MIDBRAIN basic anatomy and applied aspects.
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The document provides an overview of the anatomy and structures of the midbrain. It notes that the midbrain connects the pons and cerebellum to the forebrain, is about 0.8 inches long, and is traversed by the cerebral aqueduct filled with CSF. Key structures discussed include the crus cerebri, oculomotor nerve, superior and inferior colliculi, brachium, and trochlear nerve. The midbrain is divided into cerebral peduncles, tectum, and tegmentum. Transverse sections show structures like the substantia nigra, red nucleus, and tracts. Blood supply comes from the posterior cerebral, superior cerebellar, and basilar arteries.
MIDBRAIN basic anatomy and applied aspects.
- 1. Basic Anatomy & Applied aspects By: Pulak Agrawal Roll No.: 001
- 2. Midbrain:Midbrain: The midbrain develops from mesencephalon. Cells within the midbrain multiply continually and are compressed to form cerebral aqueduct. MidbrainMidbrain Connects the pons and cerebellum with the forebrain. It is about 0.8 inch in length The midbrain is traversed by a narrow channel called cerebral aqueduct filled with CSF.
- 3. AnteriorlyAnteriorly, it presents two large bundles of fibers, one on each side of the midline, called crus cerebricrus cerebri.. The oculomotor nerveoculomotor nerve emerges from the medial aspect of the crus of the same side The crus cerebri bounds the interpeduncular fossainterpeduncular fossa on either side. ANTERIOR SURFACEANTERIOR SURFACE
- 4. POSTERIOR SURFACEPOSTERIOR SURFACE PosteriorlyPosteriorly, the midbrain presents four rounded swellings called colliculi- Onecolliculi- One SuperiorSuperior and inferiorinferior colliculi on either side. Each colliculus is laterally related to a ridge called brachium.brachium. o Superior and inferiorSuperior and inferior brachiumbrachium arises from respective colliculi o Superior brachium connects the superior colliculus to laterallateral geniculate bodygeniculate body o Inferior brachium connects the inferior colluculus to medialmedial geniculate bodygeniculate body o In the midline below the inferior colliculus, the trochlear nervetrochlear nerve emerges which then winds round the side of the midbrain to reach its ventral aspectventral aspect
- 5. Lateral view
- 6. Structure of MidbrainStructure of Midbrain The midbrain comprises two lateral halves called- Cerebral pedunclesCerebral peduncles; which is again divided into 1. anterior part- Crus cerebri 2. posterior part -Tegmentum by a pigmented band of gray matter, substantia nigrasubstantia nigra The central narrow cavity is called the cerebral aqueduct or aqueduct of Sylvius, which connects the 3rd and 4th ventricles. The tectum is the part of the midbrain posterior to the cerebral aqueduct; it has four small surface swellings referred to previously; these are two superior and two inferior colliculi. The tegmentum forms the floor of mid brain
- 7. TECTUM & TEGMENTUMTECTUM & TEGMENTUM
- 9. Transverse section at theTransverse section at the levellevel ofof Superior ColliculiSuperior Colliculi Superior colliculi Substantia nigra Oculomotor nucleus Red nucleus Mesencephalic nucleus of trigeminal n. Edgnger-westphal nucleus
- 10. Tracts:Tracts: MotorMotor Corticospinal Corticonuclear Temporopontin e Frontopontine Medial longitudinal fasciculas Decussation of rubrospinal tract SensorySensory Trigeminal Spinal Medial
- 12. TransverseTransverse Section at the level ofSection at the level of Inferior ColliculiInferior Colliculi Substantia nigra Troclear nucleus Mesencephal ic nucleus of trigeminal nerve
- 13. Tracts:Tracts: MotorMotor Corticospinal Corticonuclear Temporopontine Frontopontine Medial longitudinal fasciculas SensorySensory Lateral Trigeminal Spinal Medial lemnisci Decussation of superior cerebellar peduncles
- 14. Blood Supply:Blood Supply: Artery –Artery – posterior cerebral artery superior cerebellar artery basilar artery Veins –Veins – Drained by basal or great cerebral veins
- 19. Due to lesion of tegmentum of midbrain. 1. External strabismus(lateral squint) & ptosis on same side – due to involment of occulomoter nerve. 2. Tremor & twitching movement of opposite arm and leg – due to involment of Red nucleus & superior cerebellar peduncle.
- 20. Rubral tremor (Holme’s tremor): A coarse, slow (4Hz) tremor, especially present in the upper extremities, that is found at rest, postural and intention. Claude Syndrome: Ipsi CN III, contra tremor, ataxia and incoordination Parinaud’s Syndrome: Due to lesion of superior colliculi as occurs when this area becomes compressed by tumour of pineal gland. Weakness of upward gaze& vertical nystagmus
- 21. Refrences: Snell's Clinical Neuroanatomy IB Singh - Textbook of Human Neuroanatomy internet