Sensory Function (Big Red Ch. 3) Flashcards
Feedback control loop
Receives sensory info and then adjusts motor response.
Feedforward control loop
Remembers sensory info from previous experiences and makes anticipatory adjustments before the event happens.
Somatosensation
- Sensation received from the skin and musculoskeletal system
- Input from visual and auditory cranial nerves
Common diagnoses with decreased sensation
CVA, TBI, SCI, MS, peripheral nerve injuries
Age-related sensory changes
- Reduced nerve conduction velocity
- Reduced number of Meissner’s corpuscles
- Decreased concentration of Pacinian corpuscles
- Degenerative changes in myelin in the CNS and PNS
- Decreased distance between the nodes of Ranvier
- Taking more medications
Alert
Awake and attentive to normal stimuli
Lethargic
Drowsy, may fall asleep if not stimulated
Obtunded
Difficult to arouse, confused when awakened
Stupor
Semi-coma, responds only to strong or painful stimuli
Coma
Cannot be aroused by any type of stimuli, may or may not have reflexes
Attention
Selective awareness of the environment or response to a stimulus without being distracted by another stimulus.
Orientation and how is it measured?
- Awareness of time, person, and place
- If person is correct in all 3 categories they are “oriented x3”
- If person can also provide correct info about current situation, they are “oriented x4”
3 ways to test cognition
1) Fund of knowledge
- general knowledge based on life experience
2) Calculation ability
- math
3) Proverb interpretation
- word meaning out of context
3 major tracts of the spinothalamic system
- Anterior spinothalamic tract
- Lateral spinothalamic tract
- Spinoreticular tract
Non-discrimintive sensations: pain, temp, tickle, itch, sexual sensation
Anterolateral spinothalamic pathway is activated by…
- Mechanoreceptors
- Thermoreceptors
- Nociceptors
Anterior spinothalamic tract
Crude touch and pressure
Lateral spinothalamic tract
pain, temp, crude touch on opposite side
Spinoreticular tract
Dorsal column (medial lemniscal pathway)
- Discriminative touch and pressure sensations - Vibration
- Stereognosis
- Barognosis
- Graphesthesia
- 2-point discrimination
- Texture
- Proprioception
- Conscious kinesthesia
Superficial sensation
exteroreceptors
Deep sensation
proprioceptors
Combined cortical sensation
Combo of superficial and deep sensory mechanisms
Mechanoreceptors detect…
mechanical deformation
Thermoreceptors detect…
changes in temp
Nociceptors detect…
pain, noxious stimuli
Chemoreceptors detect…
levels of chemical substances
Photic (electromagnetic) receptors respond to…
light
Types of cutaneous receptors
- free nerve endings
- hair follicle endings
- Merkel’s disks
- Ruffini endings
- Krause’s end bulb
- Meissner’s corpuscles
- Pacinian corpuscles
Where are deep sensory receptors located?
Muscles, tendons, and joints
Types of muscle receptors
- Muscle spindles
- Golgi Tendon Organs
- Free nerve endings
- Pacinian corpuscles
Types of joint receptors
- Golgi-type endings
- Free nerve endings
- Ruffini endings
- Paciniform endings
Primary somatosensory cortex (S-I)
- Postcentral gyrus
- 4 distinct areas
- Identifies the location of a stimulus
- Discerns shape, size, and texture of an object
Secondary somatosensory cortex (S-II)
- Superior aspect of lateral sulcus
- Tactile memory
Posterior parietal cortex
- Behind S-I
- Consists of Brodmann’s areas 5 and 7
Brodmann’s area 5
Integrates tactile input from mechnoreceptors in the skin with proprioceptive input from the muscles and joints.
Brodmann’s area 7
Integrates stereognostic and visual info from visual, tactile, and proprioceptive input.
Sensory testing sequence
1) superficial sensation
2) deep sensation
3) combined sensation
