9.0 Somatosensory Tracts 1 Flashcards
What are the functions of the sensory nuclei of the trigeminal nerve?
Main sensory nucleus (msT)
- Touch and pressure.
Spinal nucleus
- Touch
- Pressure
- Proprioceptin
- Pain
- Temperature
Mesencephalic nucleus (mes)
- Proprioception for chewing.
What are the two divisions of the main sensory nucleus of the trigeminal nerve?
The main sensory nucleus has two divisions:
- Dorsomedial division
- Afferents just from the oral cavity.
- Ventrolateral division
- Afferents from V1, V2, and V3
In the fasciculae gracilis and cuneatus, are the fibers from the upper extremity more lateral or more medial to the fibers from the lower extremity?
Upper extremity fibers are more lateral in the PCML system.
Where do the third order neurons of the PCML system travel?
What important structure do they pass through?
What is the name of the pathway?
The fibers from the ventral posterolateral nucleus runs through the thalamocortical pathway, through the posterior limb of the internal capsule, and to the somatosensory cortex.
What is the specialization of the outer shell and inner core of the nuclei gracilis and cuneatus?
The outer shell of the nuclei gracilis and cuneatus specializes in proprioception.
The inner core specializes in sensation.
What do we call the decussation of the PCML secondary fibers immediately after the synapse of the nucleus gracile/cuneatus?
Internal arcuate fibers.
Where would lesions to the middle cerebral artery cause loss of sensation?
Where would lesions to the anterior cerebral artery cause loss of sensation?
The anterior cerebral artery damage would eradicate sensation from the lower extremity.
Middle cerebral artery damage would eradicate damage from the upper extremity and face.
What are the three parts of the spinal nucleus of the trigeminal nerve?
Pars caudalis,
Pars oralis,
Pars interpolaris
Where do the dorsomedial and ventrolateral fibers of the main sensory nucleus of the trigeminal nerve synapse?
On the ventral posteromedial nucleus of the thalamus.
What nucleus in the thalamus does the PCML pathway synapse onto?
The ventral posteriolateral nucleus of the thalamus.
What artery supplies the PCML in the spinal cord?
What artery supplies the PCML in the medulla (and up from there)?
Spinal cord = posterior spinal artery
Medulla and up = anterior spinal artery
Where do the afferent first order fibers of the PCML system enter the spinal cord?
At the medial division of the posterior root.
What symptom is associated with damage to the secondary somatosensory area?
Agnosia – the loss of ability to recognize a limb as part of the body.
What artery supplies the ventral posterolateral nucleus?
What would happen if these were occluded?
The thalamogeniculate branches of the posterior cerebral artery.
Complete loss of discriminative touch, pressure sensation, and proprioception to the contralateral body.
Where are the cell bodies for first order sensory neurons?
What type of nerves are these?
From what layer are these nerves derived?
Dorsal root ganglion.
Pseudounipolar nerves.
Neuroectoderm.
