Lecture 9: Somatosensory Pathways Part 1 Flashcards
If the PCML pathway is affected from a spinal cord lesion, what can happen?
Ipsilateral reduction or loss of discriminative, positional, and vibratory tactile sensations
Will happen at and below level of injury
If there is a lesion to the Anterior Cerebral Artery, where would there be tactile loss?
Contralateral lower limb
If there is a lesion to the Middle Cerebral Artery, where would there be tactile loss?
Contralateral upper body and face
What supplies the Ventral Posterolateral Nucleus of the Thalamus?
Thalamogeniculate Branches of Posterior Cerebral Artery
Which fibers are found more medially?
Sacral and the more rostral you go, the more lateral those fibers are found
What is the role the mesencephalic nucleus?
Conveys unconscious proprioceptive afferents and pressure afferents from TMJ, masticatory, and extraocular muscles
What supplies the Principal/Chief Sensory Nucleus?
Superior Cerebellar Artery
Long Circumferential branches of Basilar Artery
How does the dorsomedial division reach the thalamus?
Travels ipsilaterally via posterior trigeminothalamic tract to
What are the Brodmann Areas of the Primary Somatosensory Cortex?
31, 3b, 1, and 2
In the Sensory Trigeminothalamic Pathway, where are primary afferents from?
Trigeminal Ganglion
What areas would have high density of tactile receptors?
Digits
Perioral region
How does the ventrolateral division reach the thalamus?
Travels contralaterally via anterior trigeminothalamic tract
What is two point discrimination?
Ability to discriminate between two stimuli simultaneously
In the medial lemniscus, where do the upper and lower extremity fibers now reside after the rotation in the pons?
Upper: Medial
Lower: Lateral
Where are the gracile and cuneate nuclei receiving their input from?
First order neurons (primary afferents) from ipsilateral dorsal root ganglion
In the PCML pathway, what do primary afferent fibers after entering the spinal cord?
Posterior Columns: Fasciculus Gracilis and Cuneatus
What are the two divisions of the principal/chief sensory nucleus and what do they receive information from?
Dorsomedial: Oral Cavity
Ventrolateral: V1, V2, V3
What type of axons are primary afferent fibers?
Sensory