192 



MUSCLES OF THE HEAD AND NECK. 



the upper extremity a few fibres are often found to blend with the thyro-hyoid muscle 

 and the inferior constrictor of the pharynx. 



Fig. 166. Fig. 166. VIEW OP THE 



StTBMAXILLARf MUSCLES 



AND THE DEPRESSORS OP 

 THE HyoiD BONE AND 

 LARYNX, FROM BEFORE. 



The explanation of the 

 references to the upper 

 parts of the figure is given 

 at p. 184. c, middle of 

 the body of the hyoid bone ; 

 d, mastoid process; e, placed 

 on the front of the thyroid 

 cartilage, points to the thy- 

 ro-hyoid muscle ; /, upper 

 part of the sternum ; g, 

 lateral lobe of the thyroid 

 gland ; +, its isthmus, 

 above which is the cricoid 

 cartilage covered by the 

 crico-thyroid muscle ; 8, 

 placed on the levator sca- 

 pulae, points to the left 

 middle constrictor of the 

 pharynx ; 9, placed on the 

 middle scalenus, points to 

 the left inferior constrictor ; 

 10, right sterno-hyoid ; 11, 

 placed on the left sterno- 

 thyroid, points also to the 



lower part of the right muscle ; 12, placed on the right sterno-mastoid, points to the 



upper and lower bellies of the right omo-hyoid. 



The thyro-Tiyoid muscle is continued upwards from the preceding ; it 

 arises from the oblique line on the ala of the thyroid cartilage, and is 

 inserted into the lower border of the body and great cornu of the hyoid 

 bone, near the place where these unite. 



This muscle is concealed by the sterno-hyoid and omo-hyoid, and rests on the ala 

 of the thyroid cartilage, and on the thyro-hyoid membrane. Between that membrane 

 and the muscle, the superior laryngeal nerve and artery are placed before entering the 

 larynx. 



The omo-hyoid is a long ribbon-shaped muscle, consisting of two bellies 

 united by an intervening tendon. It arises from the upper border of the 

 scapula, near the suprascapular notch, and occasionally from the ligament 

 which crosses the notch. Thence it extends forwards and only slightly 

 upwards, across the root of the neck, till it enters beneath the sterno-mas- 

 toid muscle, and then, curving rapidly, it ascends nearly vertically, to be 

 inserted into the lower border of the body of the hyoid bone. The ten- 

 don which divides the muscle is placed beneath the sterno-mastoid muscle, 

 and varies much in length and form in different bodies. The tendon is 

 enclosed within the deep cervical fascia, which, after forming a sort of 

 sheath for it, is prolonged downwards and becomes attached to the sternum 

 and the cartilage of the first rib ; and by this means, as also by fascia 

 investing the posterior belly and descending to the clavicle, the muscle is 

 maintained in its curved position. 



