Muscles of the Back. 



291 



Protuberantia 

 occipitalis externa 



Tiiberculum posterius 

 atlantis 



Processus spiuosus ver- 

 tebrae cervicalis VII 



M. iliocostalis 

 cervicis 



336. Long muscles of the back (pMayer), 



(On the right sicb' thi> in. ihucostalis has heen pulled lateralward, on 



reflected.) [Text see also pp. 292 and 293.] 



M. sacrospinalis (O.T. erector 

 spmae) (see also Figs. 332, 333 

 and 337 340. Form: trian- 

 gular-prismatic, long. Position: 

 on each side along the median 

 plane from the sacral region to 

 the neck. r i g i n : fleshy in the 

 depth, otherwise by lung tendons 

 from the crista iliaca, posterior 

 surface of the sacrum, spinous 

 processes of the lumbar vertebrae, 

 inner surface of the fascia lim]bo- 

 dorsalis. The mass of fibers is divi- 

 sible in the lumbar region into three 

 separate mucles : m. iUocostalis, 

 m. longissimus and m. spinalis. 

 M. iliocostalis (0. T. external 

 division of erector spinae), farthest 

 lateralward, extends between the 

 ribs or their homologues. 



M. iliocostalis lumborum 

 (O.T. sacrolumbalis) .Insert! o n : 

 by nine processes, the lower ones 

 fleshy, the upper ones thin and 

 tendinous, to the angles of the 



12*11 4tii rib. Action: it can 

 depress the ribs. 



M. iliocostalis dorsi (0. T. 

 accessory to the iUocostal). Ori- 

 gin: covered by the preceding, 

 it arises by six fleshy digitations 

 from the angles of the \2^^ 7* 

 rib. Insertion: by eight thin 

 tendons to the angles of the 1^^ to 



1st ]-[i3 ami the transverse process 



of the 7tli cervical vertebra. 

 M. iliocostalis cervicis (0. 



T. cervicalis ascendens) (see also 



Fig. 335). Position: it is bound- 

 ed in front by the m. scalenus 



posterior, lateralward by the m. 



levator scapulae, medianward by 



the mm. splenius and longissimus 



cervicis. Origin: covered by 



the preceding muscle, it arises 



bv 4 6 fleshy processes from 



the angles of the 6tli 3i-'i (2"<i 



or 1^) rib. Insertion: by three 



narrow tendons to the transverse 



processes of the 6*^1 4fh cervical 



vertebra. Action: it bends the 



neck backward and toward the 



same side: it can elevate the ribs. 

 Action of the whole m. ilio- 

 costalis : it bends the spinal 



colunm backward and toward the 



same side. Innervation: rami 



laterales of the rami posteriores 



of the nn. cervicales III VIII, 



thoracales I XII and lumbalis I. 



viewed from behind. 



the left side it has been 



M. longissimus capitis 



M. interspinalis 

 - M. longissimus cervicis 

 M. spinalis cervicis 



M. iliocostalis 

 cervicis 



Proc. 



spin.ver- 

 tebrae 

 thora- 



calis VI 



M. ilio- 

 costalis 

 dorsi 



Proc. spin. 



vertebrae 



thoracalis 



XII 



Costa XII 



Pelvis 



Mm. 



intercostales 



externi 



M. 



iliocostalis 

 dorsi 



M. 



longissimus 



dorsi 



M. spinalis 

 dorsi 



M. iliocostalis 

 lumborum 



M. iliocostalis 

 lumborum 



Ligamentum 

 sacrospinosum 



Ligamentum 

 sacrotuberosum 



Tuber ischiadicuni 



