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.
2
Q
Brachial Plexus
A
- Posterior cord – ARTS
- Axillary, Radial, Thoracodorsal, Subscapular.
- Musculocutaneous nerve – BBC
- Biceps, brachialis, coracobrachialis.
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.
4
Q
Figure 9.3 Lumbosacral Plexus
A
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
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
7
Q
Important Nerves of the Leg
A
8
Q
Important Nerves of Leg
A
9
Q
Cervical Plexus
A
CN XII and C1 - C5
Phrenic nerve;
C3,4,5 keeps the diaphragm alive.
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.
11
Q
Five Important Nerves in the Arms
A
12
Q
Five Important Nerves in the Arm
A
13
Q
Upper Extremity Strength Testing:
A
https://drive.google.com/file/d/0B5o1XviBdHwrbU00cm9IaW9fMkE/view?usp=sharing
14
Q
Thumb Strength Testing & Nerves:
A
https://drive.google.com/file/d/0B5o1XviBdHwrTGMxYWZNUlNnVGM/view?usp=sharing
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.
16
Q
Figure 9.6 Three Nerves Acting on the Thumb
A
17
Q
Muscles Contributing to Flexion and Extension at Finger Joints
A
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.
19
Q
Figure 9.7 “Bellman’s,” or “Waiter’s Tip,” Pose Assumed in Upper-Plexus Lesions
A
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).
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
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.)
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.
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Radial Neuropathy
* 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
Ulnar Neuropathy
* 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.
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Figure 9.8 Classic Hand Poses in Lesions of the Radial, Median, and Ulnar Nerves
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Five Important Nerves in the Arm
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Carpal Tunnel Syndrome
* 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
Ulnar Neuropathy
* 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.
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Median Neuropathy
* 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.
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Ulnar Neuropathy
* 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.
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Simian Hand
* Combination of chronic median and ulnar lesions.
* Thenar & hypothenar atrophy.
* Lack of opposition.
= Simian hand or monkey’s paw.
34
Simian Hand
* Combination of chronic median and ulnar lesions.
* Thenar & hypothenar atrophy.
* Lack of opposition.
* = Simian hand or monkey’s paw.
35
Lower Extremity Nerve Injury
* Femoral Neuropathy.
* Pelvic surgery.
* Pelvic Mass.
* Retroperitoneal hematoma.
* Weakness thigh flexion & knee extension.
* Loss of patellar reflex.
* Sensory loss anterior thigh.
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Figure 9.8 Classic Hand Poses in Lesions of the Radial, Median, and Ulnar Nerves
37
Carpal Tunnel Syndrome
* 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
Important Nerves in the Leg
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Figure 9.8 Classic Hand Poses in Lesions of the Radial, Median, and Ulnar Nerves
40
Lower Extremity Nerve Injur
* Femoral Neuropathy.
* Differenetial Dx.
* L3 or L4 radiculopathy.
* L3 or L4 may have thigh adduction weakness/not in femoral nerve neuropathy.
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Important Nerves in the Leg
42
Lower Extremity Nerve Injury
* Peroneal palsy.
* Fibular head.
* Laceration.
* Stretch injury.
* Forcible foot inversion.
* Compression (tight stockings).
* Trauma.
* Foot drop.
* Weakness dorsiflexion, eversion & sensory loss dorsolateral foot & shin.
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Important Nerves in the Leg
44
Lower Extremity Nerve Injury
* Sciatica.
* Painful paresthesias in a sciatic distribution.
* Compression of L/S nerve roots.
* Disc.
* Osteophytes.
45
Lower Extremity Nerve Injury
* Obturator palsy.
* L2-4.
* Compression in complicated deliveries.
* Pelvic trauma or surgery.
* Gait instability .
* Pain & numbness in medial thigh.
46
Important Nerves in the Leg
47
Lower Extremity Nerve Injury
* 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
Lower Extremity Nerve Injury
* Morton’s metatarsalgia.
* Tight fitting shoes compressing digital nerves (esp. 3rd & 4th toes.)
* Patches of numbness & paresthesias.
49
Lower Extremity Nerve Injury
* Meralgia paresthetica.
* Differential dx.
* L2 or L3 radiculopathy.
* Usually has motor changes or decreased patellar reflex.
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Distinguishing PNS from CNS Deficits
* Electrodiagnostic testing can be useful.
* Can help determine nerve & muscle disorders.
* Electromyography (EMG).
* Nerve conduction studies (NCV).
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Figure 9.9 Nerve Conduction Study
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NCV (nerve conduction velocity)
* 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
NCV
* 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
NCV
* Slow conduction – demyelination.
* Decreased SNAP amplitude – axonal damage.
* CMAP – evaluate function of NMJ with repetitive stimulation.
55
EMG (electromyography-eval and recording electrical activity by skeletal muscles
* 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
EMG
* Myopathic disease (muscle disease).
* Reduced MUP
* Continuous or increased recruitment patterns.
* Decreased amplitude.
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