| terminal ventricle | A dilation of the central canal of the spinal cord at the tip of the medullary cone. Synonym: ventriculus terminalis. (05 Mar 2000) |
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| third ventricle | A narrow, vertically oriented, irregularly quadrilateral cavity in the midplane, extending from the lamina terminalis to the rostral opening of the mesencephalic aqueduct. This ventricle communicates at its rostrodorsal corner with each of the two lateral ventricles through the left and right interventricular foramen of Monro. Its narrow roof is formed by the tela choroidea which is attached on either side to the tenia thalami; its lateral wall by the medial surface of the thalamus and, below the hypothalamic sulcus, by the hypothalamus which also forms its floor. In lateral profile, the third ventricle exhibits a number of recesses: in its floor, from before backward, 1) the preoptic recess in the acute angle between the base of the lamina terminalis and the dorsum of the optic chiasm, 2) the infundibular recess extending ventrally into the infundibulum but (in humans) not into the hypophysial stalk, and 3) the mamillary or inframamillary recess caused by the protrusion of the mamillary bodies into the ventricle. From its dorsocaudal corner, the pineal recess extends caudally into the pineal stalk. Synonym: ventriculus tertius, diacele, ventricle of diencephalon. (05 Mar 2000) |
| trigone of lateral ventricle | A triangular prominence of the floor of the lateral ventricle at the transition between occipital and temporal horn, continuous rostrally with the collateral eminence and, like the latter, caused by the deep penetration of the collateral sulcus from the ventral surface of the temporal lobe. Synonym: trigonum collaterale, trigone of lateral ventricle, trigonum ventriculi, ventricular trigone. (05 Mar 2000) |
| fifth ventricle | A slitlike, fluid-filled space of variable width between the left and right transparent septum, which occurs in less than 10% of human brains and may communicate with the third ventricle. Synonym: cavum septi pellucidi, Duncan's ventricle, fifth ventricle, pseudocele, pseudoventricle, sylvian ventricle, ventricle of Sylvius, ventriculus quintus, Vieussens' ventricle, Wenzel's ventricle. (05 Mar 2000) |
| laryngeal ventricle | The recess in each lateral wall of the larynx between the vestibular and vocal folds and into which the layrngeal sacculus opens. Synonym: ventriculus laryngis, laryngeal sinus, Morgagni's sinus, Morgagni's ventricle, sinus laryngeus. (05 Mar 2000) |
| lateral aperture of the fourth ventricle | One of the two lateral openings of the fourth ventricle into the subarachnoid space at the cerebellopontine angle. Synonym: apertura lateralis ventriculi quarti, foramen lateralis ventriculi quarti, foramen of Key-Retzius, foramen of Luschka, Retzius' foramen. (05 Mar 2000) |
| fourth ventricle | A cavity of irregular tentlike shape extending from the obex rostralward to its communication with the sylvian aqueduct, enclosed between the cerebellum dorsally and the rhombencephalic tegmentum ventrally, having a rhomboid-shaped floor (rhomboid fossa) and a tentlike roof which in its caudal part is formed by the tela choroidea and the posterior medullary velum, in its middle part by the white matter of the cerebellum, and in its narrowing rostral part (recessus superior) by the anterior medullary velum. The fourth ventricle reaches its greatest width at the pontomedullary transition, where it expands laterally behind the cerebellar peduncles into the spoutlike lateral recess, and its greatest height at the fastigial recess, which reaches up into the cerebellar white matter. Direct communication of the brain's ventricle system and the subarachnoid space is established at the level of the fourth ventricle by a median opening in the tela choroidea, the medial aperture of Magendie's foramen, which opens into the cerebellomedullary cistern, and on both sides by the lateral aperture or foramen of Luschka, which connects the lateral recess with the interpeduncular cistern. Synonym: ventriculus quartus, ventricle of rhombencephalon. (05 Mar 2000) |
| fourth ventricle mass | <radiology> IN ADULTS: choroid plexus papilloma, haemangioblastoma, vermian metastasis, arteriovenous malformation (AVM), inflammatory mass/cyst IN KIDS: medulloblastoma, uniform enhancement, homogeneous, ependymoma, patchy enhancement, heterogeneous, calcified (12 Dec 1998) |
| lateral recess of fourth ventricle | The narrow recess of the ventricle that extends laterally over, and down along the side of, the inferior cerebellar peduncle and the overlying cochlear nuclei; at its tip it opens by way of Luschka's foramen into the interopeduncular cistern of the subarachnoid space. By way of this recess, part of the choroid plexus of the fourth ventricle protrudes into the subarachnoid space. Synonym: recessus lateralis ventriculi quarti. (05 Mar 2000) |
| lateral vein of lateral ventricle | A vein draining deep portions of the temporal and parietal lobes; it runs in the lateral wall of the lateral ventricle to terminate in the superior thalamostriate vein. Synonym: vena ventriculi lateralis lateralis, lateral atrial vein, lateral vein of lateral ventricle. (05 Mar 2000) |
| lateral ventricle | A cavity shaped somewhat like a horseshoe in conformity with the general shape of the hemisphere; each lateral ventricle communicates with the third ventricle through the interventricular foramen of Monro, and expands from there forward into the frontal lobe as the anterior horn as well as caudally over the thalamus as the central part or cella media which, behind the thalamus, curves ventrally and laterally, then forward into the temporal lobe as the inferior horn; from the apex of the curve a variably sized posterior horn extends back into the white matter of the occipital lobe. The large choroid plexus of the lateral ventricle invades the cella media and the inferior horn (but not the anterior and posterior horn) from the medial side. Synonym: ventriculus lateralis, ventricle of cerebral hemisphere. (05 Mar 2000) |
| left ventricle | <anatomy> The muscular chamber of the heart which accepts blood from the left atrium and ejects it into the aorta to the systemic circulation. (27 Sep 1997) |