Lecture 5: General Sensory Mechanisms II Flashcards
Somatic senses
Collect sensory information from all over the body; mechanoreceptive, thermoreceptive, pain
Special senses
Refer to vision, hearing, smell, taste, equilibrium
Exteroreceptive sensations
From the surface of the body
Proprioceptive sensations
Refer to the physical state of the body (position, muscle sensation, pressure, equilibrium)
Deep sensations
Deep pressure, pain, vibration
What are the 3 physiological types of somatic senses?
Mechanoreceptive somatic senses, Thermoreceptive senses, Pain sense
Which ascending pathways are used for conscious perception?
Spinothalamic system, Medial lemniscal system
Which ascending pathways are used for unconscious perception?
Spinocerebellar, spino-olivary, spinotectal, spinoreticular
What sensations does the lateral spinothalamic tract carry?
Pain and temperature
What sensations does the anterior spinothalamic tract carry?
Light touch/crude touch, pressure, tickle itch
What sensations does the medial lemniscus system carry?
Two-point sensation (fine touch), pressure, vibration
What structure conveys sensations from below midthoracic level?
Nucleus gracilis
What structure conveys sensations from above the midthoracic level?
Nucleus cuneatus
Primary somatosensory area
Composed of Brodmann’s areas 1,2, and 3
Somatosensory association area
Composed of Brodmann’s areas 5 and 7
What are the results of widespread bilateral excision of the Somatosensory Area I?
Loss of fine sensation, judging degrees of pressure, judging weight/shape of objects, etc; pain and temperature preserved but poorly localized
Somatosensory Area II
Receives signals from brainstem, somatosensory area I, other sensory areas; must have projections from area I for area II to function
Layers I and II of Somatosensory cortex
Receive input signals from lower brain centers
Layers II and III of Somatosensory cortex
Send information through corpus callosum to opposite hemisphere
Layers V and VI of Somatosensory cortex
V projects to basal nuclei/brainstem/spinal cord; VI projects to thalamus
Layer IV of Somatosensory cortex
Receives incoming sensory signals
Which neurons decussate in the ascending pathways?
A. Primary sensory neurons
B. Secondary neurons
C. Tertiary neurons
D. Collateral neurons
B. Secondary neurons
