L10: Musculo-neuro-vascular systems of the hand and carpal tunnel

Question 1

palmar surface anatomy

Answer 1

central concavity separates 2 eminences

thenar eminence: lateral, more prominent

hypothenar eminence: medial, smaller

Question 2

intrinsic muscles of the hand, 5 compartments

Answer 2

5 compartments separated by fibrous septa

1. thenar compartment: thenar muscles (3)
2. adductor compartment: adductor pollicis (1)
3. hypothenar compartment: hypothenar muscles (3)
4. central compartment: lumbricals (4)
5. interosseous compartment: interossei (7)

Question 3

thenar compartment: abductor pollicis brevis; origin + insertion

Answer 3

origin:
- tubercle of scaphoid
- flexor retinaculum

insertion:
- proximal phalanx of thumb, lateral surface of base

Question 4

thenar compartment: abductor pollicis brevis; innervation + actions

Answer 4

innervation: recurrent branch of median nerve

actions: abducts thumb and assists in opposition at CMC joint

Question 5

thenar compartment: flexor pollicis brevis; origin + insertion

Answer 5

two heads superficial and deep

origin: trapezium and adjacent flexor retinaculum

insertion: proximal phalanx of thumb

Question 6

thenar compartment: flexor pollicis brevis; innervation + actions

Answer 6

innervation: recurrent branch of median nerve (superficial head), deep branch of ulnar nerve (deep head)

actions: flexes thumb at CMC/MCP joint

Question 7

thenar compartment: opponens pollicis; origin + insertion

Answer 7

lies deep to abductor pollicis brevis (APB) and flexor pollicis brevis (FPB)

origin: trapezium and adjacent flexor retinaculum

insertion: lateral border of 1st metacarpal

Question 8

thenar compartment: opponens pollicis; innervation + action

Answer 8

innervation: recurrent branch of median nerve

actions: assists with opposition of thumb, flexion, adduction + medial rotation at 1st CMC joint

Question 9

adductor compartment: adductor pollicis; origin + insertion:

Answer 9

origin:
- transverse head: anterior surface of body of 3rd metacarpal
- oblique head: bases of metacarpals 2 and 3, capitate, and trapezoid

insertion: medial side of proximal phalanx of thumb

Question 10

adductor compartment: adductor pollicis; innervation + actions:

Answer 10

innervation: deep branch of ulnar nerve

actions: adducts thumb at 1st CMC joint

Question 11

hypothenar compartment:
abductor digiti minimi; origin + insertion

Answer 11

origin: pisiform and flexor retinaculum

insertion: medial base of proximal phalanx of little finger

Question 12

hypothenar compartment:
abductor digiti minimi; innervation + actions

Answer 12

innervation: deep branch of ulnar nerve

actions: abducts little finger

Question 13

hypothenar compartment:
flexor digiti minimi brevis; origin + insertion

Answer 13

origin: hook of hamate and flexor retinaculum

insertion: medial surface of base of proximal phalanx (little finger)

Question 14

hypothenar compartment:
flexor digiti minimi brevis; innervation + actions

Answer 14

innervation: deep branch of ulnar nerve

actions: flexes little finger at CMC/MCP joint

Question 15

hypothenar compartment:
opponens digiti minimi; origin + insertion

Answer 15

lies deep to abductor digiti minimi (ADM) and flexor digiti minimi brevis (FDMB)

origin: hook of hamate and flexor retinaculum

insertion: medial border of 5th metacarpal

Question 16

hypothenar compartment:
flexor digiti minimi brevis; innervation + actions

Answer 16

innervation: deep branch of ulnar nerve

actions: rotates 5th metacarpal to oppose little finger to thumb

Question 17

palmaris brevis; origin + insertion

Answer 17

is in hypothenar region, but not contained within the hypothenar compartment. it is superficial to this compartment

origin: proximal border of palmar aponeurosis

insertion: skin over hypothenar eminence

Question 18

palmaris brevis; innervation + actions

Answer 18

innervation: superficial branch of ulnar nerve

actions: wrinkles of hypothenar eminence - aids in palmar gripping

Question 19

central muscles:
Lumbricals (4)

Answer 19

4 lumbricals in total numbered 1 to 4
1 is most radial, 4 is most ulnar
1 and 2 are unipennate, 3 and 4 are bipennate

Question 20

central muscles:
Lumbricals (4); origin

Answer 20

origins: in anterior hand they are attached to sides of flexor digitorum profundus (FDP) tendons

1st lumbrical> lateral 1st FDP tendon
2nd Lumbrical> lateral 2nd FDP tendon
3rd Lumbrical> medial 2nd FDP + lateral 3rd FDP tendon
4th lumbrical> medial 3rd FDP + lateral 4th FDP tendon

Question 21

central muscles:
Lumbricals (4)
insertions:

Answer 21

insert into the posterior [dorsal] region of digits 2-5

all lumbrical insert into the lateral part of their respective extensor expansion

e.g. 1st lumbrical inserts into lateral part of extensor expansion covering dorsal index finger

Question 22

central muscles:
Lumbricals (4)
innervation + actions

Answer 22

innervation:
- lateral 2 (1&2) median nerve
- medial 2 (3&4) ulnar nerve

actions:
- flex digits 2-5 at MCP joints
- extend digits 2-5 at IP joints

Question 23

interosseous muscles (7)

Answer 23

simply called interossei
7 in total (3palmar, 4 dorsal)
all innervated by deep branched of ulnar nerve

'’3 on the P, 4 on the dor’’

Question 24

palmar interossei (3), origin + insertion

Answer 24

origin: palmar surface of metacarpal 2,4,5

insertion:
1. medial base of proximal phalanx of index finger
2. lateral surface of base of 4th proximal phalanx
3. lateral surface of base of 5th proximal phalanx

Question 25

palmar interossei (3); innervation + action

Answer 25

innervation: deep branch of ulnar nerve action: palmar ADduct: ''pAD'' > adduction of index, ring and little fingers

Question 26

dorsal interossei (4); origin + insertion

Answer 26

origin: bipennate muscles, originate on adjacent sides of metacarpal insertion: 1. lateral base of index proximal phalanx + DDE 2. lateral base of middle finger proximal phalanx + DDE 3. medial base of middle finger proximal phalanx + DDE 4. medial base of 4th finger proximal phalanx + DDE DDE= dorsal digital expansion

Question 27

dorsal interossei (4); innervation + action

Answer 27

innervation: deep branch of ulnar nerve action: Dorsal ABduct: ''DaB'' abducts digits 2-4

Question 28

innervation of hand

Answer 28

motor *Thenar Muscles: median nerve branches* Adductor Pollicis: deep branch of ulnar nerve *Hypothenar Muscles – deep branch of ulnar nerve *Lumbricals Lateral 2 – median nerveMedial 2 – ulnar nerve *Interossei – deep branch of ulnar nerve

Question 29

arterial supply to hand

Answer 29

*Superficial Palmar Arch *Located between palmar aponeurosis and tendons of flexor digitorum superficialis (FDS) *Formed from: *Terminal branch of ulnar artery *Superficial palmar branch of radial artery*Deep Palmar Arch *Located between metacarpals and deep flexor tendons *Formed from: *Deep palmar branch of ulnar artery *Branch of radial artery *Common palmar digital arteries *Proper palmar digital arteries

Question 30

dorsal surface of hand

Answer 30

- dorsal carpal arch -ulnar-radial anastomosis - dorsal metacarpal arteries - dorsal digital arteries

Question 31

deep venous drainage of hand

Answer 31

*Deep veins tend to follow arteries *Superficial and deep venous palmar arches both drain into radial and ulnar veins

Question 32

superficial venous drainage of hand

Answer 32

dorsal venous plexus ^ dorsal metacarpal veins ^ dorsal digital veins

Question 33

anatomical snuffbox; floor

Answer 33

styloid process of radius scaphoid proximally trapezium distally base of 1sy metacarpal

Question 34

anatomical snuffbox; boundaries

Answer 34

extensor pollicis longus extensor pollicis brevis abductor pollicis longus

Question 35

anatomical snuffbox; roof

Answer 35

skin superficial branch of radial nerve

Question 36

carpal tunnel

Answer 36

located at anterior surface of wrist floor: carpal bones walls: carpal bones roof: flexor retinaculum many structure pass through to access anterior hand

Question 37

carpal tunnel contents

Answer 37

*Flexor digitorum profundus tendons (4) *Flexor digitorum superficialis tendons (4) *Flexor pollicis longus tendon *Median nerve *Flexor carpi radialis tendon* > Does not strictly pass through carpal tunnel, rather passes through an adjacent tunnel

Question 38

carpal tunnel syndrome

Answer 38

Compression of median nerve as it passes through the carpal tunnel Causes sensory and motor symptoms Sensory: Paraesthesia (tingling), hypoesthesis(diminished sensation), anaesthesia (numbness) Motor: reduced power in abductor pollicis brevis and opponens pollicis muscles, over time reduced muscle bulk (atrophy)

Question 39

simian hand (ape hand)

Answer 39

Median nerve injury causes paralysis of the thenar muscles: *Abductor Pollicis Brevis *Flexor Pollicis Brevis *Opponens Pollicis Unopposed action of Adductor Pollicis leaves thumb fixed in same plane as other fingers (like an ape's hand)