134 SPECIAL ANATOMY. 



from the last by Vena jugular, extern, and Flex. nerv. cervical, 

 superfic. Behind it, 1. Mm. sterno-hyoideus, thyreoid., omo- 

 hyoid., splenius, digastricus, scaleni. 2. Nn. vagus and acces- 

 sor., sympathicus, hypoglossus, cervicales. 3. Carotis commu- 

 nis, Vena jugular, intern. On the anterior border above, Parotis. 

 The two diverge from below upwards. The posterior border 

 forms with the Clavicula an acute angle, with these and the M. 

 trapezius a triangle. Or.: two portions. 1. Cleido-mast. from 

 the internal extremity of the Clavicula. 2. Sterno-mast. from 

 manubrium sterni. Ins. : external surface of Proc. mastoid. oss. 

 lemporis and linea semicircular, superior oss. occipitis. Act. : 

 both together draw the head directly forwards and downwards, 

 bowing it; one alone acting draws it in such a direction that the 

 face looks towards the opposite side. 



Nerves : accessor. Willis., plexus cervical. 



a. Below the Os Hyoides. 



184. 3. Sterno-hyoideus (often double). 



Pos. : vertical in the centre of the neck; covered by M. platys- 

 mam., sterno-cleidom. and fascia cervicalis, before the deep cervi- 

 cal muscles and Art. thyreoidea superior. The inner borders 

 meet together. Fig.: flat, riband-like, thin. Or.: the posterior 

 surfaces of the Sternal ends of the Clavicula (frequently the 

 Manubrium sterni). Ins.: the inferior border of the body of os 

 hyoides, close to the middle line, to the inside of M. brachyoideus. 

 Act. : draws the os liyoid. downwards. 



185. 4. Omo-hyoideus (sometimes wanting). 



Pos. : oblique on the side of the neck, commencing parallel 

 with the Clavicula, then forming an obtuse angle 'upwards and 

 inwards; covered by trapezius, subclavius, platysmam., sterno- 

 cleido-mast. ; it crosses Mm. scaleni, the Flex, brack., Ven. jugu- 

 lar, intern., Carotis comm., near m. sterno-hyoideus. Or. : Sca- 

 pula (the superior border) behind the Incisura scapulae. Ins. : 

 external and close to the before-described muscle. Fig. : two- 

 bellied, in the centre tendinous, angular. Act.: the superior 

 belly draws the hyoid bone downwards. The posterior belly is 

 said to stretch theysc. cervic. which attaches it to the clavicle. 



[Co raco- cervicalis (Krause), a small m. before m. omo-hyoideus, 

 arises from Proc. coracoid., and is attached to the fascia cervi- 

 calis, which it stretches.] 







