Neuroscience Major Plexuses and Peripheral Nerves Flashcards

1
Q

Brachial Plexus

A
  • Nerve roots from C5, C6, C7, C8, T1.
  • Major sensory & motor innervation for U.E.
  • Robert Taylor Drinks Cold Beer.
  • Roots, Trunks, Divisions, Cords, Branches.
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2
Q

Brachial Plexus

A
  • Posterior cord – ARTS
  • Axillary, Radial, Thoracodorsal, Subscapular.
  • Musculocutaneous nerve – BBC
  • Biceps, brachialis, coracobrachialis.
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3
Q

Figure 9.2 Brachial Plexus: Simplified Schematic

A

Lth = Bell’s long thoracic n.

DSc = dorsal scapular n.

SuSc = suprascapular n.

SuCl – n. to subclavius

LP = lateral pectoral n.

A = axillary n.

R = radial n.

T = thoracodorsal n.

S = subscapular n.

MP = medial pectoral n.

MC,A = medial cutaneous n. of arm

MC,F = medial cutaneous n. of forearm

Musc. = musculocutanous n.

Med. = median n.

Uln. = ulnar n.

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4
Q

Figure 9.3 Lumbosacral Plexus

A
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5
Q

Figure 9.4 Lumbosacral Plexus: Simplified Schematic

A

Most Clinically Relevant:

F = femoral

Obt - obturator

Sc = sciatic

T = tibial

(CP = common peroneal)

SP = superficial peroneal

DP = deep peroneal

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6
Q

Lower Extremity Strength Testing:

A

https: //drive.google.com/file/d/0B5o1XviBdHwrOC1mNU5ZbEl0cFU/view?usp=sharing
https: //drive.google.com/file/d/0B5o1XviBdHwrc21rcHRBTlFEX00/view?usp=sharing

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7
Q

Important Nerves of the Leg

A
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8
Q

Important Nerves of Leg

A
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9
Q

Cervical Plexus

A

CN XII and C1 - C5

Phrenic nerve;

C3,4,5 keeps the diaphragm alive.

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10
Q

Brachial Plexus

A
  • Axillary Nerve: C5, C6.
  • Musculocutaneous Nerve: C5, C6, C7.
  • Radial Nerve: C5, C6, C7, C8,T1.
  • Median Nerve: C6, C7, C8, T1.
  • Ulnar Nerve: C8, T1.
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11
Q

Five Important Nerves in the Arms

A
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12
Q

Five Important Nerves in the Arm

A
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13
Q

Upper Extremity Strength Testing:

A

https://drive.google.com/file/d/0B5o1XviBdHwrbU00cm9IaW9fMkE/view?usp=sharing

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14
Q

Thumb Strength Testing & Nerves:

A

https://drive.google.com/file/d/0B5o1XviBdHwrTGMxYWZNUlNnVGM/view?usp=sharing

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15
Q

Intrinsic Hand Muscles

A

innervated by ulnar nerve except LOAF
Lumbricals 1 and 2
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis

  • Thunor eminence.
  • Opponens pollicis, ABD pollicis brevis, flexor pollicis brevis.
  • Hypothenar eminence.
  • Opponens digiti minimi, flexor digiti minimi, ABD digit minimi.
  • Lumbricals.
  • Interossei.
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16
Q

Figure 9.6 Three Nerves Acting on the Thumb

A
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17
Q

Muscles Contributing to Flexion and Extension at Finger Joints

A
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18
Q

Upper Extremity Nerve Injuries

A
  • Brachial plexus, upper trunk injury = (Erb-Duchenne palsy).
  • Traction of infants shoulder.
  • Motorcycle accident.
  • Loss of C5C6 = weak biceps, deltoids, infraspinatus & wrist extensors.
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19
Q

Figure 9.7 “Bellman’s,” or “Waiter’s Tip,” Pose Assumed in Upper-Plexus Lesions

A
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20
Q

Upper Extremity Nerve Injuries

A
  • Brachial plexus, lower trunk injury = Klumpke’s palsy.
  • Grabbing a branch during a fall, TOS, Pancoast tumour.
  • Weakness C8, T1 = hand & finger weakness, atrophy of hypothenar, sensory loos ulnar side of hand & forearm.
  • If T1 is damaged proximal to sympathetic trunk; Horner’s syndrome: triad of miosis (constricted pupil), partial ptosis, and loss of hemifacial sweating (anhidrosis).
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21
Q

Thoracic Outlet Syndrome

A

Lower brachial plexus compressed between clavicle & 1st rib

*Cervical rib?

*ABD with ext. rot. increases symptoms & maybe decrease arterial pulse.

*EMG & X-Ray

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22
Q

Pancoast Syndrome

A
  • Apical lung tumour (usually small cell carcinoma.)
  • Affects lower brachial plexus.
  • Sometimes Horner’s syndrome.
  • Sometimes hoarseness (recurrent laryngeal nerve.)
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23
Q

Axillary Neuropathy

A
  • Dislocation of proximal humerus compressing axillary nerve.
  • Weak deltoid.
  • Shoulder numbness.
  • Differential dx – C5 radiculopathy.

(biceps).

24
Q

Brachial Neuritis

A
  • Unknown cause, inflammation?
  • Burning shoulder or lateral neck pain.
  • Weakness of muscles innervated by brachial plexus.
  • Recovery usually 6-12 weeks.
25
Q

Radial Neuropathy

A
  • Saturday night palsy.
  • Crutch palsy.
  • Humeral fx at spiral groove.
  • Weakness in all extensors of arm, hand, fingers.
  • Weakness in supinator.
  • Loss of triceps reflex.
  • Sensory loss radial nerve distribution.
  • Wrist drop.
  • Handcuff neuropathy; sensory loss in dorso- lateral hand.
26
Q

Ulnar Neuropathy

A
  • Compression of ulnar nerve in hand / passing over hamate in Guyon’s canal.
  • Prolonged leaning forward, resting on handlebars.
  • Weakness in finger ADD or Abduction but no sensory loss.
27
Q

Figure 9.8 Classic Hand Poses in Lesions of the Radial, Median, and Ulnar Nerves

A
28
Q

Five Important Nerves in the Arm

A
29
Q

Carpal Tunnel Syndrome

A
  • Differential Dx:
  • C6 C7 radiculopathy.
  • Compression of median nerve proximal to carpal tunnel.
  • Tinnel’s Sign (percuss median nerve.)
  • Phalen’s Sign (compress dorsal surfaces of hands together.)
30
Q

Ulnar Neuropathy

A
  • Entrapment in cubital canal.
  • Post traumatic, degenerative or congenital increased carrying angle at the elbow.
  • Acute fx of medial epicondyle.
  • Habitual resting on hard surface.
  • Weakness wrist flexion, adduction, finger add &abduction, flexion of 4th & 5th digits.
  • Hypothenar atrophy.
31
Q

Median Neuropathy

A
  • Humeral fx or distal radial dislocation.
  • Pronator teres entrapment.
  • Weakness in wrist flexion, ABDuction & opposition, flexion of 2nd & 3rd digits = make a fist/preacher’s hand.
  • Median nerve sensory distribution loss.
32
Q

Ulnar Neuropathy

A
  • Entrapment in cubital canal.
  • Post traumatic, degenerative or congenital increased carrying angle at the elbow.
  • Acute fx of medial epicondyle.
  • Habitual resting on hard surface.
  • Weakness wrist flexion, adduction, finger add &abduction, flexion of 4th & 5th digits.
  • Hypothenar atrophy.
33
Q

Simian Hand

A
  • Combination of chronic median and ulnar lesions.
  • Thenar & hypothenar atrophy.
  • Lack of opposition.

= Simian hand or monkey’s paw.

34
Q

Simian Hand

A
  • Combination of chronic median and ulnar lesions.
  • Thenar & hypothenar atrophy.
  • Lack of opposition.
  • = Simian hand or monkey’s paw.
35
Q

Lower Extremity Nerve Injury

A
  • Femoral Neuropathy.
  • Pelvic surgery.
  • Pelvic Mass.
  • Retroperitoneal hematoma.
  • Weakness thigh flexion & knee extension.
  • Loss of patellar reflex.
  • Sensory loss anterior thigh.
36
Q

Figure 9.8 Classic Hand Poses in Lesions of the Radial, Median, and Ulnar Nerves

A
37
Q

Carpal Tunnel Syndrome

A
  • Differential Dx:
  • C6 C7 radiculopathy.
  • Compression of median nerve proximal to carpal tunnel.
  • Tinnel’s Sign (percuss median nerve.)
  • Phalen’s Sign (compress dorsal surfaces of hands together.)
38
Q

Important Nerves in the Leg

A
39
Q

Figure 9.8 Classic Hand Poses in Lesions of the Radial, Median, and Ulnar Nerves

A
40
Q

Lower Extremity Nerve Injur

A
  • Femoral Neuropathy.
  • Differenetial Dx.
  • L3 or L4 radiculopathy.
  • L3 or L4 may have thigh adduction weakness/not in femoral nerve neuropathy.
41
Q

Important Nerves in the Leg

A
42
Q

Lower Extremity Nerve Injury

A
  • Peroneal palsy.
  • Fibular head.
  • Laceration.
  • Stretch injury.
  • Forcible foot inversion.
  • Compression (tight stockings).
  • Trauma.
  • Foot drop.
  • Weakness dorsiflexion, eversion & sensory loss dorsolateral foot & shin.
43
Q

Important Nerves in the Leg

A
44
Q

Lower Extremity Nerve Injury

A
  • Sciatica.
  • Painful paresthesias in a sciatic distribution.
  • Compression of L/S nerve roots.
  • Disc.
  • Osteophytes.
45
Q

Lower Extremity Nerve Injury

A
  • Obturator palsy.
  • L2-4.
  • Compression in complicated deliveries.
  • Pelvic trauma or surgery.
  • Gait instability .
  • Pain & numbness in medial thigh.
46
Q

Important Nerves in the Leg

A
47
Q

Lower Extremity Nerve Injury

A
  • Meralgia Paresthetica.
  • Lateral femoral cutaneous nerve (L2L3).
  • Entrapment under inguinal ligament or fascia lata.
  • Paresthesia & loss of sensation in lateral thigh.

-Pregnancy, obesity, weight loss, heavy equipment belts, worse with prolonged walking, sitting or standing

48
Q

Lower Extremity Nerve Injury

A
  • Morton’s metatarsalgia.
  • Tight fitting shoes compressing digital nerves (esp. 3rd & 4th toes.)
  • Patches of numbness & paresthesias.
49
Q

Lower Extremity Nerve Injury

A
  • Meralgia paresthetica.
  • Differential dx.
  • L2 or L3 radiculopathy.
  • Usually has motor changes or decreased patellar reflex.
50
Q

Distinguishing PNS from CNS Deficits

A
  • Electrodiagnostic testing can be useful.
  • Can help determine nerve & muscle disorders.
  • Electromyography (EMG).
  • Nerve conduction studies (NCV).
51
Q

Figure 9.9 Nerve Conduction Study

A
52
Q

NCV (nerve conduction velocity)

A
  • CMAP recorded over muscle belly innervated by nerve, get summated electrical activity of muscle cells.
  • SNAP if distal sensory nerve branch is stimulated getting summated electrical activity in sensory neuron axons of the nerve.
53
Q

NCV

A
  • Lesions proximal to DRG leave cell bodies & axons intact so SNAP is normal.
  • Proximal lesions of motor nerve roots cause degeneration of distal motor neuron axons & decrease CMAP.
  • Standard values for SNAP and CMAP latencies or conduction velocity for each major nerve at certain points.
54
Q

NCV

A
  • Slow conduction – demyelination.
  • Decreased SNAP amplitude – axonal damage.
  • CMAP – evaluate function of NMJ with repetitive stimulation.
55
Q

EMG (electromyography-eval and recording electrical activity by skeletal muscles

A
  • Electrode inserted into a muscle and MUP is recorded and evaluated.
  • EMG patterns distinguish weakness of
  • Neuropathic disorders (nerve or motor disease).
  • Increased spontaneous activity (fibrillations & (+) sharp waves), large MUPs and duration & see fasciculations.
56
Q

EMG

A
  • Myopathic disease (muscle disease).
  • Reduced MUP
  • Continuous or increased recruitment patterns.
  • Decreased amplitude.
57
Q
A