GUIDE TO THE HEAD AND NECK 1569 



it is essential that the dissector should, in the first place, make himself 

 thoroughly familiar with the landmarks of the side and front of the neck, 

 particularly the latter in connection with goitre, laryngotomy, and tracheo- 

 tomy. 



The skin is to be removed by means of the following incisions : a mesial 

 incision is to be carried from the chin to the upper border of the manubrium 

 stemi ; another from the lower end of the preceding outwards along the 

 clavicle to the acromion process of the scapula ; and a third from the chin 

 along one half of the base of the inferior maxilla to the angle of that bone, 

 and thence to the mastoid region. These incisions have to be made with 

 great care, on account of the thinness of the skin and the important sub- 

 cutaneous structures. 



The muscular sheet, called the platysma myoides, requires very careful 

 dissection, inasmuch as its fasciculi are very pale and delicate, but principally 

 because these fasciculi are embedded in the superficial fascia. Inexperienced 

 dissectors may be surprised when informed that they have removed the 

 muscle in their haste to expose what lies underneath it. The muscle, after 

 examination, is to be reflected from below upwards, and laid over the side 

 of the face. This must be done with the greatest care. Thereafter the 

 following veins £ire to be dissected, namely, the anterior jugular, near 

 the median line of the neck ; the external jugular, crossing the stemo- 

 cleido-mastoid ; and the posterior jugular, which is the most external 

 occipital vein. The dissector must be prepared for finding these veins not 

 quite normal. Along the course of the external jugular vein the superficial 

 cervical glands are to be displayed. The nerves which fall to be dissected 

 at this stage axe as follows : (i) the great auricular, passing upwards and 

 forwards over the stemo-cleido-mastoid towards the lobule of the auricle ; 

 (2) the superficial or transverse cervical, passing forwards over the stemo- 

 cleido-mastoid, and beneath the external jugular vein ; and (3) the suprasternal, 

 supraclavicular, and supra-acromial, which three take a downward course. 

 The inframandibular or cervical branch of the facial nerve must also be 

 dissected. 



Posterior Triangle. — The dissection of this region should be accomplished 

 in the course of the first four days after the subject has been placed with 

 its face upwards, in order that the dissectors of the neck and upper limb 

 may work in concert. In his mode of procedure the dissector must keep 

 carefully before him the disposition of the deep cervical fascia, which un- 

 doubtedly is of a very complicated and, it may be, perplexing nature. But, 

 perhaps, if he masters the description given in the text as a preliminary, it 

 may clear up matters. The boundaries of the posterior triangle are now 

 to be clearly defined, though in the dissection of the back of the neck they 

 would be apparent to a certain extent. The deep cervical fascia, as it extends 

 from the anterior border of the trapezius to the posterior border of the stemo- 

 cleido-mastoid, is to be studied, and its deep expansion to embrace the pos- 

 terior belly of the omo-hyoid is to be kept in view. This belly is to be at 

 once laid bare and studied. The dissector will note that it divides the pos- 

 terior triangle into two, a superior or occipital triangle, and an inferior or 

 subclavian (supraclavicular) mangle. The occipital triangle should receive 

 attention first. The structures within it have been already referred to, 

 whilst the subject lay upon its face, e.g., the superficial group of branches 

 of the cervical plexus of nerves, the spinal accessory nerve, the branches 

 from the third and fourth cervical nerves to the trapezius, the glands known 

 as the glandulae concatenatae, and the following muscles in pjirt : a small 

 angle of the complexus, provided the trapezius is not well developed at its 

 occipital origin ; the splenius capitis ; the levator anguli scapulae ; Eind the 

 scalenus medius. If the posterior border of the stemo-cleido-mastoid be 

 pulled forwards and maintained in that position by hooks, there is no objec- 

 tion to the dissection of the very complicated cervical plexus being partially 

 made at this stage. The dissector, however, must first master the description 

 which is given of the plexus in the text, from which he may see that the 

 evolution of its branches is a complicated process. No hard-and-fast lines 



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