Lab 4 Reflexes

Question 1

why body has reflexes

Answer 1

protect tendons from rupturing and muscles from overstretching

Question 2

why are reflexes tested

Answer 2

part of larger neurological examination, tests functional integrity of nerves

Question 3

name of grooves

Answer 3

sulcus

Question 4

name of elevated folds

Answer 4

gyrus

Question 5

fMRI and PET scan

Answer 5

shows anatomy and metabolic activity of brain - used to study pre and post central gyrus

Question 6

precentral gyrus

• alternate name
• main function

Answer 6

motor cortex, houses cell bodies of UMN, sends motor commands to effectors

Question 7

postcentral gyrus

• alternate name
• main function

Answer 7

somatosensory cortex, processes sensory information

Question 8

what determines amount of area in pre/postcentral gryus given for each body part

Answer 8

density of receptors is proportional to amount of area in the brain dedicated to the body part

Question 9

relation of pre and postcentral gyrus in terms of location mapped to each body part

Answer 9

they are mirrors of each other

Question 10

decussation

Answer 10

crossing over of sensory and motor neurons in the spinal tract / medulla oblongata to the opposite side

Question 11

tract vs nerve

Answer 11

tract = axon bundle in CNS 
nerve = axon bundle in PNS

Question 12

ascending vs descending tract

Answer 12

ascending = sensory neurons
descending = motor neurons

Question 13

ascending tract naming scheme

- explain anterior spinothalamic and posterior spincerebellar

Answer 13

• name based on start to end
• anterior spinothalamic = spine –> thalamsu
• posterior spincerebellar = spine to cerbellum

Question 14

name of pain receptors

Answer 14

nociceptors

Question 15

role of thalamus

Answer 15

relay center for all sensory information except smell - amplifies signals coming in

Question 16

2 types of descending tracts and their alternate names

Answer 16

• pyramidal = corticospinal
• extra pyramidal = reticular, does not go through pyramids
• pyramids are structure in medulla oblongata

Question 17

why is coordinated movement so hard?

Answer 17

• involves a lot of parts of the brain which send a mix of excitatory and inhibitory signals to different skeletal muscles
• involves reciprocal loops that are underdeveloped in infants

Question 18

LMN vs UMN damage

Answer 18

• LMN damage = flaccidity, muscular atrophy

- UMN damage = exaggerated reflex since UMN usually inhibits LMN

Question 19

dorsal root

Answer 19

• house sensory neurons coming in

Question 20

ventral root

Answer 20

• houses motor neurons going out

Question 21

reflex arch series of events

Answer 21

sensory stretch receptors –> stimulate sensory neurons –> spine/brain where it may connect to interneurons –> motor neuron –> effector tissue

Question 22

monosynaptic reflex

Answer 22

1 synapse only between sensory and motor neuron - no interneuron

Question 23

2 types of reflex based on type of muscle

Answer 23

• autonomic = smooth muscle, glands

- somatic = skeletal muscle under voluntary control

Question 24

2 types of reflex based on synapse location

Answer 24

• cerebral = in brain

- spinal = in spine

Question 25

Plantar reflex stimulation

Answer 25

• stimulate nociceptors by pressing from lateral (outside) of foot to big toeo

Question 26

plantar reflex responses

Answer 26

• positive babinski = dorisflexion and plantar extension, seen in babies.
• dorsiextension and plantar flexion seen in healthy adults

Question 27

what does plantar reflex test

Answer 27

tests corticospinal tract that houses UMN

Question 28

plantar reflex response in health adult, adult with spinal damage, otherwise healthy baby

Answer 28

• healthy adult = toes curl in
• adult with spinal damage = toes curl out
• healthy baby = toes curl out because UMN are not as myelinated yet

Question 29

series of events for plantar reflex

Answer 29

• nociceptors in foot –> sensory neuron –> S1 and synapse with LMN –> foot
• UMN usually prevents sensory information from traveling to L4/L5 which stimulates the toes to extend

Question 30

pupillary light reflex - cerebral or spinal?

Answer 30

cerebral

Question 31

what is the effect of the pupillary light reflex

Answer 31

both pupils contract

Question 32

delete

Answer 32

delete

Question 33

why does the pupillary light reflex cause constriction in both eyes

Answer 33

light –> information sent to pretectal area of the brain –> interneuron goes to BOTH Edinger westphal nuclei –> motor command sent to ciliary ganglion –> pupil constriction

Question 34

hypo vs hyper reflexive

Answer 34

hypo = very little reflex 
hyper = exaggerated reflex

Question 35

how to increase reflexivity

Answer 35

jendrassik maneuever - patient locks fingers together and bears down

Question 36

5 components of reflex arch

Answer 36

sensory receptors, sensory neuron, interneuron, motor neuron, and effector

Question 37

ankle reflex - stimulation, nerve, and expected effect

Answer 37

• hit large tendon in the back of ankle, food should drop, medial popliteal nerve

Question 38

patellar reflex - stimulation, nerve, and expected effect

Answer 38

• hit patellar tendon, leg should kick out, test femoral nerve

Question 39

tricep reflex - stimulation, nerve, and expected effect

Answer 39

• hit tricep tendon in the back of elbow, arm should jerk, test radial nerve

Question 40

bicep reflex - stimulation, nerve, and expected effect

Answer 40

• cover tendon with thumb and hit, arm should jerk and rotate in (or maybe just the fingers), test musculocutaneous nerve