Chaper 9: The Somatic Sensory System Flashcards
What are the critical links to supply the CNS with information about what happens in the periphery in the BODY and the HEAD?
In head: Cranial Nerve Ganglia
In body: Dorsal Root Ganglia
Mechanoreceptors are found at the end of WHAT KIND of fiber?
Afferent
Name the types of mechanoreceptors from BEST to WORST spacial acuity.
Merkel > Meissner > Ruffini > Pacinian
Which to mechanoreceptors are SLOW adapting?
Merkel and Ruffini
Which two mechanoreceptors are RAPID adapting?
Meissner and Pacinian
Which mechanoreceptor is best at processing form and texture (edges, points, corners, curvature)? (Not be be confused with identifying when an object is moving across the skin)
Merkel Afferents
Where are Merkel afferents found?
in epidermal redges
Where are Meissner afferents located?
in tips of dermal papillae
Which mechanoreceptor is sensitive to internally generated stimuli?
Ruffini
Which mechanoreceptor is best suited to detect when an object is moving across the skin?
Meissner Afferents
What are free nerve endings good at processing?
The sensation of pain
Are free nerve endings LESS or MORE sensitive than mechanoreceptors?
Less
A smaller receptive field is associated with a __________ amount of arborization.
smaller
RAPID adapting mechanoreceptors are good at sensing stimuli that _____ (change/do not change).
Change
________ adapting afferents are best suited for processing spacial attributes (size, shape).
Slowly
Describe the structure of a nociceptor.
free nerve ending
A nociceptor is best as processing ________.
Pain
Somatic sensory afferents constitute ______ pathways. Meaning that…
Parallel; meaning that they work together at the same time and only later will integrate their signals
What is a dermatome?
Area innervated by each spinal nerve
T/F: Dermatomes do not overlap.
False. They slightly overlap.
Overlap in dermatomes is more extensive for what types of sensation?
Touch, pressure, vibration. There is less overlap for pain.
Name the nerve ending types from MOST to LEAST superficial.
Free Nerve Endings Merkel Meissner Ruffini Pacinian
Ipsilateral vs. Contralateral
Ipsilateral: same side
Contralateral: different side
Of the autonomic division, the _______ branch is more active during stress.
Sympathetic
Dorsal roots carry…
sensory afferents
Ventral roots carry…
motor efferents.
If the VENTRAL ROOT is cut, what function is affected?
Ability to control muscles
The Diencephalon contains what?
Thalamus and Hypothalamus
The Brainstem contains….
Midbrain, pons, medulla
The forebrain contains…
Diencephalon and Cerebral Hemisphere
“Nerves” in ______: “Tracts” in ______
Nerves in PNS; Tracts in CNS
The subcortical ganglia contains…
basal ganglia
amigdala
The cerebral cortex is ______ (gray/white) matter.
gray
What number Broadman’s area is the primary motor cortex?
4
The basal ganglia mediates….
unconscious decisions regarding movement
The _____ is the highest level of sensory integration in most organisms.
midbrain
Function of the TECTUM
attention to visual and auditory stimuli
Thalamus is relay station for all sensory inputs except THIS.
smell
What structure contains the superior and inferior colliculus?
Tectum
The superior colliculus collects inputs from the ______; Inferior collects from ____.
eye; ear
Which brain part mediates reflex control of posture?
Pontine Nuclei
Visceral receptors are found in…
blood vessels, heart, lungs, GI tract, bladder
What two mechanoreceptors are very superficial in the skin?
Meissner and Merkel
What mechanoreceptors are deepest in skin?
Pacinian and Ruffini
What mechanoreceptors respond best to SUSTAINED stimulus
Merkel and Ruffini
Define: Commisure
Tract that crosses midline of brain
Sagittal Section:
Axial Section:
Coronal Section:
Sagittal Section: Across brain horizontally
Axial Section: vertically, front to back
Coronal Section: Vertically, side to side
Efferent fibers go from _____ to _____
CNS to muscles
Afferent fibers go from _____ to ______.
Muscle to CNS
If you increase the intensity of a stimulus you _____ the rate of AP discharge.
increase
