Pons and Cerebellum Flashcards
Where do the Raphe nuclei of the pons project?
Rostrally throughout the forebrain and modulate responses of hypothalamic and cerebral neurons. (serotonergic)
Where is the locus ceruleus located, what type of neurons does it project, to where, and what is it known to do?
Located in the rostral pons and caudal midbrain next to superior cerebellar peduncle, noradrenergic (melanin granules). Widespread projections that modulate neurons throughout the brain including the spinal cord, cerebral and cerebellar cortices. Important for vigilance and responsiveness to unexpected environmental stimuli
What is the trapezoid body?
The trapezoid body consists of the medial lemnisci and the auditory fibers decussating from the cochlear nuclei to the contralteral superior olive.
What is the Paramedian pontine reticular formation, where is it located and what does it do?
It is in the pons near the abducens nucleus and it is also involve in coordinating conjugate horizontal eye movements.
What are the three major outputs of the Vestibular Nuclei?
1) to the cranial nuclei that move the eyes (3,4,6) via the MLF
2) to the spinal cord via the Vestibulospinal Tract. these are important for maintaining posture
3) To the cerebellum via the inferior cerebellar peduncle. These play a role in balance and the control of reflexive eye movements.
What are some of the symptoms of pathologies to the vestibular nuclei?
Nystagmus (slow in one direction then quickly back)
Loss of balance (particularly with eyes closed - Romberg test)
Vertigo, dizziness, nauseousness (spinning) - to be distinguished from light headed
Name the muscles that the facial nerve innervates
Facial expression muscles, stapedius, auricularis, stylohyoid and posterior belly of digastic muscles
What are some signs of pathologies to the facial nuclei?
Paralysis of ipsilateral facial muscles, loss of PNS control to lacrimal-> dry eyes. Loss of corneal reflex, even though patient still feels pain. Sensitivity to sound.
What are some signs of pathologies to the CN VI?
Paralysis of the ipsilateral lateral rectus. As a result the eye deviates towards the nose (internal strabismus) leading to diplopia (Double Vision)
What are the three major input pathways of the inferior cerebellar peduncles?
1) Spinocerebellar tracts (proprioception about position and velocity of limbs)
2) Inferior Olivary Complex - receives information from most areas of cerebral cortex, the red nucleus, and from the spinal cords and sends it to cerebellum
3) Vestibular Nuclei - direct connection
What are the major inputs of the middle cerebellar peduncle?
Carries info from the pons to the cerebellum. Neurons in the basis of the pons as well as the pontine nuclei, receive innervation largely from cerebral cortex and relay this info to the contralateral cerebellum.
Where does the outflow of the Superior Cerebellar Peduncle enter the pons? What are the prominent targets?
The enter to the tegmentum of the pons just caudal to the inferior colliculus.
1) Areas of the Pontine Reticular Formation
2) Red Nucleus in the midbrain
3) Ventral Anterior and Ventral Later nuclei of the thalamus which in turn project to the precentral gyrus and the premotor cortex.
What are the medial deep cerebellar nuclei and what are their main connections?
The fastigial and globose receive the majority of their input from axial related structures such as the vestibular nuclei and the reticular formation and project back to these nuclei.
What are the lateral deep cerebellar nuclei and what are their main connections?
The embolliform and the dentate are more related to appendicular structures
Describe the general trend of midline and hemisphere pathologies in the cerebellum.
Midline pathologies (Vermis and Flocculus) affect the axial muscles -> Balance Hemisphere/Lateral Pathologies tends more to impair limb movement.
