252 THE MUSCLES. 



mastoido-humeralis. It covers the occipito-atloid articulation, the occipital inser 

 tioii of the posterior straight muscles of the head, and the origin of the occipitO' 

 styloid and digastric muscles. It inclines the head on the atlas^ and slightly 

 extends it. 



10. PosTEEioR Great Straight Muscle of the Head (Rectus Capitis 

 Posticus Major) (Fig. 161, 5). 



Synonyms.— fimaAl complexus and greut posterior straiglit muscle — Bourgelat. Long and 

 short ax'ddo-occipitalis— Gmirfi. (Complexus minor and rectus capitis posticus major. — 

 Percioail. Leyli j^dvcs thi.s muscle the same designation as Girard. It is the rectus capitis 

 posticus major and medius of Man.) 



Form — Structure — Situfition. — Elongated, prismatic, easily divisible into two 

 fasciculi — one superficial, the complexus minor of Bourgelat (and Percivall) ; the 

 other deep, the cireat posterior straight muscle of Bourgelat (and the rectus capitis 

 posticus major of Percivall) — entirely fleshy, and formed of parallel fibres, this 

 muscle is lodged, with the small posterior straight muscle, in a triangular space 

 circumscribed by the cord of the cervical ligament and the internal border of the 

 obUque muscles. 



Attachments. — It is attached, by its superioi- extremity, to the whole extent of 

 the uneven lip which teiininates the spinous process of the a.xi&—;ffxed insertion. 

 Its anterior extremity is insinuated beneath the small oblique muscle, and is fixed 

 to the occipital bone, behind the superior insertion of the great complexus, the 

 tendon of which receives some of the fibres of the superficial fasciculus — morable 

 insertion. 



Relations. — Above, with the complexus ; below, with the small straight 

 muscle ; inwards, with the cord of the cervical ligament and the analogous muscle 

 of the opposite side ; outwards, with the oblique muscles. 



Action. — This muscle, a congener of the complexus, aids in extending the 

 head. 



11. Posterior Small Straight Muscle (Rectus Capitis Posticus 

 Minor) (Fig. 161, 6). 



Synonyms. — Atloido-occipitalis — Girard. (Rectus capitis posticus minor — Percivall. The 

 Atloido-occipitalis superior of Leyh. The rectus capitis posticus minor of Man.) 



A very small, wide, and triangular muscle, flat above and below, and lying 

 immediately upon the fibrous capsule of the occipito-atloid articulation. It is 

 attached, posteriorly, to the superior face of the atlas — origin ; in front, to the 

 external surface of the occipital bone, below the preceding muscle, the action of 

 which it shares. 



Differential Characters in the Muscles of the Cervical Eegion in the other 



Animals. 



1. Ruminants.— In the Ox, the angularis scapulas arises by six digitations from all the 

 cervical vertebrae except the first; the splenius is little developed, and is not attached to either 

 the third or fourth cirvical vertrbra. 



In the Camel, the angularis scanulse is very small, and does not go beyond the fiifth cervical 

 vertebra in front. All the other muscles in this region are very much reduced in size. "If 

 the spl.nius ex.sts in tlie Camel, it is so small that it often esc.ipes dissection" (Cnvier). 



2- Pig.— The muscles of the superior cervical region in this animal are generally very 

 developed. The rhomboideus is divided into two flesliy bodies, one of whicli proceeds to the 

 occipital protuberance, and the other to the rudimentary cervical ligament und the first dorsal 

 vertebrae. The angularis is attached, as in Rumiuants, to the six cervical vertebn-e ; sometimes 

 it even shows a digitation that descends to the atlas. The splenius only termiuates anteriorly 



