Topic 6.3 : Brainstem, Cerebellum & 4th Ventricle

Cranial fossa housing the brainstem and cerebellum

Posterior cranial fossa

Anatomical longitudinal extent of the brainstem

Extends from sphenoid below thalamus to foramen magnum

Anatomical position of the cerebellum relative to the brainstem

Cerebellum lies posterior to the brainstem

Ventricular cavity located between brainstem and cerebellum

Fourth ventricle

Three anatomical divisions of the brainstem from superior to inferior

Midbrain (mesencephalon), pons (bridge), and medulla oblongata (bulb)

Three major functional contents of the brainstem

Vital reflex centers, cranial nerve nuclei, and afferent and efferent pathways

Three fiber tract categories forming brainstem white matter

Ascending, descending, and association tracts

Three nuclear categories forming brainstem gray matter

Intrinsic nuclei, cranial nerve nuclei, and reticular nuclei

Vital autonomic control centers located within the medulla oblongata

Respiratory centers and cardiac control

Specific protective vital reflexes coordinated by the medulla oblongata

Swallowing, coughing, vomiting, sneezing, and hiccup

Clinical deficits associated with lesions of the medulla oblongata

Dysarthria, dysphagia, respiratory disturbances, and cardiac rhythm alterations

Primary functional roles of the pons (protuberance)

Connection with cerebellum, sleep regulation, and respiratory centers

Specific respiratory control centers located in the pons

Pneumotaxic and apneustic centers

Clinical deficits associated with pontine lesions

Facial palsy, diplopia, and respiratory disorders

Primary functional roles of the midbrain (mesencephalon)

Visual and auditory reflexes, eye movements, and tone modulation

Midbrain structure containing descending pathways for motor control

Substantia nigra

Clinical deficits resulting from midbrain lesions

Oculomotor, pupillary, and consciousness disturbances

Cranial nerve true origin versus apparent origin diagnostic rule

True origin is brainstem nuclei while apparent origin is surface emergence

Eponym for the decussation of motor pathways in the medulla

Mistichelli decussation

Cranial nerves emerging directly from the midbrain

CN III (oculomotor) and CN IV (trochlear)

Cranial nerves emerging directly from the pons

CN V (trigeminal), CN VI (abducens), CN VII (facial), and CN VIII (vestibulocochlear)

Cranial nerves emerging directly from the medulla oblongata

CN IX (glossopharyngeal), CN X (vagus), CN XI (accessory), and CN XII (hypoglossal)

Horizontal groove separating the pons from the medulla oblongata

Pontomedullary sulcus

Paired longitudinal elevations on anterior medulla carrying motor pathways

Pyramids

Oval elevations situated immediately lateral to the medullary pyramids

Medullary olives

Small blind depression at superior end of medullary anterior median sulcus

Foramen cecum

Brainstem structure connected by the superior cerebellar peduncles

Midbrain (mesencephalon)

Brainstem structure connected by the middle cerebellar peduncles

Pons

Brainstem structure connected by the inferior cerebellar peduncles

Medulla oblongata

Posterior midbrain elevations mediating visual reflexes

Superior colliculi

Posterior midbrain elevations mediating auditory reflexes

Inferior colliculi

Narrow channel traversing the midbrain connecting third and fourth ventricles

Cerebral aqueduct (aqueduct of Sylvius)

Parasympathetic cranial nerve nucleus located in the midbrain

Edinger-Westphal nucleus

Prominence on fourth ventricle floor formed by facial fibers looping over CN VI

Facial colliculus

Motor nucleus located immediately deep to the facial colliculus in the pons

Abducens nucleus (CN VI)

Medullary motor nucleus supplying skeletal muscles of larynx and pharynx

Nucleus ambiguus

Primary motor projection forming the pyramids on anterior medulla

Pyramids

Embryological brain vesicle from which the cerebellum develops

Metencephalon

Central narrow structural portion of the cerebellum

Vermis

Two lateral expanded anatomical masses of the cerebellum

Cerebellar hemispheres

Three anatomical lobes composing the cerebellum

Anterior lobe, posterior lobe, and flocculonodular lobe

Deepest cerebellar groove separating anterior and posterior lobes

Primary fissure

Three structural layers forming the cerebellum microscopically

Cerebellar cortex, subcortical white matter, and deep nuclei

Four deep cerebellar nuclei listed from medial to lateral

Fastigial, globose, emboliform, and dentate nuclei

Largest and most lateral deep cerebellar nucleus

Dentate nucleus

Alternative anatomical descriptive name for the fourth ventricle

Rhomboid fossa

Ventral anatomical floor of the fourth ventricle

Dorsal surface of pons and medulla oblongata

Lateral anatomical boundaries of the fourth ventricle

Superior, middle, and inferior cerebellar peduncles

Superior opening of the fourth ventricle and its communication

Cerebral aqueduct communicating with the third ventricle

Inferior median opening of the fourth ventricle and its communication

Median aperture (foramen of Magendie) communicating with subarachnoid space

Functional structures regulating CSF flow through fourth ventricle openings

Valves