This lab session is designed to allow you to appreciate how the cranial nerves are related to the surface features of the brainstem, and then to appreciate the major features of each major subdivision of the brainstem and spinal cord. Be sure to examine more than one brain specimen, since not all 11 (of the 12) cranial nerves are still attached to any given specimen (typically, CN IV and CN XI are not present in brains ex situ). We will supplement the actual brain specimens with rubber models of the brainstem that highlight the surface features of the human brainstem and the attachments of the cranial nerves. These models also present the diencephalon, basal ganglia and internal capsule—all structures that you will encounter in our final lab before winter break. Tip: this same brainstem model is featured in Sylvius4 Online, where you can manipulate perspective and identify features of interest.
To help you review what you learned already about the longitudinal organization of the spinal cord and the roots of the spinal nerves, we will have several special demonstration specimens in the lab with the brain and spinal cord removed intact from the dorsum of their cadavers. Use these specimens to appreciate the continuity of the medulla and cervical cord, as well as to inspect the dorsal and ventral roots, including the caudal equina, and the regional variation in the cord along its longitudinal extent.
- Spinal cord
- Learning ojectives:
- recognize the principal features of the spinal cord, including the longitudinal organizatin of spinal sements and internal distinctions among levels.
- Specimens: whole CNS specimen (with brain and spinal cord attached) available at demonstration stations in lab room
- Activities:
- Open to Figure 2.2 and visit the demonstration CNS specimen
- Identify the cervical and lumbosacral enlargements, and the thoracic and sacral regions
- Identify dorsal and ventral roots
- Differentiate the dura mater from arachnoid mater, and identify denticulate ligaments
- Identify the posterior and anterior spinal arteries, and draining veins
- Medulla oblongata
- Learning ojectives:
- localize the principal features of the medulla oblongata as seen from the surface, including the attachments of cranial nerves VI-X and XII (and XI).
- Specimens:whole brains, mid-sagittal hemispheres, or brainstem models
- Activities:
- Open to Figure 2.3 and refer to the pink chart on the following page
- Find each of the features listed in the chart and described in the text on actual specimens of the human brainstem. Some surface features may be best observed in whole brain specimens, but some may be appreciated just as easily in hemi-brains that were sectioned in the mid-sagittal plane. You may wish to refer the actual specimens to the models available in the lab for comparison.
- Pons
- Learning objectives:
- localize the principal features of the pons as seen from the surface, including the attachments of cranial nerves V and VI-VIII.
- Specimens:whole brains, mid-sagittal hemispheres, or brainstem models
- Activities:
- Open to Figure 2.4 and refer to the green chart on the following page
- 1. Find each of the features listed in the chart and described in the text on actual specimens of the human brainstem. Some surface features may be best observed in whole brain specimens, but some may be appreciated just as easily in hemi-brains that were sectioned in the mid-sagittal plane. You may wish to refer the actual specimens to the models available in the lab for comparison.
- Midbrain
- Learning ojectives:
- localize the principal features of the midbrain as seen from the surface, including the attachments of cranial nerves III & IV.
- Specimens: whole brains, mid-sagittal hemispheres, or brainstem models
- Activities:
- Open to Figure 2.5 and refer to the purple chart on the following page
- 1. Find each of the features listed in the chart and described in the text on actual specimens of the human brainstem. Some surface features may be best observed in whole brain specimens, but some may be appreciated just as easily in hemi-brains that were sectioned in the mid-sagittal plane. You may wish to refer the actual specimens to the models available in the lab for comparison.
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