Where do the palmar interossei muscles run from
3 palmar interossei
- Run from the metacarpals to the extensor hoods (d2, d4, d5)
Role of palmar interossei muscles
- Palmar adduct (PAD) MCP joints - relative to middle finger (D3)
- No palmar interossei for D1(performed by adductor pollicis muscle) or D3
Where do the dorsal interossei run from
4 dorsal interossei
- Run from metacarpals to extensor hoods d2, d3(x2), d4
Action of dorsal interossei
- Dorsal abduct (DAB) MCP joints - relative to middle finger (D3)
- No dorsal interossei for D1 or D5 (performed by thenar and hypothenar muscles)
Role of thenar and hypothenar muscles
Thenar muscles - fine movements of the thumb (d1)
Hypothenar muscles - fine movements of the little finger (d5)
Origin of thenar and hypothenar muscles
Thenar muscles - fine movements of the thumb (d1)
Hypothenar muscles - fine movements of the little finger (d5)
Thenar muscles
- Opponens pollicis (deepest) - inserts into first metcarpal
- Abductor pollicis brevis
- Flexor pollicis brevis - inserts into proximal phalanx
Hypothenar muscles
- Opponens digiti minimi (deepest) - inserts into fifth metacarpal
- Abductor digiti minimi
- Flexor digiti minimi - inserts into proximal phalanx
Adduction of the thumb
- Adductor pollicis
- Oblique head from the base of 2nd and 3rd metacarpal + carpal bones into proximal phalanx
- Transverse head -from the 3rd metacarpal into the proximal phalanx
- Deep to thenar muscles
Blood supply to the hand
Radial artery - towards dorsal surface
Ulnar artery
- Form complex anastomosis in hand so that blood can reach all parts in hand positions
Deep palmar arch
- Below long flexor tendons
- Radial artery enters between first dorsal interosseous muscle and floor of anatomical snuff box
- D1 and 1/2 D2 = mainly radial artery
Superficial palmar arch
- Above long flexor tendons
- Ulnar artery
- Lead to 3 common palmar digital arteries and proper palmar digital arteries
- 1/2 d2 to d5 = mainly ulnar artery
Which nerve passes through carpal tunnel
Median
Branches of median nerve in hand
- Recurrent branch –> thenar muscles
- Digital nerves –> lateral 2 lumbricals + sensory d1 to 1/2 d4
Ulnar nerve branches in hand
Deep branch - hypothenar muscles, interossei, medial 2 lumbricals, adductor pollicis
Superficial branch - sensory 1/2 d4 and d5
ulnar nerve clinical relevance - hand
clawed hand
