Brainstem and Cerebellum Nestor T. Hilvano, M.D., M.P.H.

Learning Objectives 1.Describe the structures and functions of the medulla oblongata. 2.Describe the structures and functions of the pons. 3.Describe the structures and functions of the midbrain. 4.Describe the structures and functions of the cerebellum. 5.Correlate common anatomic and functional basis of lesions of the brainstem and cerebellum.

Brainstem Process information between the spinal cord and cerebrum/cerebellum Consists of: midbrain pons medulla oblongata

Midbrain Tectum (corpora quadrigemina)- posterior part –superior colliculus: visual relay –inferior colliculus : auditory relay Tegmentum – middle part –connects to cerebellum and helps control fine movements through red nucleus –CN III and IV Substantia nigra –sends inhibitory signals to basal ganglia Cerebral aqueduct Cerebral peduncles – anterior part Process sight, sound, & associated reflexes

Pons Connect cerebellum w/ brainstem Sensory and motor nuclei of cranial nerves Control of respiration -apneustic and pneumotaxic centers Ascending, descending, transverse fibers ( link nuclei of pons w/ opposite cerebellum) Nuclei and tracts to or from cerebellum Involved in somatic and visceral motor control

Medulla Oblongata Reticular formation – regulates vital autonomic functions * Cardiovascular center * Respiratory (rhythmicity) center Sensory and motor nuclei of cranial nerves Relay of sensory and motor pathways * sensory- nucleus gracilis and nucleus cuneatus; solitary tract nucleus; olivary nuclei * Motor- pyramidal tracts

Reticular Activating System Clusters of gray matter scattered throughout the brainstem Regulate balance and posture –relays information from eyes and ears to cerebellum –gaze centers and central pattern generators Includes cardiac and vasomotor centers Regulates sleep and conscious attention –injury leads to irreversible coma

Cerebellum Two hemispheres connected by _____ Cerebellar Lobes- anterior lobe, posterior lobe, and flocculonodular lobe. Gray matter= consists of cerebellar cortex and cerebellar nuclei Surface folds are called __________ Characteristic cells are ___________ White matter = cerebellar medulla; arbor vitae a. Vermis b. folia c. purkinje cells

Cerebellum Sits atop 4 th ventricle Arbor vitae (tree of life) connects cerebellar cortex and nuclei with the cerebellar peduncles Connected to brainstem by cerebellar peduncles –superior peduncle –middle peduncle –inferior peduncle

Cerebellar Function and Injury Adjusting postural muscles of the body - coordination Programming and fine tuning movements Lesions result to ___. a. ataxia b. aphasia c. anosmia d. atonia Damage from trauma or stroke Intoxication (temporary impairment) Disturbs muscle coordination

Homework (Self Review) 1.Name the 3 components of brainstem. 2.Discuss why damage to medulla oblongata can cause death? 3.Describe the tectum, tegmentum, and cerebral peduncles of midbrain. 4.Describe the superior, middle and inferior cerebellar peduncles. 5.Give the function of : inferior colliculi, superior colliculi, arbor vitae, nucleus gracilis, nucleus cuneatus, vermis 6.List the cranial nerves located at midbrain, pons, and medulla oblongata. 7.What is ataxia?