Vascular Channels in the Auditory Ossicles in Man

A second, extended study was made on the pattern of internal vascular anatomy of the stapes, incus, and malleus, employing serially sectioned specimens and reconstructions prepared from the sections. The descriptions and figures account, in detail, for the structural features in a specimen of a newborn infant and a 19-year-old male. Statements based mainly thereupon are supported by a study of a large number of additional otological series, from fetal stages in which the process of bone formation was just initiated to those of advanced years. It is established that the numerous blood vessels of intraosseous supply traverse channels of widespread distribution in the malleus and incus, or of restricted regional presence in the stapes — Differences wholly dependent upon the developmental changes which bring the ossicle to maturity. Vessels gain access to, and leave, these internal channels by openings that are unlike the nutrient foramina in a typical long bone of the human skeleton: they are distributed along the external surface of each ossicle, rather uniformly in the case of the malleus and incus, less so in that of the stapes; they are not limited to the extremities. Through the peripheral apertures, the contained blood vessels communicate with those of submucosal location. Some of the latter then pass through the numerous mucosal septa, becoming continuous with other arteries and veins of ossicular supply situated as follows: medially, on the wall of the cochlear and canalicular parts of the middle ear; laterally, on the surface of the tympanic membrane; midway, with vessels which course with the stapedius tendon as branches or tributaries of vessels in the facial canal. The vacant spaces of the autograft or homograft are ready for fresh occupancy by the blood vessels of the operated tympanic cavity. The extent to which the channels are reclaimed in transplants that are interposed in the ossicular chain of the human ear remains to be determined. In the larger sense, the local changes made around the ossicles are but part of a more inclusive process of reconstitution of a vascular complex that encompasses the entire middle ear.