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ANAT102 > Topic 5: Muscles of the Forearm and Hand > Flashcards

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
What muscles are left in the anterior forearm excluded from the counting method?
1. pronator teres 2. pronator quadratus
26
Landmark method
What is it: 1. next to/ deep to/ superficial to? 2. what pierces it? e.g. radial nerve pierces supinator
27
Where do the carpi muscles attach to?
bases of metacarpals
28
Where do the digitorum muscles attach to?
1. phalanges (flexor side) 2. extensor expansion (extensor side)
29
Where do the pollicis muscles attach to?
the thumb
30
INTRINSIC HAND MUSCLES Axis of the hand
3rd finger (middle finger)
31
How far can the thumb rotate medially?
through 90 degrees
32
INTRINSIC MUSCLES OF THE HAND Counting method for intrinsics
3 + 3 + 3
33
Thenar muscles (lateral to medial)
1. abductor pollicis brevis 2. flexor pollicis brevis 3. opponens pollicis
34
Hypothenar muscles (lateral to medial)
1. abductor digiti minimi 2. flexor pollicis brevis 3. opponens digiti minimi
35
Middle muscles (lateral to medial)
1. adductor pollicis 2. lumbricals 3. interossei -- palmar and dorsal
36
Pneumonic for intrinsic muscles of the hand
The Three Musketeers! - All - For - One ----> and - One - For - All
37
What joints do the abductor muscles act at?
MCP and CMC jts (outermost of the 3 muscles)
38
What joints do the flexor muscles act at?
MCP and CMC jts (innermost of the 3 muscles)
39
What joints do the opponens muscles work at?
CMC jts - rotation of the metacarpal (deepest of 3 muscles)
40
What are the two heads of the ADDuctor pollicis?
Oblique & transverse heads
41
Where does the ADDuctor pollicis arise from?
capitate, base of 2nd & 3rd MC's, palmar surface of 3rd MC
42
distal Attachment of the ADDuctor pollicis
base proximal phalanx 1st digit
43
What joints does the ADDuctor pollicis act at?
MCP and CMC jts
44
What does the ADDuctor pollicis do?
brings thumb to palm of hand
45
Where does the palmaris brevis arise from?
1. flexor retinaculum and palmar aponeurosis & insets in to skin on ulnar border of hand
46
What does the palmaris brevis do?
1. wrinkles skin on ulnar side of hand 2. deepens hollow of hand
47
What are the lumbricals associated with?
The tendons of FDP (flexor digitorum profundus)
48
What are the lumbricals attached to?
The extensor expansion
49
What actions do the lumbricals do?
1. flex the MCPs 2. extend the IPs Proprioceptive role as well
50
How many Palmar interossei muscles are there?
3
51
What actions do the palmar interossei muscles do?
adduction
52
How many dorsal interossei muscles are there?
4
53
What actions do the dorsal interossei muscles do?
ABduction
54
Where do the interossei muscles attach?
extensor expansion
55
What joints do the interossei muscles act at?
MCP and IP jts
56
FUNCTIONAL ANATOMY OF THE HAND Accessory structures of the hand 1. Retinaculum
- extensor - flexor
57
FUNCTIONAL ANATOMY OF THE HAND Accessory structures of the hand 2. Aponeurosis
Palmar aponeurosis
58
FUNCTIONAL ANATOMY OF THE HAND Accessory structures of the hand 3. connections
intertendinous connections
59
FUNCTIONAL ANATOMY OF THE HAND Accessory structures of the hand 4. dorsal digital expansion
extensor aponeurosis/ extensor expansion/ dorsal digital expansion/ extensor hood
60
FUNCTIONAL ANATOMY OF THE HAND Accessory structures of the hand 5. sheaths
- fibrous flexor sheaths - synovial flexor sheaths
61
Attachments of the extensor retinaculum
Radius, ulna, pisiform, triquetrum, ulnar collateral ligament
62
Where does the extensor retinaculum run?
septa run to the carpal bones to form separate tunnels for the extensor tendons
63
flexor retinaculum attachments
scaphoid & trapezium to pisiform and hamate
64
General functions of the retinacula
prevent bowstringing protect underlying structures
65
additional functions of the flexor retinaculum
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
What shape & what is the palmar aponeurosis?
Triangular shaped sheet of fascia
67
Where does the palmar aponeurosis extend from and to?
from the flexor retinaculum to the deep transverse metacarpal ligaments
68
Function of palmar aponeurosis
1. protects underlying vessels and nerves 2. anchors the skin 3. aids grip (by anchoring the skin)
69
What are the intertendinous connections?
Fibrous connections between the bands of the extensor digitorum muscles just proximal to the MCP jts
70
Function of intertendinous connections
prevents independent extension of any one finger, ensures hand opens as a unit when releasing grip (protective mechanism for the hand)
71
Dorsal digital expansion/ extensor aponeurosis/ extensor expansion/ extensor hood what is it
forms an aponeurosis over the posterior surface of each finger
72
Where does the Dorsal digital expansion/ extensor aponeurosis/ extensor expansion/ extensor hood receive attachments from?
ED, lumbricals, interossei
73
What does the Dorsal digital expansion/ extensor aponeurosis/ extensor expansion/ extensor hood ensure?
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
What is a fibrous flexor sheath?
Fibro-osseus tunnel for the flexor tendon in the digits
75
Fibro-osseus part of the fibrous flexor sheaths
Bone posteriorly, fibrous sheath anteriorly
76
What do fibrous flexor sheaths do?
act as pulleys for the flexor tendons, binding them onto the bones & preventing bowstringing within the digits --> increases leverage & efficiency
77
What is a synovial flexor sheath?
double layered tube which surrounds each tendon as it passes under the fibrous sheath
78
Function of a synovial flexor sheath
allows friction free gliding of the tendon under the fibrous sheath
79
What is the position of rest?
- palm hollow - fingers flexed (index least, little most) - thumb slightly opposed and slightly flexed
80
Position of function
- wrist in slight DF - fingers slight flexion at IP, more flexion at MCP - thumb opposed and slightly flexed
81
Functional advantages of the Position of function
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
What does digital sweep describe?
the longest path taken by the fingertips as the hand closes
83
Why is it desirable to have a long path in DS?
so that the fingertips make the largest arc possible - allows grip of large objects
84
Role of lumbricals and interossei in DS
moderate the effect of the long flexors and long extensors
85
2 types of grip
1. power grip 2. precision grip
86
What parts of the hand does the power grip involve?
whole hand
87
What parts of the hand does the precision grip involve?
thumb & fingers
88
What size objects is power grip good for?
large ones
89
How much force is required for power grip?
considerable force reqd
90
How much skin contact in power grip
whole hand = maximal skin contact with teh surface
91
Jt positions (power grip) 1. Thumb
Abducted and adducting --> adductor pollicus
92
Jt positions (power grip) 2. fingers
flexion at all jts of fingers --> long flexor muscles
93
Jt positions (power grip) 3. Palm
cupped --> thenar and hypothenar muscles
94
Jt positions (power grip) 4. Wrist
Dorsiflexion +/- ulnar deviation --> wrist flexors & extensors working to stabilise wrist
95
Size of objects for precision grip
small objects -- sometimes fragile
96
how much force is reqd for precision grip
less force reqd
97
Which digits do precision grip?
lateral digits only
98
How much skin contact in precision grip?
limited skin contact, but high sensory acuity
99
Jt positions (precision grip) 1. Thumb
opposed - opponens pollicus - CMC jt --> FPB, FPL, AddPol - MCP jt --> FPL, FPB - IP jt --> FPL
100
Jt positions 2. MCP of fingers
Flexion - intrinsics of hand - MCP --> FDS, FDP - PIP --> FDS, FDP - DIP --> FDP
101
Jt positions 2. IP's
may be flexed or extended depending on the task

ANAT102 (9 decks)

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