Brain Stem

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Brain Stem
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Brain Stem

• Brain stem
• consists of medulla oblongata, pons, and midbrain.

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Medulla

• Medulla oblongata (Medulla)
• continues with spinal cord. The junction between
  spinal cord and medulla is the upper rootlet of
  the first cervical nerve. Junction between pons
  and medulla is an imaginary transverse line that
  passes the middle cerebellar peduncles.
• Eminences
• Anterior
• Pyramind consists corticospinal fibers.
• Olive oval swelling that marks the position of
  olivary nucleus.
• Posterior
• Gracile and Cuneate tubercles elevations,
  indicates the continued gracile and cuneate
  fasciculi
• Obex apex of the V shaped boundary of fourth
  ventricle.

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Cranial Nerves

• Abducens nerve near the midline between the pons
  and medulla
• Facial nerve caudal border of the pons,
  laterally. Has sensory and motor roots.
• Vestibulocochlear nerve more laterally to the
  facial N
• Glossopharngeal and vagusbetween olive and the
  tuberculum cinereum
• hypoglossal nerve between pyramid and the olive

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Pons

• Has basal (ventral) and dorsal portions.
• Basal portion (ventral)basilar
  sulcustrigeminal nerve has sensory and motor
  (smaller) roots. Trigeminal N is terminated by
  three branches 1). Ophthalmic 2).
  Maxillary3). Mandibular

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Pons

• Dorsal portion
• also called tegmentum of the pons
• Formed by the floor of fourth ventricle

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Midbrain

• Ventral side
• basis pedunculi (including corticospinal,
  corticobulbar, and corticopontine
  fibers)interpeduncular fossa depression in
  between these two pedunculi
• In the fossa, many blood vessels penetrate
  through (posterior perfoated substance).
  Oculomotor nerve also emerges from here.
• Lateral surface
• cerebral peduncles

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Midbrain

• Dorsal surface
• superior colliculi (colliculus) part of the
  vision pathway, control visual movement
• inferior colliculi (both paired), part of the
  auditory pathway
• inferior brachium connects inferior colliculi
  with thalamic nuclei for hearing
• superior brachium connects cerebral cortex and
  retina with superior colliculi for vision
• trochlear nerve emerges caudal to the inferior
  colliculi

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Fourth ventricle

• diamond shaped, produce CSF, median and lateral
  apertures

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