Pons introduction external features internal features arterial supply of pons

Pons medical sciences

1. PONS Name- Sohrab Alam Roll No- 87 Batch- 2021-22

2. contents Introduction External features Internal features Arterial supply of pons Clinical

3. Introduction Middle part of brainstem situated between midbrain and medulla Lies in the posterior cranial fossa anterior to cerebellum On either side the pons is continuous as the middle cerebellar peduncle forming bridge between two cerebellar hemisphere

4. External features Two surfaces Ventral Dorsal Two borders Superior Inferior

5. Ventral surface Convex Transversely striated due to underlying pontocerebellar fibres In median plane, vertical groove called basilar groove is present which lodges basilar artery

6. Dorsal surface Triangular in shape Covered by cerebellum and separated from it by cavity of fourth ventricle

7. Borders Superior border -Cerebellar peduncle attached -Superior cerebellar arteries curve along this border Inferior border -Upper end of medulla is continuous to this border -Anterior inferior cerebellar arteries curve along this border

8. Internal features Large ventral or basilar part -is continuos inferiorly with the pyramids of the medulla Small dorsal or tegmental part -is a direct upward continuation of the medulla excluding pyramids

9. Basilar part Composed of longitudinal bundles of fibres , transverse fibres and the pontine nuclei Longitudinal bundle of fibres include corticonuclear and corticospinal fibres

10. Transverse fibres Arise in the pontine nuclei and cross to opposite side to form middle cerebellar peduncle Pontine nuclei Scattered among longitudinal and transverse fibres

11. Tegmental part Traverse by a number of ascending and descending tracts

12. T.S THROUGH LOWER PART OF PONS

13. T.S THROUGH UPPER PART OF PONS

14. Arterial supply of pons Pontine nuclei branches from the basilar artery Anterior inferior cerebellar artery

15. Clinical Millard- Gubler syndrome (medial inferior pontine syndrome) -Lesion in the lower part of the pons, which is so placed that it includes the pyramidal tract,the emerging fibres of the abducent and facial nerves. Characteristics features:- -Medial squint due to involvement of abducent nerve -Facial palsy, due to involvement of facial nerve fibres -Contralateral hemiplegia, due to involvement of corticospinal tract

16. Bibliography Textbook of clinical neuroanatomy, 4 th edition by Vishram Singh

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