Lecture 23: intrinsic hand Flashcards
Surface anatomy of hand
Hypothenar eminence = movement of pinky, pinky side
Thenar eminence = intrinsic thumb msucles
Describe palmar aponeurosis
Starts and ends in hand
Triangle of deep v thick fascia in superficial layer of palm
Deep to skin and anchored to it, but superficial to digital flexor tendons and palmar n/v structures
TRANSVERSE AND LONGITUDINAL FIBERS
What is point of Palmaris aponeurosis
Protect underlying neurovasculature Structrues and tendons
What muscle is near Palmaris aponeurosis
PALMARIS brevis = little muscle, variably present
Describe Palmaris brevis
Thin quadrangualr muscle
Stretches between palmar aponeurosis and skin of hypothenar eminence, draws hypothenar skin over to centre of palms (tenses palmar aponeurosis) = strengthends palmar grip
What does Palmaris longus do
When present = blends and ends into palmar aponeurosis
Describe palmar carpal ligament
Communicates with palmar aponeurossi
(Not flexor retinaculum, not roof of carpal tunnel)
What is carpal tunnel
3rd and most distal n/v funnel of upper limb
Describe flexor retinaculum
Ligamentous band stretching from pisiform and hook of hamate (medial) to trapezium and scaphoid (lateral)
What does flexor retinaculum create
Forms carpal tunnel
What does flexor retinaculum do
Prevents bowing of tendons of digital flexors originating in forearm when these contract
Describe carpal tunnel
Carpal bones form carpal arch - flexor retinaculum closes it = forms carpal tunnel
Describe contents of carpal tunnel
Tendons of flexor digitorum superficialis - 4x
Flexor digitorum profundus tendons = 4x
Flexor pollicis longus = 1x
Median nerve
= 10 total things, 9 tendons, 1 nerve
What does median nerve do
Passes through all 3 funnels in arm
Where is carpal tunnel
On palm
Not wrist region
Describe carpal tunnel syndrome - clinical correlate
Chronic pressure on median nerve deep to flexor retinaculum = causes numbness, weakness, tingling in intrinsic hand msucles = compression of contents of carpal tunnel
Describe ulnar canal
Formed by palmar carpal ligament stretching from tendon of flexor carpi ulnaris to flexor retinaculum
What’s in ulnar canal
Ulnar nerve and artery
Describe clinical correlate ulnar canal
Can cause chronic compression of these structures = muscle weakness, deprivation of blood too
Name intrinsic muscles - thenar eminence
Flexor pollicis brevis
Abductor pollicis brevis
Opponens pollicis
Attachments flexor pollicis brevis
Flexor retinaculum and scaphoid/trapezium to lateral side of first proximal phalanx
Functions flexor pollicis brevis
Flex and abduct thumb mcp joint
Assist in opposition
abductor pollicis brevis attachments
Flexor retinaculum and scaphoid/trapezium to lateral side of first proximal phalanx
abductor pollicis brevis Functions
Flex and abduct thumb mcp joint, assist in opposition
opponens pollicis attachments
Flexor retinaculum and scaphoid/trapezium to lateral side of first metacarpal
opponens pollicis Functions
Opposition = bring thumb to hypothenar side palm
Innervation of flexor pollicis brevis, abductor pollicis brevis, opponens pollicis
Reccurrent branch fo median nerve = goes back and innervates these 3 muscles
Name intrinsic muscles - deep thenar eminence
Adductor pollicis- 2 heads
Adductor pollicis Attachments oblique head
Capitate, base of mc ii and iii to medial side of base of first proximal phalanx - heads converge
Adductor pollicis FUCNTION
Adduction of thumb cmc joint
= trapezium and 1st metacarpal
Also bit of flexion of thumb mcp joint
Adductor pollicis INnervation
Deep ulnar nerve
- arcs to innervate adductor policis
Name muscles of hypothenar eminence
Abductor digiti minimi
Flexor digiti minimi brevis
Opponens digiti minimi
Abductor digiti minimi Attachments
Pisiform to medial side proximal phalanx v
Abductor digiti minimi FUCNTION
Abducts, flexes mcp 5th digit
Flexor digiti minimi brevis Attachments
Hamate hook and flexor retinaculum to medial side proximal phalanx v
Flexor digiti minimi brevis Functions
Abducts, flexes mcp 5th digit
Attachments Opponens digiti minimi
Hamate hook and flexor retinaculum To medial side of metacarpal v
Functions Opponens digiti minimi
Brings 5th digit into opposition to thumb
Innervation of Abductor digiti minimi
Flexor digiti minimi brevis
Opponens digiti minimi
Deep ulnar nerve
Describe ulnar nerve/artery - branches and pathway
Passes under ulnar canal then splits = to deep ulnar nerve and artery, and superificial ulnar nerve (sensory) and artery
Both send deep branches to metacarpals to innervate hypothenar msucles
Name muscles of central compartment of hand
Lumbricals
Lumbricals attachments
Tendons of flexor digitorum profundus to lateral aspect fo extensor hood
NOT TO THUMB
Lumbricals Functions
Flexion of mcp and extension of ip joints via extensor hood =
Passes anterior to palmar mcp but post/dorsal to ip joints
Lumbricals Innervation
Lumbricals1 and 2 = median nerve (to digits 2 and 3)
Lumbricals 3 and 4 = deep ulnar nerve (to digits 4 and 5)
Name muscles of interosseous - deep - compartment
Palmar interossei
Dorsal interossei
Attachments of interossei
Shafts of metacarpals —> sides of proximal phalanges + extensor hoods (distal)
= all contribute to extensor hood
Palmar interossei FUCNTION
3 msucles =
Abduction and flexion of mcp, extension of ip joints for digits ii, iv, v
(Towards 3rd digit)
Dorsal interossei FUCNTION
4x
Abduction and flexion of mcp, extension of ip joints for digits ii, iii, if
(Deepest in hand, but can see on dorsal aspect)
Way to remember functions interossei
PAD = palmar adducts
Vs
DAP = dorsal abducts
Describe abduction and adduction at mcp joints ii-v - interossei
Defined in relation to 3rd digit
Third digit has 2 abductors in relation to this axis = dorsal interossei ii and iii = so 3rd digit abducts in both direction
(No adductors= palmar interossei)
Abducts - medial, and then abducts back to lateral aspect - midline
What are tendons of digital flexors and extensors surrounded by
Synovial sheaths
And encapsulate by fibrous sheaths
How do synovial sheaths help
Reduces friction bc filled with synovial fluid
How do fibrous sheaths help
Keep tendons from bowing - including extensor hood = at each joints they pass
Describe extensor retinaculum
Dorsum of hand
Functionally analogous to felxor retinaculum
Describe ulnar nerve - motor
In ulnar canal - deep to palmar carpal ligament
Splits
Describe median nerve - motor
Deep to felxor retinaculum - through carpal tunnel
Describe deep ulnar nerve - motor
Hypothenar eminence, medial 2 Lumbricals (iii and iv), adductor pollicis (arcs over), interossei
Describe reccurent branch medial nerve - motor
To thenar eminence expect adductor pollicis
What innervates lumbricals I and ii
Median nerve
What innervates adductor pollicis
Deep ulanr nerve
Describe palmar sensory - ulnar nerve
Sends off dorsal branch early - that goes on top of flexor retinacula
Then splits = superficial branch of ulnar nerve (mostly sensory to palmar medial 1.5 digits, motor to palmaris brevis)
—> digital branches, sensory
Describe palmar sensory - Median nerve
Before passes under flexor retinaculum = gives off palmar branches (sensory)
—> recurrent branch median nerve = motor
Then digital branches - sensory = to rest of Palm and hand, also wrap arounf nail beds - to dorsal side
Describe dorsal sensory - radial nerve
Superficial branch radial nerve (recall snuff box)
—> dorsal digital branches of radial nerve
Describe dorsal sensory -Ulnar nerve
Dorsal branch of ulnar nerve - part of dorsum, medial side
—> dorsal digital branches of ulnar nerve
Describe dorsal sensory -Median nerve
Wrapped arounf nail beds = tips of fingers supplied by digital branches of median nerve
Describe vascular supply to hand - Gen
3 arterial arches =
2 palmar
1 dorsal
= branch out to provide blood to metacarpals and digits, forms extensive anastomoses
Which artery supplies more fo hand
Ulnar artery on palmar side
Describe ulnar artery in hand
Splits after ish flexor retinaculum = deep ulnar artery
Describe radial artery in hand
Split before flexor retinaculum —> superficial branch of radial artery
Describe superficial palmar arch
Ulnar artery and palmar branch radial artery
—> sends off common palmar digital arteries —> proper palmar digital arteries
Describe deep palmar arch
Radial artery and deep ulnar artery
Describe dorsal carpal arch
From radial artery
—> dorsal metacarpal arteries —> dorsal digital arteries
Under tendons extensor digitorum
What does the regions of sensory innervation allow for clinicians
Allow clinicians to pin point injuries
Adductor pollicis Attachments transverse head
Shaft of mc iii to medial side of base of first proximal phalanx - heads converge
What is extensor hood
Broadening of tendon of extensor digitorum
Innervation interossei
Deep ulnar nerve
What happens if injure deep ulnar nerve
Loose adduction of all digits
