MSK Blue Boxes Midterm

Question 1

CNS Damage: physiological response

Answer 1

Proximal stumps of injured axons begin to regenerate
Send sprouts to area of lesion
Growth blocked by ASTROCYTE PROLIFERATION at injury site
Axonal sprouts retracted
Result: permanent disability

Question 2

Rhizotomy

Answer 2

spastic paralysis

Question 3

Intractable pain vs Rhizotomy

Answer 3

Sensory/motor fibers of spinal nerves are ONLY segregated at the POST/ANT ROOTS
At these sites the doctor can selectively section each to relieve either intractable pain (sensory/post root) or rhizotomy (motor/ant root)

Question 4

Adult neuron proliferation

Answer 4

only in the olfactory epithelium (smell)

others destroyed by disease/trauma-> not replaced

Question 5

Nerve Degeneration

Answer 5

Nerves stretched/crushed/severed
Axons degenerate distal to nerve lesion
Intact cell body + damaged axon = possible regeneration/return of fxn
Best chance of survival w/compressed nerve (paresthesia)

Question 6

Paresthesia

Answer 6

pins-and-needles sensation due to compressed nerve

ex- when you sit too long with legs crossed

Question 7

Crushing nerve injury

Answer 7

Damages/kills axon distal to injury site
Nerve cell bodies usually survive
Nerve conn tissue coverings intact-> guide growth of axons to distal targets-> no surgery needed

Question 8

Cutting nerve injury

Answer 8

Sprouting occurs at proximal ends of axons (but may not reach distal target)
Requires surgery b/c regeneration requires apposition of cut ends (sutures in epineurium)-> realign nerve bundles

Question 9

Anterograde/wallerian degeneration

Answer 9

Degeneration of axons detached from their cell bodies

Axon and myelin sheath degenerate (despite sheath not being injured)

Question 10

Compression of vasa nervorum

Answer 10

Cuts off a nerve’s blood supply (ischemia)

Prolonged ischemia-> nerve degeneration (can be just as severe as crushing/cutting the nerve)

Question 11

Ischemia

Answer 11

inadequate blood supply

Question 12

Saturday night syndrome

Answer 12

drunk person passes out w/limb dangling off side of bed-> nerve ischemia-> paresthesia (often permanent)

Question 13

Transient paresthesia

Answer 13

common in dental surgery anesthetics

Question 14

Accessory/Supernumerary Bones

Answer 14

Develop when additional ossification centers appear-> form extra bones
Normal: several centers of ossification-> develop many bones-> bones fuse
Extra: bones don’t fuse-> appearance of “extra” bone (missing part of main bone)
Common in foot
Sutural bones in cranium

Question 15

Sutural Bones

Answer 15

Small, irregular, worm-like bones

Circumscribed areas of bone along suture of cranium (where flat bones abut, esp parietal)

Question 16

Heterotropic Bones

Answer 16

Bones form in soft tissues where not normally present
ex- horse riders develop in their thighs due to chronic muscle strain-> small hemorrhagic areas-> calcification-> ossification

Question 17

Fracture Reduction

Answer 17

Broken ends of bone brought together to heal

Normal position approximated

Question 18

Bone healing

Answer 18

Surrounding fibroblasts proliferate-> secrete collagen-> collar of callus (holds bones together)
Bone remodeling-> callus calcifies-> callus resorbed/replaced by bone
Fractures heal faster in growing bones (children)

Question 19

Collar of Callus

Answer 19

Forms around broken bones due to fibroblast proliferation and their secretion of collagen
Holds bones together
Calcifies, then resorbed and replaced by bone

Question 20

Green-stick fractures

Answer 20

incomplete breaks caused by bending of the bones

Question 21

Osteoporosis

Answer 21

Reduction in quantity of bone or atrophy or skeletal tissue
Dec in organic/inorganic bone components-> brittle bones-> lose elasticity-> fracture more easily
Assessed by bone scanning

Question 22

Sternal Puncture

Answer 22

Wide-bore needle inserted through cortical bone into spongy bone
Sample of red bone marrow aspirated w/syringe-> evaluate for hematological diseases
Sternum used because close to surface and easily accessible
ex- bone marrow transplantation for leukemia patients

Question 23

Bone Age

Answer 23

determined by
1. appearance of calcified material in diaphysis/epiphyses
2. disappearance of epiphyseal plate (no dark line-> fusion)
Helps predict adult height and approximate age of skeletal remains

Question 24

Lines of arrested growth

Answer 24

Bone with thickened trebeculae

Dense line of provisional calcification caused by cartilage degeneration in columns of bones

Question 25

Bone injury adult v child

Answer 25

Adult: fracture Child:: epiphysis displacement

Question 26

Avascular necrosis

Answer 26

Loss of arterial supply to bone tissue-> tissue death | Fracture-> areas of adjacent bone necrotize (OSTEOCHONDROSIS)

Question 27

Osteochondrosis

Answer 27

avascular necrosis of epiphyses in children

Question 28

Calvaria

Answer 28

skullcap

Question 29

Fontanelles

Answer 29

wide areas of fibrous tissue at sutures where cranial bones do not make full contact w/each other (in newborn) Anterior is most prominent ("soft spot"), usually flat Feel like ridges due to cranial bone overlapping (during passage through birth canal) Bulging=> increased intracranial pressure (or baby is crying) Depressed=> dehydration Pulsates w/cerebral arteries

Question 30

Osteoarthritis

Answer 30

Degenerative Joint Disease Sx: stiffness, discomfort, pain common in older people, weight-bearing joints Substances in blood stream easily enter joint cavity Traumatic joint infection-> arthritis, inflammation, septicemia

Question 31

Arthroscopy

Answer 31

Examination of synovial joint cavity Insert cannula and arthroscope Enables orthopedic surgeons to examine joints and perform certain surgeries (allows more rapid healing than traditional joint surgery)

Question 32

Absence of muscle tone

Answer 32

Normal: gentle force that helps maintain pressure on other structures Absent: may allow joints to dislocate, antagonist muscle may cause limb to assume abnormal resting position Denervated muscle-> fibrosis, loses elasticity-> abnormal resting position

Question 33

Muscle soreness

Answer 33

Due to excessive/novel eccentric contractions (lengthening type more likely to create micro-tears/periosteal irritation)

Question 34

Pulled muscles

Answer 34

Skeletal muscles have limited ability to lengthen (+ ~1/3) Skeletal attachments usually prevent excessive lengthening except in hamstring (w/knee ext, hamstring reaches max length before hip fully flexes-> common hamstring tears)

Question 35

Satellite cells of skeletal muscle

Answer 35

turn into new muscle fibers that individually replace skeletal striated muscle fibers (fibers can't divide) Source of myoblasts (which can fuse together to create new muscle fibers)

Question 36

Hypertrophy of existing fibers

Answer 36

Lengthens and increases myofibrils w/in muscle fibers Increases amount of work muscle can perform Occurs in response to frequent strenuous exercise

Question 37

Muscle testing

Answer 37

Helps diagnose nerve injury | 2 types: patient resists examiner (power) or examiner resists patient (compare bilateral pairs)

Question 38

Electromyography (EMG)

Answer 38

Place surface electrodes over muscle, patient performs movements, examiner amplifies/records electrical action potentials Normal resting: baseline activity (muscle tone, disappears during deep sleep/paralysis/anesthesia) Contracting: variable peaks of phasic activity Analyze activity of individual muscles during different movements Help restore muscle activity