-5-

Alternate Image

Dissection Instructions:
Stay on the Ventral Surface--

Several cranial nerves can be seen exiting from the medulla. At its rostral end, you may be able to see the thin (and easily ripped off, see "Other View") abducens nerve (VI). The abducens exits from the trapezoid body (a thin transverse band of fibers on the surface of the brain just caudal to the pons, see Plate 8) at a point just lateral to the longitudinally coursing pyramidal tracts (see Plate 8). Lateral to the abducens is the more substantial facial nerve (VII). Lateral to this, tucked up just under the cerebellum, you may see the tuft that forms the vestibulocochlear nerve (VIII). Caudal to the vestibulocochlear nerve you may see another light tuft of nerves that are made up of the glossopharyngeal nerve(IX) blending into the more caudal vagus nerve (X). Caudal to this you may see the spinal accessory nerve (XI) which appears as a line of connected filaments running in a rostral-caudal direction (they may take on the appearance of a broad yard rake). The hypoglossal nerve (XII) exits in several branches from the lateral edge of the caudal medulla (see "Other View").