Organization of Brainstem Flashcards
3 Major functions of the Brainstem
- Conduit - (ascending and descending tracts)
- Site for all cranial nerve nuclei (except 1 and 2)
- Integration (regulates consciousness, motor function and respiration/ CV function)
What are the pathways through the brainstem?
- Dorsal Column/ Medial Meniscal pathway (propriocention and touch)
- Spinothalamic (pain and temperature)
- Corticospinal (motor)
Blood Supply of the anteromedial area of brainstem? lateral and posterior?
- anteromedial - perforating arteries of verterbal and basilar
- lateral and posterior - circumferential arteries (PICA, AICA, posterior cerebral, and pontine)
Parts of the brainstem
- Midbrain
- Medulla
- Pons
*Note that there is a caudal and rostral portion to each
Caudal Medulla is split into dorsal and ventral parts via the ______ _______. Describe the layout.
- Sulcus Limitans
• Somatic sensory-most dorsal
• Visceral sensory-ventral to somatic sensory dorsal to sulcus limitans
• Visceral motor-ventral to sulcus limitans
• Somatic motor-most ventral
Via nucleus gracilis/ cuneatus, primary motor neurons synapse with _________ ________. Secondary neurons cross as ________ _______ _______ and enters the medial lemniscal tract.
- Secondary neurons
- Internal arcuate fibers
The medial lemniscal tract connects what structures? Describe the homonculus.
- Connects nucleus cuneatus/gracilis to thalamus
* Homunculus-body standing upright
What is the function of the spinal trigeminal tract?
Pain and temperature sensation in the head`
UMN project via the pyramids to the ______ ________ where 85% cross the midline.
-Pyramidal decussation
Via the spinothalamic tract, axons from interneurons in the dorsal horn project to the ______
- Thalamus
In the rostral medulla, sensory information becomes _____ while motor information becomes ______.
- Lateral
- Medial
What is the function of the inferior olivary nucleus?
- Receives input from the cerebellum, cerebral cortex and spinal cord
- acts as a “mini thalamus” for the cerebellar cortex
What is the function of the medial longitudinal fasiculus?
- Receive input from extraocular muscle cranial nerves and control of spinal neck muscles
- Coordination of CN III, IV, and VI for eye movement and tracking
What is the function of the hypoglossal nucleus?
- Serves like a ventral horn for motor neurons controlling muscles of tongue
- Nerve exits between olive and pyramid
What is the function of the solitary tract?
• Visceral sensory fibers from CN VII, IX and X
What is the function of the dorsal motor nucleus of the vagus?
• LMN responsible for speech
What is the function of the glossopharyngeal and vestibulocochlear nuclei?
- taste, hearing and equilibrium
What nerves exit via the pontomedullary junction?
From medial to lateral: VI, VII, VIII
What is the function of the pontine nuclei?
Synapses for cortical neurons before information passes to contralateral cerebellar cortex
The middle cerebellar peduncle serves as a connection point between what two structures?
Pons and brainstem
The deep cerebellar nuclei are composed of what 3 structures? They are the output neruons of the ______.
- Dentate, interposed and fastigial nuclei
- Cerebellum
The fibers of the ipsilateral facial neruons wrap around the ______ ________ .
- Abducens nucleus
The abducens nucleus serves as a motor neuron for what muscles?
- Ipsilateral lateral rectus muscle
The trigeminal nuclei in the rostral pons function?
- sensory and motor information of the head
