Diseases of muscle and peripheral nerve: review of the CNS blood supply

Question 1

Cerebrum

Answer 1

..

Question 2

Frontal lobe

Answer 2

cognition, motor activity

Question 3

Parietal lobe

Answer 3

sensory input

Question 4

temporal lobe

Answer 4

memory storage

Question 5

Occipital lobe

Answer 5

visual perception

Question 6

hypothalamus

Answer 6

vital center for regulation of body temperature and blood circulation

Question 7

Cerebellum

Answer 7

right and left hemispheres

equilibrium and coordination

Question 8

brainstem

Answer 8

midbrain, pons, medulla

vital centers: respiration, heart rate, blood pressure

Question 9

spinal cord

Answer 9

traversed by nearly all the nerves carrying information to and from the body.

cervical: arms, diaphragm (respiration)
thoracic: chest, abdomen
lumbo-sacral: legs, urinary blader, rectum reproductive organs.

Question 10

Peripheral nervous system

Answer 10

crania (sensory and motor) nerves: eye muscles, ear, face, tongue, mouth and viscera

spinal (sensory and motor) nerves: limbs and trunk, skin, musculoskeletal and viscera.

Question 11

meninges

Answer 11

fibrous tissue covering the brain

1. dura: tough outer layer, separates cranial activity into compartments
2. pia-arachnoid: thin inner layers containing many blood vessels

Question 12

4 ventricular system

Answer 12

..

Question 13

1. cerebrospinal fluid (CSF)

Answer 13

produced by choroid plexus, flows through the ventricles and is reabsorbed by special cells of the pia-arachnoid (arachnoid villi)

Question 14

2. Lateral ventricle with inter ventricular foramen

Answer 14

3. third ventricle with cerebral (sylvian) aqueduct

Question 15

4. forth ventricle with a median aperture (magnedie) and two lateral foramina (luschka)

Answer 15

..

Question 16

Neuron components

Answer 16

cell body: resides in grey matter
axons: may be extremely long, mainly contained in white matter
myelin sheath: multiple lamellae of specialized cell membrane surround and insulate axons (speed conduction)

Question 17

neuron metabolic activity

Answer 17

very high, requires a high demand for glucose and oxygen and very susceptible to a lack of them

Question 18

upper motor neuron

Answer 18

cell body: resides in grey matter of the frontal lobe. axon travels great distance to braistem and spinal cord to synapse with corresponding lower motor neuron (efferent motor).

Question 19

lower motor neuron

Answer 19

cell body in spinal cord grey matter
axon exists in anterior nerve root to become peripheral motor nerve (efferent motor)
innervates skeletal muscles

Question 20

Glia

Answer 20

astrocytes: supporting cell, proliferate in area of injury to form a “scar”

Oligodendrocytes: produce and maintain myelin sheath in CNS

microglia: function not well understood, may be macrophages of CNS

Schwann cell: produce and maintain myelin sheath in PNS.

Question 21

Etiology of diseases

Answer 21

genetic/heredity
traumatic
infectious
inflammatory
vascular/connective tissue
metabolic
toxic
neoplastic

Question 22

Neurogenic atrophy

Answer 22

degeneration of peripheral nerves which in turn may all lead to atrophy of skeletal muscles.

results in a pattern of atrophy referred to as GOUP ATROPHY.

Small fibers with angular outlines occur together in groups in fascicles that may also have fibers of normal size and morphology or hypertrophied fibers.

Question 23

Two types of muscle fibers

Answer 23

type 1: acidic condition stains darker. has lots of mitochondria and lipid droplets ==> sustained contractions
type 2: basic condition gets darker, less mitochondria, has glycogen, undergo glycolysis to provide quick energy.
birds on the ground: all type 2 (white muscle)
fly birds: all red, type 1
human: mix

Question 24

Mechanism of neurogenic/denervation atrophy

Answer 24

progression of denervation and renervation results in grouping of same muscle fiber types.
if disease continue, they will continue to die ==> angular outlined fibers, shrunk and angulated.
characteristics: 1. they are grouped 2. they are atrophic

Question 25

Myopathies (primary disease of skeletal muscle)

Muscular dystrophy

Answer 25

genetically determined, inherent loss or abnormality of the contractile proteins in the muscle resulting in weakness.
Most common disease: PROGRESSIVE (DUCHENNE) MUSCULAR DYSTROPHY. sex-linked, recessive disorder affects male children.
loss of an important contractile protein DYSTROPHIN
deficiency of dystrophin molecule ==> actin is not anchored in the cell membrane ==> after multiple muscle contraction cell membrane breaks down, influx of Ca2+ into the cell attracts macrophages and kill the cell.
progressive, fatal outcome ~20

Question 26

epineurium

Answer 26

connects all the neuronal fascicles together. contains blood vessels

Question 27

endoneurium

Answer 27

connective tissue in between individual nerve fibers

Question 28

features of muscular dystrophy

Answer 28

1. lack of dystrophin molecule
2. necrosis
3. release of Ca2+ and macrophages come in
4. fibrosis
5. can document absence of dystrophy by the antibody molecule

Question 29

axonal degeneration

Answer 29

disease in peripheral nerves results from mechanical insults such as compression or transection.
under suitable conditions, nerve regeneration may be observed.

Question 30

features of axonal degeneration

Answer 30

myelin sheath break down but schwann cells remain ==> WALLERIAN DEGENERATION
myelin debris phagocytize by macrophages entering the basal lamina surrounding each nerve fiber.
retrograde proximal to the site of injury.
axon regeneration after removal of debris
nerves damaged by closed injuries (crush and freeze) are more likely to regenerate with return of function. Open injuries (penetrating wounds) commonly result in aberrant regenerative sprouting in the form of TRAUMATIC NEUROMA (scar tissue build up, which blocks the growth of axon to its original place).
regeneration forms an axonal CLUSTER

Question 31

most common trauma to peripheral nerves

Answer 31

metabolic (acquired) and toxic. 50%
==> inflammatory/infectious, hereditary, cytogenic 10-20% each
==> neoplastic 5-10%