PONS
- PONS
- EXTERNAL FEATURES
- VENTRAL ( ANTERIOR SURFACE )
- convex in both directions
- Transversely striated by ponto-cerebellar fibres ( अनुप्रस्थ रेखा से रहता हैं )
- Median plane divided by a groove ( बीच में एक खात )
- basilar sulcus ( आधारी खात )
- lodges basilar artery ( आधारी धमनी)
- trigeminal nerve attached to this surface by two roots ( त्रिधारा तंत्रिका के दो जड़ )
- large sensory root
- small motor root
- BORDERS ( किनारा )
- Rostrally ( ऊपर और आगे की तरफ )
- junction between midbrain and pons by dissappearing cerebral peduncles in pons
- caudally ( नीचे और पीछे )
- junction of medulla and pons or pontomedullary junction marked by
- shallow groove
- in this groove medial to lateral
- abducent , facial , nervus intermedius , vestibulocochlear
- laterally junctions of
- middle cerebellar peduncle and anterior surface
- DORSAL ( POSTERIOR SURFACE ) - सेतु का पीछे का भाग
- covered by cerebellum ( अनुमस्तिष्क के द्वारा ढका हुया रहता है
- separated from it by cavity of fourth ventricle
- shape
- triangular ( त्रिकोण )
- forms upper part of floor of fourth ventricle ( चौथी विलय का तल बनाता है )
- borders
- superior border
- cerebral peduncles
- inferior border
- upper end of medulla continuous
- lower or closed part of dorsal surface of pons
- upper triangular part of Floor or fourth ventricle
- longitudinal divisions
- dorsal median sulcus ( पृष्ठ मध्य परिखा )
- divides it in to equal halves
- sulcus limitans divides it in to ( सीमा परिखा )
- depression at cranial end in sulcus limitans
- superior fovea ( अधि छिद्र )
- median eminence medially ( मध्य उत्सेध )
- laterally vestibular area ( पार्श्व में
- wider above
- narrow below
- junction of pons and medulla
- stria medullares
- INTERNAL STRUCTURE
- VENTRAL OR BASILAR PART
- Longitudinal fibers ( अनुधैर्य तन्तु / अनुर्ध्व )
- corticopontine fibers
- relay in ipsilateral pontine nuclei
- corticonuclear fibers
- terminate in contralateral ( some ipsilateral) motor nuclei of cranial nerves
- corticospinal fibers
- converge toward lower part of pons
- pyramids of medulla
- transverse fibers ( अनुप्रस्थ तन्तु )
- arise from pontine nuclei
- cross to opposite side to form
- middle cerebellar peduncle
- pontocerebellar fibers
- pontine nuclei
- cortico-ponto-cerebellar pathway
- connects
- cerebebral cortex of one side to cerebellar hemisphere of opposite side
- DORSAL OR TEGMENTAL PART
- ascending fibers
- descending fibers
- grey matter
- trigeminal nucleus (V) , facial (VII) , Abducent (VI) , Vestibulocochlear (VIII)
- SECTIONS
- Transverse section at the upper ( cranial ) level of pons
- boundaries
- dorsolaterally by
- superior cerebellar peduncle
- roof
- superior medullary velum
- grey matter
- white mater
- four lemnisci
- medial lemniscus
- lateral lemniscus
- trigeminal lemniscus
- spinal lemniscus
- Transverse section at the lower ( caudal ) part of pons ( passes through facial colliculus)
- Grey matter
- Vestibulocochlear (VIII)
- vestibular area
- vestibular nuclei
- cochlear nuclei
- Abducent (VI) nucleus
- facial (VII) colliculus
- facial nerve
- facial nucleus
- spinal nucleus
- superior and inferior salivatory and lacrimatory
- white matter
Discussion