11. Upper limb nerve injuries Flashcards

1
Q

Where do LMN arise?

A

anterior horn cells

therefore anything before this is UMN

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2
Q

Characteristic features of UMN lesion?

A
  • Held in flexed posture if chronic.
  • Increased tone
  • Pyramidal weakness (Flexor muscles stronger than extensors)
  • Brisk reflexes.
  • Loss of sensation at sensory level
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3
Q

Characteristic features of LMN lesions?

A
  • Wasting/Fasciculations
  • Flaccid tone
  • Weakness in either a myotomal distribution or a peripheral nerve distribution
  • Reduced reflexes.
  • Dermatomal or peripheral nerve distribution of sensory loss.
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4
Q

How is Biceps reflex conveyed?

A

C5 reflex conveyed through the musculocutaneous nerve.

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5
Q

How is the Supinator jerk conveyed?

A

C6 reflex conveyed through the radial nerve

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6
Q

How is the Triceps jerk conveyed?

A

C7 reflex conveyed through the radial nerve.

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7
Q

How is the Finger jerk reflex conveyed?

A

C8 reflex conveyed through the median and ulnar nerve.

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8
Q

What type of lesions cause flail arm (cervical root avulsion)?

A

C5-T1 lesions

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9
Q

Erbs palsy

A

a.k.a. ‘waiters tip’

  • during childbirth- stretching of top brachial plexus
  • upper plexus palsy
  • C5/C6 innervated muscles (weakened)

e.g. biceps, brachioradialis, deltoid, supraspinatus, supinator- so arm can not be elevated, abducted, externally rotated etc.

HANDS WORK BUT ARM DOES NOT

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10
Q

Klumpke’s Palsy

A

-Inferior brachial plexus is injured

  • Arm works but hand does not
  • C8/T1/Inferior trunk injury
  • normally supplying median and ulnar nerves
  • Unable to flex wrist or fingers
  • Weakness of all small muscles of the hand
  • Sensory loss hand and inner border of forearm
  • Claw hand

E.g breech delivery

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11
Q

Lesions to the long thoracic nerve

A

-Long thoracic nerve supplies the serratus anterior muscle.

-The serratus anterior muscle pulls the medial border of the scapula
to the posterior thoracic wall and stabilises it there

-leads to “winging” of the scapula

Causes: Radial Mastectomy, heavy bags

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12
Q

What muscles are innervated by the median nerve? [4]

-What do these muscles form?

A

LOAF:

  • Lateral 2 lumbricals
  • Opponens pollicis
  • Abductor pollicis brevis
  • Flexor pollicis brevis
  • forms thenar eminence, damage causes thenar wasting

3 AND A HALF FINGERS

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13
Q

Common sites of compression of median nerve [2]

A

wrist (carpal tunnel)

elbow

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14
Q

Causes of Carpal Tunnel Syndrome

A
Diabetes
Pregnancy
Hypothyroidism
Rheumatoid arthritis
Repetitive strain

tested by tinels(tap), phalens (flex wrists)

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15
Q

Anterior interosseous nerve syndrome

A

-arises from median nerve above elbow

motor branch of median nerve

-Prone to compression between 2 heads of
pronator teres muscle

  • can be damaged in careless blood taking
  • weakness in FPL + FDL
  • weakness of pronation
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16
Q

Cancers causing brachial plexus injury

A

Pancoat tumour- infiltration of lower brachial plexus

-Pain

17
Q

Post radiation damage causing brachial plexus injury

A

Upper brachial plexus injury

Pain is not a consistent feature

18
Q

Inflammatory pathologies causing brachial plexus injury

A

Idiopathic brachial neuritis

severe pain
followed by weakness and wasting
Treatment: analgesis

19
Q

Structural anomalies causing brachial plexus injury

A

thoracic outlet syndrome

Anatomical variation causing compression sites

vascular vs neurogenic

20
Q

Lesion in the forearm vs lesion in carpal tunnel

A

Because the palmar cutaneuous sensory branch branches before carpal tunnel, the palm is affected

If it occurs in the carpal tunnel then the palm is spared

21
Q

Dermatome of middle finger

A

C7

22
Q

Dermatome of index AND thumb

A

c6

23
Q

Dermatome of ring finger and little finger

A

c8

24
Q

Explain why a patient gets an ulnar claw when their ulnar nerve is damaged

A

Muscles work in pairs

ED-L (ED is spared)
L-FDS (FDS is spared)
L-FDP (FDP is spared- only 3rd and 4th FDP are by ulnar nerve)

25
Q

Sensory innervation of the ulnar nerve

A

dorsal cutaneous branch

palmar cuteaneous branch

26
Q

Fromnents sign

A

sign of ulnar nerve palsy

cant grip so used median nerve structures

27
Q

Saturday night palsy

A

Radial nerve palsy
so all extensors are affected
always check anatomical snuff box bc that is innervated by radial nerve

28
Q

Ulnar nerve injury vs C8 injury

A

All finger extensors (radial nerve)

-FDP of index/middle (median nerve)