Anatomical diagram depicting the surgical anatomy of the rhomboid fossa, specifically the inferior aspect of the floor of the fourth ventricle. The illustration uses a schematic sketch format to identify key neuroanatomical landmarks. At the most inferior point of the ventricular floor is the obex (1), marking the transition to the central canal. Just superior to the obex lies the area postrema (2). The ventricular floor displays distinct trigones: the trigonum nervi hypoglossi (3) located medially, and the trigonum nervi vagi (5) situated laterally and slightly inferiorly. Further lateral is the area acustica (4). The superior boundary of this region is demarcated by the striae medullares (6), which run transversely across the floor. The lateral borders of the inferior ventricle are formed by the taenia (7). This diagram serves as an educational resource for identifying critical brainstem structures during sub-occipital surgical approaches, emphasizing the spatial relationships within the medulla oblongata's posterior surface.

This composite educational resource illustrates the endoscopic management of intraventricular hemorrhage (IVH) via transaqueductal navigation. (a) A sagittal anatomical diagram depicts the trajectory of a flexible neuroendoscope from a precoronal burr hole through the lateral and third ventricles into the fourth ventricle. (b) An intraoperative endoscopic image shows the internal anatomy of the cerebral aqueduct, identifying the floor (fc), ampulla (am), and second constriction (sc). A prominent blood clot (*) is visible obstructing the distal egressus of the aqueduct near the posterior commissure (pc). (c) A subsequent intraoperative view demonstrates the inferior triangle of the fourth ventricle post-aspiration. Key landmarks include the choroid plexus (chp) on the ventricular roof and the canalis centralis medullaris at the calamus scriptorius (arrow). Residual blood clots (bc) are noted obstructing the foramen of Magendie. This visual sequence highlights the surgical approach to restoring cerebrospinal fluid (CSF) pathway patency in cases of obstructive hydrocephalus caused by hemorrhage.

This medical illustration depicts an anatomical diagram of the human brain's ventricular system in a sagittal view, highlighting the surgical placement of a fourth ventricle catheter and ventricular access device (VAD). The ventricular system is rendered in red, showing the bilateral C-shaped lateral ventricles, the centrally located third ventricle, and the diamond-shaped fourth ventricle in the posterior fossa near the brainstem and cerebellum. A gray ventricular catheter is shown inserted directly into the fourth ventricle, positioned parallel to the ventricular floor. The catheter exits the cranium and incorporates a 'relief loop' designed to prevent mechanical tension during neck movement. It terminates in a subcutaneous VAD positioned at the base of the neck/posterior scalp area. This illustration serves to demonstrate a neurosurgical approach for direct ventricular access, often utilized for localized chemotherapy delivery or cerebrospinal fluid (CSF) management. Key anatomical landmarks include the cerebral cortex, brainstem, and the suboccipital region where the surgical incision and device tunneling occur.