468 



THE MUSCULAE SYSTEM. 



Serratus posterior 

 superior (insertion) 



Serratus anterior 

 (origin) 



Pectoralis minor (occasional origin) 



FIG. 414. MUSCLE- ATTACHMENTS TO THE SUPERIOR SURFACE OF THE 

 FIRST RIB, AND THE EXTERNAL SURFACE OF THE SECOND KIB 



(EIGHT SIDE). 



A, First rib ; B, Second rib. 



Nerve-Supply. The mus- 

 cle receives nerves directly from 

 the anterior rami of the first 

 four cervical nerves. 



Action. Flexion of the 

 head and cervical vertebrse. 



M. Rectus Capitis 

 Anterior. The rectus 

 capitis anterior (O.T. 

 rectus capitis anticus 

 minor) arises, under cover 

 of the preceding muscle, 

 from the lateral mass of 

 the atlas. It is inserted 

 into the basilar part of 

 occipital bone between the 

 preceding muscle and the 

 occipital condyle (Fig. 417, 

 p. 469). 



Nerve -Supply. The scalene 

 muscles are supplied by branches 

 which arise directly from the 

 anterior rami of the lowest four 

 or fiv6 cervical nerves. 



Actions. The actions of those 

 muscles are twofold. They are 

 lateral flexors of the vertebral 

 column, and are also important 



Scalenus medius (insertion) mugcles of reS piration, as elevators 



of the first and second ribs. 



M. Longus Capitis. 

 The longus capitis (O.T. 

 rectus capitis anticus 

 major) arises from the an- 

 terior tubercles of the trans- 

 verse processes of the third, 

 fourth, fifth, and sixth cervi- 

 cal vertebrse. 



It forms a fiat triangular 

 muscle, which is directed up- 

 wards, alongside the longus 

 colli muscle and behind the 

 carotid sheath, to be inserted 

 into an impression on the 

 inferior surface of the basilar 

 part of the occipital bone, 

 anterior and lateral to the 

 pharyngeal tubercle (Fig. 

 417, p. 469). 



RECTUS CAPITIS 

 ANTERIOR 



RECTUS CAPITIS 

 LATERALIS 



RECTUS CAPITIS 

 ANTERIOR 



LONGUS CAPITIS 



Nerve -Supply. The mus- 

 cle is innervated by the loop 

 between the first two cervical 

 nerves (anterior rami). 



Action. Flexion of the 

 head on the vertebral column. 



M. Longus Colli. The 

 longus colli is a flattened 

 muscular band extending 

 from the third thoracic 

 vertebra to the atlas. It 



LONGUS COLLI 



FIG. 415. THE PR^EVERTEBRAL MUSCLES OF THE NECK. 



