Lecture 36. Touch: Body + Head to Cortex	Lab. 34. Orbit/ear, V3/4, H+N II	Quiz 7
Lecture 37. Axoplasmic Transport, Neuron Injury.	Lab 35. Smell, vision, hearing, touch
Lecture 38. Corticobulbar/spinal motor systems	Lab 35. Corticobulbar/spinal motor systems

LABORATORY ON THE FUNCTIONAL TOPOGRAPHY OF SMELL, VISION, TOUCH AND HEARING

This laboratory consists of two parts. First, in the gross anatomy laboratory you will identify the major sensory structures in the wet brain (left half of below tables). You will use only one hemisphere for this exercise. Your atlas will be your guide to the identification of structures. To define the course of each sensory system, begin by identifying its most peripheral structure and trace its relays centrally. Second, you will be taken to the histology laboratory where you will be shown these structures on coronal, stained sections (right half of below tables). The structures in these tables are listed in their synaptic sequence, and you should practice learning and thinking about these and all other functional systems in this sequence.

OLFACTORY SYSTEM

View the ventral surface of a hemisphere. What type of neuron (by shape) is the first neuron of the olfactory system? What part of this neuron can be considered homologous to other cranial nerves in the peripheral nervous system? What other sensory systems have the same neuron type? Find the olfactory bulb and follow caudally axons leaving it. Point out and name the structures in which these axons terminate. A symptom of temporal lobe epilepsy is the perception of disagreeable odors. Why?

CHECKLIST

© Blair H. Turner, Ph.D. 1997

SOMATOSENSORY SYSTEM

Point out the dorsal columns, and trace them to their terminations in the dorsal column nuclei. The next relay ends in the nucleus ventralis posterolateralis of the thalamus. Point it out. This relays ends in the postcentral gyrus. Trace the entire extent of this gyrus, and demonstrate its functional organization.

CHECKLIST

AUDITORY SYSTEM

Point out Cranial Nerve VIII. Show and name the auditory structures in which it terminates. The next relay ends in the inferior colliculus. Point it out, along with the axons leaving it (the brachium of the inferior colliculus). This relay ends in the medial geniculate. Point it out. Axons of these cells terminate in Heschl's transverse gyri. Visualize them by gently widening the posterior part of the lateral fissure. There are one or two of them. In back of them, show the planum temporale. What is its function. Trace the entire extent of the superior temporal gyrus. Where is Wernicke's speech area located?

CHECKLIST

VISUAL SYSTEM

Almost the entire visual pathway can be seen on the intact hemisphere. Start with the optic nerve and follow the axons back to the lateral geniculate, retracting gently the temporal lobe. Notice the relationship of the pathway to the internal capsule, caudal thalamus and midbrain. Relate the structures you have just seen to the plastic embedded dissection of the visual system.

CHECKLIST