Exploration of the cerebellum and brain stem from above and behind

Rhomboid fossa of fourth ventricle

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Image #24-5
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Exploration of the cerebellum and brain stem from above and behind
Rhomboid fossa of fourth ventricle
The tela chorioidea has been removed and the posterior parts of the cerebellum resected so that the floor of the fourth ventricle (the rhomboid fossa) can be seen. This fossa is divided into superior, intermediate and inferior areas which are not labelled in the drawing. The lateral recess lies opposite the intermediate area. Although the position of the obex (10) is indicated, no evident thickening of the pia mater was present in this specimen.
1 . Anterior medullary velum
2 . Median eminence
3 . Dentate nucleus
4 . Prominence in wall of ventricle produced by medial part of dentate nucleus
5 . Medullary striae
6 . Sulcus limitans (pointer on inferior fovea rhomboid fossae)
7 . Hypoglossal trigone
8 . Wing of gray matter (overlying dorsal motor nucleus nerve X)
9 . Calamus scriptorius (dorsal median sulcus)
10 . Posterior median fissure and obex
11 . Inferior colliculus
12 . Trochlear nerve (IV)
13 . Median sulcus of rhomboid fossa
14 . Superior fovea rhomboid fossa
15 . Facial colliculus
16 . Fibers from peduncle of flocculus ascending into tegmentum
17 . Lateral recess of rhomboid fossa
18 . Taenia fourth ventricle
19 . Restiform body (inferior cerebellar peduncle)
20 . "Funiculus separans"
21 . "Area postrema"
22 . Clava
23 . Medullary substance of biventral lobule (ventral paraflocculus)