128 ANATOMY OF UPPER EXTREMITY, ETC. 



serted into that part of the border of the scapula opposit 

 the triangular space by which its spine commences. 



The RHOMBOIDEUS MAJOR MUSCLE, double the width oi 

 the preceding, arises from the spinous processes and from 

 the supra-spinous ligament of the upper four or five dorsal 

 vertebrae, and is inserted into the posterior border of the 

 scapula, below the spine ; it is separated from the rhom- 

 boideus minor by a slight cellular interspace. 



These two muscles must be carefully removed, in order to expose 

 those next to be described ; in so doing twigs of the postei'ior scapu- 

 lar artery will be found distributed to them, and that artery must be 

 respected, as it passes along the posterior border of the scapula. 



The SERRATUS POSTICUS SUPERIOR is a thin muscular 

 plane, arising from the spinous processes of one or two of 

 the last cervical and two or three of the upper dorsal ver- 

 tebrae ; it passes downward and outward, and is inserted 

 by fleshy serrations into the upper borders of the second, 

 third, and fourth ribs. 



The SERRATUS POSTICUS INFERIOR, the tendon of which 

 is inseparably connected with the aponeurosis of the latissi- 

 mus dorsi and the fascia lumborum, arises from the spinous 

 processes of the last two dorsal and first two or three lum- 

 bar vertebrae, and passing obliquely upward, is inserted by 

 fleshy serrations into the last four ribs, each successive 

 process extending further outward than the one below. 



A thin aponeurotic lamina, called the vertebral aponeuro- 

 sis extends between these two last-described muscles, bind- 

 ing down the deeper muscles, and separating them from the 

 more superficial ones. 



By dividing the serratus posticus superior and the subjacent ver- 

 tebral aponeurosis the splenius muscle will be exposed. 



THE SPLENIUS MUSCLE, single in its origin, divides into 

 a cervical and cranial part, known respectively as splenius 

 capitis and splenius colli. It arises from the spinous pro- 

 cesses and inter-spinous ligaments of the last two cervical 

 and four or five upper dorsal vertebrae, and, separating into 

 its two divisions, the sinenius capitis is inserted into the 

 space between the two curved lines of the occipital bone 

 and into the mastoid process of the temporal bone, where 

 it is overlapped by part of the sterno-mastoid muscle ; the 

 splenius colli is inserted into the posterior tubercles of the 

 transverse processes of three or four of the upper cervical 

 vertebrae. 



