8. Wrist and Hand

Lecture 8 - tompkins

carpal bones

some lovers try positions that they cant handle

scaphoid, lunate, triquetrum, posiform, trapezium, trapezoid, capitate, hamate

physes (growth plate) of the hand

is at the base of each phalanx of all five digits

physis is at the junction of the head and neck of metacarpals 2-5

physis of first metacarpal is at its base

thumb motion of carpo-metacarpal joints

complex motion of the saddle joint between the trapezium and base of the 1st metacarpal

index finger motion of carpo-metacarpal joints

almost no motion

middle motion of carpo-metacarpal joints

almost no motion

ring finger motion of carpo-metacarpal joints

a little flexion/extension

pinkie finger motion of carpo-metacarpal joints

small, much more flexion/extension (plus some degree of opposition

boxers fracture

fracture of the neck or distal shaft of the 5th metacarpal (rarely 4th)

very common in males

angular malunion well tolerated because of the relatively wide moriton of the 5th CMC joint

radio carpal joint is between

distal radius

scaphoid and lunate

ulno carpal joint

includes the triangular fibrocartilage complex

lunate bone

“lunar” appearance

articulates with the distal radius proximally and capitate distally

mild volar tilt of the articular surface of the distal radius

ligaments of the carpus

radioscapholunate ligament and short radiolunate ligament

palmar aspect of wrist

flexor retinaculum (deep to ulnar nerve)

triangular fibro-cartilage complex lies here

ulnar styloid

distal radio-ulnar joint

radial styloid

scapho-lunate ligament tear

typical mechanism of injury is a fall on outstretched hand

allows separation between scaphoid and lunate, creating a gap

the gap might be seen only on a clenched fist AP xray

gap is named “terry thomas sign”

blood supply to scaphoid

enters only through distal pole

if scaphoid is fractured, avascular necrosis of proximal pole is a potential complication on a scaphoid fracture non-union

osteonecrosis

six dorsal wrist compartments

first compartment: abductor pollicis longus, extensor pollicis brevis

third compartment contains the extensor pollicis longus

between the first and third dorsal compartments lies the so-called anatomic snuff box (deep to which lies the scaphoid)

tenderness in anatomic snuff box

if a patient has fallen on outstretched hand and is tender in the snuff box, assume the scaphoid is broken

scaphoid fractures can be subtle

consider CT or MRI scan if in doubt

de Quervain’s tenosynovitis

stenosing tenosynovial “inflammation” (not really) of first dorsal compartment

very common malady

pain on radial side of wrist

tender over first dorsal compartment

finkelstein’s maneuver (passive flexion of thumb with ulnar deviation of wrist) elicits radial wrist pain

movements at wrist joints

flexion, extension, radial deviation (abduction), ulnar deviation(adduction), pronation and supination of DRUJ

MCP joints allow what movement of the finger joint

flexion and extension and (in most people) marked hyperextension

abduction and adduction (especially when MCP joints are extended)

PIP joint movement

flexion and extension

DIP joint movement

allow flexion and extension

two views of metacarpo-phalangeal (MCP) joint

note that on the lateral view of the finger, the metacarpal (MC) head has a slightly cam-shaped contour

dorsal capsule is illustrated as having a wavy appearance, indicating laxity

cord portion of collateral ligament has wavy contour along its superior border in this illustration, indicating that when the MCP joint is in extension, the collateral ligament is lax

MCP flexion tightens collateral ligaments

in extension, the collateral ligaments of the MCP joint are relaxed, allowing abduction and adduction

in flexion, the collateral ligaments of the MCP joint are taut, restricting abduction and adduction

collateral ligaments importance

if a MCP joint is immobilized in extension for very long, the collateral ligaments will become contracted, and it will be difficult for the patient to regain MCP joint flexion

the opposite is true for an interphalangeal joint. it tends to get stiff if it is immobilized in flexion because its volar plate becomes contracted

the safe position for hand immobilization

MCP joints in 80-90 degrees of flexion

PIP joints in full extension

DIP joints in full extension

wrist in mild extension

coronal plane thumb movement

radial abduction/adduction

sagittal plane thumb movement

palmar abduction/adduction

combined thumb movements

allow for opposition of the thumb across the palm and repostition back to the anatomic position

opposition of the thumb

complex combination of motions allowed by the saddle design of the carpo-metacarpal joint of the thumb along with some motion at the scapho-trapexial joint

thenar compartment of the hand

contains flexor pollicis longus tendon and 3 muscles (including flexor pollicis brevis

hypothenar compartment of the hand contains

3 muscles

central compartment of the hand contains

all 8 long finger flexor tendons and lumbrical muscles

superficial palmar (volar) arterial arch

palmar branch of median nerve and superficial ulnar n

interosseous compartment of hand contains

adductor pollicis and all interossei muscles

deep palmar (volar) arterial arch

deep branch of ulnar nerve

metacarpal bones 2-4

contents of the thenar compartment

thenar eminence muscles (abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis)

flexor pollicis longus tendon

palmar branch of radial artery

general rule of hand innervation

ulnar nerve innervates the intrinsic muscles of the hand except:

the recurrent branch of the median nerve innervates the three thenar muscles

the median nerve innervates lumbrical muscles 1 and 2

contents of the hypothenar compartment

abductor digiti minimi

flexor digiti minimi brevis

opponens digiti minimi

innervated by ulnar nerve

four short muscles of the thumb

abductor pollicis brevis

flexor pollicis brevis

opponens pollicis

(above is innervated by median nerve)

adductor pollicis muscle (in the interosseus compartment and is innervated by the ulnar nerve

motor branch of the median nerve is called

the recurrent branch because it (sort of) loops backward

has a variable pattern, in some patients it penetrates the flexor retinaculum

innervates the three thenar muscles

action of lumbricals

flexion of MCP joint and extension of PIP and DIP joints

innervation of lumbricals

1st and 2nd: median nerve

3rd and 4th: ulnar nerve

adductor pollicis

has transverse and oblique head

inserts on medial side base proximal phalanx

innervated by ulnar nerve

opponens pollicis

originates from trapezium and retinaculum

inserts on first metacarpal shaft

innervated by recurrent median nerve

palmar and dorsal interossei muscles of hand

insertions for palmar interossei are entirely into the extensor tendons

insertion for 1st dorsal interosseus is entirely into bone

insertion for the other 3 dorsal interossei is partially into bone and partially into the extensor tendons

actions of interossei muscles

palmar interossei adduct digits (PAD)

Dorsal interossei abduct digits (DAB)

both flex MCP joints and extend PIP and DIP joints

innervation is ulnar nerve

carpal tunnel contains nine tendons and one nerve

median nerve

2 tendons to each finger (8)

flexor pollicis longus

ulnar artery

main contributor for superficial palmar arch

palmar metacarpal arteries

come off the deep palmar arch

Dupuytren’s contracture

fibroproliferative disorder

myofibroblasts are culprits

nodules and skin pits might be seen in early stage

benign, usually painless disorder, but impairs function

typically affects ring finger but often affects little and middle finger

dupuytren’s contracture more info

etiology is unknown

risk factors: northern europe ancestry, diabetes mellitus

spreads from palm to fingers

digital neurovascular bundles can be displaced, placing them at risk of injury during surgical release

paronychia

inflammation of nail fold

very common'

often infectious in nature

relatively benign

treatment: warm soaks, antibiotics, drainage

felon (infection)

infection of palmar aspect of distal phalanx (pad of finger)

closed spaces in pad containing fatty tissue are created by fibrous septa

if abscess is present, urgent surgical drainage is needed to prevent necrosis of tissue

septic flexor tenosynovitis

knavel signs in classic cases

closed synovial sheath impairs hosts defenses

poor outcome if treatment is delayed

surgical drainage is typically necessary

septic MCP joint

skin and subcutaneous tissue covers the finger extensor tendon

the tendon partially covers MCP joint

penetration of the skin, tendon, or joint capsule can occur when a fist strikes a tooth

eikenella corrodens in human bites

myotome of upper extremity

C5- shoulder abduction

C6- elbow flexion

C7- elbow extension

C8- thumb extension

T1- finger adduction