Brain: Brain Stem

Chapter 12.4

General Features of the brain stem

Nuclei surrounded by white matter

• nuclei of cranial nerves

• tracts to and from spinal cord

• tract to and from cerebellum

• reticular formation

Regulation of Automatic behaviors

Midbrain (mesencephalon)

Cerebral peduncles: motor tracts to spinal cord

cerebellar peduncles: tracts to cerebellum

2 cranial nerves

• III Oculomotor

• IV Trochlear

Corpora Quadrigemina (nuclei)

• reflex eye, head, and neck movement

• superior colliculus (visual)

• inferior colliculus (auditory)

Reticular formation

Periaqueductal gray matter

• pain suppression

• surrounds the cerebral aqueduct (3rd and 4th ventricles CSF)

Pons

Tracts

• Ascending/descending tracts to/from higher brain centers and spinal cord

• To/from cerebellum (cerebellar peduncles)

Cranial Nerves

• V Trigeminal

• VI Abducens

• VII Facial

Respiratory Center

Reticular Formation

4th ventricle

Medulla Oblongata

Tracts

• Ascending/descending tracts to/from higher brain centers

  • Pyramids - motor tracts

• Decussation of the pyramids – crossover area before tracts enter spinal cord

• Tracts to/from cerebellum

  • Cerebellar peduncle

Cranial nerves

• VIII Vestibulocochlear

• IX Glossopharyngeal

• X Vagus

• XI Accessory

• XII Hypoglossal

medulla oblongata cont.

Controls automatic behaviors necessary for survival

• Cardiovascular center

• Respiratory center

• Regulation of swallowing, coughing, hiccuping, sneezing, vomiting

Reticular formation

4th Ventricle

• CSF