L13 UL Bones and Muscles Flashcards
Hand
Features of the human hand
- not weight bearing
- for power and precision grips
- palm to pad interactions
- gripping action - use of tools
- opposable thumb
carpal bones
- proximal row (from radial to ulna)
- scaphoid - contact with radius
- lunate - contact with radius
- triquetrum - no contact with ulna
- pisiform - no contact with ulna but sits on top of triquetrum
cartilaginous disc b/w 3./4. and ulna
- distal row (from radial to ulna)
- trapezium
- trapezoid
- capitate
- hamate
scaphoid bone
“wasting” in the centre - weak point ⇒ FOOSH weakness
- convex part of scaphoid and lunate - connect to radius
- concave part of scaphoid and lunate - join with distal row of carpal bones
lunate bone
semilunar shape
- convex part of scaphoid and lunate - connect to radius
- concave part of scaphoid and lunate - join with distal row of carpal bones
triquetrum bone
pyramidal shape
pisiform bone
sesamoid bone that is embedded in flexor calpi ulnaris
trapezium bone
articular facet with first metacarpal - saddle joint
- saddle joint is key for thumb opposition
- has tubercle and grooves (2x flexor retinaculum attachments)
trapezoid bone
triangular and “just inzoid” - just inside the trapezium
capitate bone
largest carpal bone and centrally placed
- contact with 3rd metacarpal (axis of the hand - 3rd metacarpal)
hamate bone
distinctive hook on palmar side - “Hook of Hamate”
- hook of hamate connects to pisiform via pisohamate ligament
- ulnar nerve and artery passes here
scaphoid fracture
- most susceptible carpal bone to fracture - commonly fractures at wasting area
- can get necrotic and die
- compromised blood supply to proximal half
fracture of hook of hamate
- hook of hamate can be easily palpated
- when hook is compressed ⇒ handlebar neuropathy → press on ulnar nerve
- ulnar nerve innervates only flexor carpi ulnaris and 1/2 of flexor digitorum profundus in forearm
- but innervates a lot in hand → pain detected via muscles of hand
metacarpals
- base articulates proximally
- body long stick part
- head articulates distally
above also applies to phalanges
- most robust metacarpal = 1st metacarpal - shortest & fattest
phalanges
- base articulates proximally
- body long stick part
- head articulates distally
usually three parts
- proximal phalanx
- middle phalanx
- distal phalanx
thumb only has proximal and distal phalanges
fascia in the hand
- deep antebrachial fascia → retinacula
-
flexor retinaculum - aka transverse carpal ligament
- forms pyramid shaped palmar aponeurosis - apex is at flexor retinaculum
- extensor retinaculum
-
flexor retinaculum - aka transverse carpal ligament
fascial compartments
- hypothenar: pinky
- thenar: thumb
- central: middle
- adductor: below thenar - but also technically part of thenar
- is just the adductor pollicis muscle
- interosseous: most dorsal - between bones
hypothenar fascial compartment
- medial fibrous septum
- from medial of hand to 5th metacarpal - separates little finger compartment
- little finger compartment
thenar fascial compartment
- lateral fibrous septum: from lateral border of palmar aponeurosis to 3rd metacarpal, another fibrous tissue goes beyond this septum and attaches onto the 1st metacarpal
- thumb compartment
central fascial compartment
- b/w medial and lateral fibrous septa
- muscles that work on main fingers
thenar space
deep to thenar compartment
adductor pollicis muscle is deeper than thenar space
palmar aponeurosis
-
palmaris brevis: small muscle - attaches to palmar aponeurosis
- when flexed - helps make fist
- palmar aponeurosis - main function = make fist
contracture of palmar fascia
thickening and shrinking of the palmar fascia, usually affecting ring and little finger - no known aetiology, but believed to be hereditary
Dupuytrens contracture
ring and little finger go into palmar flexion, difficult for movement - needs to be surgically corrected and relieved
flexor retinaculum
- forms roof of carpal tunnel - fibro-osseous
- contains median nerve, tendons etc.
- attachments: tubercle of Scaphoid, tubercle of Trapezium, hOok of hamate, Pisiform bone - STOP
carpal tunnel
hollow shape w/ tendons, synovail sheaths and median n.
- floor: carpal bones
- proximal end: distal wrist crease
carpal tunnel syndrome = inflammation
structures passing superficial to flexor retinaculum
- palmaris longus tendon: inserts onto palmar aponeurosis
- ulnar artery, ulnar nerve: deep to pisohamate ligament
-
superficial branch of radial nerve: travels past wrist and goes posteriorly
- ulnar and radial a. from brachial a.
- cutaneous branch of median nerve - doesn’t go via tunnel
- flexor carpi ulnaris: placed very medially
structures passing deep to flexor retinaculum
- flexor digitiorum superficialis tendons: attaches to base of middle metacarpal, bunches up at carpal tunnel
- flexor digitorum profundus tendons
- median nerve: recurrent thenar branch - lateral and medial branch
- flexor carpi radialis: trapezium has groove - 2 places of attachement for flexor retinaculum = FCR place
- flexor pollicis longus
also synovial sheaths - these can get inflammed
extensor retinaculum
- posterior side
- don’t typically have many problems
- attachments:
- laterally → radius
- medially: triquetrum, pisiform, FCU tendon (extensor retinaculum wraps around this)
contents of extensor retinaculum
six tunnels
- APL, EPB (outcropping)
- ECRL, ECRB
- EPL (also outcropping)
- ED, EI
- EDM
- ECU
anatomical snuff box
- found by extending the thumb
- b/w EPL (medial) and EPB (lateral)
- roof structures: skin, cutaneous tissue, cephalic vein, radial nerve
- floor structures: scaphoid and trapezium
- most important structure: radial artery - scaphoid fracture in snuff box = damaged radial artery
intrinsic muscles of the hand (layer 1)
- originates: edges of flexor retinaculum
- inserts: base of proximal phalanx
intrinsic muscles of the hand (layer 2)
- lumbricals (x4) - because they’re “worm-like”
- no bony origins
- originates: FDP tendons
- goes to lateral side of digit
- inserts dorsally to external expandion
- helps with finger flexion
intrinsic muscles of the hand (layer 3)
- opponens pollics: starts from scaphoid and trapezium - inserts at first metacarpal
- opponens digiti minimi: from edges of flexor retinaculum - inserts at 5th metacarpal
- adductor pollicis: only on thumb - quite large and deep
- 2 heads: base of 2nd and 3rd metacarpal + body of 3rd metacarpal
- inserts: proximal phalanx of thumb
intrinsic muscles of the hand (layer 4)
interossei muscles
- lie b/w metacarpals
- 3 x palmar - unipennate - adduction (pAd)
- 4 x dorsal - bipennate - abduction (dAb)
- from metacarpals (similar to lumbricals)
nerve supply of intrinsic hand muscles
-
median nerve: most of forearm
- thenar compartment - recurrent branch of median n.
- AbdPB, FPB, OP
- lateral branch of median n.: 1st and 2nd lumbrical
- thenar compartment - recurrent branch of median n.
-
ulnar nerve:
- hypothenar compartment: AbdDM, FDM, ODM, AddP
- 3rd and 4th lumbrical
- interossei muscles
