OF THE BACK 413 



The Cervicalis ascendens (m. iliocostalis cervicis) is the continuation of the Acces- 

 sorius upward into the neck; it is situated on the inner side of the tendons of the 

 Accessorius, arising from the angles of the four or five upper ribs, and is inserted 

 by a series of slender tendons into the posterior tubercles of the transverse pro- 

 cesses of the fourth, fifth, and sixth cervical vertebrae. 



2. The Longissimus dorsi is the middle and largest portion of the Erector spinae. 

 In the lumbar region, where it is as yet blended with the Iliocostalis, some of the 

 fibres are attached to the whole length of the posterior surface of the transverse 

 processes and the accessory processes of the lumbar vertebrae, and to the middle 

 layer of the lumbar fascia. In the thoracic region the Longissimus dorsi is 

 inserted, by long, thin tendons, into the tips of the transverse processes of all the 

 thoracic vertebrae, and into from seven to eleven of the lower ribs between their 

 tubercles and angles. This muscle is continued upward to the cranium and cer- 

 vical portion of the vertebral column by means of two additional muscles, the 

 Transversalis cervicis and Trachelomastoid. 



The Transversalis cervicis (m. longissimus cervicis], placed on the inner side 

 of the Longissimus dorsi, arises by long, thin tendons from the summits of the trans- 

 verse processes of the six upper thoracic vertebrae, and is inserted by similar 

 tendons into the posterior tubercles of the transverse processes of the cervical 

 vertebrae, from the second to the sixth inclusive. 



The Trachelomastoid (m. longissimus capitis) lies on the inner side of the pre- 

 ceding, between it and the Complexus muscle. It arises, by tendons, from the 

 transverse processes of the five or six upper thoracic vertebras, and the articular 

 processes of the three or four lower cervical vertebrae. The fibres form a small 

 muscle, which ascends to be inserted into the posterior margin of the mastoid 

 process, beneath the Splenius and Sternomastoid muscles. This small muscle is 

 almost always crossed by a tendinous intersection near its insertion into the mastoid 

 process. 1 



3. The Spinalis dorsi is situated at the inner side of the Longissimus dorsi, 

 with which it is intimately blended. It arises, by three or four tendons, from the 

 spinous processes of the first two lumbar and the last two thoracic vertebrae; these, 

 uniting, form a small muscle, which is inserted, by separate tendons, into the 

 spinous processes of the thoracic vertebrae, the number varying from four to eight. 

 It is intimately united with the Semispinalis dorsi, which lies beneath it. 



The Spinalis colli (ra. spinalis cervicis) is a small muscle, connecting the spinous 

 processes of the cervical vertebrae, and analogous to the Spinalis dorsi in the thoracic 

 region. It varies considerably in its size and in the extent of its attachment to 

 the vertebrae, not only in different bodies, but on the two sides of the same body. 

 It usually arises by fleshy or tendinous slips, varying from two to four in number, 

 from the spinous processes of the fifth, sixth, and seventh cervical vertebrae, and 

 occasionally from the first and second thoracic, and is inserted into the spinous 

 process of the axis, and occasionally into the spinous processes of the two vertebrae 

 below it. This muscle was found absent in five cases out of twenty-four. 



The Complexus (ra. semispinalis capitis] is a broad thick muscle, situated at 

 the upper and back part of the neck, beneath the Splenius, and internal to the 

 Transversalis cervicis and Trachelomastoid. It arises, by a series of tendons, 

 from the tips of the transverse processes of the upper six or seven thoracic and the 

 last cervical vertebrae, and from the articular processes of the three cervical 

 vertebrae above this. The tendons, uniting, form a broad muscle, w r hich passes 

 obliquely upward and inward, and is inserted into the innermost depression be- 

 tween the two curved lines of the occipital bone. At about its middle it is traversed 



1 These two muscles (Transversalis cervicis and Trachelomastoid) are sometimes described as one having a 

 common origin, but dividing above at their insertion. The Trachelomastoid is then termed the Transversalis 

 capitis. 



