Malleus

The malleus (plural: mallei) is the most lateral middle ear ossicle, located between the tympanic membrane and the incus.

Gross anatomy

The malleus has a head, neck, and three distinct processes (manubrium (handle), anterior and lateral processes).

The head is oval in shape, and articulates posteriorly with the incus by a small facet joint. The facet for articulation with the incus is saddle-shaped, constricted near the middle, and consists of an upper larger and lower smaller part, which form nearly a right angle with each other.

The neck is the narrow contracted part just beneath the head; below it, is a prominence to which the various processes are attached.

The manubrium (handle) is connected by its lateral margin with the tympanic membrane. It is directed downward, medially, 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 muscle is inserted.

The anterior process 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.

The lateral process 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.

Radiographic appearance

CT

Its appearance on axial CT is that of a ball of ice cream on a cone, representing the body and short crus of the incus (the ice cream cone sign).

History and etymology

"Malleus" is Latin for hammer.