Henry Gray (18251861). Anatomy of the Human Body. 1918.
almost horizontally backward, and is attached to the fossa incudis, in the lower and back part of the epitympanic recess.
The long crus (crus longum; long process) descends nearly vertically behind and parallel to the manubrium of the malleus, and, bending medialward, ends in a rounded projection, the lenticular process, which is tipped with cartilage, and articulates with the head of the stapes.
The Stapes(Fig. 918), so called from its resemblance to a stirrup, consists of a head, neck, two crura, and a base.
The head (capitulum stapedis) presents a depression, which is covered by cartilage, and articulates with the lenticular process of the incus.
The neck, the constricted part of the bone succeeding the head, gives insertion to the tendon of the Stapedius muscle.
The two crura (crus anterius and crus posterius) diverge from the neck and are connected at their ends by a flattened oval plate, the base (basis stapedis), which forms the foot-plate of the stirrup and is fixed to the margin of the fenestra vestibuli by a ring of ligamentous fibers. Of the two crura the anterior is shorter and less curved than the posterior.
Articulations of the Auditory Ossicles (articulationes ossiculorum auditus).The incudomalleolar joint is a saddle-shaped diarthrosis; it is surrounded by an articular capsule, and the joint cavity is incompletely divided into two by a wedge-shaped articular disk or meniscus. The incudostapedial joint is an enarthrosis, surrounded by an articular capsule; some observers have described an articular disk or meniscus in this joint; others regard the joint as a syndesmosis.
Ligaments of the Ossicles (ligamenta ossiculorum auditus).The ossicles are connected with the walls of the tympanic cavity by ligaments: three for the malleus, and one each for the incus and stapes.
The anterior ligament of the malleus (lig. mallei anterius) is attached by one end to the neck of the malleus, just above the anterior process, and by the other to the anterior wall of the tympanic cavity, close to the petrotympanic fissure, some of its fibers being prolonged through the fissure to reach the spina angularis of the sphenoid.
The superior ligament of the malleus (lig. mallei superius) is a delicate, round bundle which descends from the roof of the epitympanic recess to the head of the malleus.
The lateral ligament of the malleus (lig. mallei laterale; external ligament of the malleus) is a triangular band passing from the posterior part of the notch of Rivinus to the head of the malleus. Helmholtz described the anterior ligament and the posterior part of the lateral ligament as forming together the axis ligament around which the malleus rotates.
The posterior ligament of the incus (lig. incudis posterius) is a short, thick band connecting the end of the short crus of the incus to the fossa incudis.