L10: Musculo-neuro-vascular systems of the hand and carpal tunnel Flashcards
palmar surface anatomy
central concavity separates 2 eminences
thenar eminence: lateral, more prominent
hypothenar eminence: medial, smaller
intrinsic muscles of the hand, 5 compartments
5 compartments separated by fibrous septa
- thenar compartment: thenar muscles (3)
- adductor compartment: adductor pollicis (1)
- hypothenar compartment: hypothenar muscles (3)
- central compartment: lumbricals (4)
- interosseous compartment: interossei (7)
thenar compartment: abductor pollicis brevis; origin + insertion
origin:
- tubercle of scaphoid
- flexor retinaculum
insertion:
- proximal phalanx of thumb, lateral surface of base
thenar compartment: abductor pollicis brevis; innervation + actions
innervation: recurrent branch of median nerve
actions: abducts thumb and assists in opposition at CMC joint
thenar compartment: flexor pollicis brevis; origin + insertion
two heads superficial and deep
origin: trapezium and adjacent flexor retinaculum
insertion: proximal phalanx of thumb
thenar compartment: flexor pollicis brevis; innervation + actions
innervation: recurrent branch of median nerve (superficial head), deep branch of ulnar nerve (deep head)
actions: flexes thumb at CMC/MCP joint
thenar compartment: opponens pollicis; origin + insertion
lies deep to abductor pollicis brevis (APB) and flexor pollicis brevis (FPB)
origin: trapezium and adjacent flexor retinaculum
insertion: lateral border of 1st metacarpal
thenar compartment: opponens pollicis; innervation + action
innervation: recurrent branch of median nerve
actions: assists with opposition of thumb, flexion, adduction + medial rotation at 1st CMC joint
adductor compartment: adductor pollicis; origin + insertion:
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
adductor compartment: adductor pollicis; innervation + actions:
innervation: deep branch of ulnar nerve
actions: adducts thumb at 1st CMC joint
hypothenar compartment:
abductor digiti minimi; origin + insertion
origin: pisiform and flexor retinaculum
insertion: medial base of proximal phalanx of little finger
hypothenar compartment:
abductor digiti minimi; innervation + actions
innervation: deep branch of ulnar nerve
actions: abducts little finger
hypothenar compartment:
flexor digiti minimi brevis; origin + insertion
origin: hook of hamate and flexor retinaculum
insertion: medial surface of base of proximal phalanx (little finger)
hypothenar compartment:
flexor digiti minimi brevis; innervation + actions
innervation: deep branch of ulnar nerve
actions: flexes little finger at CMC/MCP joint
hypothenar compartment:
opponens digiti minimi; origin + insertion
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
hypothenar compartment:
flexor digiti minimi brevis; innervation + actions
innervation: deep branch of ulnar nerve
actions: rotates 5th metacarpal to oppose little finger to thumb
palmaris brevis; origin + insertion
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
palmaris brevis; innervation + actions
innervation: superficial branch of ulnar nerve
actions: wrinkles of hypothenar eminence - aids in palmar gripping
central muscles:
Lumbricals (4)
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
central muscles:
Lumbricals (4); origin
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
central muscles:
Lumbricals (4)
insertions:
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
central muscles:
Lumbricals (4)
innervation + actions
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
interosseous muscles (7)
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’’
palmar interossei (3), origin + insertion
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
palmar interossei (3);
innervation + action
innervation: deep branch of ulnar nerve
action: palmar ADduct: ‘‘pAD’’ > adduction of index, ring and little fingers
dorsal interossei (4); origin + insertion
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
dorsal interossei (4);
innervation + action
innervation: deep branch of ulnar nerve
action: Dorsal ABduct: ‘‘DaB’’ abducts digits 2-4
innervation of hand
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
arterial supply to hand
*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 arteryDeep 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
dorsal surface of hand
- dorsal carpal arch
-ulnar-radial anastomosis - dorsal metacarpal arteries
- dorsal digital arteries
deep venous drainage of hand
*Deep veins tend to follow arteries
*Superficial and deep venous palmar arches both drain into radial and ulnar veins
superficial venous drainage of hand
dorsal venous plexus
dorsal metacarpal veins
dorsal digital veins
anatomical snuffbox; floor
styloid process of radius
scaphoid proximally
trapezium distally
base of 1sy metacarpal
anatomical snuffbox; boundaries
extensor pollicis longus
extensor pollicis brevis
abductor pollicis longus
anatomical snuffbox; roof
skin
superficial branch of radial nerve
carpal tunnel
located at anterior surface of wrist
floor: carpal bones
walls: carpal bones
roof: flexor retinaculum
many structure pass through to access anterior hand
carpal tunnel contents
*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
carpal tunnel syndrome
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)
simian hand (ape hand)
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)
