566 



NECK. 



separated by a distinct cellular interspace, cor- 

 responding to the sterno-clavicular articulation : 



1. from the anterior surface of the first bone 

 of the sternum close to its clavicular joint, by 

 a very strong Hat tendon which is directed up- 

 ward and backward for the space of more than 

 an inch, before terminating in fleshy fibres ; 



2. from the upper edge of the inner third of 

 the clavicle by a thin origin composed of pa- 

 rallel aponeurotic fibres, which directly be- 

 come fleshy, and take a nearly vertical course. 

 As these two bundles ascend, the sternal, more 

 oblique in its course, seems to overlap the 

 other, and, both by difference of direction and 

 by a line of cellular separation, can often be 

 distinguished from it in the lower two-thirds of 

 the neck ; but in approaching the mastoid pro- 

 cess they are indistinguishably fused together. 

 The insertion is, 1. by a strong and rounded 

 tendon into the mastoid process, of which it 

 seems to embrace the tip and anterior border ; 

 2. by a thin aponeurosis along the posterior 

 edge of the process, and about a third of the 

 superior semicircular line, which is continued 

 into it. 



This muscle, to which I shall have abun- 

 dant occasion to refer in speaking of the sur- 

 gical anatomy of the neck, has very important 

 relations : the space between its heads corres- 

 ponds to the bifurcation of the arteria inno- 

 minata ; and the broad band-like muscle, as 

 it ascends, crosses in succession the subclavian 

 and carotid arteries, the jugular and subclavian 

 veins, the hypo-glossal, pneumogastric, phrenic, 

 sympathetic, spinal accessory nerves, and a 

 portion of the cervical plexus ; the sterno- 

 nyoid, sterno-thyroid, omo-hyoid, scaleni, le- 

 vator anguli scapulae, splenius, and digastric 

 muscles, besides many lymphatic glands and 

 branches from several of the nervous and vas- 

 cular trunks which have been enumerated. Its 

 superficial aspect corresponds to the integu- 

 ments and platysma, to the external jugular 

 vein and superficial branches of the cervical 

 plexus ; its thick anterior edge bounds the 

 anterior triangle of the neck, receives branches 

 from the external carotid artery or from its 

 thyroid branch, and corresponds above to the 

 parotid gland and posterior aural artery ; its 

 thin posterior edge limits the other great trian- 

 gle of the neck, is pierced by the spinal acces- 

 sory nerve, corresponds to a chain of lymphatic 

 glands, and is wound round by the nerves and 

 vein which lie on the surface of the muscle. 



The two sterno-mastoid muscles acting toge- 

 ther directly bend the head on the chest, and 

 their joint action is well illustrated in an en- 

 deavour to raise the head from the supine 

 position. But when the head is thrown far 

 back, a predominance is given to the posterior 

 fibres of the muscle, which being attached 

 behind the line of the occipito-vertebral arti- 

 culation, become then capable of increasing 

 this direction of the head. The sterno-mastoid 

 of one side, acting singly, rotates the head and 

 flexes it with a lateral inclination to its own 

 sid, so as to bring the side of the head nearer 

 to the shoulder, and to turn the face in the op- 

 posite direction. 



The platysma myoides (lutissimus colli of 

 Albinus) is a broad, thin, membraniform mus- 

 cle, which covers the side of the neck and 

 lower part of the face, and is in its whole 

 course subcutaneous. It arises by scattered 

 fibres in the superficial fascia below the clavicle, 

 and covers by its origin the upper part of the 

 pectoralis major and deltoid, as also the space 

 between those muscles, which corresponds to 

 the coracoid process. This origin does not 

 extend within an inch or two of the median 

 line, but reaches as far outwardly as the acro- 

 mial process. The fibres become more closely 

 aggregated as they ascend, and the muscle 

 accordingly narrows. Its direction is obliquely 

 upward and to the median line; it passes over 

 the base of the lower jaw, and its fibres again 

 spread to their insertion : those which are pos- 

 terior lose themselves in the skin covering the 

 parotid gland and masseter muscle ; others 

 from this neighbourhood bend forward toward 

 the angle of the mouth, and in some subjects 

 constitute a very distinct horizontal retractor 

 anguli oris, which is generally known as the 

 risorius Santorini : some fibres from the middle 

 of the muscle obtain a more fixed insertion 

 about the base of the jaw and into the skin 

 covering it; while the anterior portion of the 

 muscle, which is most constant in its relations, 

 is inserted into the lower lip by blending its 

 fibres with those of the depressor labii infe- 

 rioris, and by decussating toward the border 

 of the lip and in the substance of the chin 

 with the mesial fibres of its fellow. 



This muscle is subcutaneous in its whole 

 extent, and by its extremities intimately at- 

 tached to the deep surface of the skin which 

 covers it. In approximating its extreme attach- 

 ments, it wrinkles the skin in a direction trans- 

 verse to that of its fleshy fibres. It is a single 

 and partial relique in the human subject of 

 that general muscular investment, which fulfils 

 various functions in different orders of Mam- 

 malia, as an appendage of the tegumentary 

 system : rolling the hedge-hog in a ball, erect- 

 ing the quills of the porcupine, and the bristles 

 of the boar, or dislodging insects from the 

 hide of grazing cattle. Its relations to the 

 deeper parts in the neck will be detailed here- 

 after: between it and the cervical aponeu- 

 rosis lie chiefly, cutaneous nerves and veins; 

 branches from the cervical division of the 

 portio dura are distributed to its upper portion, 

 reaching the deep surface just below the angle 

 of the jaw, and branches from the cervical 

 plexus crossing the sterno-mastoid partly sup- 

 ply the platysma, partly pierce it in their course 

 to the skin ; the superficial pectoral branches 

 lie beneath it till they reach the clavicle; the 

 external jugular vein lies immediately beneath 

 this muscle, and runs nearly parallel to its 

 fibres, crossing transversely those of the sterno- 

 mastoideus. 



II. FASCIAE OF THE NECK. 



1. The superficial Jascia, or subcutaneous 

 areolar tissue, presents characters in common 

 with the same structure in other parts of the 

 body, and is universally continuous with that 



