Henry Gray (18251861). Anatomy of the Human Body. 1918.
by the Salpingopharyngeus and Dilatator tubæ. The latter arises from the hook of the cartilage and from the membranous part of the tube, and blends below with the Tensor veli palatini.
1d. 3. The Auditory Ossicles
The tympanic cavity contains a chain of three movable ossicles, the malleus, incus, and stapes. The first is attached to the tympanic membrane, the last to the circumference of the fenestra vestibuli, the incus being placed between and connected to both by delicate articulations.
The Malleus(Fig. 916), so named from its fancied resemblance to a hammer, consists of a head, neck, and three processes, viz., the manubrium, the anterior and lateral processes.
The head (capitulum mallei) is the large upper extremity of the bone; it is oval in shape, and articulates posteriorly with the incus, being free in the rest of its extent. The facet for articulation with the incus is constricted near the middle, and consists of an upper larger and lower smaller part, which form nearly a right angle with each other. Opposite the constriction the lower margin of the facet projects in the form of a process, the cog-tooth or spur of the malleus.
The neck (collum mallei) is the narrow contracted part just beneath the head; below it, is a a prominence, to which the various processes are attached.
The manubrium mallei (handle) is connected by its lateral margin with the tympanic membrane. It is directed downward, medialward, and backward; it decreases in size toward its free end, which is curved slightly forward, and flattened transversely. On its medial side, near its upper end, is a slight projection, into which the tendon of the Tensor tympani is inserted.
The anterior process (processus anterior [Folii]; processus gracilis) is a delicate spicule, which springs from the eminence below the neck and is directed forward to the petrotympanic fissure, to which it is connected by ligamentous fibers. In the fetus this is the longest process of the malleus, and is in direct continuity with the cartilage of Meckel.
The lateral process (processus lateralis; processus brevis) is a slight conical projection, which springs from the root of the manubrium; it is directed laterally, and is attached to the upper part of the tympanic membrane and, by means of the anterior and posterior malleolar folds, to the extremities of the notch of Rivinus.
The Incus(Fig. 917) has received its name from its supposed resemblance to an anvil, but it is more like a premolar tooth, with two roots, which differ in length, and are widely separated from each other. It consists of a body and two crura.
The body (corpus incudis) is somewhat cubical but compressed transversely. On its anterior surface is a deeply concavo-convex facet, which articulates with the head of the malleus.
The two crura diverge from one another nearly at right angles.
The short crus (crus breve; short process), somewhat conical in shape, projects