The 4th ventricle is a tent-shaped structure in the midline, the complete knowledge of its anatomical details is necessary for surgical approaches to lesions of the posterior fossa, brainstem, and the fourth ventricle.

The floor of the fourth ventricle is located in its anterior part, and the rostral two-thirds of it includes the pons and the caudal third includes the medulla. The roof of this tent-shaped structure includes the superior and inferior parts, the superior part of the roof consists of the superior medullary velum and superior cerebral peduncle, and the inferior part consists of the inferior medullary velum, tela choroidea, nodule, and uvula. Lateral recesses are the expansion of the 4th ventricle, which opens into the space of the cerebellomedullary angle.

The tonsillomedullary and tonsillo-uvula fissures are located in the lower medial surface of the tonsil and separate the tonsil from the medulla and uvula that can be used as a surgical corridor to the 4th ventricle.

The constructive structures of the anterior wall of the cerebellomedullary fissure are posterior structures of the medulla, inferior medullary velum, and tela choroidea. The uvula and tonsil form the posterior wall of the cerebellomedullary fissure and the biventer lobule is located lateral to this fissure.

Moving the tonsils laterally exposes the tela choroidea and inferior medullary velum. The opening of the tela is the way to access the fourth ventricle from the obex to the aqueduct, and opening the velum is also the way to access the upper half of the fastigium and lateral recesses.

Tumors in the fourth ventricle can be critical due to its small size, which causes symptoms to be detected even in the presence of lesser mass effects. As a result, compression of the cerebellum, brainstem, or fourth ventricle, as well as the potential risk of superior vermian or inferior tonsillar herniation, can be expected to be presented in the tumors of this region.

Transvermian and telovelar are the two main approaches to access lesions of the fourth ventricle, and the fissures around the roof of the fourth ventricle, tonsils, and medulla are landmarks for these approaches.

A proper surgical approach to the fourth ventricle poses challenges due to its deep location and proximity to vital compartments within the brainstem. The two commonly used approaches to these tumors are the transvermian and telovelar approaches. In the transvermian approach, the inferior vermis of the cerebellum is incised, and its two parts are retracted laterally. The telovelar approach involves exposing the tela choroidea and inferior medullary velum and retracting the lower vermis to uncover the posterior fossa. These approaches differ in their exposure of the fourth ventricle floor, lateral recess, and foramen of Luschka [1]. This systematic review aimed to compare the complications associated with the transvermian and telovelar approaches in the treatment of fourth ventricle tumors.