Biology 122 Spring, 2008

Laboratory 21

Cranial cavity, dural sinuses, meninges, cerebral vasculature & cranial nerves

OBJECTIVES

At the end of this laboratory you should know and understand:

1. The bony elements which make up the skull base and form the floor of the three cranial fossae (anterior, middle and posterior) and the ridges (sphenoidal and petrosal) which bound these fossae. The radiographic images of the fossae and the ridges should also be appreciated. In addition, the main parts of the brain that occupy each fossa should be known.

2. The bony elements of the calvaria and the major sutures associated with the calvaria of both the adult and newborn. The association of these bones and sutures with the anterior and posterior fontanels in the skull of an infant should also by known.

3. The meninges (dura mater, arachnoid, pia mater) and their relationships to the brain and surrounding spaces (epidural, subdural, subarachnoid). The position and causes of epidural, subdural and subarachnoid hemorrhages should also be understood along with the contribution of the dura to the formation of the falx cerebri and tentorium cerebelli.

4. The names and numbers assigned to the 12 pairs of cranial nerves and the points on the brain surface where the individual cranial nerves emerge

I = olfactory; olfactory bulb

II = optic; optic chiasma

III = oculomotor; interpeduncular fossa

IV = trochlear; tectum of midbrain (dorsally)

V = trigeminal; pons

VI = abducens; junction of pons & medulla

VII = facial; sulcus superior to olive

VIII = vestibulocochlear; sulcus superior to olive

IX = glossopharyngeal; sulcus superior to olive

X = vagus; sulcus superior to olive

XI = accessory; sulcus superior to olive, spinal cord between dorsal and ventral roots

XII = hypoglossal; sulcus inferior to olive

5. The names of the major parts of the brain and their position in the cranial vault.

6. The position of the major dural sinuses, the course of the cerebral veins which empty into the superior sagittal sinus and the great cerebral vein. The interconnections of the sinuses with each other and with the cerebral, emissary, and meningeal veins and diploic channels should also be appreciated.

7. The contribution of the internal carotid and vertebral arteries to the overall blood supply of the brain; the structure of the cerebral arterial circle, and the major branches associated with the circle

8. The structure and position of the pituitary gland.

PRELAB PREPARATION

1. Study the bones and sutures of the skull, pp. 886-905 of Moore and Dalley.

2. Read those parts of your textbook which deal with the meninges and the relationships of these layers to epidural, subdural and subarachnoid hemorrhages (pp. 908-921).

3. Read the sections in your textbook which cover the gross structure and blood supply of the brain (pp.921-933).

4. Read the introductory material on cranial nerves in the textbook (pp. 1124-1155) and study table 9.1 and 9.2, and figure 9.1.