Sensory system Flashcards
What are exteroreceptors?
Sensitive to stimuli arising from outside the body
What are interoceptors?
Receive stimuli from viscera
What are proprioceptors?
Monitor degree of stretch - body position sense
What are mechanoreceptors?
Respond to mechanical forces
What are thermoreceptors?
Respond to changes in temperature
What are Nociceptors?
Respond to harmful stimul/pain
What are electromagnetic receptors?
Respond to changes in light intensity and wavelength
What are chemoreceptors?
Responds to chemical changes associated with taste and smell, and concentrations in blood
What are the nonencapsulated receptors?
Free nerve endings
Merckel’s discs
Hair follicle receptors
What are the encapsulated receptors?
Meissner’s corpuscles
Pacinian corpuscles
Ruffini’s corpuscles
Neuromuscular spindles
Neurotendinous spindles
What is the spinocuneocerebellar tract?
DCML relay for conscious proprioception
What are epicritic receptors sensitive to?
Vibration
Conscious proprioception
Fine touch
What are protopathic receptors sensitive to?
Diffuse touch
Temperature
Pain
What are the three general parts of the ascending sensory pathway?
First-order neuron with cell body in dorsal root ganglion
Second-order neuron with axon that decussates and ascends
Third-order neuron usually in thalamus that projects to cerebral cortex
What ascending tract is for pain and temperature?
Lateral spinothalamic tract
What ascending tract is for light touch and pressure?
Anterior spinothalamic tract
What ascending tract is for discriminative touch?
Posterior white columns
What ascending tract is for unconscious information from the muscles, joints, skin, and subcutaneous tissues?
Anterior and posterior spinocerebellar tracts
Cuneocerebellar tract
What is the ascending tract for spinovisual reflexes?
Spinotectal tract
What tract provides an indirect pathway for information to reach cerebellum?
Spino-olivary tract
What are clinical features of DCML lesions?
Decreased 2-point discrimination
Decreased vibratory sense
Decreased proprioception
Astereognosis
Unilateral extinction
Agraphesthesia
What is the main pathway for pain and temperature?
Free nerve endings
Posterior root ganglion
Lateral spinothalamic tract and spinal lemniscus
Substantia gelatinosa
VPL of thalamus
Posterior central gyrus
What is the main pathway for light touch and pressure?
Free nerve endings
Posterior root ganglion
Anterior spinothalamic tract and spinal lemniscus
Substantia gelatinosa
VPL of thalamus
Posterior central gyrus
What is the main pathway for discriminative touch, vibratory sense, and proprioception?
Meissner corpuscle, pacinian corpuscle, muscle spindles
Posterior root ganglion
Fasciculus gracilis and cuneatus, and medial lemniscus
Nuclei gracilis and cuneatus
VPL of thalamus
Posterior central gyrus
What would you see with a lateral spinothalamic lesion?
Loss of pain and temperature below the level of the lesion
What would you see with anterior spinothalamic lesion?
Loss of light touch and pressure below the level of the lesion
What would you see with dorsal fasciculi lesion?
Ipsilateral loss of vibration and tactile discrimination
Ipsilateral ataxia
What are the characteristics of Brown-Sequard syndrome?
Total loss of sensation at level of lesion
Loss of tactile discrimination, vibration, and proprioception of limb on side of lesion
Loss of pain and temperature of opposite limb
What can cause Horner syndrome?
Lesion of brainstem or cervical part of spinal cord
Compression of stellate ganglion
What is the general idea of Gating theory of pain?
Non-painful tactile stimulation can lesson pain felt
