Tuberculum Acusticum

TUBERCULUM ACUSTICUM, acoustic tubercle, a nucleus belonging to the auditory system, located along the floor of the fourth ventricle, at the level of the lateral recess of the fourth ventricle (Fig. 1), where it

Figure 1. Cross-section of the medulla oblongata in its upper parts: 1-nucl. teres; 2-nucl. vestibularis dorsalis; 3-corpus restiforme; 4-cerebellum; 5-pedunculus flocculi; 6-tuberculum acusticum; 7-flocculus; 8-n. acusticus; 9-n. glossopharyngeus; 10-radix spinalis n. V; 11-substantia grisea Rolandi; 12-nucl. ambiguus; 13-oliva inferior; 14-pyramis; 15-lemniscus medialis; 16-nuclei centrales; 17-fasciculus tectospinalis; 18-fasciculus longitudinalis posterior.

constitutes part of the acoustic area. At the site of the lateral recess, the gray layer of the rhomboid fossa extends onto the outer surface of the corpus restiforme and forms the T. a.; anterior to it is located the nucleus ventralis n. cochleae, and laterally, the cerebellum. When transitioning into the pons, the outer surface of the corpus restiforme ceases to be free, fuses with the cerebellum, and the T. a. disappears, while the anterior auditory nucleus remains. In the T. a., some fibers of the n. acusticus terminate, and from it originates the central auditory pathway, which is represented by the auditory striae, s. striae acusticae Monakov's (see Auditory pathways, centers). The T. a. is formed by cells arranged in a radial direction, having strongly branching dendrites at both ends (Fig. 2); the axial cylinder extends caudally and forms the auditory striae. Centripetal fibers entering the T. a. form "baskets" (Held) around its cells.

Figure 2. Structure of the acoustic tubercle: 1 and 4 - anterior nucleus of the auditory nerve; 2-corpus restiforme; 3-radix spinalis nervi trigemini; 6-tuberculum acusticum.

Centripetal fibers entering the T. a. form "baskets" (Held) around its cells.