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THE MUSCLES AND FASCIAE OF THE TRUNK. 



ribs, and the crest of the ilium ; and they extend from the superior curved line of 

 the occipital bone to the lower part of the sacrum. Some of them are small and are 

 limited to certain parts of the extensive region now referred to ; others extend, 

 either continuously or by the serial repetition of similar short fasciculi, throughout 

 the greater part of it. They may be arranged for purposes of description, according 

 to the order in which they occur, in the following groups, viz., #, the posterior 

 serrati muscles ; I, the splenius ; c, the erector spinse ; d, the complexus and trans- 

 verso-spinales ; e, the interspinales and intertrarisversales ; /, the short cranio- 

 vertebral muscles. Of these muscles the serrati act solely on the ribs and are closely 

 related to the thoracic muscles, although from their position they are most con- 

 veniently described in this place. The remainder act on the spinal column and 

 head, and considered with regard to thejdirection of their fibres fall into three main 



PART OF THE TRUNK. 

 SOD. ) ^ 



(Allen Thom- 



I, first, VI, sixth dorsal vertebra ; 



1, upper part of the complexus muscle ; 



2, splenius capitis ; 3, 3', splenius colli ; 

 4, serratus posticus superior ; 5, upper 

 part of longissimus dorsi ; 5', the same 

 continued up on the left side into the 

 transversalis cervicis ; 5", 5", on the 

 right side, the transversalis cervicis 

 spread out from its attachments ; 6, upper 

 insertions of ilio-costalis and accessorius ; 

 6', the same continued up on the left side 

 into the cervicalis ascendens ; 6", lower 

 end of the latter muscle of the right side 

 showing its attachments ; 7, small part 

 of spinalis dorsi ; 8, 8, right levator 

 scapulae ; 8', on the left side, its upper 

 part divided ; 9, 9, 9, levatores costarum 

 on the right side. 



divisions. In the first division 

 (splenius) the muscular fibres are 

 directed obliquely upwards and 

 outwards, or from spinous to 

 transverse processes ; in the 

 second (trans verso-spinales and 



complexus) the fibres pass obliquely upwards and inwards, or from transverse to 

 spinous processes ; in the third the fibres run longitudinally between corresponding 

 parts of the vertebrse or ribs, being either of considerable length and passing over 

 several segments (erector spinae), or short and attached to adjacent vertebrae (inter- 

 spinales and intertransversales). The short cranio-vertebral muscles may be regarded 

 as presenting examples of each of these divisions. 



SERRATI MUSCLES. The serratus posticus superior is a thin flat muscle 

 which is covered, excepting at its upper border, by the rhomboid and levator anguli 

 scapulas muscles. It arises from the lower part of the ligamentum nuchse, from the 

 spines of the last cervical and two or three upper dorsal vertebrae, and from the 

 supraspinous ligament, by a thin aponeurotic tendon forming nearly half of the 

 length of the muscle. The fibres are directed obliquely downwards and outwards, 

 and form four fleshy digitations which are inserted by tendinous extremities into the 

 upper borders and outer surfaces of the second, third, fourth and fifth ribs, a little 

 beyond their angles. 



Varieties. The slips are sometimes only three in number ; or less frequently there are 

 five or even six. In very rare cases absence of the muscle has been observed. 



