Stalk Like n Connects n Narrow Spinal Cord

Stalk Like. n Connects: n Narrow Spinal Cord with the n Expanded Fore Brain. Occupies: n Posterior Cranial Fossa. n Lies Against: n Basilar part of Occipital Bone. Largely Covered by: n Cerebellum.

MID BRAIN MEDULLA OBLONGATA PONS

BULB. n Entering Fibers: n Cortico Bulbar. n Syndromes Associated: Pseudo Bulbar Palsy. n n

(1) A conduit for: n Ascending and Descending n tracts between the Spinal Cord and the Higher Centers in the Forebrain. (2) Contains: n A. Cranial Nerve Nuclei (111 x 11). B. Reflex Centers for n Respiratory and Cardiovascular systems. (3) Controls over: Level of Consciousness n

The Ventral Median Fissure Divides it into Two Halves. Each Half Presented the following : n n n

A Longitudinal Elevation along the side of the fissure. The pyramids are n composed of: Bundles of Nerve Fibers (Corticospinal). They originate from n Large Nerve Cells in the Motor Cerebral Cortex. n n

The Pyramids Taper n Inferiorly. The Majority of the n Descending Fibers (75 -90%) Cross Over to the opposite side. They form Decussation of the n Pyramids. It partially obscures n the ventral fissure.

Oval Elevation. Lateral to the Upper Part of the Pyramid. Produced by The underlying Inferior Olivary Nucleus It is Important in the Control of Movement. n

1. Hypoglossal (12 TH) n nerve: Between the Pyramid n and Olive. 2. Glossopharyngeal, n Vagus and Cranial part of Acessory (9, 10 and 11 TH) nerves : Between the Olive and n the Inferior Cerebellar Peduncle.

The Anterior surface is n Convex from side to side. It shows: n Basilar Sulcus : n A Median Groove which n lodges the Basilar Artery. Many Transverse n Pontocerebellar Fibers. They are collected Laterally n to form the Middle Cerebellar Peduncles.

1. Trigeminal (5 th) nerve: Attached to the side of n the Pons near its upper border. It has Two Roots: n Large Sensory. n Small Motor. n Motor root is Antero n Medial to the Sensory root. n

2. Abducent (6 th) nerve: n Between the Lower border of the Pons and the Pyramid. 3. Facial (7 th) nerve : n Between the Lower border of the Pons and the Inferior Cerebellar Peduncle. 4. Vestibulo cochlear (8 th) nerve : Lateral to the Facial. n The vestibular nerve is n anterior to the cochlear. n n n

It is the : n Massive Basis n Pedunculi (Crura Cerebri). The Crura are made by: Corticobulbar. n Corticospinal Fibers. n

Separates the Cerebral Peduncles. Boundaries: n Inferiorly : n Pons. n Anteriorly : n Optic Chiasma. n Laterally: n Optic Tracts. n Posterolaterally: n Cerebral Peduncles. n n

Oculo motor (3 rd) n nerve : At the medial side of the cerebral peduncle. n

Closed (Lower) Medulla It is the Continuation of the Posterior Surface of the Spinal Cord. Posterior Median Sulcus divides it into two halves. n n

Gracile Tract: n A Longitudinal Column on both sides of the Median Sulcus. Superiorly: n It expands. n It ends in the Gracile Tubercle (produced by the underlying (Gracile Nucleus). Cunate Tract and Tubercle : n Lateral to the Gracile Tract and Tubercle respectively. n

Forms the Lower 1/3 of n the Floor of the Fourth Ventricle. Divided by the Median n Sulcus into two halves. Has an inverted (V) n Shaped Depression (Inferior Fovea). The Fovea separates: n Motor nuclei (Medial) from Sensory nuclei (Lateral).

Medial : n Hypoglossal Nucleus. n Lateral : n Vestibular Nucleus. n At the Fovea : n Nuclear Complex n (Glossopharyngeal and Vagus nerves). The Fovea represents n the Sulcus Limitans of the Spinal Cord.

Forms the Upper 2/3 of the n Floor of the 4 th Ventricle. Hidden by the Cerebellum. n Widest at the Pontomedullary n junction. Lateral Aperture (Foramen of n Luschka): Allows passage of CSF from n the 4 TH ventricle to the Subarachnoid space around the brain.

Divided into Symmetrical Halves by the Median Sulcus. Medial Eminence: n An Elongated Elevation Lateral n to the Sulcus. Facial Colliculus: n The Inferior Expanded end of n the Eminence. Produced by the fibers of the n Facial Nerve winding around the Abducent Nucleus.

Vestibular Area n Lateral to the Medial Eminence. Produced by the n underlying Vestibular Nuclei. n

Corpora Quadregimina Four Rounded Colliculi Divided into Superior and Inferior Pairs. Superior Colliculi: n Centers of Visual Reflexes. Inferior Colliculi: n Lower Auditory Centers. The Cerebral n Aqueduct traverses through the length of the mid brain. n

Trochlear Nerve n It is the Only cranial n nerve that can be identified in the dorsal aspect of brain stem. It emerges in the midline. Caudal to the Inferior n Colliculs. n

Superior. n Middle. n Inferior Peduncles. n Connect Cerebellum to : Mid brain. n Pons. n Medulla. n n

Middle. n Inferior Cerebellar Peduncles. Olive. n Pyramid. n Attached Cranial n Nerves. n