NECK. 



581 



approaches the root of the neck than in adult 

 growth, and, as also the branches arising from 

 it, may more easily be endangered in trache- 

 otomy and other operations in the neighbour- 

 hood. Its length is somewhat above an inch : 

 its direction obliquely upward and outward, 

 toward the sterno-clavicular joint, opposite to 

 which it divides. In this course it corres- 

 ponds, behind, to the trachea, in front to the 

 sternum, from which the remains of the thy- 

 mus gland, the origin of the sterno-hyoid and 

 sterno-thyroid muscles, and (close to its origin) 

 the transverse crossing of the left vena inno- 

 minata separate it, externally, to its accom- 

 panying vein, and, mediately, to the pleura, 

 internally, to the left carotid from which it is 

 separated by a triangular interval in which the 

 thymus, or its remnant, lies upon the trachea. 



The frequency of its undue extension be- 

 yond the precise limit assigned to it, and con- 

 sequent appearance in the sub-hyoid region of 

 the neck, together with the fact of its often 

 furnishing a middle inferior thyroid artery, are 

 contingencies never to be disregarded in ope- 

 rations thereabout. 



This artery has now been tied for cure of 

 aneurism at least six times; unsuccessfully 

 it is true but with such nearness to success 

 as not to forbid cautious repetition. The mode 

 of procedure adopted by Dr. Mott consisted 

 in a transverse division of the skin, muscles, 

 and fasciae along the edge of the clavicle and 

 sternum, in raising these, and taking the sub- 

 clavian and carotid arteries (which he seems to 

 have denuded to some extent) as guides to the 

 innominata, in drawing the jugular vein, the 

 vagus, phrenic and recurrent nerves outwards, 

 in pressing the pleura carefully downwards 

 with the convexity of the needle, while he 

 carried its point from below upwards around 

 the vessel. 



6. The digastric space is bounded below by 

 the curve of the digastric muscle, and extends 

 above within the angle and horizontal ramus of 

 the jaw, so that, if considered as a triangle, it 

 may be described as having its base represented 

 by the internal oblique (or myloid) ridge of 

 the lower jaw, and an imaginary prolongation of 

 this to the root of the mastoid process, its an- 

 terior border formed by the ascending belly of 

 the digastric muscle, its posterior by the de- 

 scending fibres of the same; and its apex will 

 obviously be at the point of their reflexion by 

 the hyoid bone. The skin, the superficial fascia 

 with the platysma, and the cervical aponeurosis, 

 wall it in, and that part of the inferior maxilla 

 which lies beneath the oblique line, to the ba- 

 sial edge of which the fascia adheres, overhangs 

 it ; its deep surface is constituted by the mylo- 

 hyoid muscle and by the side of the tongue and 

 pharynx in front, by the vaginal and styloid 

 processes of the temporal bone behind. A 

 fibrous slip, reflected outwardly from the sty- 

 loid process to the angle of the jaw, and to the 

 deep surface of the aponeurosis, distinctly di- 

 vides the digastric space into two parts. Of 

 these, the posterior is the smaller ; its vertical 

 extent is to the temporo-maxillary articulation : 

 backwards it is bounded by the auditory cuiud 



and mastoid process ; inwardly, by the vaginal 

 plate, the styloid process and its muscles. In 

 the anterior direction the border of the jaw, to- 

 gether with the septum just described, are its 

 limits : whence it seems, within the neck of the 

 jaw, to prolong itself as an interspace between 

 the attachments of the pterygoid muscles. 



Between the unyielding walls of this nar- 

 row space, the parotid gland contracts itself 

 into a wedge-like form, reaches in the one 

 direction to the styloid process and is folded 

 round it, in the other is prolonged with the max- 

 illary vessels between the insertions of the 

 pterygoidei. In its substance the external ca- 

 rotid ascends to its terminal subdivision, the 

 portio dura curves from the stylo-mastoid fora- 

 men, and breaks into the lash of communicating 

 branches, known as pes anserinus, the roots of 

 the external jugular vein unite to assume that 

 name, and junctions of the portio dura with the 

 superficial temporal nerve, and with the auri- 

 cular branch of the cervical plexus, are met 

 with. Its remarkable impaction behind the 

 jaw is probably designed for affecting its func- 

 tion by the mechanical stimulus of the masti- 

 catory movements. Its enlargement may in- 

 conveniently hinder these motions, and, where 

 accompanied by much induration, actually lock 

 the jaw. The merely anatomical difficulties of 

 extirpating the parotid gland have probably 

 been somewhat over-rated ; but cases requiring 

 the operation must be of exceeding rareness. 

 Absorbent glands lie on many points of its sur- 

 face, and in its substance ; their enlargement is 

 frequent, and has been mistaken, in several 

 instances, for an affection of the parotid itself. 



The arteries met with in this space are all 

 branches of the external carotid : the occipital 

 and auricular follow its posterior border, the 

 latter usually traversing a part of the gland ; 

 the temporal artery emerges at the upper, the 

 transverse facial at the anterior edge of the pa- 

 rotid, while from its deep portion the internal 

 maxillary passes forward, within the neck of 

 the jaw, toward the zygomatic fossa. 



The anterior division of the digastric space 

 considerably exceeds the posterior in size : its 

 vertical extent behind is from the curve of the 

 digastric up to the outward surface of the buccal 

 mucous membrane, where reflected from the 

 molar alveoli to the side of the tongue ; but an- 

 teriorly it seems to be limited by the lower sur- 

 face of the mylo-hyoid muscle, and so to be 

 shallower ; though, in reality, this is not the 

 case, for the muscle referred to merely forms a 

 partial septum, dividing the shallow and super- 

 ficial part, just mentioned, from a deeper, sub- 

 lingual portion of great importance. The ante- 

 rior division of the digastric space may accord- 

 ingly be considered as bounded above by the 

 mucous membrane of the mouth in its reflexion 

 from the oblique line of the jaw to the border 

 of the tongue, in an extent reaching from the 

 base of the coronoid process to the symphysis ; 

 and, internally, by the side of the tongue, 

 (presenting the muscular substance of the genio- 

 hyoideus, genio-hyoglossus, hyoglossus, and 

 stylo-glossus,) and by that of the pharynx. It 

 is only in front that the mylo-hyoid muscle, as 



