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Pontine Anatomy

Learning objectives

  • Learning
  • Understand
  • Integrate
  • Reflect

Note that anatomical pictures of the pons are upside down compared with the CT/MRI except below

Functional Anatomy of the Pons
  • Ventrally rather bulbous due to large cell groups and fibres running transversely between large pontine nuclei and the cerebellum. Laterally lies the bulging middle cerebellar peduncle. The pontine nuclei mediate fibres coming from cerebral cortex to the cerebellum.
  • The VI, VII, VIII and V nerves all leave ventrally. As its name suggests it is bridge like and like any bridge it is a major crossover centre for fibres carrying signals bidirectionally from above and below and communication with the cerebellum. Like any bridge it covers the CSF filled 4th ventricle which separates it from the cerebellum with its vermis and hemispheres which sit tightly behind.
  • The Pons contains the
    • Corticospinal fibres
    • Corticopontine fibres
    • Pontocerebellar fibres
    • Raphe nuclei.
  • The lower Pons contains
    • Nuclei of VI
    • Nuclei of VII and Facial nerve
    • Superior salivatory Gustatory.
    • Medial lemniscus (carries contralateral dorsal column), Spinothalamic tract (carries pain and temperature)
    • Middle cerebellar peduncle which contains fibres from c/L pons to cerebellum.
  • The facial nerve and abducent nerve are closely associated as the exiting VII nerve loops around the nucleus of VI.
Medial structures
  • Medial longitudinal fasciculus
  • VI (Abducent) nerve nucleus and fibres
  • Genu of VII (Facial) closely associated with VI
  • Medial lemniscus (carries contralateral dorsal column)
  • Corticospinal tract
Lateral structures
  • Facial nucleus VII and nerve fibres
  • Spinal nucleus and tracts of V
  • Lateral spinothalamic tract (spinal lemniscus)
Vascular supply
  • From the basilar artery which lies anteriorly and provides median and paramedian perforators.
  • Short circumferential branches irrigate more laterally
  • Middle cerebral peduncle is supplied by branches of the superior cerebellar and anterior inferior cerebellar arteries.
Pontine Symptoms