Surgical anatomy of the head and neck : neck mouth pharynx larynx nose orbit eyeball organ of hearing brain back of neck cranium scalp face / by John B. Deaver.

Deaver, John B. (John Blair), 1855-1931

Date:: 1904

Credit: Surgical anatomy of the head and neck : neck mouth pharynx larynx nose orbit eyeball organ of hearing brain back of neck cranium scalp face / by John B. Deaver. Source: Wellcome Collection.

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$however, is exceptional. Below this cartilage is the crico-thyroid space, wdiich is occupied by the crico-thyroid membrane. It is through this membrane that laryn- gotomj' is ])erformed, care being taken to hug the upper border of the cricoid cartilage, so that the incision may be as far as possible from the vocal cords and the crico-thyroid arteries. The vocal cords are situated slightly below a point midwa}^ between the deep- est part of the incisura thyroideae and the lower border of the thyroid cartilage. The cricoid cartilage is always prominent, and can readily be discerned. It lies opposite the sixth cervical vertebra. Its lower border is on a level Avith the commencement and naiTOwest part of the esophagus; for this reason all bodies which have entered the pharynx but are too large to pass through the gullet will lodge behind the cricoid cartilage. The cricoid cartilage is just above the level at Avhich the omo-hyoid muscle and the inferior thyroid artery cross the carotid sheath, the muscle being in front of the sheath and the artery behind. Slightly below the level of this cartilage and beneath the anterior border of the sterno- mastoid muscle is the carotid tubercle, against which the common carotid artery ma} be compressed. This is the anterior tubercle of the transA^erse process of the sixth ceiwical A^ertebra. The movements of the larynx are frequently overlooked. The larynx rises during deglutition, in singing a high note, and in expiration ; it descends in singing Ioaa' notes, in inspiration, after deglutition, and during retching and Ammiting. When the larynx is moA^ed from side to side, a grating sensation, due to the friction of the superior cornua of the thyroid cartilage against the s])inal column, is perceh^ed. The larynx is pushed fonvard in the passage of masses through the loxA'er pharynx. The sudden upAA^ard rush of A'omited matter produces suction upon the larynx, draAA’ing out obstinately adherent false membrane and collections of glairy mucus; this is one reason for giving children emetics in croup. The trachea is situated immediately beloAV the cricoid cartilage. Ordinarily, not more than one and one-half inches of it appear aboA^e the sternum ; an inch more, hoAA’ever, may be reA^ealed if the neck be in extreme extension. This usually leaves about eight rings in the neck, of A\diich the second, third, and fourth are covered by the thyroid isthmus. The front of the trachea ma}' lie one and one-half inches deep at the top of the sternum, owing to the recession of the loAA'er cerAucal and upper thoracic A^ertebrse. Opening of the trachea to relieA’e d}spnea is beset with many difficulties not all demonstrable in the cadaver—the strong and rapid alternate muscular contractions, the heaAung larynx, the distended anterior jugular veins, the flexed neck, the SAA’ollen thyroid isthmus, the distended thyroid plexus of A^eins, and, frequently, a middle th}U’oid arteiy. All incisions into the trachea should be in the median line, AA'here feAA-er important structures need be seA^ered. It is often adAusable in cases of dyspnea to incise the crico-tliA’roid$