II26 



A MANUAL OF ANATOMY 



Great Comu of Hyoid Bone 



Small Comu of Hyoid Bone._ 

 Body of Hyoid Bone 



Thyro-hyoid Membrane -■ 

 Levator Glandulae \ 

 Thyroidae Muscle/ 

 Thyroid Cartilage - - 



Cricothyroid Membrane _ 



Pyramid- - 



Cricoid Cartilage " 



Lateral Lobe of Thyroid Body - 



Isthmus - 



pass downwards, one on either side of the median line. The 

 arteria thj^roidea ima may ascend to the isthmus of the thyroid 

 body, lying in front of the trachea at the median line, or 

 slightly to the right of it. The anterior jugular veins, right and 

 left, are anterior to it, and just above the manubrium sterni it is 

 crossed by the communicating branch which passes between these 

 two veins. In children under two years of age the cervical portion 

 of the thymus body forms an important anterior relation. Close 

 to the upper border of the manubrium sterni the innominate artery 



Epiglottis may encroach slightly upon it. 

 The pretracheal lamina of the 

 deep cervical fascia forms an 

 anterior relation, as well as the 

 superficial layer of that fascia, 

 which layer is here arranged 

 in two divisions enclosing the 

 space of Bums and the anterior 

 jugular veins, along with one 

 or two lymphatic glands. The 

 sterno-hyoid and stemo-thy- 

 roid muscles cover it in the 

 following manner: the sterno- 

 hyoid muscles are separated 

 by an interval below, but they 

 come nearly into contact 

 above; and the sterno-thyroid 

 muscles are in contact below, 

 but diverge above. Between 

 the muscles of opposite sides 

 there is a very narrow interval, 

 along which the trachea 

 is free from muscular 

 covering, the pretracheal 

 fascia being here of some 

 strength. 



Lateral. — The trachea 

 is closely embraced on 

 either side by the lateral 

 lobe of the thyroid body 

 as low as about the level 

 of the fifth ring, and external to this is the carotid sheath with its 

 contents, the common carotid artery being nearest the lateral lobe. 

 Posterior. — The trachea rests upon the oesophagus, which pro- 

 jects a little to its left side towards the root of the neck. Between 

 the two there is a groove, in which the recurrent laryngeal nerve 

 and inferior laryngeal artery ascend. For a reference to the high 

 and low operations of tracheotomy, see p. 1107. 



Blood-supply.— The arteries of the cervical part of the trachea arc 

 derived from the inferior thyroid of each side, which is a branch of 

 the thyroid axis. 



Right Bronchus 

 Eparterial Bronchus. 

 HVparterial Bronchus..!^' 



Left Bronchus 



Fig. 459. — The Hyoid Bone, Larynx, 

 Trachea, Bronchi, and Thyroid Body 

 (Anterior View). 



