The brainstem consists of three parts: the midbrain, pons, and medulla oblongata. It serves several broad functions including transmitting ascending and descending nerve pathways, containing important reflex centers that control cardiovascular and other bodily functions, and housing the nuclei of cranial nerves III through XII. The midbrain is involved in visual and auditory processing as well as voluntary motor control. The pons acts as a relay station between the cerebellum and medulla and helps control subconscious movements. The medulla regulates vital functions like respiration, circulation, and digestion.

1. BRAINSTEM

2. BRAIN STEM 3 PARTS : MIDBRAIN PONS MEDULLA OBLANGATA HAS 3 BROAD FUNCTIONS – Serves as a conduit for the ascending & descending tracts Contains important reflex centers(RS.CVS) Control of consciousness Contains cranial nerves nuclei (CN3-CN12) Brainstem occupies the posterior cranial fossa of the skull

4. MIDBRAIN

5. MIDBRAIN VENTRAL SURFACE Crus cerebri of midbrain Optic tract Mammillary body Posterior perforated substance Oculomotor nerve Trochlear nerve Interpedencular fossa

6. MIDBRAIN ( Dorsal surface)

7. BLOOD SUPPLY OF MIDBRAIN ARTERIAL SUPPLY : Posterior cerebral artery. Superior cerebellar artery. VENOUS PLEXUS: Basal vein. Great cerebral vein.

8. PONS

9. PONS(Ventral view) Basilar groove Motor root of trigeminal nerve Sensory root of trigeminal nerve Abducent nerve Roots of facial nerve vestibulocochlear nerve

10. PONS (dorsal view) Trochlear nerve Superior medullary velum Floor of 4 th ventricle Striae medullaris Median sulcus Medial eminence Facial colliculus Sulcus limitans Vestibular area Hypoglossal triangle Vagal traingle

11. BLOOD SUPPLY OF PONS ARTERIAL SUPPLY: Pontine branches of basilar artery. Superior cerebellar artery. Anterior inferior cerebellar artery. VENOUS SUPPLY: Basilar venous plexus. Inferior petrosal sinuses.

12. MEDULLA OBLANGATA

13. THE ANTERIOR SURFACE (medulla) On the anterior surface of the medulla is the anterior median fissure ( Continuous with the AMF of the spinal cord ) PYRAMIDS ( decussation of the pyramids) in lower portion. OLIVES ( Inferior olivary nuclei lies beneath them ) INFERIOR CEREBELLAR PEDUNCLE HYPOGLOSSAL NERVE (XII) ( groove between the pyramids & olives )

14. THE ANTERIOR SURFACE (medulla) From the grove between the olives & the inferior cerebellar peduncle, emerge the nerve roots of : Glossopharyngeal (IX) Vagus (X) Accessory nerve (XI) – Cranial roots

15. THE POSTERIOR SURFACE (medulla) Superior half : FLOOR OF THE 4 TH VENTRICLE Inferior half : POSTERIOR MEDIAN SULCUS ( PMS ) GRACILE TUBERCLE (Produced by underlying gracile nucleus ) CUNEATE TUBERCLE (Produced by underlying cuneate nucleus )

16. BLOOD SUPPLY OF MEDULLA ARTERIAL SUPPLY : Medullary br. of vertebral artery. Medullary br. Of basilar artery. Posterior inferior cerebellar artery. Anterior spinal artery. VENOUS SUPPLY: Basilar venous plexus. Inferior petrosal sinus. Occipital sinus.

17. FUNCTION OF THE BRAINSTEM Midbrain: Visual & auditory processing and reflexes Fine-tuning of voluntary movements Pons: Relay station for cerebellum Control of sub-conscious movement Medulla Oblongata: Control of cardiovascular functions Control of respiration Control of gastrointestinal functions

18. What brainstem structures are visible here? MID BRAIN PONS MEDULLA

19. Cranial Nerves

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