320 



THE MUSCLES AND FASCIAE. 



below the origin of the Sterno-hyoid, and from the edge of the cartilage of the 

 first rib, occasionally of the second rib also, and is inserted into the oblique 

 line on the side of the ala of the thyroid cartilage. This muscle is in close contact 

 with its fellow at the lower part of the neck, and is occasionally traversed by a 

 transverse or oblique tendinous intersection, like those in the Rectus abdominis. 



Relations. By its anterior surface, with the Sterno-hyoid, Omo-hyoid, and 

 Sterno-mastoid ; by its posterior surface, from below upward, with the trachea, 

 vena inriominata, common carotid (and on the right side the arteria innominata), 

 the thyroid gland and its vessels, and the lower part of the larynx and pharynx. 

 The inferior thyroid vein lies along its inner border, a relation which it is 

 important to remember in the operation of tracheotomy. On the left side the deep 

 surface of the muscle is in relation to the oesophagus. 



The Thyro-hyoid is a small, quadrilateral muscle appearing like a continuation 

 of the Sterno-thyroid. It arises from the oblique line on the side of the thyroid 

 cartilage, and passes vertically upward to be inserted into the lower border of the 

 body and greater cornu of the hyoid bone. 



Relations. By its external surface, with the Sterno-hyoid and Omo-hyoid 

 muscles ; by its internal surface, with the thyroid cartilage, the thyro-hyoid 

 membrane, and the superior laryngeal vessels and nerve. 



The Omo-hyoid passes across the side of the neck, from the scapula to the 



Symphysis 

 of jaw. 



Sternum. 

 FIG. 203. Muscles of the neck. Anterior view. 



hyoid bone. It consists of two fleshy bellies, united by a central tendon. It 

 arises from the upper border of the scapula, and occasionally from the transverse 

 ligament which crosses the suprascapular notch, its extent of attachment to the 

 scapula varying from a few lines to an inch. From this origin the posterior belly 

 forms a flat, narrow fasciculus, which inclines forward and slightly upward across 

 the lower part of the neck, behind the Sterno-mastoid muscle, where it becomes 

 tendinous ; it then changes its direction, forming an obtuse angle, and terminates 

 in the anterior belly, which passes almost vertically upward, close to the outer 

 border of the Sterno-hyoid, to be inserted into the lower border of the body of the 



