Functional anatomy of hand and wrist

Question 1

What comprises the wrist joint?

Answer 1

Distal radius (NOT ulna), triangular fibrocartilage complex (TFCC), scaphoid + lunate

Question 2

What type of joint is the wrist joint?

Answer 2

Ellipsoid synovial = allows movement in 2 axes (flex, ext., adduct, abduct = circumduction)

Question 3

What 4 ligaments stabilise the wrist joint?

Answer 3

Dorsal + palmar radiocarpal ligaments = attach radius to carpal
Ulnar + radial collateral ligaments

Question 4

How many carpal, metacarpals + phalanges?

Answer 4

8
5
14 (proximal, middle + distal, ONLY proximal + distal on thumb)

Question 5

What are the 8 carpal bones in the proximal and distal rows from radial (lateral) to ulnar?

Answer 5

Some Lovers Try Positions That They Can’t Handle

PROXIMAL = Scaphoid, Lunate, Triquetrum, Pisiform
DISTAL = Trapezium, trapezoid, capitate hamate

Question 6

What is the blood supply of the scaphoid?

Answer 6

Dorsal carpal branch of radial artery

Retrograde

Question 7

Describe the articulations of the 5 metacarpals (radial to ulnar)

Answer 7

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

Question 8

What are the 4 compartments of hand muscles?

Answer 8

Thenar compartment
Adductor compartment
Hypothenar compartment
Central compartment

Question 9

Generally, describe the thenar compartment

Answer 9

Cause thenar eminence = prominence on radial palm
Median nerve (exc. deep head flexor pollicis brevis = ulnar)
Opponens pollicis, abductor pollicis brevis, flexor pollicis brevis

Question 10

Describe opponens pollicis

Answer 10

From trapezium + flex. retinaculum to lateral border 1st metacarpal
Opposes thumb

Question 11

Describe abductor pollicis brevis

Answer 11

Scaphoid/trapezium/flexor retin. to lat. border of proximal phalanx thumb
Palmar abduction of thumb

Question 12

Describe flexor pollicis brevis

Answer 12

SUPERFICIAL HEAD = trapezium + flex. retin.
DEEP HEAD = trapezoid + capitate
Ulnar aspect base of proximal phalanx thumb
Flex MCPJ

Question 13

What compartment is adductor pollicis in? Describe the muscle

Answer 13

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

Question 14

Describe the hypothenar compartment

Answer 14

Causes hypothenar eminence = ulnar aspect
Ulnar nerve
Opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis

Question 15

Describe opponens digit minimi

Answer 15

Hook of hamate/flex. retin. to ulnar margin 5th metacarpal

Rotates 5th metacarpal to palm = allows opposition against thumb

Question 16

Describe abductor digiti minimi

Answer 16

Pisiform + tendon of flexor carpi ulnaris to base prox. phalanx little finger
Abducts little finger (only in coronal plane)

Question 17

Describe flexor digiti minimi brevis

Answer 17

Hook of hamate/flex. retin. to base prox. phalanx little finger
Flex MCPJ little finger

Question 18

Describe the central compartment

Answer 18

Palmaris brevis, palmar + dorsal interossei + 4 lumbricals
Radial 2 lumbricals = median nerve
Ulnar 2 lumbricals = ulnar nerve
Palmaris brevis + interossei = ulnar nerve

Question 19

Describe palmaris brevis

Answer 19

From palmar aponeurosis + flex. retin. to dermis of skin on medial margin
Wrinkles skin of hypothenar eminence = deepens curvature of palm, improves grip

Question 20

What is the role of the lumbricals?

Answer 20

Link flexor digitorum profundus tendon on palmar surface to ext. digitorum tendon on dorsum
Contract = flex fingers @ MCPJ, extend @ IPJ

Question 21

Which lumbricals are bipennate and which are unipennate? What innervates them?

Answer 21

Unipennate = index, middle = median nerve
Bipennate = ring, little = ulnar nerve

Question 22

Describe lumbricals I and II (index + middle)

Answer 22

I = FDP from index finger to extensor digitorum of index
II = FDP from middle to ED of middle

Question 23

Describe lumbricals III and IV (ring + little)

Answer 23

III = FDP from middle + ring to ED of ring
IV = FDP from ring + little to ED of little

Question 24

Where are the interossei? What are the actions for the dorsal and palmar interossei? What innervates the interossei?

Answer 24

Between metacarpals
DAB = dorsal abduct
PAD = palmar adduct
(assist lumbricals in flex./ext. @ MCPJ + IPJ)
Ulnar nerve

Question 25

Describe dorsal interossei I and II

Answer 25

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)

Question 26

Describe dorsal interossei III and IV

Answer 26

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)

Question 27

Why is there no dorsal interossei muscle to the little finger?

Answer 27

Little finger abduction by abductor digiti minimi

Question 28

Describe the palmar interossei

Answer 28

Unipennate

Only 3 as thumb adducted by adductor pollicis + middle finger moves side-side by 2nd + 3rd dorsal interossei

Question 29

Describe the 3palmar interossei

Answer 29

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