13S THE CAT. [chap. v. 



scapula, between the liiiidermost and uppermost part of the deltoid, 

 and the posterior end of the insertion of the trapezius. Blending 

 "with the internal dorso-epitrochlear, it is inserted as above stated. 



The serratus posticus anterior arises by fascia from, the mid- 

 line of the back, and is inserted by vei'}^ thin and faintly marked 

 muscular digitations, into the outer surfaces of the ribs, from the 

 second to the twelfth — the digitations inclining downwards and 

 very much backwards. Posteriorly it is over-lapped by the next 

 mupcle to be noticed. 



The aci'ratus 'posticus posterior arises from the fascia of the middle 

 of the back, and is inserted by six digitations into the outside of the 

 eighth, ninth, tenth, eleventh, and twelfth ribs. The digitations 

 are inclined downwards and very slightly forwards. Anteriorly it 

 overlaps the hinder part of the serratus posticus anterior. 



A membrane called the " vertebral aponeurosis," is continuous 

 with the serratus posticus posterior, and passing forwards between 

 the muscles of the shoulder and those of the trunk, it also binds 

 down the great muscle to be next described. 



Erector spinrc. — Under this title is included a very large and 

 complex muscular mass occupying the groove which exists on each 

 side of the dorsum of the skeleton, between the neural spines and 

 the ribs at the j^oint where the latter are much arched upwards. 

 It is divided into two parts, one being nearer to, the other farther 

 from the neural spines. Each of these two parts extends forwards 

 towards the neck from the common origin of both in the sacral 



'O' 



region. 



Sacro-l/iii/hntis. — This name designates that part of the erector 

 spinas which is the more externally placed, and is attached to the 

 ribs. It is a very thick muscle at its origin from the ilium and 

 sacrum close to their line of junction. It is inserted into the 

 lumbar transverse processes on their dorsal aspect and, by tendons, 

 into all the ribs at their angles — the tendons becoming longer as the 

 muscle advances forwards. The last portion, that inserted into the 

 transverse process of the seventh cervical vertebra, is the represen- 

 tative of a muscle called the cerviccdis asccndens. 



Longissimus (torsi is the term applied to the inner part of the 

 erector spina\ It is much smaller posteriorly than the last described, 

 but extends further forwards. It arises from the anterior margin of 

 the ilium, and the fascia investing the erector spinas dorsally, and 

 is inserted into the dorsal surface of the lumbar transverse pro- 

 cesses, the motapophyses and the ribs on the dorsal side of their 

 angles. 



The traitsrcrsatis ccrricis is the continuation of the last described 

 muscle into the neck, where it is invested by firm, strong tendons into 

 the transverse processes of the five last cervical vertebnv. 



The spiiiatis (torsi is really but an inner portion of the longissimus 

 dorsi, and goes from the neural spines of the more posterior to those 

 of the more anterior dorsal vertebrae As continued on to the spine 

 of the axis, it is catted the spinalis colti. 



