Page:Muscles and Regions of the Neck.djvu/15

Rh except a proposal made by M. Malgaigne for reaching the larynx through it, which has not yet received the sanction of practice. 2. The angle, in which the alæ of the thyroid cartilage meet, having—under the quaint name of pomum Adami—its extreme prominence above. Within it are the essential organs of voice, which, buckler-like, it protects: the inward aspect of its angle attaches the vocal ligaments; its outward jutting marks their length, and measures the development of the larynx. Hence the pomum Adami, as indicating by its prominence that matured growth of the organs of voice, which belongs to male puberty, is a physiognomical character of sex. Desault's mode of laryngotomy consists in a vertical division of this angle from below upward, and has the recommendations of easy performance and of efficiency for the extraction of a foreign body. That it invades parts of high functional endowment and extreme irritability,—that ossification of the cartilage may unexpectedly prevent its completion,—that perfect reunion of the divided structure is uncertain—are alleged as objections to it, and perhaps over-estimated as such; for to the first may be answered, that the operation is of relief, and hence little likely to aggravate an irritation, the cause of which it removes; to the second may be conceded, that the mode of operation is not eligible for cases likely to present the bony deposit referred to; and against the third may be adduced the evidence of the French surgeons, by whom chiefly the operation has been performed, that the parts are as quickly repaired, and their functions as completely recovered, as after any other mode of operative procedure. As regards its anatomy, nothing can be easier than to lay bare the pomum Adami; a division of the skin, of the superficial and proper fasciæ, with some lateral displacement of the sub-hyoid muscles, will suffice for its exposure: and, for its division,—the closest following of the medial line, in order that the knife may pass between the vocal ligaments, leaving both uninjured, is the chief precaution to be observed. The upper edge of the glottis is on a level just below that of the superior thyroid notch. The prominence of the thyroid cartilage and the unyielding support which the borders of its arched surface receive from the bony column behind it, render it liable to be crushed by any considerable, direct, antero-posterior violence. Such has, more than once, been the cause of immediate death where a straightforward blow has reached the larynx in prize-fighting; and such, too, is a not infrequent effect in death by hanging, especially where, as in the English mode of judicial execution, the rope is made to tighten itself jerkingly. The thyroid cartilage is sometimes partially divided in attempts at self-destruction, which it commonly frustrates by defending more important parts. 3. A depression which answers to the crico-thyroid ligament: it is here that the usual operation for urgent glottic dyspnœa is performed. The common integuments and the fascial raphe cover the little interspace in question, which is safely reached—between the crico-thyroidei—by displacing in a slight extent the sub-hyoid muscles. It has about half an inch of transverse breadth, and about a third of an inch of height,—is bounded by the inferior thyroid notch and by the anterior part of the circumference of the cricoid cartilage; which borders give attachment to the strong yellow elastic membrane that closes the space. This depression is so readily felt through the integuments—its boundaries are so definite and its relations so simple, as to render it a peculiarly eligible spot for bronchotomy, when suddenly and urgently required. A small artery sometimes forms, with its fellow of the opposite side, a transverse communication across this membrane, and its presence has been much insisted on as a circumstance of practical importance: it is of extreme minuteness, and by no means constantly present: it is the crico-thyroid, and arises from the thyroid branch of the external carotid, near the upper angle of the thyroid body, and runs across the membrane toward the median line. The necessity for haste is commonly of too urgent a character to admit of any deliberate, layer-by-layer, dissective operation: a single steady puncture with a canulated trocar, or with a bistoury—directly followed by a tube—is the usual mode of conducting it. In such instances the minute artery can hardly be avoided with certainty, but neither can its division be injurious, since the closely fitting canula will secure the cavity of the air-tube against its trifling hemorrhage. In the rarer cases, where time is allowed for a slower division of the tissues, it would be desirable not to puncture the membrane till the artery, if present, had been disposed of. It usually lies near to the border of the cricoid cartilage, and might easily be drawn downward away from injury; or its division might be rendered harmless by torsion, or by a fine ligature. In the more extemporaneous mode of laryngotomy the bistoury should be guided flatly, close beneath the thyroid cartilage; in so making a transverse division of the membrane, it is parallel to the line of the artery, but above its usual position. 4. The slight prominence of the cricoid cartilage, and the series of tracheal rings—becoming progressively deeper toward the sternum,—are next felt. In some subjects their chain is seemingly interrupted by a transverse fleshy eminence (which, however, is in health generally imperceptible through the skin), the isthmus of the thyroid gland. To the lateral portions of this body I shall presently return: the isthmus is its only part having relations in the median line, which it crosses to a very variable extent. Most frequently it measures about half an inch in breadth, and corresponds by its middle to the second ring of the trachea: but from this, its normal extent may vary on the one hand to the extreme of entire absence—on the other to that of being an uncontracted, flattened union of the lateral lobes, which it may so equal in its vertical dimension. Downward from its lower edge, in front of the remaining rings of the