578 



NECK. 



thorax, at which during life the pleura bul- 

 gingly rises, deriving considerable support 

 i'rom the horizontal infixion of the cervico- 

 thoracic fascial septum. Externally to the curve 

 of the rib, (with the coracoid process bounding 

 it outwardly, the clavicle in front, and the su- 

 perior costa of the scapula behind,) is the space 

 through which vessels and nerves connect the 

 cervical and axillary regions ; to the borders of 

 which, deep layers of aponeuroses are so fixed 

 that the regions only communicate in the line 

 of the vessels, within the infundibulum of pre- 

 vertebral fascia. Its anterior or covering wall 

 presents, in addition to the platysma and sub- 

 cutaneous areolar tissue, which in all direc- 

 tions extend beyond its margins, the cervical 

 fascia, as a single layer (except where it splits 

 at the trapezius and sterno-mastoid) fixed to the 

 clavicle below, and enclosing the omo-hyoid 

 above. From the higher part of its posterior 

 wall, originating at the anterior tubercles of 

 the transverse processes, descends the scalenus 

 anticus to fix itself in the floor of the space, 

 on the upper surface of the rib, anteriorly. It 

 intercepts, like a flying buttress, a space be- 

 tween itself and the posterior wall, occupied 

 by the brachial plexus and subclavian artery, 

 round all which, as also round the subclavian 

 vein, which lies in front of the scalenus, the 

 prevertebral aponeurosis is folded and prolongs 

 itself as a funnel ; it is from this, that the slip 

 of fascia is derived, which passes to the cla- 

 vicle, in the manner described above, as a ho- 

 rizontal process, dividing the axilla from the 

 neck. 



As the distributive anatomy of the vessels 

 and nerves will be detailed in a future article, 

 (vide SPINAL NERVES, SUBCLAVIAN ARTERY), 

 their arrangement will now be only sketched, 

 in its regard to surgical relations. The many 

 important points of distinction between the 

 fight and left sides of the body in this region 

 will presently be considered, the description 

 meanwhile applying to both indifferently. The 

 subclavian artery, from the sterno-clavicular 

 joint outward, over-arches the floor of this 

 region, presenting upwards a convexity in the 

 interspace of the scaleni, downwards a con- 

 cavity, which adapts itself to the pleura and to 

 the rib. It gives off, as from an axis, branches 

 from the four cardinal points of its circum- 

 ference: 1. downwards the internal mammary, 

 which, crossed at its origin by the phrenic 

 nerve, descends within the cartilages of the 

 ribs; 2. upwards the vertebral, which, after a 

 course of an inch between the scalenus anticus 

 and longus colli, enters the canal of the trans- 

 verse processes, usually at the sixth ; 3. for- 

 wards the thyroid axis, a short trunk giving 

 origin to the inferior thyroid branch (already 

 seen obliquely ascending behind the carotid 

 sheath), the ascending cervical, which mounts 

 beside the phrenic nerve, along the scalenus 

 anticus, and two transverse branches, which 

 direct themselves outwardly, crossing that mus- 

 cle, thetransversalis humeri along the clavicle, 

 the transversalis colli higher, amid the branches 

 of the brachia! plexus and winding round the 

 scalenus posticus to gain the inner edge of the 



scapula; lastly, 4. backwards an artery, which, 

 directing itself to the neck of the rib, sub- 

 divides there into two branches, one of which 

 descends across the rib to the thorax, the supe- 

 rior intercostal, while the other continues, be- 

 tween the neck of the rib and the seventh cer- 

 vical transverse process, the backward direc- 

 tion of the common trunk, and then ascends 

 among the deep muscles of the dorsal region 

 the arteria cervicalis profunda. The course of 

 the subclavian artery is conveniently divided 

 into three stages ; a last or distal one, in which 

 after having passed behind the scalenus anticus, 

 it has, behind it, the scalenus posticus, below 

 it the groove of the rib, above it (extending 

 likewise a little behind) the brachial plexus of 

 nerves, in front of it the coverings of the space 

 we are considering, a familiar knowledge of 

 which is here especially needed, since it is in 

 this portion of its course that the artery is 

 usually tied for axillary aneurism : a second 

 stage, in which it lies between the scaleni, its 

 convexity toward their origin from which the 

 brachial plexus divides it, its concavity re- 

 posing on the pleura; and a first or tracheal 

 portion of its course, differently related on the 

 two sides of the body, but thus far alike in 

 both, that from it the branches originate, that 

 its concavity is to the pleura and its convexity, 

 almost at right angles to the direction of the 

 carotid, looks upward ; that it is related, be- 

 hind, to the sympathetic and to the last cervical 

 transverse process, in front, to the vagus and 

 phrenic nerves and to the jugular and sub- 

 clavian veins, inwardly to the carotid artery. 

 The circumstances of difference are mainly due 

 to the fact, that, while on the right side a com- 

 mon brachio-cephalic trunk exists the arteria 

 innominata, which lies at no great depth from 

 the sternum, so that its branches diverge to 

 their respective destinations from a compara- 

 tively superficial and single point, behind the 

 sterno-clavicular joint ; on the left side, con- 

 trarily, the carotid and subclavian arise sepa- 

 rately from the arch, the latter, at a vast depth 

 from the surface, actually beside the vertebrae ; 

 with the exception of having a thoracic com- 

 mencement (nearly corresponding to the tra- 

 cheal half of the arteria innominata), the left 

 carotid can scarcely be said to differ impor- 

 tantly from the right, at least in virtue of its 

 own course; it is somewhat deeper, lies in 

 front of the oesophagus from the inclination 

 of that tube, has the thoracic duct ascending 

 at its outer side, and is, as will be explained 

 directly, overlapped by the jugular vein in the 

 lower part of the neck. The subclavian artery 

 on the right side passes from its origin almost 

 transversely to the scalene space, covered by 

 the muscles which have been enumerated, 

 crossed at right angles by the phrenic and 

 pneuino-gastric nerves and by the jugular vein; 

 the left subclavian, on the other hand, reaches 

 the groove on the rib after a very deep and a 

 very oblique course ; it can scarcely be said to 

 have any transverse direction, but gradually, 

 by an inclination outwards and forwards, ap- 

 proaches the rib during its ascent, so that, if 

 traced toward its origin from the tracheal edge 



