LONGTSSIMUS DORSI. 363 



The cervicalis ascendens is a muscular slip prolonging the accessorius 

 into the neck : this muscle is attached to four ribs (third, fourth, fifth, and 

 sixth), and is inserted into the posterior transverse processes of three cer- 

 vical vertebras, viz., sixth, fifth, fourth. 



* The LONGISSIMUS DORSI gradually decreases in size as it ascends 

 along the thorax. Internally the muscle is inserted into the transverse 

 processes of all the dorsal vertebrae by a series of tendinous and fleshy bun- 

 dles ; and externally it is attached to the ribs, except the first two or 

 three, by thin fleshy processes between the tubercle and angle. Its mus- 

 cular prolongation to the neck is united with the upper fleshy fibres, and 

 splits into the two following pieces : 



The transversalis colli (fig. 118, B ) arises from the transverse pro- 

 cesses of the upper six dorsal vertebrae, and is inserted into the posterior 

 transverse processes of the cervical vertebrae, except the first two and the 

 last. 



The trachelo-mastoid muscle (fig. 118, c ) (transversalis capitis?) arises 

 in common with the preceding, and is attached, besides, by distinct ten- 

 dons to the articular processes of the last three or four cervical vertebrae. 

 The muscle is thin, and is inserted beneath the splenius into the upper 

 half of the posterior part of the mastoid process : its insertion is about 

 three-quarters of an inch wide. 1 



* Connections of the erector spince. The erector spinas and its prolonga- 

 tions occupy the lumbar, thoracic, and cervical parts of the Back. 



In the loins the muscle is contained in an aponeurotic sheath (p. 358), 

 and has the multifidus spinae on its inner side : its attachment on the in- 

 ner surface of the innominate bone corresponds in part with the origin of 

 the glutens maximus on the outer side. The superficial tendon, which is 

 common to.it and the multifidus, will be described with the last-mentioned 

 muscle (p. 371). 



Opposite the ribs the ilio-costalis and longissimus dorsi are concealed by 

 the muscles of the other layers already examined. 



In the neck its accessory small muscles lie underneath the splenius and 

 the trapezius : the cervicalis ascendens is attached in a line with, but 

 below the splenius colli ; and the transversalis colli and trachelo-mastoid 

 are more internal, or between the splenius and cervicalis and the corn- 

 plexus. 



Action. Taking their fixed point at the pelvis, both erectors will keep 

 the spine straight in sitting and standing ; and, in rising from stooping to 

 the ground, they will bring the trunk into the erect posture. In laborious 

 respiration, the spine being fixed, the muscles are able to depress the ribs, 

 and assist in the expulsion of the air from the thorax. 



One muscle will incline the spinal column laterally and to its own side. 



The cervical prolongations of the erector act on the neck and head, as 

 below : 



The cervicalis ascendens. Taking their fixed point below, both mus- 

 cles will extend the cervical part of the spine : and acting from the trans- 

 verse processes they will elevate the ribs. One muscle will give a lateral 

 movement to the neck. 



1 The anatomy of the prolongation from the longissimus might he simplified^ by 

 describing it as the transversalis muscle with a douhle insertion, like the splenius, 

 into the head and neck. In accordance with the nomenclature of the splenius the 

 part to the head might he named transversalis capitis, and the part to the neck 

 transversalis colli, as at present. 



