LECTURE - Muscle and PNS

Question 1

three types of muscles

Answer 1

• skeletal
• cardiac
• smooth

Question 2

contraction unit of skeletal muscle

Answer 2

sarcomere

Question 3

central core disease

Answer 3

ultrastructural disorganization (Z-band streaming)

Question 4

voluntary control of body movements and sensory

Answer 4

somatic

Question 5

autonomic

Answer 5

unconscious control of bodily functions
(heart rate, BP, etc.)
- sympathetic (F or F)
- parasympathetic (R & D)

Question 6

Pacinian corpuscle

Answer 6

an encapsulated ending of a sensory nerve that acts as a receptor for pressure and vibration (skin)

Question 7

epineurium

Answer 7

outermost protective layer = composed of dense connective tissue

Question 8

perineurium

Answer 8

surrounding each individual fascicle (by collagenous tissue w a layer of flat epithelial cells)

Question 9

endoneurium

Answer 9

surrounding individual nerve fiber (by loose vascular supporting tissue)

Question 10

nerve teasing

Answer 10

technique of manually separating axons following osmication
- used to assess segmental demyelination and other myelin abnormalities
- time-intensive due to fragility of axons
TEDIOUS!

Question 11

T or F. Cardiac muscle cells can regenerate

Answer 11

F!

Skeletal muscle cells can due to satellite cells and smooth muscle cells can under special conditions

Question 12

bone is attached to muscle via

Answer 12

tendon

Question 13

sarcomere structure

Answer 13

• 2 bands, 2 lines, 1 zone
• bands:
  > anisotropic (dark); myosin
  > isotropic (light); actin
• lines:
  > Mittelscheibe (middle disc)
  > Zwischenscheibe (intercalated disc)
• H zone:
  > Heller (bright in German)
  > absent thin filaments

Question 14

sarcomere disruption

Answer 14

• central core disease

> ultrastructural disorganization (Z-band streaming)

Question 15

the link between depolarization of the muscle membrane and contraction

Answer 15

excitation-contraction coupling

Question 16

rigor mortis

Answer 16

stiffening of the joints and muscles of a body a few hours after death, usually lasting from one to four days

Question 17

skeletal muscle contraction

Answer 17

• requires ATP to detach myosin head from actin

- rigor mortis occurs if no ATP = no detachment of myosin from actin = stiff muscles

Question 18

this can be used to select pathological muscle site in difficult cases

Answer 18

MRI

Question 19

best specific muscles for biopsy

Answer 19

deltoid
biceps
quadriceps

Question 20

selection of muscle to biopsy

Answer 20

• chronic disease: muscle with moderate, but not severe, weakness
• acute disease: muscle with severe or moderate weakness

AVOId muscles that were site of EMG, injections, or trauma

Question 21

muscle processing technique

Answer 21

• open biopsy procedure
• do not use cautery, sutures, or clamps
• needle to minimize trauma (may miss patchy or epimysial pathology)
• obtain several samples from biopsy site

Question 22

muscle processing transportation

Answer 22

• may be saved in saline moistened gauze for several hrs
• keep cool
• should NOT be immersed in saline, fixative, or other liquids
• adequate dry ice = frozen for shipping ‘overnight’

Question 23

muscle processing preservation

Answer 23

• freeze most tissue in isopentane precooled to -160C in liquid nitrogen
  > freezing process should be rapid to prevent artifact
  > store frozen muscle at -80C
• fix some muscle in 4% glutaraldehyde
  > embed momst fixd muscle in plastic = for ultrastructural analysis + good visualization of muscle endomysial capillaries
  > paraffin embedded material = useful for surveys for inflammation & morphology of inflammatory cells; gives poor muscle fiber morphology

Question 24

basic panel of stains in muscle biopsy

Answer 24

• Gomori trichrome
• acid phosphatase: lysosomal activity
• NADH: mitochondrial activity
• ATPase: fiber type (differentiates using different pHs)
• non-specific esterase: denervation
• COX/SDH: mitochondrial activity
• PAS/PASD: glycogen
• oil red O/sudan black: fat

NOTE: many of these are enzyme-based and thus will not work on formalin-fixed paraffin embedded material

Question 25

basic panel of stains in muscle biopsy

Answer 25

- Gomori trichrome - acid phosphatase: lysosomal activity - NADH: mitochondrial activity - ATPase: fiber type (differentiates using different pHs) - non-specific esterase: denervation - COX/SDH: mitochondrial activity - PAS/PASD: glycogen - oil red O/sudan black: fat *NOTE: many of these are enzyme-based and thus will not work on formalin-fixed paraffin embedded material*

Question 26

nemaline rod myopathy

Answer 26

congenital, often hereditary neuromuscular disorder with many symptoms that can occur such as muscle weakness, hypoventilation, swallowing dysfunction, and impaired speech ability

Question 27

T or F. cardiac muscle is not attached to tendon

Answer 27

T! attached to each other by intercalated discs

Question 28

T or F. Cardiac muscle only has one cell with one nuclei

Answer 28

T! unlike skeletal muscle which has multiple nuclei; this one cannot regenerate; this one has branching connections

Question 29

pacemaker cells

Answer 29

sinoatrial cells | - produce depolarization and action potentials to drive cardiac cell contraction

Question 30

voluntary control of body movements and sensory

Answer 30

somatic

Question 31

autonomic

Answer 31

- unconscious control of bodily functions (heart rate, BP, etc.) - sympathetic = fight or flight - parasympathetic = rest + digest

Question 32

peripheral nerve biopsy

Answer 32

``` - sural nerve most often sampled > pure sensory nerve (no motor deficit post-biopsy) > easily accessible and identifiable - superficial peroneal - superficial radial ```

Question 33

how should a nerve biopsy arrive

Answer 33

- fresh on saline moist gauze - split into three parts: > paraffin (FFPE) > plastic embedded sections for Toluidine blue sections + electron microscopy > teased nerve fibers

Question 34

neurofilament IHC

Answer 34

labels axons

Question 35

Bielschosky stain

Answer 35

silver stain that stains axons black

Question 36

oligodendrocytes vs Schwann cells

Answer 36

- oligo = myelinates many axons in CNS | - Schwann = myelinates a single axon in PNS

Question 37

Node of Ranvier

Answer 37

space between myelin sheath which allows saltatory conduction

Question 38

Masson Trichrome stain (peripheral nerve)

Answer 38

stains myelin fuschia

Question 39

Toluidine blue stain for peripheral nerve

Answer 39

- highlights myeline sheath with dark blue staining | - assesses myelination and axonal density and myelin loss

Question 40

types of axons in a peripheral nerve fascicle (3)

Answer 40

- large myelinated axons = fastest conduction - small myelinated - unmyelinated axons = slowest

Question 41

T or F. pain sensors are myelinated

Answer 41

F! they are unmyelinated which is why you feel the heat first and pull way THEN you feel pain; heat sensors (myelinated = faster)

Question 42

an example of demyelinated peripheral neuropathy

Answer 42

Guillain-Barre syndrome

Question 43

congo red stain

Answer 43

- for amyloid - stains amyloid salmon pink - when polarized, shows apple-green birefringence

Question 44

dorsal root ganglia

Answer 44

aggregate of sensory neuronal cell bodies