Lab Manual - Neuroanatomy 1

Assignments:

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Identify the following surface features of the brain: cerebrum, cerebellum, brainstem; longitudinal fissure; lateral sulcus (including opercula) and central sulcus; and the pre- and post-central gyri; frontal, parietal, temporal, occipital and insular lobes.
  2. Identify the three meninges (dura, arachnoid, and pia) and the middle meningeal artery.
  3. Identify the three parts of the brainstem (midbrain, pons, and medulla oblongata), the 12 pairs of cranial nerves as they arise from the brain and brainstem, and the relative position of cranial nuclei.
  4. Identify each of the 12 pairs of cranial nerves in the three cranial fossae (anterior, middle and posterior), and the relative positions of their sensory ganglia (if appropriate).
  5. Identify the surface features of the cerebellum, including the lateral hemispheres connected by the vermis, the lobes (anterior, posterior, and flocculonodular) and lobules (10, but not their names), cerebellar cortex and folia, peduncles (superior, middle, inferior), and the tonsils.
  6. Identify the inner features of the cerebellum, including the superior and inferior medullary velum and 4th ventricle, and the cerebellar nuclei (dentate, globose, emboliform, and fastigial).

Procedure:

1. Review the osteology of the skull. (Play movie; View images: N 2, 6, 7A, 7B, 8, 9, 11, TG 7-05B, 7-05C, 7-06, 7-07, 7-08, 7-57)

Distinguish between the calvaria and the base of skull. Identify the anterior, middle, and posterior cranial fossae, crista galli, greater and lesser wings of sphenoid, sella turcica, clivus, petrous ridge of temporal bone, internal occipital protuberance, and foramen magnum.

Find the following openings: cribriform plate of ethmoid, optic canal, superior orbital fissure; foramen rotundum, f. ovale, f. spinosum, f. lacerum; internal acoustic meatus, jugular foramen, hypoglossal canal; foramina of condyloid and mastoid emissary veins. Examine the base of the skull and the interior of the calvaria for sulci or grooves produced by various sinuses and arteries.

2. Identify the major features of the brain. (Play movie; View images: N 99, 105, 107, 108, 109, 115, TG 7-49, 7-50A, 7-50B, 7-53B, 7-53C, 7-54)

Identify the frontal, parietal, occipital and temporal lobes of the cerebrum, and the longitudinal fissure. On the inferior side find the cerebellum, midbrain, pons and medulla oblongata. Compare the brain to the cranial fossae, note how the lobes fit in the fossae and relate to the dural folds.

Brain structures in MRI
Ventricles of the brain

3. Identify the cranial nerves within the cranial cavity. (Play movie; View images: N 11, 104, 114, 115, 118, 126, TG 7-07, 7-47, 7-55A, 7-55B)

On the brain, identify the twelve pairs of cranial nerves: olfactory (I), optic (II), oculomotor (III), trochlear (IV), trigeminal (V), abducens (VI), facial (VII), vestibulocochlear (VIII), glossopharyngeal (IX), vagus (X), spinal accessory (XI), hypoglossal (XII). Identify these nerves at their exit foramina on the base of the skull. What cranial nerves exit the skull through the jugular foramen? Identify cervical fibers of the accessory nerve. Identify the internal carotid artery as it perforates the dura and the vertebral arteries in the foramen magnum.

4. Identify the features of the cranial cavity and meninges. (Play movie; View images: N 9, 11, 69, 70, 98, 99A, 99B, 101, 102, 103, 104A, TG 104B, 108, 109, 147, 7-07, 7-19, 7-35, 7-46, 7-47, 7-48, 7-49A, 7-49B, 7-50, 7-51, 7-73)

Examine the arachnoid mater, its extent and attachment to the pia mater (via trabeculae). Consider the subarachnoid space, continuities and content. Enlargements of the subarachnoid space at the base of the brain constitute cisterns. Consider the function of cerebellomedullary, pontine and interpeduncular cisterns. Look for arachnoid granulations (villi). What is their function? Note their impressions on the overlying calvaria. Examine the pia mater on the brain. How does it differ from the arachnoid mater in covering the brain?

Subarachnoid space

Observe the arrangement of the cranial dura mater. Note differences from spinal dura, continuities and layers. Note dural attachment to the calvaria and the base of the skull. Is there any difference? Examine falx cerebri and falx cerebelli (on the left side), tentorium cerebelli, and diaphragma sellae. Are these infoldings periosteal or meningeal? Define attachments and relationship of each and the compartmentalization of the cranial cavity produced by these infoldings. What does each compartment contain? What is the tentorial notch? Observe meningeal arteries in all cranial fossae. Which is the largest? How is it held within the dura? Relation to greater wing of sphenoid? (Significance?) What is the innervation of dura?

Identify the cavernous sinus on either side of the body of the sphenoid bone. Do the two sides communicate? As they enter the lateral wall of the cavernous sinus, locate the oculomotor nerve (III), trochlear nerve (IV), and the trigeminal nerve (V). Identify the severed end of the internal carotid artery (course? ). Identify the abducens nerve (VI) as it pierces the dura covering the inferior petrosal sinus. Enlarge the opening in the diaphragma sellae and remove the hypophysis (pituitary gland). Determine anterior and posterior lobes and stalk. Locate the middle meningeal artery beneath the dura of the middle cranial fossa, noting its position in the dura and its course and entrance through the foramen spinosum.

5. Examine the external and internal features of the cerebellum. (NI35A, NI35B, NI35C, TG7-52)

On the brain, identify the cerebellum. Identify the lateral hemispheres and the vermis uniting them; the folia; and the primary fissure separating the anterior and posterior lobes. Identify the cerebellar peduncles (superior, middle, and inferior), and (on your donor's brain only) cut through them to remove the cerebellum. On the undersurface of the cerebellum, identify the small flocculonodular lobe. Using the long brain knife, section the cerebellum in a transverse plane in approximately the middle. Examine the cut surfaces to identify the nuclei of the cerebellum: dentate nucleus, emboliform and globose (together called the interposed nucleus), and the fastigial nucleus.