Functional anatomy of hand and wrist Flashcards
What comprises the wrist joint?
Distal radius (NOT ulna), triangular fibrocartilage complex (TFCC), scaphoid + lunate
What type of joint is the wrist joint?
Ellipsoid synovial = allows movement in 2 axes (flex, ext., adduct, abduct = circumduction)
What 4 ligaments stabilise the wrist joint?
Dorsal + palmar radiocarpal ligaments = attach radius to carpal
Ulnar + radial collateral ligaments
How many carpal, metacarpals + phalanges?
8
5
14 (proximal, middle + distal, ONLY proximal + distal on thumb)
What are the 8 carpal bones in the proximal and distal rows from radial (lateral) to ulnar?
Some Lovers Try Positions That They Can’t Handle
PROXIMAL = Scaphoid, Lunate, Triquetrum, Pisiform DISTAL = Trapezium, trapezoid, capitate hamate
What is the blood supply of the scaphoid?
Dorsal carpal branch of radial artery
Retrograde
Describe the articulations of the 5 metacarpals (radial to ulnar)
1 = trapezium + prox. phalanx thumb 2 = trapezoid + prox. phalanx index 3 = capitate + prox. phalanx middle finger 4 = hamate + prox. phalanx ring 5 = hamate + prox. phalanx little
What are the 4 compartments of hand muscles?
Thenar compartment
Adductor compartment
Hypothenar compartment
Central compartment
Generally, describe the thenar compartment
Cause thenar eminence = prominence on radial palm Median nerve (exc. deep head flexor pollicis brevis = ulnar) Opponens pollicis, abductor pollicis brevis, flexor pollicis brevis
Describe opponens pollicis
From trapezium + flex. retinaculum to lateral border 1st metacarpal
Opposes thumb
Describe abductor pollicis brevis
Scaphoid/trapezium/flexor retin. to lat. border of proximal phalanx thumb
Palmar abduction of thumb
Describe flexor pollicis brevis
SUPERFICIAL HEAD = trapezium + flex. retin.
DEEP HEAD = trapezoid + capitate
Ulnar aspect base of proximal phalanx thumb
Flex MCPJ
What compartment is adductor pollicis in? Describe the muscle
Adductor
Ulnar nerve
TRANSVERSE HEAD = shaft of 3rd metacarpal
OBLIQUE HEAD = capitate, base of 2nd + 3rd metacarpals
Ulnar aspect base of prox. phalanx thumb
Adducts thumb
Describe the hypothenar compartment
Causes hypothenar eminence = ulnar aspect
Ulnar nerve
Opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis
Describe opponens digit minimi
Hook of hamate/flex. retin. to ulnar margin 5th metacarpal
Rotates 5th metacarpal to palm = allows opposition against thumb
Describe abductor digiti minimi
Pisiform + tendon of flexor carpi ulnaris to base prox. phalanx little finger
Abducts little finger (only in coronal plane)
Describe flexor digiti minimi brevis
Hook of hamate/flex. retin. to base prox. phalanx little finger
Flex MCPJ little finger
Describe the central compartment
Palmaris brevis, palmar + dorsal interossei + 4 lumbricals
Radial 2 lumbricals = median nerve
Ulnar 2 lumbricals = ulnar nerve
Palmaris brevis + interossei = ulnar nerve
Describe palmaris brevis
From palmar aponeurosis + flex. retin. to dermis of skin on medial margin
Wrinkles skin of hypothenar eminence = deepens curvature of palm, improves grip
What is the role of the lumbricals?
Link flexor digitorum profundus tendon on palmar surface to ext. digitorum tendon on dorsum
Contract = flex fingers @ MCPJ, extend @ IPJ
Which lumbricals are bipennate and which are unipennate? What innervates them?
Unipennate = index, middle = median nerve Bipennate = ring, little = ulnar nerve
Describe lumbricals I and II (index + middle)
I = FDP from index finger to extensor digitorum of index II = FDP from middle to ED of middle
Describe lumbricals III and IV (ring + little)
III = FDP from middle + ring to ED of ring IV = FDP from ring + little to ED of little
Where are the interossei? What are the actions for the dorsal and palmar interossei? What innervates the interossei?
Between metacarpals DAB = dorsal abduct PAD = palmar adduct (assist lumbricals in flex./ext. @ MCPJ + IPJ) Ulnar nerve
Describe dorsal interossei I and II
I = from shaft of 1st + 2nd metacarpals to radial aspect base of prox. phalanx index finger (abducts index) II = shaft of 2nd + 3rd metacarpals to radial aspect base of prox. phalanx middle finger (radially abducts middle)
Describe dorsal interossei III and IV
III = shaft of 3rd + 4th metacarpals to ulnar aspect prox. phalanx middle finger (ulnar abducts middle) IV = shaft 4th + 5th to ulnar aspect base prox. phalanx ring finger (abducts ring)
Why is there no dorsal interossei muscle to the little finger?
Little finger abduction by abductor digiti minimi
Describe the palmar interossei
Unipennate
Only 3 as thumb adducted by adductor pollicis + middle finger moves side-side by 2nd + 3rd dorsal interossei
Describe the 3palmar interossei
Shaft of 2nd metacarpal = to ulnar side base prox. phalanx index = adducts index to middle
Shaft 4th metacarpal = radial side base prox. phalanx ring = adducts ring to middle
Shaft 5th metacarpal = radial side base prox. phalanx little = adducts little toward middle + ring
