Topic 5: Muscles of the Forearm and Hand Flashcards

1
Q

Where do muscles act?

A

At joints

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2
Q

What tells you the main action of a joint?

A

the position a muscle crosses at a joint

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3
Q

Anterior position of a joint and its movement & action

A

Movement - anteriorly directed
Action - flexion

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4
Q

Posterior position of a joint and its movement & action

A

Movement- posteriorly directed
Action - extension

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5
Q

Medial position of a joint and its movement & action

A

Movement - medially directed
Action - adduction

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6
Q

Lateral position of a joint and its movement & action

A

Movement - laterally directed
Action - abduction

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7
Q

What movements do horizontal horizontal/ oblique fibres produce?

A

Rotational movements

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8
Q

What movements do vertical muscular fibres produce?

A

Flexion, extension, adduction, abduction

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9
Q

Extrinsic hand muscles definiton

A

Connects outside of the hand but acts on the hand to move the hand

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10
Q

Counting method rules

A
  1. start laterally and count medially
  2. only count the muscles that cross the wrist joint
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11
Q

How many extrinsic muscles of the FLEXOR side of the hand according to the Counting Method?
SUPERFICIAL

A

3

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12
Q

How many extrinsic muscles of the FLEXOR side of the forearm according to the Counting Method?
MIDDLE

A

1

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13
Q

How many extrinsic muscles of the FLEXOR side of the hand according to the Counting Method?
DEEP

A

2

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14
Q

How many extrinsic muscles of the EXTENSOR side of the hand according to the Counting Method?
SUPERFICIAL

A

5

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15
Q

How many extrinsic muscles of the EXTENSOR side of the hand according to the Counting Method?
DEEP

A

4

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16
Q

What is the Common Extensor Origin (CEO)?

A

Lateral epicondyle of the humerus

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17
Q

What is the Common Flexor Origin (CFO)?

A

Medial epicondyle of the humerus

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18
Q

POSTERIOR FOREARM
Muscles of the superficial layer (lateral to medial)

A
  1. extensor carpi radialis longus
  2. extensor carpi radialis brevis
  3. extensor digitorum
  4. extensor digiti minimi
  5. extensor carpi ulnaris
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19
Q

POSTERIOR FOREARM
Deep layer (lateral to medial)

A
  1. abductor pollicis longus
  2. extensor pollicis brevis
  3. extensor pollicis longus
  4. extensor indicis
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20
Q

What muscles make up the anatomical snuffbox?

A
  1. extensor pollicis brevis
  2. abductor pollicis longus
  3. extensor pollicis longus
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21
Q

What muscles are left in the posterior forearm that arent counted with the counting method?

A
  1. brachioradialis
  2. anconeus
  3. supinator
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22
Q

ANTERIOR FOREARM
Superficial layer (lateral to medial)

A
  1. flexor carpi radialis
  2. palmaris longus
  3. flexor carpi ulnaris
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23
Q

ANTERIOR FOREARM
Middle layer (lateral to medial)

A

Flexor digitorum superficialis

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24
Q

ANTERIOR FOREARM
Deep layer (lateral to medial)

A
  1. flexor digitorum profundus
  2. flexor pollicis longus
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25
Q

What muscles are left in the anterior forearm excluded from the counting method?

A
  1. pronator teres
  2. pronator quadratus
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26
Q

Landmark method

A

What is it:
1. next to/ deep to/ superficial to?
2. what pierces it? e.g. radial nerve pierces supinator

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27
Q

Where do the carpi muscles attach to?

A

bases of metacarpals

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28
Q

Where do the digitorum muscles attach to?

A
  1. phalanges (flexor side)
  2. extensor expansion (extensor side)
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29
Q

Where do the pollicis muscles attach to?

A

the thumb

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30
Q

INTRINSIC HAND MUSCLES
Axis of the hand

A

3rd finger (middle finger)

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31
Q

How far can the thumb rotate medially?

A

through 90 degrees

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32
Q

INTRINSIC MUSCLES OF THE HAND
Counting method for intrinsics

A

3 + 3 + 3

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33
Q

Thenar muscles (lateral to medial)

A
  1. abductor pollicis brevis
  2. flexor pollicis brevis
  3. opponens pollicis
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34
Q

Hypothenar muscles (lateral to medial)

A
  1. abductor digiti minimi
  2. flexor pollicis brevis
  3. opponens digiti minimi
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35
Q

Middle muscles (lateral to medial)

A
  1. adductor pollicis
  2. lumbricals
  3. interossei – palmar and dorsal
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36
Q

Pneumonic for intrinsic muscles of the hand

A

The Three Musketeers!
- All
- For
- One
—-> and
- One
- For
- All

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37
Q

What joints do the abductor muscles act at?

A

MCP and CMC jts
(outermost of the 3 muscles)

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38
Q

What joints do the flexor muscles act at?

A

MCP and CMC jts
(innermost of the 3 muscles)

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39
Q

What joints do the opponens muscles work at?

A

CMC jts
- rotation of the metacarpal
(deepest of 3 muscles)

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40
Q

What are the two heads of the ADDuctor pollicis?

A

Oblique & transverse heads

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41
Q

Where does the ADDuctor pollicis arise from?

A

capitate, base of 2nd & 3rd MC’s, palmar surface of 3rd MC

42
Q

distal Attachment of the ADDuctor pollicis

A

base proximal phalanx 1st digit

43
Q

What joints does the ADDuctor pollicis act at?

A

MCP and CMC jts

44
Q

What does the ADDuctor pollicis do?

A

brings thumb to palm of hand

45
Q

Where does the palmaris brevis arise from?

A
  1. flexor retinaculum and palmar aponeurosis & insets in to skin on ulnar border of hand
46
Q

What does the palmaris brevis do?

A
  1. wrinkles skin on ulnar side of hand
  2. deepens hollow of hand
47
Q

What are the lumbricals associated with?

A

The tendons of FDP (flexor digitorum profundus)

48
Q

What are the lumbricals attached to?

A

The extensor expansion

49
Q

What actions do the lumbricals do?

A
  1. flex the MCPs
  2. extend the IPs
    Proprioceptive role as well
50
Q

How many Palmar interossei muscles are there?

A

3

51
Q

What actions do the palmar interossei muscles do?

A

adduction

52
Q

How many dorsal interossei muscles are there?

A

4

53
Q

What actions do the dorsal interossei muscles do?

A

ABduction

54
Q

Where do the interossei muscles attach?

A

extensor expansion

55
Q

What joints do the interossei muscles act at?

A

MCP and IP jts

56
Q

FUNCTIONAL ANATOMY OF THE HAND
Accessory structures of the hand
1. Retinaculum

A
  • extensor
  • flexor
57
Q

FUNCTIONAL ANATOMY OF THE HAND
Accessory structures of the hand
2. Aponeurosis

A

Palmar aponeurosis

58
Q

FUNCTIONAL ANATOMY OF THE HAND
Accessory structures of the hand
3. connections

A

intertendinous connections

59
Q

FUNCTIONAL ANATOMY OF THE HAND
Accessory structures of the hand
4. dorsal digital expansion

A

extensor aponeurosis/ extensor expansion/ dorsal digital expansion/ extensor hood

60
Q

FUNCTIONAL ANATOMY OF THE HAND
Accessory structures of the hand
5. sheaths

A
  • fibrous flexor sheaths
  • synovial flexor sheaths
61
Q

Attachments of the extensor retinaculum

A

Radius, ulna, pisiform, triquetrum, ulnar collateral ligament

62
Q

Where does the extensor retinaculum run?

A

septa run to the carpal bones to form separate tunnels for the extensor tendons

63
Q

flexor retinaculum attachments

A

scaphoid & trapezium to pisiform and hamate

64
Q

General functions of the retinacula

A

prevent bowstringing
protect underlying structures

65
Q

additional functions of the flexor retinaculum

A
  1. converts anterior concavity of carpal bones into carpal tunnel, forms the anterior boundary of carpal tunnel
  2. provides attachment for muscles (6 muscles attach here)
66
Q

What shape & what is the palmar aponeurosis?

A

Triangular shaped sheet of fascia

67
Q

Where does the palmar aponeurosis extend from and to?

A

from the flexor retinaculum to the deep transverse metacarpal ligaments

68
Q

Function of palmar aponeurosis

A
  1. protects underlying vessels and nerves
  2. anchors the skin
  3. aids grip (by anchoring the skin)
69
Q

What are the intertendinous connections?

A

Fibrous connections between the bands of the extensor digitorum muscles just proximal to the MCP jts

70
Q

Function of intertendinous connections

A

prevents independent extension of any one finger, ensures hand opens as a unit when releasing grip (protective mechanism for the hand)

71
Q

Dorsal digital expansion/ extensor aponeurosis/ extensor expansion/ extensor hood what is it

A

forms an aponeurosis over the posterior surface of each finger

72
Q

Where does the Dorsal digital expansion/ extensor aponeurosis/ extensor expansion/ extensor hood receive attachments from?

A

ED, lumbricals, interossei

73
Q

What does the Dorsal digital expansion/ extensor aponeurosis/ extensor expansion/ extensor hood ensure?

A

simultaneous extension of the IP jts in each finger when releasing grip (imp for digital sweep)
(intertend connectios= for each individual digit, DDE = for IP jts)

74
Q

What is a fibrous flexor sheath?

A

Fibro-osseus tunnel for the flexor tendon in the digits

75
Q

Fibro-osseus part of the fibrous flexor sheaths

A

Bone posteriorly, fibrous sheath anteriorly

76
Q

What do fibrous flexor sheaths do?

A

act as pulleys for the flexor tendons, binding them onto the bones & preventing bowstringing within the digits
–> increases leverage & efficiency

77
Q

What is a synovial flexor sheath?

A

double layered tube which surrounds each tendon as it passes under the fibrous sheath

78
Q

Function of a synovial flexor sheath

A

allows friction free gliding of the tendon under the fibrous sheath

79
Q

What is the position of rest?

A
  • palm hollow
  • fingers flexed (index least, little most)
  • thumb slightly opposed and slightly flexed
80
Q

Position of function

A
  • wrist in slight DF
  • fingers slight flexion at IP, more flexion at MCP
  • thumb opposed and slightly flexed
81
Q

Functional advantages of the Position of function

A
  1. stable wrist position; ligaments taut, stable base for action of finger flexors & extensors
  2. long finger flexors are stretched, therefore all force of contraction exerted at finger jts rather than in taking up slack (optimal length tension relo)
  3. position used for splinting
    - allows prehensile grip
    - reduces the occurrence of contractures
    (not in scaphoid fracture)
82
Q

What does digital sweep describe?

A

the longest path taken by the fingertips as the hand closes

83
Q

Why is it desirable to have a long path in DS?

A

so that the fingertips make the largest arc possible
- allows grip of large objects

84
Q

Role of lumbricals and interossei in DS

A

moderate the effect of the long flexors and long extensors

85
Q

2 types of grip

A
  1. power grip
  2. precision grip
86
Q

What parts of the hand does the power grip involve?

A

whole hand

87
Q

What parts of the hand does the precision grip involve?

A

thumb & fingers

88
Q

What size objects is power grip good for?

A

large ones

89
Q

How much force is required for power grip?

A

considerable force reqd

90
Q

How much skin contact in power grip

A

whole hand = maximal skin contact with teh surface

91
Q

Jt positions (power grip)
1. Thumb

A

Abducted and adducting –> adductor pollicus

92
Q

Jt positions (power grip)
2. fingers

A

flexion at all jts of fingers
–> long flexor muscles

93
Q

Jt positions (power grip)
3. Palm

A

cupped
–> thenar and hypothenar muscles

94
Q

Jt positions (power grip)
4. Wrist

A

Dorsiflexion +/- ulnar deviation
–> wrist flexors & extensors working to stabilise wrist

95
Q

Size of objects for precision grip

A

small objects – sometimes fragile

96
Q

how much force is reqd for precision grip

A

less force reqd

97
Q

Which digits do precision grip?

A

lateral digits only

98
Q

How much skin contact in precision grip?

A

limited skin contact, but high sensory acuity

99
Q

Jt positions (precision grip)
1. Thumb

A

opposed
- opponens pollicus
- CMC jt –> FPB, FPL, AddPol
- MCP jt –> FPL, FPB
- IP jt –> FPL

100
Q

Jt positions
2. MCP of fingers

A

Flexion
- intrinsics of hand
- MCP –> FDS, FDP
- PIP –> FDS, FDP
- DIP –> FDP

101
Q

Jt positions
2. IP’s

A

may be flexed or extended depending on the task