1. PONS & MID-BRAIN STRUCTURE/BLOOD SUPPLY/CRANIAL NERVES ATTACHMENTS
Lecture….by Prof. Ansari
Wednesday, April 26, 2017
(for MBBS SEMESTER II students only)

2. OBJECTIVES STRUCTURE OF PONS AND MIDBRAIN. CRANIAL NERVES ATTACHMENT.
OTHER NUCLEI PRESENT AT THESE LEVELS.
BLOOD SUPPLY
CROSS SECTION- GREY MATTER AND WHITE MATTER.

3. PONS It is a part of brain stem.
It lies between midbrain and medulla oblongata.
It has a basilar part/ ventral part, and a dorsal part which forms the floor of IV ventricle.
Three cranial nerves are related to pons, trigeminal nerve is attached to the pons on ventral part.
Abducent nerve is related at the lower border of pons and pyramid.
Occulomotor nerve arises at the upper border of pons, in the interpeduncular fossa.

5. CRANIAL
NERVES
ATTACHED
AT THE BASE
OF BRAIN

6. CROSS SECTION OF PONS

7. IV
VENTRICLE
TEGMENTUM PART
BASILAR PART

10. NUCLEI OF CRANIAL NERVES IN PONS
Facial nerve nuclei, motor / sensory/autonomic.
Trigeminal nuclei, motor/ main sensory/spinal/ mesencephalic.
Abducent nucleus / purely motor.
Nuclei pontis.

11. Floor of IV ventricle

12. WHITE FIBERS AT PONS CORTICOPONTINE FIBERS CORTICOSPINAL FIBERS
CORTICOPONTOCEREBELLAR FIBERS
CORTICONUCLEAR FIBERS
TRAPEZOID BODY

13. OVERVIEW OF PONS

14. MESENCEPHALON It is at the cranial end of pons.
It has a dorsal portion called as tectum.
The ventral portion is called as cerebral peduncle.
The space between the two cerebral peduncle is the interpeduncular fossa.

15. Structures in the interpeduncular fossa
1.Optic nerve
2.Optic chiasma
3.Optic tract
4.Tuber cinereum
5.Mammillary bodies
6.Ant.perforated substance.
7.Olfactory tract
8.Pons
9=Uncus

16. Cross section of midbrain
Inferior colliculus
Substantia
nigra
Superior
Cerebellar
Peduncle
decussation
PAG
Cerebral peduncle

17. Superior colliculus
Oculomotor fibers

18. VARIOUS NUCLEI AT MIDBRAIN
Oculomotor nucleus
Trochlear nucleus
Mesencephalic nucleus
Red nucleus
Substantia nigra
Edinger-Westphal nucleus

19. White matter at mesencephalon
Superior cerebellar peduncles decussations
Medial lemniscus/lateral lemniscus/trigeminal lemniscus/spinal lemniscus
Crus cerebri

20. BLOOD SUPPLY OF PONS &MIDBRAIN
CORTICAL BRANCHES AND CENTRAL BRANCHES ARISE FROM BASILAR ARTERY AND CIRCLE OF WILLIS.
PONTINE HAEMORRAGE LEADS TO BURSTING HEAD ACHE, PINPOINT PUPIL, AND HYPERTHERMIA.
INJURY TO THE CORTICOSPINAL FIBERS LEADS TO HEMIPLEGIA.

21. CIRCLE OF WILLIS

22. RED NUCLEUS AND SUBSTANTIA NIGRA
THEY ARE CONCERNED WITH THE EXTRAPYRAMIDAL TRACT.
INJURY TO THESE NUCLEI WILL RESULT IN TREMORS, PARKINSONISM, AND NYSTAGMUS.
THESE SYMPTOMS CAN BE CORRECTED BY SUPPLIMENTING THE NEUROTRANSMITTER DOPAMINE.

23. Periaqueductal gray

24. Electrical stimulation of the PAG results in immediate and profound analgesia
Stimulation of the dorsal and lateral aspects of the PAG (in the rat) can provoke defensive responses characterised by freezing immobility, running, jumping, tachycardia, and increase in blood pressure.
Stimulation of the caudal ventrolateral PAG can result in an immobile, relaxed posture known as quiescence.
It also plays a role in female copulatory behavior.

25. CEREBRAL
AQUEDUCT
PAG
RED NUCLEUS

26. References

27. A 62-year old male has sustained several injuries from a car accident
A 62-year old male has sustained several injuries from a car accident. Upon administering a neurological examination, you suspect that the patient has damage to the right caudal medulla. Why do you think this?
A. The patient's right eye exhibits hypertropia and he complains of diplopia,
B. The patient's tongue deviates towards to right when you asked him to stick it out and his uvula deviates towards the left when you ask him to say, "aahhh". (Your Answer)
C. The patient has a loss of taste on the right anterior 2/3rds of his tongue
D. The patient exhibits anosmia (inability to smell)
E. The patient complains of excruciating pain on the right side of his face