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ESA 2 > MSK 5b: the hand > Flashcards

MSK 5b: the hand Flashcards

1
Q

Describe the articulations of the carpal bones with the hand and the forearm bones

A

Proximally: scaphoid and lunate articulate with the radius
Distally: trapezium, trapezoid, capitate and hamate articulate with the metacarpals

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2
Q

Describe some common fractures of the wrist bones and associated complications

A

Scaphoid: FOOSH: fall on palm when hand abducted. Pain on lateral side of wrist (anatomical snuffbox), esp during dorsiflexion and abduction. Poor blood supply to proximal part so may cause avascular necrosis of this area, leading to degenerative joint disease of the wrist

Lunate: FOOSH when wrist is hyperextended. May damage median nerve

Hamate: may result in non-union of the fractured parts due to the traction of the attached muscles. Ulnar artery and ulnar nerve may be damaged (nerve close to hook of hamate)

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3
Q

Describe the metacarpals

A

Moving distally, the next set of bones of the hand after the carpals. Form skeleton of the palm
1st (thumb, shortest and thickest) to 5th (little finger)
Each has a base, a shaft and a head
3rd metacarpal has a styloid process on the lateral part of its base
Proximal bases articulate with carpal bones, and distal heads articulate with proximal phalanges forming the knuckles
Medial and lateral surfaces are slightly concave to allow attachment of interossei muscles

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4
Q

Metacarpal fractures

A

Usually stable as 2nd-5th close together

Boxer’s fracture: fracture of 5th metacarpal as clenched fist (closed and abducted) strikes someone/thing. Head of bone rotates over distal end of shaft causing a flexion deformity

Bennett’s fracture: base of 1st metacarpal extending into carpometacarpal joint, caused by hyperabduction of thumb

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5
Q

Phalanges

A

Thumb has proximal and distal (stouter than fingers)
2nd-5th digits have proximal (largest), intermediate and distal (smallest; flattened at distal ends underlying nail beds)
Each phalynx has base, shaft and head

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6
Q

How might the phalanges be damaged?

A

Crushing injuries: usually of distal, e.g. finger caught in car door
Very painful due to highly-developed sensation in fingers
Fracture of distal phalynx usually comminuted, haematoma develops

Fracture of proximal and intermediate due to crushing of hyperextension

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7
Q

Outline briefly the muscles that supply the hand

A

Extrinsic: see anterior and posterior forearm. Control crude movements and produce a forceful grip:

  • flexor digitorum superficialis
  • flexor digitorum profundus
  • flexor pollicis longus
  • flexor carpi radialis and ulnaris and palmaris longus
  • abductor pollicis longus
  • extensor pollicis longus and brevis
  • extensor indices
  • extensor digitorum
  • extensor digiti minimi
  • extensor carpi radialis longus+brevis and extensor carpi ulnaris

Intrinsic: located within the hand, for fine motor functions

  • thenar muscles (4)
  • hypothenar muscles (3)
  • lumbricals (4)
  • interossei (7)
  • palmaris brevis (1)
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8
Q

Describe the muscles of the thenar eminence

A

OPPONENS POLLICIS: deepest and largest

  • from flexor retinaculum and tubercle of scaphoid and trapezium, to lateral side of 1st metacarpal
  • N: recurrent branch of median (C8,T1)
  • A: opposes thumb by medial rotation & flexion

ABDUCTOR POLLICIS BREVIS: anterior to OP, posterior to FPB

  • from flexor retinaculum and tubercle of scaphoid and trapezium to lateral side of base of proximal phalynx of thumb
  • N:recurrent branch of median (C8,T1)
  • A: abducts thumb and helps oppose

FLEXOR POLLICIS BREVIS: most distal

  • same insertions as ABD
  • N: superficial head median, deep head ulnar
  • A: flexion @ MCP joint

ADDUCTOR POLLICIS:

  • Oblique head: from bases of 2nd and 3rd metacarpals and capitate to proximal phalynx of thumb
  • Transverse head: from anterior surface of 3rd metacarpal shaft, to proximal phalynx of thumb
  • N: deep branch of ulnar (C8, T1)
  • A: adducts thumb
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9
Q

Describe the hypothenar muscles

A

All innervated by deep branch of ulnar nerve (C8, T1)

OPPONENS DIGITI MINIMI: deepest

  • from hook of hamate and flexor retinaculum to medial border of 5th metacarpal
  • rotates MC and draws anteriorly to palm (opposition)

ABDUCTOR DIGITI MINIMI: most superficial

  • from pisiform to base of proximal phalynx of 5th digit
  • abducts 5th digit and assists flexion of proximal phalynx

FLEXOR DIGITI MINIMI BREVIS

  • from hook of hamate and flexor retinaculum to base of prox phalynx
  • flexes proximal phalynx @ MCP joint
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10
Q

Palmaris brevis

A

Small and thin, very superficial in subcutaneous tissue
From palmar aponeurosis and flexor retinaculum to dermis on medial margin of hand
Ulnar innervates
Deepens the curvature of the hand and improves grip

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11
Q

Lumbricals

A

4 muscles, each associated with a finger. Slender and “worm-like” muscles
Actions: flex at MCP joints and extend IP joints of each finger
All insert onto lateral sides at extensor hoods

Origins and innervations:

  • Lateral (I and II; index and middle): lateral two tendons of FDP (as unipennate), Median nerve (C8, T1)
  • Medial (III and IV; ring and little): medial 3 tendons of FDP (as bipennate). Ulnar nerve (deep C8, T1)`
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12
Q

Interossei

A

Between metacarpals. Have individual actions but in general help MCP flexion and IP extension. All innervated by ULNAR (C8, T1)

Dorsal interossei (1st-4th):

  • most superficial of all dorsal muscles
  • O: adjacent surfaces of 2 metacarpals (bipennate)
  • I: extensor hood and proximal phalynx of each finger
  • A: abductrs digits 2-4 from axial line

Palmar interossei (1st-3rd)

  • located anteriorly on hand
  • O: palmar surface of 2nd, 4th and 5th metacarpals (unipennate)
  • I: extensor hood and base of proximal hood of same finger
  • A: adducts fingers at MCP joint
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13
Q

Describe the fascia of the hand

A

Palmar fascia is thin over the thenar and hypothenar regions but thick centrally:

  • centrally: PALMAR APONEUROSIS (overlies the long flexor tendons)
  • proximal end: continuous with flexor retinaculum and palmaris longus tendon
  • distal end: forms 4 longitudinal bands that attach to the bases of the proximal phalanges. These become continuous with the FIBROUS DIGITAL SHEATHS
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14
Q

List the movements of the thumb and the muscles that facilitate them

A 
Extension: EPL, EPB, AbPL
Flexion: FPL and FPB
Abduction: AbPL and APB
Adduction: AdP and 1st dorsal interossei
Opposition: opponens pollicies
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15
Q

Describe the arterial supply to the hand

A

Radial artery supplies floor and the lateral half of the index finger, ulnar artery supplies the rest of the digits:

Superficial palmar arch: from ulnar
Deep palmar arch: from radial
Common palmar digital: from SPA
Proper palmar digital: from CPDs
Princeps pollicis: from radial
Radialis indicis: from radial
Dorsal carpal arch: radial and ulnar
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16
Q

Describe the venous supply to the hand

A

Superficial and deep venous palmar arches drain into the deep veins of the forearm
Dorsal digital veins drain into 3 dorsal metacarpal veins to form a dorsal venous network. Prolonged proximally on the lateral side as the cephalic vein, and on the medial side as the basilic vein

17
Q

Describe the modified Allen’s test

A

Measures arterial competence before taking an arterial blood sample to analyse gases

Instruct the patient to clench their fist then apply occlusive pressure to both the ulnar and radial arteries
While applying occlusive pressure to both arteries, have the patient relax their hand, and check whether the palm and fingers have blanched. If this is not the case, you have not completely occluded the arteries with your fingers.
Release the occlusive pressure on the ulnar artery only to determine whether the modified Allen test is positive or negative.

Positive modified Allen test – If the hand flushes within 5-15 seconds it indicates that the ulnar artery has good blood flow; this normal flushing of the hand is considered to be a positive test.
Negative modified Allen test – If the hand does not flush within 5-15 seconds, it indicates that ulnar circulation is inadequate or nonexistent; in this situation, the radial artery supplying arterial blood to that hand should not be punctured.

18
Q

Describe the nerves in the hand

ALSO LEARN THEIR PERIPHERAL DISTRIBUTION

A

Median:

  • recurrent (thenar) branch)
  • lateral branch
  • medial branch
  • palmar cutaneous branch

Radial: superficial branch

Ulnar:

  • palmar cutaneous branch
  • dorsal branch
  • superficial branch
  • deep branch
19
Q

Damage to median nerve at elbow?

A

Hand of Benediction: can’t flex index and middle fingers when asked to make a fist, because the long flexors of the anterior forearm (except FCU and medial half of FDP) and the lateral 2 lumbricals are paralysed

Simian hand: inability to oppose and limited abduction of thumb when recurrent branch of median nerve severed in thenar eminence

20
Q

Damage to ulnar nerve at wrist?

A

Ulnar claw: ring and little fingers hyperextended at MCPJ and flexed at IPJ-looks like hand of benediction but at rest. I.e.unopposed extension at MCP and unopposed flexion at IP. Due to paralysis of medial 2 lumbricals [loss of flexion at MCP and loss of extension at IP], interossei, hypothenar muscles and adductor pollicis

Ulnar paradox: ulnar nerve damaged at elbow. Paralyses medial half of FDP and all of FCU AS WELL AS the hand muscles in ulnar claw. Claw much less evident: FDP paralysed so no flexion @ distal IP joints, so only hyperextension at MCP and flexion at proximal IP

21
Q

Which tendons pass through the carpal tunnel?

A

4 x FDP
4 x FDS
1 x FPL

22
Q

FDP and FDS flexor tendons

A

On palmar side

  • allow flexion, pass through carpal tunnel, protected by common flexor sheath then digital synovial sheaths in each finger
  • FDS tendon splits near base of each proximal phalynx, so FDP tendon can passthrough and insert onto distal phalanges
23
Q

Joints of the hand

A

Intercarpal joints: plane joints, between carpal bones

Carpometacarpal joints: plane, between distal surfaces of distal carpals and bases of metacarpals

Intermetacarpal joints: plane, between adjacent metacarpals

Metacarpophalangeal joints: condyloid joints, between metacarpal and proximal phalynx in each digit, permit flexion-extension and abduction-adduction. Knuckles

Interphalangeal joints: hinge joints, 2 per digit: PIPJ and DIPJ. Thumb only has one. Flexion and extension

24
Q

Ligaments of the hand

A

FLEXOR RETINACULUM: roof of carpal tunnel. Attaches medially to pisiform and hook of Hamate, and laterally to trapezium and scaphoid

EXTENSOR RETINACULUM: dorsum of hand-keeps extensor tendons in place to prevent bowstringing

PALMAR PLATES: palmar side of each MCP and IP joint, limits hyperextension

COLLATERAL LIGAMENTS: on medial and lateral sides of each MCP and IP joint. Limit abduction when hand in fist, lax when extended to allow adduction

25
Q

What are the borders of the anatomical snuffbox? [from anatomical position..often on patient is pronated]. when thumb extended

A

Medial (ulnar): tendon of EPL
Lateral (radial): tendons of APL and EPB
Proximal: styloid process of radius
Floor: scaphoid and trapezium

26
Q

Contents of the anatomical snuffbox

A

Radial artery: crosses floor obliquely, deep to extensor tendons, can be palpated
Radial nerve: superficial branch across roof. Innervates skin of lateral 3.5 digits on dorsum and associated palm area
Cephalic vein: arises from dorsal venous network

27
Q

All For One And One For All: intrinsic muscles of hand and relative palmar anatomical position, from lateral to medial

A 
A: abductor pollicis brevis
F: flexor pollicis brevis
O: opponens pollicis
A: adductor pollicis
O: opponens digiti minimi
F: flexor digiti minimi
A: abductor digiti minimi
28
Q

PAd DAb: function of palmar and dorsal interossei

A

P: palmar interossei
Ad: adduction
D: dorsal interossei
Ab: abduction

29
Q

LOAF: the 4 intrinsic muscles innervated by median nerve (Rest are ulnar)

A

Lumbricals 1 and 2
Opponens pollicis
Abductor pollicis breivs
Flexor pollicis brevis (Deep head often some ulnar)

ESA 2 (58 decks)

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