Barry J. Anson

LIII Surgical Anatomy of the Facial Canal and Facial Nerve

In recent years, many important new and detailed observations have been made in anatomy, gross and macroscopic, in response to surgical requirements. The store of knowledge has been dramatically enlarged in the case of the stato-acoustic organ. The location of the mechanisms for equilibrium and hearing, in rendering examination and study difficult has accounted for the stereotyped descriptions of aural structure to which the anatomist and the surgeon had ready access.

The Endolymphatic and Perilymphatic Aqueducts of the Human Ear: Developniental and Adult Anatomy of their Parietes and Contents in Relation to Otological Surgery

The fetal development of both the vestibular and cochlear aqueducts will be followed in otological series beginning with tlie 4-month stage. Postnatal progress and mature structure will be traced from the newborn infant to the adult of 70 years (in dissections, serial sections and reconstructions prepared from the latter).These features will be emphasized: histology of the osseous wall and the contained connective tissue; source and course of blood vessels derived from labyrinthine periotic tissue internally and meningeal layers externally; normal range in adult anatomy. On these structural bases, the two channels will be compared, with special reference to their present and prospective role in otological surgery.

Surgical Anatomy of the Chorda Tympani

The present report is based upon the following: dissection of both unembalmed and skeletal (“cleaned”) * specimens; selected Ievels in two series of sectioned temporal bones ( 17 and 19 years of age). In addition, the set of illustrations is introduced by a schematized treatment of the source, neural connections and relationships of the chorda tympani and terminated with a drawing of an undissected specimen so viewed as to show channels and sulci which traverse or indent the temporal bone.

The gross and macroscopic anatomy of the labyrinths.

INTRODUCTION Among the important and frequent factors contributing to sensorineural hearing loss is disturbance of normal pressure in the membranous and the osseous labyrinths, which contain, respectively, the endolymph and the perilymph. Each of these conditions finds dramatic clinical expression in otological disease: endolymphatic hydrops in the case of the membranous labyrinthine system; perilymphatic leakage (following stapedectomy) in the case of the osseous labyrinth.

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.

The blood supply of the otic capsule of the human ear, with special reference to that of the cochlea.

This is taken to be the case because of the following circumstances: 1) variation in the source-vessels is considerable, since they arise in areas as far separated as subclavian and intracranial; 2) their developmental course is exceptional, being the supply to a skeletal element of the cranium which, despite its small size, is a composite of fourteen ossification centers; 3) the adult relation of the vessels to the three-layered osseous cochlea is determined by steps in morpho-

XCII Postnatal Growth and Adult Structure of the Otic (Endolymphatic) SAC

In the human fetus up to midterm, the otic sac is small and the duct and sac lie in a fairly straight line almost parallel to the crus commune (Fig. lA). The sac partly overlies the sigmoid sinus into which the rich venous plexus surrounding the caudo-medial surfaces of the sac drains. The close relationship between the otic sac, sigmoid sinus, and posterior semicircular canal are well illustrated in Fig. lA.

LVI Scientific Papers of the American Otological Society: Intra-Osseous Blood Supply of the Auditory Ossicles in Man

Each year it is the duty of the President on this occasion to address the members and guests of the American Otological Society. The President has no escape from this responsibility. He is adjured by the precedent and tradition of eighty-five annual scientific meetings to respond in his very best manner at this time. He may have tried to delegate this part of the program to other more distinguished members of the Society but with no success. On each occasion he is reminded magnanimously of the superior privileges of the President and cajoled to exercise his prerogative at this important funtcion, One distinguished member of the Society, frank and less felicitous, asked me to spare him from a grave and expounding discourse but nevertheless to discharge the duties avowedly those of the office of the President no matter how disagreeable or reprehensible they might be.

IV Terminal Stages in the Development of the Human Stapes

In the course of its morphogenesis as a cartilaginous, and later as an osseous, skeletal element in vertebrates, the stapes has undergone a remarkable transformation. Some of the more primitive steps in the alteration are repeated in the individual developmental history of the ossicle in man, while others are not only peculiar to the stapes but also unique in the general history of bone formation. The predecessor of the stapes functioned as a support for the respiratory mechanism in aquatic and amphibious vertebrates; in mammals it has been made over to serve as the terminal link in an ossicular chain whose function it is to convert air waves into liquid waves. In response to these new demands, the stapes of the human embryo, appearing first as part of the branchial arch system, later establishes anatomic relationships at one extremity with another ossicle, at the other with an orifice in the capsular shelter for the acoustic endorgans. The stapes develops rapidly, concomitant with a vestibular window whose dimensions are relatively fixed near the middle of fetal life, growth thereupon becoming minimal. The ossicle adapts its histologic structure to an existence within a chamber which is early invaded by pharyngeal mucous membrane, and concurrently sacrifices considerable bulk to reduce inertia. These anatomic objectives and the developmental means employed to attain them will be the subject of the current article.

NEW HISTOLOGICAL OBSERVATIONS OF LABYRINTHINE CAPSULE IN RELATION TO THE ETIOLOGY OF OTOSCLEROSIS-Reply

To the Editor : My fundamental objection to the presentation of Rius and Mendoza is that there seems to be little or no appreciation of the fact that the otic capsule, in being unlike all of the other skeletal elements in the human body, calls for interpretations new to our familiar code of diagnostics. Incidentally, and in the want of strong contraindication, it remains my notion that the etiological factors in otosclerosis, if ever uncovered, will be found in the histological fabric of the fissular region—otherwise, observed predilection would be without significance. The RiusMendoza theory covers the entire capsule.