anatomy hand 2.2

bones of hand and wrist

carpals, metacarpals, phalanges

deep transverse metacarpal ligaments

link the metacarpal bones

there is no corresponding ligament spanning the distance between the index finger and the thumb

this along with the saddle shaped trapezium permit the greater mobility of the thumb

most common metacarpal fracture

5th metacarpal neck

occurs when punching a solid object

thumb movements

abduction and adduction occur in the sagittal plane

flexion and extension occur in coronal plane

opposition brining tip of thumb to contact with pads of other fingers

proximal row from lateral to medial

scaphoid, lunate, triquetrum, pisiform

distal row from lateral to medial

trapezium, trapezoid, capitate, hamate

most commonly fractured carpal bone

scaphoid

most commonly dislocated carpal bone

lunate

scaphoid blood supply

enters the distal portion of the bone

if fractured, the proximal bone fragment may not unite with the distal or may take as long as 3 months for union. If blood supply is disrupted avascular necrosis may result

hook of hamate fracture can cause

ulnar nerve compression (Guyon's canal)

the synovial joints between the carpal bones share a

common articular cavity and the joint capsule is reinforced by numerous ligaments

the carpometacarpal joint of the thumb has the

greatest mobility of the carpometacarpal joints

metacarpophalangeal joints (MCP) are

condylar joints, which permit flexion, extension, abduction, adduction, circumduction

the interphalangeal joints (IP) are

hinge joints permitting flexion and extension

skier's or gamekeepers thumb

fall on the outstretched hand with hyperabduction force on the thumb

often occurs when skier has pole in the hand

sprain/tear of the ulnar collateral ligament (UCL) of the 1st MCP of the thumb

infection in the palm can pass into the forearm by way of the

synovial sheath

tendon sheaths contain the tendons of the

FDS and FDP muscles

Trigger Finger (Stenosing Tenosynovitis)

is a narrowing of the flexor tendon sheath

a patient has difficulty extending a finger smoothly and after additional force it snaps into extension suddenly

easily treated surgically with excision of restrictive fibrous bands

small blood vessels pass between synovial folds to supply

tendons

palmar aponeurosis

a deep triangular condensation of deep fascia that covers the palm and is anchored to the skin

continuous with the palmaris longus tendon

also contains palmaris brevis muscle

swelling from hand infections mostly appears on the

dorsum of the hand where facia is thinner

dupuytren's contracture

a disease of the fascia resulting in a thickening of the fibrous bands on the palmar surface of the hand and fingers

common bilaterally in males older than 50

associated with myofibroblast proliferation and type # collagen deposition

surgical excision of the fibrous parts of the palmar fascia frees the fingers

3 thenar muscles

abductor pollicis brevis, flexor pollicis brevis, opponens pollicis

nerve and action for the thenar muscles

N: recurrent branch of the median nerve (C8, T1)

deep head of flexor policis brevis receives ulnar nerve

A: abduct, flex, oppose thumb

abductor pollicis inserts on the

medial side of the base of the proximal phalanx of thumb

the radial artery to deep palmar arch passes between

transverse and oblique heads of muscle

adductor pollicis shares a

sesamoid bone with deep head of flexor pollicis brevis

lumbrical muscles attachment and nerve

A: originate on the FDP tendons and pass dorsally around the lateral side of each finger and insert into extensor hood

N: lateral 2 are median nerve

medial 2 are deep branch of ulnar

action of lumbrical muscles

flex the MCP joints and extend the IP joints

1st and 2nd lumbricals are for

digits 2-3

innervated by median nerve

extensor expansion hood allows

extension from lumbricals and interosseous muscles at the IP and DIP simultaneously with flexion of the MCP joints

the tendons of the lumbricals and interossei insert into the

extensor digitorum and extensor pollicis longus muscles

lumbricals and interossei flex

MCP and extend IPs

palmar vs dorsal interosseus muscles

P: adduction (PAD)

D: abduction (DAB)

the radial artery passes between heads of

1st dorsal interosseous muscles

fascia can isolate an

infection to a particular compartment or space in the palm

two entrapment injuries of the ulnar nerve

Elbow: either posterior to the medial epicondyle or the cubital tunnel between 2 heads of flexor carpi ulnaris

wrist: in guyons canal

ulnar nerve injury at wrist

lose innervation of interossei, medial 2 lumbricals and hypothenar muscles

tone of extensor digitorum is unopposed causing extension of MCP joints

tone of FDS and FDP is unopposed causing flexion of IP joints

clawing (hyperextension of the MCP joints and flexion of the IP joints) most pronounced in 4th and 5th digits

sensation is impaired in the medial 1 1/2 digits

ulnar nerve injury at elbow

in addition to claw hand the patient loses flexor carpi ulnaris innervation. This causes the wrist to deviate laterally upon attempts to flex wrist

claw hand at ulnar nerve wrist vs elbow

at wrist clawing is more pronounced than elbow bc at wrist the medial half of FDP is cut off

Guyon canal syndrome

compression of ulnar nerve within the tunnel of guyon leads to pain, paresthesias, or anesthesia in the ulnar nerve distribution of the hand

can be caused by cycling bc of compression from handle bars

also by fracture to hook of hamate

median nerve injury to arm in the cubital fossa (hand of benediction)

when a person attempts to make a fist, the 2nd and 3rd digits remain partially extended while the 4th and 5th digits flex normally

loss of FDS, thenar muscles, FDP and lumbricals to index and middle finger

carpal tunnel

the carpal bones are bound together with ligaments and tendons

the carpal tunnel is bound anteriorly by the transverse carpal ligament aka flexor retinaculum

the palmar carpal ligament is superficial and somewhat proximal to the TCL

carpal tunnel syndrome (simian hand)

compression of median nerve in carpal tunnel leads to pain and paresthesias, or anesthesia in lateral 3 1/2 digits, weakness of thenar muscles and lateral 2 lumbricals, atrophy if thenar eminence. inability to oppose thumb

sensory symptoms precede motor and symptoms can be worse at night

tinels sign

tapping over flexor retinaculum reproduces pain in the median nerve distribution. test for carpal tunnel

treatment for carpal tunnel

conservative treatments may involve splints, activity modification, stretching, vitamin B6, anti-inflammatory meds

surgical decompression by cutting transverse carpal ligament

pronator syndrome

median nerve becomes entrapped and compressed between the heads of pronator teres bc of hypertrophy or trauma

pain in proximal anterior forearm and decreased sensation of median nerve distribution in hand

symptoms proved by repetitive movements

ulnar claw hand is seen at

rest clawing is worse with distal lesion

when do you see hand of benediction proximal median nerve injury

observed during an attempt to make a fist

simian hand median nerve injury is observed at

rest the thumb is adducted and extended

present with the proximal median nerve injury in addition to hand of benediction

present with advanced case of CTS injury at wrist

median nerve branches at the wrist and hand

palmar branch

recurrent branch

digital branches

lumbricals

the thenar group is innervated by the

recurrent branch of the median nerve

the palmar branch of the median nerve innervates

skin of the palm. it does not traverse the carpal tunnel

superficial branch of ulnar nerve in hand

supplies sensation to the medial 1 1/2 digits and motor to palmaris brevis

deep branch of ulnar nerve

(C8, T1) supplies motor to most intrinsic muscles of hand

hypothenar, medial 2 lumbricals, all interossei, adductor pollicis, deep head of flexor pollicis brevis

palmar cutaneous branch and dorsal branch of ulnar nerve

sensory only

3 nerves of thumb simplified

radial nerve: thumb extension

ulnar nerve: thumb adduction

median nerve: opposition and abduction

the only part of the radial nerve that enters the hand is the

superficial branch. It crosses the snuff box and provides sensation to lateral dorsum of hand and then muscles

extension of digits tests which nerve

posterior interosseous branch of radial nerve