THE HEAD AND NECK 



1123 



thyroid, which is a branch of the external carotid, and (2) the 

 inferior thyroid, which is a branch of the thyroid axis of the first 

 part of the subclavian. Occasionally there is a third thyroid 

 artery, called the arteria ikyroidea ima, which is derived from the 

 innominate artery, or from the arch of the aorta, and is distributed 

 to the isthmus, its position being in front of the trachea at the 

 median line, or close to it. 

 The veins are three in number on either side, namely, superior, 



Anterior Belly of Digastric 

 ^Mykvhyoid 



Posterior Belly of EHgastric 

 and Stylo-hyoid 

 Hyo-glossas Muscle and 

 Hypoglossal Nerve 



ler. Head of St.-dejdo-mas. 

 Crico-thyroid Muscle 



Cricoid Cartilage. 



Lat. Lobe of Thyroid Body 



Trapezius 



Clavicular Head of _____ 

 Stemo-cleido-mas. ////■ / 

 Brachial Plexus l-Z-'-fJ 

 Subclavian Artery . 

 (third part) 



Clavicle 



-Body of Hyoid Booe 



'. Anterior Bdly of Omo-hyoid 



Stemo-hyoid 



— Thyio-hyoid 



Isthmus of Thyroid Cartilage 



Stcmo- thyroid 



— Anterior Belly of Omo-hyoiJ 



'\ fifJlMS M Crico-thyroid Membrane 



W ^'*» -Stemo-hyoid 



Isthmns of Thyroid 

 Body 



Inferior Thyroid Plexus 



of Veins 

 Cla. Head of St. -cL -mas. 



Stento-thjrrmd 



Sternal Head of Steroc^ 

 cleido-masUMd 



Stemo-tbynud 



Stemo-hyoid 



Pig. 457. — Dissection of the Front of the Neck. 



(The area bounded on either side by the Anterior Belly of the Digastric and 

 below by the body of the Hyoid Bone is the Submental Triangle.) 



middle, and inferior. The superior and middle thyroid veins 

 open into the internal jugular. The inferior thyroid veins, right 

 and left, issue from a plexus of veins in front of the trachea below 

 the isthmus. The lelt vein opens into the left innominate vein, 

 whilst the right has a variable mode of termination. It may open 

 into the left innominate vein, or into the angle of junction of the 

 right and left innominate veins, or into the lower part of the right 

 innominate vein. 



