Day 1.3 MSK Flashcards Preview

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Flashcards in Day 1.3 MSK Deck (45):
1

How is the upper trunk lesioned? What happens when it is?

Lesioned by trauma- most often in birth, but also from hyperextension of neck- so MVA.
Causes Erb-Duchenne Palsy (waiter's tip)

2

What are the characteristics of Erb-Duchenne Palsy?

Traction/tear of upper trunk (C5, C6 roots). "Waiter's tip":
paralysis of abductors (limb hangs by side)
medially rotated (paralysis of lateral rotators)
forearm is pronated (loss of biceps to supinate)

3

How is the C7 root injured?

Compressed by cervical disk lesion/herniation

4

How is the axillary nerve lesioned?

Fracture of surgical neck of humerus
Dislocation of humerus
Intramuscular injection

5

What are the characteristics of an axillary nerve lesion?

Axillary goes to deltoid m, which is the primary abductor of the arm. So loss of abduction, also decreased sensation over deltoid- check this before and after fixing a dislocation.

6

How is the radial nerve in the spiral groove lesioned?

Midshaft fracture to the humerus

7

How is the deep branch of the radial nerve injured?

Stretched by sublexation of the radius

8

How is the recurrent branch of the median nerve injured?

Lesioned by superficial laceration

9

How is the lower trunk of the brachial plexus injured?

Compressed by a cervical rib or by Pancoast's tumor. Leads to Klumpke's palsy

10

What is klumpke's palsy?

Childbirth defect affecting the inferior trunk of the brachial plexus (C8, T1)

11

What is thoracic outlet syndrome?

Cervical rib can compress the subclavian artery and inf trunk of brachial plexus, resulting in thoracic outlet syndrome
1. atrophy of thenar and hypothenar eminance
2. atrophy of interosseous muscles
3. sensory deficits on medial side of forearm and hand
4. disappearance of radial pulse when head is moved toward opposite side

12

Other than a cervical rib/Klumpke's palsy, what can cause thoracic outlet syndrome?

Hypertrophy of the anterior scalene muscle

13

What is Klumpke's total claw?

Lesion of lower trunk (C8, T1), leading to loss of fn of all lumbricals.
forearm finger flexors (part of median nerve w C5-C7) and finger extensors radial nerve) are unopposed, so there is clawing of all digits

14

How is the radial nerve injured in the axilla?

Compressed:
Incorrect use of crutch
Drunk on bench- Saturday night palsy

15

How is the median nerve injured near the elbow?

Compressed by supracondylar fracture of the humerus
Pronator teres syndrome

16

How is the ulnar nerve lesioned near the elbow?

Lesioned by repeated minor trauma
Fracture of the medial epicondyle of the humerus

17

How is the anterior interosseous nerve lesioned?

Compressed in deep forearm

18

How is the median nerve injured near the wrist?

Compressed by carpal tunnel syndrome (9 tendons run through carpal tunnel) or by dislocated lunate

19

How is the ulnar nerve lesioned near the wrist?

Trauma to the heel of the hand
Fracture of the hook of the hamate

20

In general, what muscles do each of these nerves supply:
Musculocutaneous
Radial
Median
Ulnar

MC = flexors
Radial = extensors
Median = thumb, pronators
Ulnar = wimpy. pinky, interosseous, some lumbricals

21

Axillary nerve injury

Cause: fractured surgical neck of humerus, dislocation of humerus head
Motor deficit: can't abduct arm at shoulder
Sensory: no sensation over deltoid m.
sign: flattened deltoid

22

Radial (C5-C8) nerve injury

Cause: fracture at midshaft of humerus, saturday night palsy (compresson of axilla)
Motor: can't extend wrist, can't extend fingers at MCP, can't supinate, can't extend or abduct thumb
Sensory: no sensation in posterior arm, dorsal hand, dorsal thumb
sign: wrist drop

23

Median (C6-T1) Proximal lesion

Cause: Fracture of supracondylar humerus
Motor: Can't oppose thumb
Sensory: No sensation in dorsal and palmar aspects of lateral 3.5 fingers, thenar eminence
Sign: ape hand

ALSO: lose latera lumbricals, so can't flex 2nd and 3rd digits --> pope's blessing!

24

Ulnar (C8-T1) Distal lesion

Cause: fracture of hook of hamate (fall on outstretched hand)
Motor: can't abduct or adduct fingers (interossei), can't adduct thumb, can't extend 4th or 5th fingers (lumbricals)
Sign: can't extend 4th and 5th fingers when trying to straighten fingers.

25

Median (C6-T1) Distal lesion

Cause: Carpal tunnel syndrome, dislocated lunate
Motor: can't flex lateral finger, can't flex wrist
Sensory: no sensation in dorsal and palmar parts of lateral 3.5 fingers
Sign: ulnar deviation of wrist (when wrist is flexed)

26

Ulnar (C8-T1) proximal lesion

Cause: fracture of medial epicondyle of humerus
Motor: can't flex medial finger, can't flex wrist
Sensory: can't feel medial 1.5 fingers or hypothenar eminance
Sign: radial deviation of wrist when flexing wrist

27

Musculocutanous nerve lesion

Cause: upper trunk compresison
Motor: can't flex at elbow
Sensory: can't feel lateral forearm

28

What causes Wrist Drop (can't extend wrist)?

Radial nerve injury

29

What does the radial nerve innervate?

BEST:
Brachioradialis
Extensors of wrist/fingers
Supinator
Triceps

30

What causes claw hand (can't flex DIP of 4th and 5th digits)

Ulnar nerve injury

31

What causes Saturday night palsy?

Radial nerve injury (compression in axilla)

32

What causes inability to pronate?

Median nerve injury

33

What causes Bishop's Hand/Benediction/Pope

Median nerve injury

34

What causes carpal tunnel syndrome?

Median nerve injury

35

What causes weak flexion?

MC nerve injury

36

What causes ape hand (can't oppose thumb)?

Median nerve injury

37

If the 2nd and 3rd (index and middle) digits are curled, what can it be?

If they are curled bc pt can't extend them: distal median nerve injury
If they are curled bc pt is making a fist and can't curl the 4th and 5th digits: proximal ulnar nerve injury

38

If the 4th and 5th digits are curled, what can it be?

If the 4th and 5th are curled bc they can't be extended: distal ulnar nerve injury
If they are curled bc pt is making a fist and can't curl 2nd and 3rd, it's median nerve injury (pope's blessing)

39

What happens in a distal ulnar nerve lesion?

Loss of medial lumbrical fn- 4th and 5th digits are clawed. (Hyperextension at MCP and flexion at IP)

40

What happens in a distal median nerve injury?

Loss of lateral lumbrical fn, so 2nd and 3rd digits are clawed. (Hyperextension at MCP and flexion at IP)

41

What happens in proximal median nerve injury?

Loss of oppnens pollicis muscle - so unopposable thumb. "ape hand"

42

What are the OAF muscles of the hand?

OAF = oppose, abduct, flex
Thenar = OAF pollicis:
opponens pollicis
abductor pollicis brevis
flexor pollicis brevis

Hypothenar = OAF digiti
opponens digiti minimi
abductor digiti minimi
flexor digiti minimi

43

What are the non-OAF muscles of the hand?

Dorsal interosseous muscles (ABduct)
Palmar interosseous muscles (ADduct)
DAB, PAD. Innervated by ulnar nerve
Lumbrical muscles- flex at the MP joint (if they are injured, get claws)
Innervated: ulnar lumbricals by ulnar nerve; radial lumbricals (2) by median nerve

44

T/F Pope's blessing and ape hand arise from the same nerve injury.

TRUE!
Proximal median nerve
Pope's blessing is d/t lateral lumbrical loss, so can't flex 2nd and 3rd fingers
Ape hand is d/t loss of opponens pollicis, so can't oppose thumb.

44

T/F Pope's blessing and ape hand arise from the same nerve injury.

TRUE!
Proximal median nerve
Pope's blessing is d/t lateral lumbrical loss, so can't flex 2nd and 3rd fingers
Ape hand is d/t loss of opponens pollicis, so can't oppose thumb.