perception and palpation Flashcards
the building blocks of OPP
touch, perception, palpation
define touch
a perception derived from neural activity in a complex network that includes the somatic sensory system (including portions of cortical regions in the cerebrum)
define perception
the conscious mental registration / awareness of a sensory stimulus
define receptive field
the area within which a stimulus excites a cell (causing it to fire an action potential or alter the firing of the neuron associated with it)
define two point discrimination
the ability to discern that two nearby objects are touching the skin at two distinct points
3 classifications of sensory receptors
exteroceptors (external environment)
interoceptors (internal environment)
proprioceptors (position of body)
define stereognosis in terms of perception
the ability to recognize the 3D shape of an object solely based on touch
define threshold in terms of perception
the least amount of energy / force needed to cause a measurable response
define adaptation in terms of perception
when a continuous sensory stimulus is applied the receptors initially respond at a high impulse rate but then drop off until they may no longer respond
define palpation
applying the fingers with varying pressure to the surface of the body during physical diagnosis
for the purpose of determining the condition of the parts beneath
in what context should you palpate?
in a clinical setting it is in the context of a complete history and physical exam
mechanoreceptors are sensitive to …
physical distortion: bending / stretching / vibration / pressure
nociceptors signal …
that the body is being damaged / is at risk of being damaged
thermoreceptors are …
receptors that are sensitive to extreme hot /cold
proprioceptors function in …
measuring muscle length and tendon / limb position so the body knows its location / speed / orientation
underlying the epidermis, there are 2 major groups of primary afferent nerve endings within the dermis:
I. free endings
II. encapsulated endings
free nerve endings in the dermis function to … and they are …
give sensation of general contact with an object
un-myelinated or lightly myelinated
encapsulated nerve endings in the dermis function to … and they are …
provide discriminative and localized touch
well-myelinated (group II axons)
merkel discs are …
mechanoreceptors
prolonged pressure and texture
located closer to the surface of the dermis
small receptive fields
found in greatest number in finger pads
meissner corpuscles are …
mechanoreceptors with encapsulated nerve endings
light touch
located closer to the surface of the dermis
small receptive fields
1/10th the size of pacinian corpuscles
pacinian corpuscles are … that detect …
mechanoreceptors with encapsulated nerve endings
pressure / vibration
deep in the dermis
large receptive fields & sensitive centers
onion skin-like encapsulations
ruffini endings are …
mechanoreceptors with encapsulated nerve endings
skin stretch / prolonged pressure
deep in the dermis
spindle-shaped
2 types of receptors with rapidly adapting nerve endings:
pacinian corpuscles
meissner corpuscles
(better at recording moving stimulus than a static one)
2 types of receptors with slowly adapting nerve endings:
merkel discs
ruffini endings
(better at recording a static stimulus than moving one)
hair root plexus are … and detect …
mechanoreceptors
light touch
krause end bulbs are …; detect …; are found …
mechanoreceptors
simple touch
in border regions of dry skin & mucous membranes
nociceptors are …
free, unbranching nerve endings
un-myelinated / lightly myelinated
the 4 categories of nociceptors:
mechanical (strong pressure from sharp objects)
thermal (extreme hot /cold)
chemically sensitive (pH)
polymodal (a variety of things)
1 =
5 =
1 = most sensitive
5 = least sensitive
each receptor generates a … which is then … by …
unique sensorineural code
conducted into the spinal cord
central processes of the primary neurons
a sensory pathway is …
a set of neurons arranged in series: 1st, 2nd, 3rd, 4th
1st order neuron in a sensory pathway is called … and is …; functions to …
primary afferent
periphery-sensory receptors
responds to stimulus, transduces it, transmits encoded info (the sensorineural code) to the CNS
2nd order neuron in a sensory pathway is called … and is located …
secondary afferent
spinal cord or brainstem / medulla
3rd order in a sensory pathway is located …
within the thalamus
4th order in a sensory pathway is the …; located …
somatosensory cortex
in the postcentral gyrus of the cerebral cortex
where perception occurs (conscious awareness of stimulus)
dorsal or posterior columnar-medial lemniscal pathway functions to transmit … via … to …
transmit info about touch / vibration / pressure / texture recognition / stereognosis / 2 pt discrimination / proprioception / kinesthesia from the limbs
high speed pathway
primary somatic sensory cortex
spinothalamic pathway carries …
info about pain / itch / temp / simple or non discriminative touch
what is the sensory homunculus?
distorted human figure used to represent the relative area of cerebral cortex devoted to the sensation of corresponding skin areas at the postcentral gyrus
what is the motor homonculus?
distorted human figure used to represent the relative area of cerebral cortex devoted to movement of corresponding motor areas at the precentral gyrus
altered
ex. musicians increase ability vs. loss of a digit
examples of proprioceptors:
muscle spindles
golgi tendon organs
joint / kinesthetic receptors
golgi tendon organ is …
a proprioceptor that detects muscle tension at the junction of a muscle & tendon
somatic sensory parietal cortex has a … that participates in the … pathway; and a … that participates in the … pathway
dorsally directed projection (parietal)
“where” pathway (location of stimulus)
ventrally directed projection (temporal)
“what” pathway (recognizing stimulus)
dorsolateral prefrontal cortex (in the back of the head) is interconnected with … and …; which creates …
posterior parietal cortex
inferior temporal cortex
tactile memories and working memories of experiences
4 steps of palpation:
reception/detection
transmission
interpretation
amplification
reception/detection step of palpation is to …
discover nature of the object (easier w context) using exteroceptors and proprioceptors
transmission step of palpation is when …
the info gathered is relayed to peripheral and CNS in the brain
interpretation step of palpation is when …
palpatory observations are translated into meaningful knowledge about anatomic / physiologic / pathologic states
amplification step of palpation is …
focusing on what is being palpated ?
the human hand is equipped to perceive:
2 pt discrimination
texture
contour/structure
friction/moisture
compliance
stereognosis
temp
