Surgical approaches to IV ventricle--anatomical study.
OBJECTIVE
Knowledge of anatomy of the IV ventricle is basic to surgical approach of any kind of lesion in its compartment as well as for those located in its neighborhood. The purpose of this study is to demonstrate the surgical approach options for the IV ventricle, based on the step by step dissection of anatomical specimens.


METHODS
Fifty formalin-fixed specimens provided were the material for this study. The dissections were performed in the microsurgical laboratory in Gainesville, Florida, USA.


RESULTS
The IV ventricle in a midline sagittal cut shows a tent-shaped cavity with its roofs pointing posteriorly and the floor formed by the pons and the medulla. The superior roof is formed by the superior cerebellar peduncles laterally and the superior medullary velum on the midline. The inferior roof is formed by the tela choroidea, the velum medullary inferior, and the nodule. The floor of the IV ventricle has a rhomboid shape. The rostral two thirds are related to the pons, and the caudal one third is posterior to the medulla. The median sulcus divides the floor in symmetrical halves. The sulcus limitans runs laterally to the median sulcus, and the area between the two sulci is called the median eminence. The median eminence contains rounded prominence related to the cranial nucleus of facial, hypoglossal, and vagal nerves. The lateral recesses are extensions of the IV ventricle that opens into the cerebellopontine cistern. The cerebellomedullary fissure is a space between the cerebellum and the medulla and can be used as a surgical corridor to the IV ventricle.


CONCLUSIONS
We obtained in this study a didactic dissection of the different anatomical structures, whose recognition is important for addressing the IV ventricle lesions.
, São Paulo, São Paulo, Brazil.
Antonio Cesar de Melo
AC
Mussi
, São Paulo, São Paulo, Brazil. Matushita@uol.com.br.
Hamilton
H
Matushita
Department of Neurosurgery, Division of Pediatric Neurosurgery, University of São Paulo, São Paulo, Brazil.
Fernanda Gonçalves
FG
Andrade
, São Paulo, São Paulo, Brazil.
Albert L
AL
Rhoton
D002531:Cerebellum / Q000033:anatomy & histology* / Q000098:blood supply; D020546:Fourth Ventricle / Q000601:surgery*; D006801:Humans; D008526:Medulla Oblongata / Q000033:anatomy & histology* / Q000098:blood supply; D009493:Neurosurgery / Q000379:methods*; D011149:Pons / Q000033:anatomy & histology* / Q000098:blood supply
Infratentorial tumors; Microsurgery; Microsurgical anatomy; Posterior fossa