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NECK. 



trachea, passes the inferior thyroid venous 

 plexus, on a level with which would be found, 

 in rare cases, the middle thyroid artery (of 

 Neubauer) ascending from the aortic arch : 

 these vessels are covered by a layer of fascia 

 dividing them from the sterno-thyroid muscles. 

 These parts are variously involved in the two 

 remaining modes of bronchotomy; one of 

 which the tracheal consists in dividing three 

 or four rings of the tube, below the isthmus of 

 the thyroid gland; the other the crico-tracheal 

 in dividing its upper rings and with them the 

 cricoid cartilage of the larynx. The first tra- 

 cheotomy (after a vertical division of the 

 tegumentary parts and a separation of the 

 muscles from the lower part of the larynx to 

 the sternum) exposes the tube in that portion 

 of its extent in which it is deepest and most 

 nearly related to vessels. The operator is 

 required to bear in mind the possible presence 

 of a middle-inferior thyroid artery, lest he 

 wound it inadvertently; he must avoid, or, 

 before opening the air-lube, must secure the 

 inferior thyroid veins ; in recollecting the great 

 lateral mobility of the trachea and its close 

 parallelism to the carotid arteries in the lower 

 part of the neck, he must guard against any 

 oblique glancing of his knife, by which these 

 great vessels might be injured ; in proceeding to 

 divide the cartilaginous rings, he must com- 

 mence below and on a completely exposed 

 part of the tube, and with the blunt border 

 of his knife toward the middle line of the 

 sternum, and with its point directed slightly 

 upward, lest (as might happen in neglect of 

 these precautions) the great vena innominata, 

 transversely crossing the tube just below the 

 level of the sternum, or the large arterial trunks, 

 which are there diverging from the median line, 

 should sustain injury: nor must he rudely 

 transfix the tube and encounter the risk of 

 puncturing parts, normally or abnormally be- 

 hind it.* The second operation, crico-tracheo- 

 tomy, first proposed by Boyer, f pretends to 

 preference over that just mentioned, on the 

 ground of obtaining an equally free opening 

 with less invasion of important parts. Indeed, 

 although M. Boyer, in proposing it, seems to 

 have considered the section of the thyroid 

 isthmus inevitable, and accordingly included 

 its division in his estimate of risks, perhaps 

 even that objection might be withdrawn from 

 the operation, if performed in exact agreement 

 witli his description ; since the finger may de- 

 press the thyroid body to an extent which 



* In suggesting the possibility of injuring organs 

 abnormally situated behind the trachea, the text 

 particularly refers to the occasional passage of a 

 right subclavian artery, from the left part of the 

 arch, either between the oesophagus and trachea, 

 or behind both those tubes. The anomaly is not a 

 very rare one ; and a case is reported, in which the 

 artery, so running, was pierced by a bone, arrested 

 in and perforating the oesophagus. (Dublin Hos- 

 pital Reports, vol. \\.) The irregularities of the 

 aorta itself, quoted by Tiedemann from Hommel 

 and Malacarne, are of almost unique occurrence, 

 hardly furnishing an additional argument for that 

 uniform caution, which the above less infrequent 

 abnormality makes imperative. 



* Maladies Chirurgicales, vol. vii. p. 131. 



admits a safe division of the first two rings of 

 the trachea. But it seems to have escaped his 

 notice, while theorising on the operation, that 

 a section of the cricoid cartilage must be use- 

 less, unless abused; that a rigid ring, divided 

 at one point of its circumference, remains un- 

 loosened; that a single section of the cricoid 

 cartilage could not be made available as a 

 means for increased access to the air-tube, over 

 and above that afforded by division of the tra- 

 chea,except by employ ing on it a disruptive force, 

 that should effect a counter-fracture at some 

 other part of its circumference. Such violence 

 on such an organ M. Boyer was far too judi- 

 cious a surgeon to have sanctioned ; and from 

 the single instance, appended (p. 142 bis) to his 

 speculations on the subject, it appears probable 

 that the upward extension of his opening in the 

 air-tube was useless ; that an incision through' 

 the upper rings of the trachea sufficed for the 

 escape of the foreign body; and that, in alt 

 essential particulars, the crico-tracheal opera- 

 tion is but tracheotomy at a higher than ordi- 

 nary level, complicated with an unadvantageous 

 and therefore objectionable intrusion on the 

 larynx. 



2. The antero-inferior triangle adjoins in- 

 wardly the space last described, is bounded 

 outwardly by the decussation of the omo-hyoid 

 muscle (which separates it from the superior 

 compartment of the great anterior triangle) 

 with the imaginary diagonal, which demarks it 

 from the postero-inferior or supra-clavicular 

 space. Its various parts and contents require 

 some separate description. As regards the inte- 

 guments, it will be remembered that the pla- 

 tysma only partly covers this space, and that 

 the anterior jugular vein, when it exists, is con- 

 tained here in the lower part of its course. The 

 sterno-cleido-mastoideus follows the outer side 

 of the triangle, but extend over it by its sternal 

 border, so as to cover a large portion of its 

 area. Beneath this muscle, the stronger deep 

 layer of the cervical fascia is extended and 

 splits internally to enclose the sterno-thyroi- 

 deus, which likewise encroaches on the space 

 by its inner side. Under this fascia the common 

 carotid artery (beside which are the jugular 

 vein and the pneumogastric nerve) ascends ver- 

 tically, and is slightly overlapped from within 

 by the thyroid body. The anatomy of the space 

 is well developed, in considering the best mode 

 of reaching the carotid artery: a vertical inci- 

 sion falling on the sterno-clavicular joint ex- 

 poses the superficial fascia and part of the pla- 

 tysma; these being divided, the sheath of the 

 sterno-mastoid is seen, and on its being opened 

 the sternal fibres of the muscle present them- 

 selves, obliquely ascending outward : their di- 

 vision and displacement exposes the posterior 

 layer of their fascial investment, which is here 

 seen to ensheath the sterno-thyroid muscle: the 

 descending branch of the lingual nerve (de- 

 scendens noni) seems almost embedded in the 

 deep layer of the aponeurosis, and reaches the 

 outer edge of this muscle in the upper part of 

 the space: beneath the stratum of parts so 

 constituted, the carotid lies with the associated 

 organs: the jugular vein is on its outer side, 



