368 



BACK. 



never be followed by troublesome hemorrhage. 

 In the fascia we generally find a vein, described 

 by Godman of Philadelphia under the name 

 of the dorsal azygos. It arises at the lower 

 part of the back by irregular roots, runs up 

 single for some time along the middle line, 

 and then divides into two branches, one of 

 which pierces each trapezius, and enters into 

 the transversalis colli vein. It is small and of 

 little importance. The other veins are not of 

 sufficient size to deserve particular notice ; 

 they are found in company with the arteries. 



Nerves. The nerves of this region are the 

 posterior branches of all the spinal nerves. The 

 cervical and bracliial plexuses also send some 

 filaments ; but its nervous supply is, like its 

 vascular, very scanty. 



Lymphatics. The lymphatics, too, are not 

 so numerous as elsewhere. We trace them 

 running to the cervical, axillary, and inguinal 

 glands, according to their proximity to these. 

 With the exception of two or three on the cer- 

 vical portion of the trapezius, lymphatic glands 

 are not met with here. 



The back is peculiarly subject to anthrax in 

 debilitated constitutions, and in some cases the 

 tumour acquires great magnitude. It some- 

 times happens that several anthraxes occur in 

 succession, until a large portion of the integu- 

 ments and fascia is destroyed, and the patient 

 sinks under the disease. Pressure is frequently 

 the exciting cause. By pressure the vessels are 

 so obstructed that the vitality of the part is 

 impaired, and its organization is too low to 

 enable it to recover from the deadening effects, 

 especially if the constitution be previously in- 

 jured. Here too we often meet with furunculi : 

 they are most common in the nape of the neck. 

 Fistuloe in the lumbar region, depending on 

 diseased kidney, sometimes present themselves. 

 There is no peculiarity in the cutaneous or 

 other diseases to which it is liable in common 

 with other regions. 



BACK, MUSCLES OF THE. The mus- 

 cles of the back are very numerous and complex. 

 There is much variety in their origins and inser- 

 tions in different subjects, and in many cases it is 

 not easy to decide with which of two adjoining 

 muscles we are to connect certain bundles of 

 fibres ; a distinct impression, therefore, is not 

 always obtained from an examination of the 

 part, nor will a repetition of the dissection pre- 

 sent us with the same view in another subject. 

 Hence it happens that anatomists differ as to 

 the number of muscles to be met with, some 

 dividing into two or more muscles what others 

 consider as one ; this proves another source of 

 difficulty. The names and the enumeration of 

 them, as given by Albinus, we shall follow 

 pretty closely : we esteem them the best on 

 the whole, and they have the advantage of being 

 generally adopted in these countries : viz. the 

 trapezius or cnculluris, latissmus dorsi, rhom- 

 boideus major, rhomboideus minor, levator an- 

 guli scapula, scrrutns posticus superior, scrralus 

 posticus inferior, splenius capitis, splenius colli, 

 sacro-lumbalis, longissimus dorsi, spinalis dorsi, 

 semi-spinalis dorsi, ccrvicalis dcscendens, t> - ans- 



versalis colli, trachelo-mastoideus, complexes, 

 spinalis colli, multifidus spimf, inter-spihales, 

 inter-transversales, rcctus capitis posticus major, 

 rectus capitis posticus minor, ob/iquns capitis in- 

 ferior, and obliyuus capitis superior. These 

 muscles are placed in pairs, one on each side 

 of the median line ; none of them can be said 

 to be exactly in the middle. We shall examine 

 them in the order they present themselves to 

 us in dissecting. 



We find these muscles disposed in layers, 

 and each layer differing from the others in the 

 shape or use of the pieces which compose it. 

 Six such layers may be enumerated. Thejirst 

 consists of the trapezius and latissimus dorsi, 

 muscles somewhat triangular in form, and 

 destined to act principally on the upper extre- 

 mity. The second consists of the rhomboidei 

 and levator anguli scapulae. These are qua- 

 drangular, approaching a square shape, and act 

 on the scapula;. The third layer is formed of 

 the serrati, of similar shape, but acting on the 

 ribs, the fourth consists of the splenii; these, 

 more elongated than the last, rotate and erect 

 the head and neck. The jifth layer is com- 

 posed of very long muscles, acting chiefly as 

 erectors of the spine and head, viz. the sacro- 

 lumbalis, longissimus dorsi, spinalis, and semi- 

 spinalis dorsi, cervicalis descendens, transver- 

 salis colli, trachelo-mastoideus and complexus. 

 The sixth layer, again, is formed of short mus- 

 cles, rotating and erecting the head or minute 

 portions of the spinal column ; these are the 

 recti and obliqui of the head, the spinalis colli, 

 inter-spinales, inter-transversales,and multifidus 

 spinae. 



First layer. The trapezius and latissimus 

 dorsi, which form the jirst layer, almost com- 

 pletely conceal all the other muscles of this 

 region, and in superficial extent are scarcely 

 succeeded by any two muscles in the body. 



The trapezius is thin, triangular, and very 

 extensive. One of its surfaces is turned to the 

 integuments, and covered by the superficial 

 fascia, and by a fine layer of cellular tissue 

 which closely adheres to it. The trapezius 

 arises from the internal third of the superior 

 oblique ridge of the os occipitis, from the liga- 

 mentum nuchse, and from the spinous pro- 

 cesses of the last cervical and of all the dorsal 

 vertebrae. The superior fibres run downwards, 

 outwards, and a little forwards, the middle 

 transversely, and the inferior upwards and out- 

 wards ; all converge, and are inserted into the 

 external third of the posterior border of the 

 clavicle, the acromio-clavicular ligament, the 

 acromion process, the upper edge of the spine 

 of the scapula, and the tubercle which termi- 

 nates this spine at the base. 



The origin of this muscle is by tendinous 

 fibres which are from half an inch to an inch 

 long in the occipital portion ; in the cervical 

 they are very short until we come down to the 

 sixth cervical vertebra, where they begin to 

 lengthen ; at the first dorsal they are an inch 

 and a half in length, again they diminish, and at 

 the fourth dorsal spine they are scarcely to be 

 seen ; but at the tenth they again increase in 

 length, and form a triangular tendon. It some- 



