Neuromuscular I (Neurophys, Plexopathy, Neuropathy) Flashcards
AR disorder with childhood-onset sensorimotor neuropathy, corticospinal degeneration, and optic neuropathy, with walking in inside of feet and tightly curled hair.
Gene?
Pathological finding?
Giant axonal neuropathy (GAN)
GAN gene - gigaxonin (cross linking of intermediate filaments)
Pathology: Large focal axonal swelling (which contains disorganized neurofilaments)
AD disorder with sensorimotor neuropathy, ataxia, hearing loss, and anosmia, as well as retinosis pigmentosa, cardiomyopathy, and skin changes.
What is elevated?
Treatment?
Refsum’s disease
Accumulation of phytanic acid.
Treatment includes dietary restriction of phytanic acid
AR disorder with neuropathy and retinosis pigmentosa, associated with intestinal pseudo-obstruction.
Myoneurogastrointestinal encephalopathy (MNGIE)
AR disorder with neuropathy, ataxia, and retinosis pigmentosa, associated with acanthocytes on smear.
Genetic mutation?
Lab finding?
Treatment?
Abetalipoproteinemia
Mutation in microsomal triglyceride transfer protein (MTTP)
Lab: Low vitamin E and beta-lipoprotein
Treatment: Vitamin E supplementation and fat restriction (especially long-chain saturated fatty acids), especially
What does the F wave reflect?
How is it obtained?
Measurement of muscle response after antidromic signal to motor neuron and then bounce-back of orthodromic signal down to the muscle
Supramaximal stimulation of a motor nerve
What does the H wave reflect?
How is it obtained?
S1 reflex arc, equivalent to ankle reflex (signal travels up tibial nerve through sensory afferent, signal in cord goes to motor neuron and stimulates muscle to contract)
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Stimulate tibial nerve at popliteal fossa and record at soleus.
Types of muscle fibers. Which are fast? Which are oxidative vs glycolytic?
Type I: Slow oxidative
Type IIa: Fast oxidative
Type IIb: Fast glycolytic (anaerobic)
Motor branches of median nerve that branch after the carpal tunnel?
Thenar/recurrent motor branch to thenar muscles (leads to weakness in thumb abduction and opposition)
Brachial plexus:
Which nerves branch directly off roots, and which roots?
What muscles do they supply?
Dorsal scapular (C5): Rhomboids and levator scapulae
Long thoracic (C5-C7): Serratus anterior
Brachial plexus:
Which nerves branch directly off trunks, and which trunk?
Which muscles do they supply?
Subscapular nerve (Upper trunk) - Supraspinatus and infraspinatus
Nerve to subclavius (Upper trunk)
No nerves directly off middle or lower trunk
Brachial plexus:
Inputs to each of the cords
Lateral: Anterior divisions of upper and middle trunks (C5-C7)
Medial: Anterior division of lower trunk (C8-T1)
POsterior: posterior divisions of all 3 trunks (C5-T1)
Brachial plexus: nerves coming off lateral cord before terminal branch?
Terminal branch?
Before terminal:
1. Lateral pectoral nerve (pectoralis major)
Terminal branches:
1. Median nerve (also contribution from medial cord)
2. Musculocutaneous nerve
Brachial plexus: nerves coming off posterior cord before terminal branch?
Terminal branch?
Before terminal:
1. Upper subscapular nerve (subscapularis)
2. Lower subscapular nerve (teres major and lower part of subscapularis)
3. Thoracodorsal nerve (latissimus dorsi)
Terminal branches:
1. Axillary nerve
2. Radial nerve
Brachial plexus:
Nerves coming off lateral cord before terminal branch?
After terminal branch?
Before terminal:
1. Medial pectoral nerve (pectoralis minor)
2. Medial brachial cutaneous nerve (sensory to medial arm)
3. Medial antebrachial cutaneous nerve (sensory to medial forearm)
Terminal
1. Ulnar nerve
2. Gives branches to median nerve
Mutation associated with familial amyloid polyneuropathy types 1 and 2?
Transthyretin
(Type 1 is more severe and has more autonomic involvement, type 1 is milder and has less autonomic involvement, carpal tunnel can be prominent feature)
Which CMTs are demyelinating?
CMT1 and CMTX
CMT4 is both demyelinatig and axonal
CMT inheritence by type
CMT1: AD
CMT2: AD except one subtype of CMT2A
CMT3: can be AD or AR - not a very useful term since caused by same genes as CMT1A (AD), CMT1B (AD), CMT1D (AD), or CMT4 (AR) - distinguished by severe, childhood onset
CMT4: AR
CMTX: X-linked
Median nerve muscles innervated by:
- Muscular branches from cubital fossa
- Anterior interosseous nerve
- After passing through carpal tunnel
Muscular branches from cubital fossa are forearm muscles
1. Pronator teres
2. Flexor carpi radialis
3. Flexor digitorum superficialis
4. Palmaris longus
Anterior interosseous nerve:
1. Flexor digitorum profundus
2. Flexor pollicis longus
3. Pronator quadratus
After carpal tunnel:
Muscular branch to thenar muscles:
1. Abductor pollicis brevis
2. Flexor pollicis brevis (superficial part, deep is ulnar)
3. Opponens pollicis
Digital branch:
1. 1st and 2nd lumbricals (Flex MCP amd extend PIP and DIP)
Tensor fascia latae:
- Role
- Innervation
- Roots
Role: hip aBduction when hip is flexed
Nerve: Superior gluteal nerve
Root: L4-S1
Lumbar plexus:
- Nerve roots
- Major nerves (3)
- Minor nerves (3)
Roots: T12-L4
Major nerves:
1. Femoral
2. Obturator
3. Lateral femoral cutaneous
Minor nerves:
1. Iliohypogastric
2. Ilioinguinal
3. Genitofemoral
What is the lumbosacral trunk?
Fibers from L4 and L5 that join the sacral plexus to form the sciatic nerve.
Lateral femoral cutaneous nerve: roots
L2, L3
Femoral nerve roots
L2, L3, L4 (posterior divisions - obturator is anterior divisions)
Obturator nerve roots
L2, L3, L4 (anterior divisions - femoral is posterior divisions)
Muscles innervated by obturator nerve, anterior and posterior divisions
Anterior division:
1. Adductor brevis
2. Adductor longus
3. Gracilis (another adductor)
Posterior division:
1. Obturator externus (external hip rotation)
2. Adductor magnus (also innervated by sciatic nerve)
Muscles innervated by femoral nerve
- Iliacus (also direct banches form lumbar plexus; hip flexion)
- Pectineus muscle (hip flexion and adduction)
- Sartorius muscle (thigh abduction, flexion, and external roation)
- Quadriceps muscles: Vastus lateralis, vastus intermedius, vastus medialis, and rectus femoris
Sensory branches of femoral nerve
Anterior femoral cutaneous (L2-3)
Saphenous nerve (L3-4, medial calf)
Sacral plexus:
- Nerve roots
- Nerves (6)
Roots: L4-S4 (L4 and L5 via lumbosacral trunk to sciatic and gluteal nerves)
Nerves:
1. Tibial (sciatic)
2. Peroneal (sciatic)
3. Superior gluteal
4. Inferior gluteal
5. Posterior cutaneous nerve of the thigh
6. Pudenal nerve
Superior gluteal nerve
- Nerve roots
- Muscles innervated
- Movements
Roots: L4-S1
Muscles:
1. Gluteus medius
2. Gluteus minimus
3. Tensor fasciae latae
Motements:
Hip aBduction: glut medius and minimus when hip extended, TFL when hip flexed)
Nerves supplying hip aDduction and hip aBduction
ADduction:
1. Obturator (L2-L4, Adductor brevis, adductor longus, gracilis)
2. Tibial portion of sciatic nerve (Adductor magnus)
ABduction: Superior gluteal nerve (L4-S1, gluteus medius, gluteus minimus, TFL)
Inferior gluteal nerve
- Nerve roots
- Muscles innervated
- Movements
Roots: L5-S2
Muscles: Gluteus maximus
Movements: thigh extension
Posterior cutaneous nerve
- Nerve roots
- Area supplied
Roots: S1-S3
Supplies lower buttock and posterior thigh
Pudendal nerve
- Nerve roots
- Area supplied
Roots: S2-S4
Supplies peineal and perianal sensation
(Also motor to pelvic muscles)
Gene affected in HNPP (hereditary neuropathy with liability to pressure palsies)
Inheritence?
PMP22 deletions (periperal myelin protein 22) (note duplications in the same gene cause CMT 1A)
Autosomal dominant with incomplete penetrance
Tibial nerve muscles supplied in thigh (via sciatic) and lower leg
Thigh
1. ADductor magnus (hip aDduction, also some supply from obturator)
Hamstrings which all flex knee and extend hip:
2. Semimebranosus
3. Semitendinosus
4. Long head of biceps femors (short head is by common peroneal)
Lower leg
1. Gastrocnemeius (calf, ankle plantarflexion and knee flexion)
2. Soleus (calf, plantaflexion)
3. Tibialis posterior (deep to calf, plantarflexion and ankle inversion)
Peroneal nerve muscles supplied in thigh (via sciatic) and lower leg (superficial and deep peroneal)
Thigh:
1. Short head of biceps femoris
Superficial peroneal: foot eversion
1. Peroneus longus
2. Peroneus brevis
Deep peroneal:
1. Tibialis anterior (dorsiflexion)
2. Extensor hallicus (first toe extension)
3. Extensor digitorum longus and brevis (toe extension)
4. Peroneus tertious (eversion and dorsiflexion)