Equine Brainstem
Brainstem Dorsal View
Sheep Brain
Brain Transection
Mesencephalon (midbrain)
Regions: [NOTE: * = not paired]
• tectum* - includes bilateral rostral & caudal colliculi
• tegmentum - nuceli, tracts, & reticular formation
• substantia nigra (neurons contain melanin in humans)
• crus cerebri (white matter tract on ventral surface)
• mesencephalic aqueduct* - surrounded by periaqueductal gray matter
Regions: [NOTE: * = not paired]
• tectum* - includes bilateral rostral & caudal colliculi
• tegmentum - nuceli, tracts, & reticular formation
• substantia nigra (neurons contain melanin in humans)
• crus cerebri (white matter tract on ventral surface)
• mesencephalic aqueduct* - surrounded by periaqueductal gray matter
Surface Features . . .
Ventral surface:
• oculomotor nerve
• crus cerebri
Dorsal surface:
• rostral colliculus - also, commissure of rostral colliculus
• caudal colliculus - also, commissure of caudal colliculus
• trochlear nerve (decussating)
Median surface:
• tectum*
• mesencepaholic aqueduct*
• tegmentum
Typical-Section Features:
• tectum*
• mesencephalic aqueduct* - surrounded by periaqueductal gray matter
• tegmentum
• substantia nigra
• crus cerebri