Chapter 14: Somatic Nervous System Flashcards
(165 cards)
1
Q
amacrine cell
A
type of cell in the retina that connects to the bipolar cells near the outer synaptic layer and provides the basis for early image processing within the retina
2
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ampulla
A
in the ear, the structure at the base of a semicircular canal that contains the hair cells and cupula for transduction of rotational movement of the head
3
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anterior corticospinal tract
A
division of the corticospinal pathway that travels through the ventral (anterior) column of the spinal cord and controls axial musculature through the medial motor neurons in the ventral (anterior) horn
4
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aqeuous humor
A
watery fluid that fills the anterior chamber containing the cornea, iris, ciliary body, and lens of the eye
5
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ascending pathway
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fiber structure that relays sensory information from the periphery through the spinal cord and brain stem to other structures of the brain
6
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association area
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region of cortex connected to a primary sensory cortical area that further processes the information to generate more complex sensory perceptions
7
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auricle
A
fleshy external structure of the ear
8
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basilar membrane
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in the ear, the floor of the cochlear duct on which the organ of Corti sits
9
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betz cells
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output cells of the primary motor cortex that cause musculature to move through synapses on cranial and spinal motor neurons
10
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binocular depth cues
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indications of the distance of visual stimuli on the basis of slight differences in the images projected onto either retina
11
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bipolar cell
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cell type in the retina that connects the photoreceptors to the RGCs
12
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brocas area
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region of the frontal lobe associated with the motor commands necessary for speech production
13
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capsaicin
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molecule that activates nociceptors by interacting with a temperature-sensitive ion channel and is the basis for “hot” sensations in spicy food
14
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cerebral peduncles
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segments of the descending motor pathway that make up the white matter of the ventral midbrain
15
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cervical enlargement
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region of the ventral (anterior) horn of the spinal cord that has a larger population of motor neurons for the greater number of and finer control of muscles of the upper limb
16
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chemoreceptor
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sensory receptor cell that is sensitive to chemical stimuli, such as in taste, smell, or pain
17
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chief sensory nucleus
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component of the trigeminal nuclei that is found in the pons
18
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choroid
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highly vascular tissue in the wall of the eye that supplies the outer retina with blood
19
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ciliary body
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smooth muscle structure on the interior surface of the iris that controls the shape of the lens through the zonule fibers
20
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circadian rythm
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internal perception of the daily cycle of light and dark based on retinal activity related to sunlight
21
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cochlea
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auditory portion of the inner ear containing structures to transduce sound stimuli
22
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cochlear duct
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space within the auditory portion of the inner ear that contains the organ of Corti and is adjacent to the scala tympani and scala vestibuli on either side
23
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cone photoreceptor
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one of the two types of retinal receptor cell that is specialized for color vision through the use of three photopigments distributed through three separate populations of cells
24
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contralateral
A
word meaning “on the opposite side,” as in axons that cross the midline in a fiber tract
25
cornea
fibrous covering of the anterior region of the eye that is transparent so that light can pass through it
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corneal relfex
protective response to stimulation of the cornea causing contraction of the orbicularis oculi muscle resulting in blinking of the eye
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cortiocbulbar tract
connection between the cortex and the brain stem responsible for generating movement
28
corticospinal tract
connection between the cortex and the spinal cord responsible for generating movement
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cupula
specialized structure within the base of a semicircular canal that bends the stereocilia of hair cells when the head rotates by way of the relative movement of the enclosed fluid
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decussate
to cross the midline, as in fibers that project from one side of the body to the other
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dorsal column system
ascending tract of the spinal cord associated with fine touch and proprioceptive sensations
32
dorsal stream
connections between cortical areas from the occipital to parietal lobes that are responsible for the perception of visual motion and guiding movement of the body in relation to that motion
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encapsulated ending
configuration of a sensory receptor neuron with dendrites surrounded by specialized structures to aid in transduction of a particular type of sensation, such as the lamellated corpuscles in the deep dermis and subcutaneous tissue
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equilibrium
sense of balance that includes sensations of position and movement of the head
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executive functions
cognitive processes of the prefrontal cortex that lead to directing goal-directed behavior, which is a precursor to executing motor commands
36
external ear
structures on the lateral surface of the head, including the auricle and the ear canal back to the tympanic membrane
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exteroreceptor
sensory receptor that is positioned to interpret stimuli from the external environment, such as photoreceptors in the eye or somatosensory receptors in the skin
38
extraocular muscle
one of six muscles originating out of the bones of the orbit and inserting into the surface of the eye which are responsible for moving the eye
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extrapyrimdal system
pathways between the brain and spinal cord that are separate from the corticospinal tract and are responsible for modulating the movements generated through that primary pathway
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fasiculus cuneatus
lateral division of the dorsal column system composed of fibers from sensory neurons in the upper body
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fasciculus gracilis
medial division of the dorsal column system composed of fibers from sensory neurons in the lower body
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fibrous tunic
outer layer of the eye primarily composed of connective tissue known as the sclera and cornea
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fovea
exact center of the retina at which visual stimuli are focused for maximal acuity, where the retina is thinnest, at which there is nothing but photoreceptors
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free nerve ending
configuration of a sensory receptor neuron with dendrites in the connective tissue of the organ, such as in the dermis of the skin, that are most often sensitive to chemical, thermal, and mechanical stimuli
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frontal eye fields
area of the prefrontal cortex responsible for moving the eyes to attend to visual stimuli
46
general sense
any sensory system that is distributed throughout the body and incorporated into organs of multiple other systems, such as the walls of the digestive organs or the skin
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gustatory receptor cells
sensory cells in the taste bud that transduce the chemical stimuli of gustation
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hair cells
mechanoreceptor cells found in the inner ear that transduce stimuli for the senses of hearing and balance
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incus (anvil)
(also, anvil) ossicle of the middle ear that connects the malleus to the stapes
50
inferior colliculus
last structure in the auditory brainstem pathway that projects to the thalamus and superior colliculus
51
inferior oblique
extraocular muscle responsible for lateral rotation of the eye
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inferior rectus
extraocular muscle responsible for looking down
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inner ear
structure within the temporal bone that contains the sensory apparati of hearing and balance
54
inner segment
in the eye, the section of a photoreceptor that contains the nucleus and other major organelles for normal cellular functions
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inner synaptic layer
layer in the retina where bipolar cells connect to RGCs
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interaural intensity difference
cue used to aid sound localization in the horizontal plane that compares the relative loudness of sounds at the two ears, because the ear closer to the sound source will hear a slightly more intense sound
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interaural time difference
cue used to help with sound localization in the horizontal plane that compares the relative time of arrival of sounds at the two ears, because the ear closer to the sound source will receive the stimulus microseconds before the other ear
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internal capsule
segment of the descending motor pathway that passes between the caudate nucleus and the putamen
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interoceptor
sensory receptor that is positioned to interpret stimuli from internal organs, such as stretch receptors in the wall of blood vessels
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ipsilateral
word meaning on the same side, as in axons that do not cross the midline in a fiber tract
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iris
colored portion of the anterior eye that surrounds the pupil
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kinesthesia
sense of body movement based on sensations in skeletal muscles, tendons, joints, and the skin
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lacrimal duct
duct in the medial corner of the orbit that drains tears into the nasal cavity
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lacrimal gland
gland lateral to the orbit that produces tears to wash across the surface of the eye
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lateral corticospinal tract
division of the corticospinal pathway that travels through the lateral column of the spinal cord and controls appendicular musculature through the lateral motor neurons in the ventral (anterior) horn
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lateral geniculate nuclus
thalamic target of the RGCs that projects to the visual cortex
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lateral rectus
extraocular muscle responsible for abduction of the eye
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lens
component of the eye that focuses light on the retina
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levatator palpebrae superioris
muscle that causes elevation of the upper eyelid, controlled by fibers in the oculomotor nerve
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lumbar enlargement
region of the ventral (anterior) horn of the spinal cord that has a larger population of motor neurons for the greater number of muscles of the lower limb
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macula
enlargement at the base of a semicircular canal at which transduction of equilibrium stimuli takes place within the ampulla
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malleus (hammer)
(also, hammer) ossicle that is directly attached to the tympanic membrane
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mechanoreceptor
receptor cell that transduces mechanical stimuli into an electrochemical signal
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medial geniculate nucleus
thalamic target of the auditory brain stem that projects to the auditory cortex
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medial lemniscus
fiber tract of the dorsal column system that extends from the nuclei gracilis and cuneatus to the thalamus, and decussates
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medial rectus
extraocular muscle responsible for adduction of the eye
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mesencephalic nucelus
component of the trigeminal nuclei that is found in the midbrain
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middle ear
space within the temporal bone between the ear canal and bony labyrinth where the ossicles amplify sound waves from the tympanic membrane to the oval window
79
multimodal integration area
region of the cerebral cortex in which information from more than one sensory modality is processed to arrive at higher level cortical functions such as memory, learning, or cognition
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neural tunic
layer of the eye that contains nervous tissue, namely the retina
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nociceptor
receptor cell that senses pain stimuli
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nucleus cuneatus
medullary nucleus at which first-order neurons of the dorsal column system synapse specifically from the upper body and arms
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nucleus gracilis
medullary nucleus at which first-order neurons of the dorsal column system synapse specifically from the lower body and legs
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odorant molecules
volatile chemicals that bind to receptor proteins in olfactory neurons to stimulate the sense of smell
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olfactory bulb
central target of the first cranial nerve; located on the ventral surface of the frontal lobe in the cerebrum
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olfactory epithelium
region of the nasal epithelium where olfactory neurons are located
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olfactory sensnory neuron
receptor cell of the olfactory system, sensitive to the chemical stimuli of smell, the axons of which compose the first cranial nerve
88
opsin
protein that contains the photosensitive cofactor retinal for phototransduction
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optic chiasm
decussation point in the visual system at which medial retina fibers cross to the other side of the brain
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optic disc
spot on the retina at which RGC axons leave the eye and blood vessels of the inner retina pass
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optic nerve
second cranial nerve, which is responsible visual sensation
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optic tract
name for the fiber structure containing axons from the retina posterior to the optic chiasm representing their CNS location
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organ of Corti
structure in the cochlea in which hair cells transduce movements from sound waves into electrochemical signals
94
osmoreceptor
receptor cell that senses differences in the concentrations of bodily fluids on the basis of osmotic pressure
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ossicles
three small bones in the middle ear
96
otolithic membrane
gelatinous substance in the utricle and saccule of the inner ear that contains calcium carbonate crystals and into which the stereocilia of hair cells are embedded
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outer segment
in the eye, the section of a photoreceptor that contains opsin molecules that transduce light stimuli
98
outer synaptic layer
layer in the retina at which photoreceptors connect to bipolar cells
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oval window
membrane at the base of the cochlea where the stapes attaches, marking the beginning of the scala vestibuli
100
palpebral conjunctiva
membrane attached to the inner surface of the eyelids that covers the anterior surface of the cornea
101
papilla
for gustation, a bump-like projection on the surface of the tongue that contains taste buds
102
photoisomerization
chemical change in the retinal molecule that alters the bonding so that it switches from the 11-cis-retinal isomer to the all-trans-retinal isomer
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photon
individual “packet” of light
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photoreceptor
receptor cell specialized to respond to light stimuli
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premotor cortex
cortical area anterior to the primary motor cortex that is responsible for planning movements
106
primary sensory cortex
region of the cerebral cortex that initially receives sensory input from an ascending pathway from the thalamus and begins the processing that will result in conscious perception of that modality
107
proprioception
sense of position and movement of the body
108
proprioreceptor
receptor cell that senses changes in the position and kinesthetic aspects of the body
109
pupil
open hole at the center of the iris that light passes through into the eye
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pyrimdal decussation
location at which corticospinal tract fibers cross the midline and segregate into the anterior and lateral divisions of the pathway
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pyramids
segment of the descending motor pathway that travels in the anterior position of the medulla
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receptor cell
cell that transduces environmental stimuli into neural signals
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red nucleus
midbrain nucleus that sends corrective commands to the spinal cord along the rubrospinal tract, based on disparity between an original command and the sensory feedback from movement
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reticulospinal tract
extrapyramidal connections between the brain stem and spinal cord that modulate movement, contribute to posture, and regulate muscle tone
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retina
nervous tissue of the eye at which phototransduction takes place
116
retinal
cofactor in an opsin molecule that undergoes a biochemical change when struck by a photon (pronounced with a stress on the last syllable)
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retinal ganglion cell (RGC)
neuron of the retina that projects along the second cranial nerve
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rhodopsin
photopigment molecule found in the rod photoreceptors
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rod photoreceptor
one of the two types of retinal receptor cell that is specialized for low-light vision
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round window
membrane that marks the end of the scala tympani
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rubrospinal tract
descending motor control pathway, originating in the red nucleus, that mediates control of the limbs on the basis of cerebellar processing
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saccule
structure of the inner ear responsible for transducing linear acceleration in the vertical plane
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scala tympani
portion of the cochlea that extends from the apex to the round window
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scala vestibuli
portion of the cochlea that extends from the oval window to the apex
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sclera
white of the eye
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semicircular canals
structures within the inner ear responsible for transducing rotational movement information
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sensory homunculus
topographic representation of the body within the somatosensory cortex demonstrating the correspondence between neurons processing stimuli and sensitivity
128
sensory modality
a particular system for interpreting and perceiving environmental stimuli by the nervous system
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solitary nucleus
medullar nucleus that receives taste information from the facial and glossopharyngeal nerves
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somatosensation
general sense associated with modalities lumped together as touch
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special sense
any sensory system associated with a specific organ structure, namely smell, taste, sight, hearing, and balance
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spinal trigeminal nucleus
component of the trigeminal nuclei that is found in the medulla
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spiral ganglion
ascending tract of the spinal cord associated with pain and temperature sensations
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stapes (stirrup)
(also, stirrup) ossicle of the middle ear that is attached to the inner ear
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stereocilia
array of apical membrane extensions in a hair cell that transduce movements when they are bent
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stretch reflex
response to activation of the muscle spindle stretch receptor that causes contraction of the muscle to maintain a constant length
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submodality
specific sense within a broader major sense such as sweet as a part of the sense of taste, or color as a part of vision
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superior colliculus
structure in the midbrain that combines visual, auditory, and somatosensory input to coordinate spatial and topographic representations of the three sensory systems
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superior oblique
extraocular muscle responsible for medial rotation of the eye
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superior rectus
extraocular muscle responsible for looking up
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supplemental nucleus
cortical area anterior to the primary motor cortex that is responsible for planning movements
142
taste buds
structures within a papilla on the tongue that contain gustatory receptor cells
143
tectorial membrane
component of the organ of Corti that lays over the hair cells, into which the stereocilia are embedded
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tectospinal tract
extrapyramidal connections between the superior colliculus and spinal cord
145
thermoreceptor
sensory receptor specialized for temperature stimuli
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topographical
relating to positional information
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transduction
process of changing an environmental stimulus into the electrochemical signals of the nervous system
148
trochlea
cartilaginous structure that acts like a pulley for the superior oblique muscle
149
tympanic membrane
ear drum
150
umami
taste submodality for sensitivity to the concentration of amino acids; also called the savory sense
151
utricle
structure of the inner ear responsible for transducing linear acceleration in the horizontal plane
152
vascular tunic
middle layer of the eye primarily composed of connective tissue with a rich blood supply
153
ventral posterior nucleus
nucleus in the thalamus that is the target of gustatory sensations and projects to the cerebral cortex
154
ventral stream
connections between cortical areas from the occipital lobe to the temporal lobe that are responsible for identification of visual stimuli
155
vestibular ganglion
location of neuronal cell bodies that transmit equilibrium information along the eighth cranial nerve
156
vestibular nuclei
targets of the vestibular component of the eighth cranial nerve
157
vestibule
in the ear, the portion of the inner ear responsible for the sense of equilibrium
158
vestibulo-ocular reflex (VOR)
reflex based on connections between the vestibular system and the cranial nerves of eye movements that ensures images are stabilized on the retina as the head and body move
159
vestibulospinal tract
extrapyramidal connections between the vestibular nuclei in the brain stem and spinal cord that modulate movement and contribute to balance on the basis of the sense of equilibrium
160
visceral sense
sense associated with the internal organs
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visual acuity
property of vision related to the sharpness of focus, which varies in relation to retinal position
162
vitreous humor
viscous fluid that fills the posterior chamber of the eye
163
working memory
function of the prefrontal cortex to maintain a representation of information that is not in the immediate environment
164
zonule fibers
fibrous connections between the ciliary body and the lens
165
nociceptor
receptor cell that senses pain stimuli
