Lab 5 (ƒ8) - Higher Motor Function
Gross Anatomy - Posterior Aspect
Note the inferior and middle cerebellar peduncles entering the cerebellum. Trace the middle cerebellar peduncle upward into the cerebellum and the superior cerebellar peduncles passing from the midbrain upward into the cerebellum. Notice that the fourth ventricle, a diamond-shaped cavity, is exposed by the removal of the cerebellum. The fourth ventricle extends from the rostral border of the pons to the middle of the medulla. The floor of the ventricle is formed by the posterior surfaces of the pons and medulla and its roof by the cerebellum and the superior and inferior medullary velli. Thechoroid plexus is on the roof of the fourth ventricle. It projects along the midline and laterally in the caudal part of the fourth ventricle, and appears as a tufted, vascular fold of pia mater.
When the roof of the midbrain is exposed, the structures forming the midbrain tectum, i.e., the inferior and superior colliculi can be seen. The trochlear nerve should be seen emerging caudal to the inferior colliculi near the pons-midbrain junction. The pineal body is attached to the posterior surface of the brain at the junction of the midbrain to the diencephalon.
