Midbrain - Anatomy & Physiology

Introduction

The midbrain or mesencephalon is located between the diencephalon and the pons. It connects higher brain centres with the lower centres and the spinal cord. It’s tectum (roof) has four colliculi, two rostral and two caudal. Cranial nerves III and IV have their nuculi within the midbrain.

Structure and Function

	Structures Present	Function
Midbrain (Mesencephalon)	Colliculi Occulomotor Nuculi	Colliculi - Processing visual and auditory information. Occulomotor Nuculi - Eyeball mm., more cranial nerves.

Oculomotor Nuclei

• See blood suppply to the brain and the relevent species differences.

• The cerebral (mesencephalic) aqueduct is a ventricular tube running through the midbrain which connects the third and fourth ventricles. It contains cerebral spinal fluid which offer it immunological protection.

See immunology.

Species Differences

• Other than size the brain of most species is fairly consistant.