Gross anatomy of the brainstem and cerebellum Fourth

Gross anatomy of the brainstem and cerebellum Fourth ventricle Dr Gallatz. Katalin

The brain n Telencephalon n Diencephalon n Cerebellum n Brainstem

Parts of the brainstem n Mesencephalon n Pons n Medulla

Ventral surface of the hypothalamus and brainstem 1. cerebral peduncle 3 2. interpeduncular fossa 1 2 3. optic tract pons 5 medulla 5

Dorsal surface of the diencephalon and brainstem sc – superior colliculus, ic – inferior colliculus, scp – sup. cerebellar peduncle thalamus sc ic pons medulla scp

Brain Stem Midbrain Cranial Nerve III. , IV. n pupillary reflex n eye movements

The midbrain or mesencephalon (from the Greek mesos – middle, and enkephalos) - is associated with vision, hearing, motor control, pain control, sleep/wake, and temperature regulation

Parts of the mesencephalon TECTUM inferior colliculi superior colliculi CEREBRAL PEDUNCLE tegmentum crus cerebri TECTUM TEGMENTUM

Midbrain - Mesencephalon Ventral surface n n n Cerebral peduncle(1) Interpeduncular fossa (2) oculomotor nerves (3) Posterior perforated substance 1 2 3

Midbrain - Mesencephalon trochlear n. Dorsal surface n Superior colliculus (1) centers for visual reflexes n Inferior colliculus (2) associated with auditory pathway n Brachium of superior colliculus n LGB n Brachium of inferior colliculus MGB scp

Brainstem PONS Cranial nerves V. , VII.

Parts of the pons tegmentum – dorsal surface base –venral surface

pontine tegmentum base

Pons Ventral surface n n Basilar sulcus Pontomedullary junction: from medial to lateral, VIII nerves Middle cerebellar peduncle n n Trigeminal nerve Pontocerebellar trigone: the junction of medulla, pons and cerebellum

Pons Dorsal surface – rostral part of the rhomboid fossa part n Medial eminence (1) n Facial colliculus (2) n Locus ceruleus (3) 1 2 3

Brain Stem Medulla Cranial Nerves IX, X, XII n Pharyngeal (Gag) Reflex n Tracheal (Cough) Reflex Cardiovascular, respiratory centers

Parts of the medulla opened part – rostral part – fourth ventricle closed part – caudal part - central canal dorsal surface ventral surface

Medulla n n Pyramid: contain pyramidal tract (corticospinal tract) Decussation of pyramid: formed by crossing fibers of corticospinal tract Olive: inferior olivary nucleus Medial parolivary sulcus hypoglossal nerve XII Lat. parolivary sulcus: glossopharyngeal, vagus accessory nerves IX, X. , XI. , ventral surface

Medulla Dorsal surface Caudal portion • Gracile tubercle • Cuneate tubercle • Inferior cerebellar peduncle • Obex Rostral portion: • forms the caudal half of rhomboid fossa • hypoglossal and vagal trigones X XII

Fourth ventricle Position n Situated ventral to the cerebellum, and dorsal to the pons and cranial half of medulla

FLOOR OF THE IV. VENTRICLE RHOMBOID FOSSA Inferolateral: inferior cerebellar peduncle Superolateral: superior cerebellar peduncle n Lateral recess

Rhomboid fossa n n n Facial colliculus, medial eminence Hypoglossal triangle hypoglossal nucleus Vagal triangle: dorsal nucleus of vagus nerve Funiculus separans Area postrema: blood –brain barrier free Locus ceruleus: noradrenerg area

Roof of the fourth ventricle n n n Anterior part: formed by superior cerebellar peduncle and superior medullary velum Posterior part: formed by inferior medullary velum, tela choroidea and choroid plexus of IVth ventricle Three apertures Median aperture (Magendi) Two lateral apertures (Luschka)

Position of the cerebellum n It lies in the posterior cranial fossa n The tentorium cerebelli separates it from the occipital lobe of the cerebrum

Cerebellar peduncles - superior cerebellar peduncle (1) 1 connects it with medulla 2 - middle cerebellar peduncle (3) connects it with pons, - inferior cerebellar peduncle (2)－ connects it with midbrain, 3

External features Consists of two cerebellar hemispheres united in the midline by the vermis

Lobes and fissures of the cerebellum n Fissures • Primary fissure • Horizontal fissure • Posterior fissure n Three lobes • Flocculonodular lobe flocculus and nodulus • Anterior lobe • Posterior lobe

MIDSAGITTAL SECTION: VERMIS, IV. VENTRICLE

Internal structures Cerebellar nuclei Fastigial nucleus Globose nucleus Dentate nucleus Emboliform nucleus Cerebellar cortex

Functional divisions n Cerebrocerebellum • Neocerebellum • Lateral zone n Spinocerebellum • Paleocerebellum • Vermis and intermediate zone Intermediate zone Vermis n Vestibulocerebellum • Archicerebellum • Flocculonodular lobe

REVISION

EARLY DEVELOPMENT OF THE BRAIN VESICLES Cavity of the telencephalon become the lateral ventricles. Cavity of the diencephalon becomes the third ventricle. Cavity of mesencephalon becomes the cerebral aueduct. Cavity of rhombencephalon become the fourth ventricle.

Myelencephalon

Development of the brain

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