DISSECTION OF THE LAKYNX. 



and li{ 



ment. 



Mucous 

 membrane 

 of larynx. 



Epithelium 



differs in 

 kind. 



Glands. 



Dissection 

 of nerves ; 



inferior, 



superior 

 laryngeal ; 



of vessels. 



membrane of the true vocal cord is very thin, and intimately united 

 to the inferior thyro-arytenoid ligament. The latter structure is the 

 upper edge of the lateral portion of the crico-thyroid membrane, and 

 consists of fine elastic tissue, which shows a slight thickening close to 

 its attachment to the thyroid cartilage. On the outer surface of the 

 ligament is the deep part of the thyro-arytenoid muscle, some of the 

 fibres of which are inserted into the band ; and a thin submucou 

 layer of elastic tissue is continued outwards from it to line th 

 ventricle of the larynx. 



The MUCOUS MEMBRANE of the larynx is continued from that 

 lining the pharynx, and is prolonged downwards into the trachea. 

 At the superior aperture of the larynx it forms the aryteno-epiglotti- 

 dean fold on each side, between the margin of the epiglottis and the 

 tip of the arytenoid cartilage : here it is very loose, and the sub- 

 mucous tissue abundant. In the larynx the membrane lines the 

 wall of the cavity closely, sinks into the ventricle, and sends a pro- 

 longation upwards into the laryngeal pouch. On the lower thyro- 

 arytenoid ligaments it is very thin and closely adherent, allowing 

 these to be visible through it. 



In the small part of the larynx above the superior vocal cords, the 

 epithelium is of the stratified squamous kind, and free from cilia. 

 But a columnar ciliated epithelium covers the edges of the superior 

 cords and the surface below these, though it becomes flattened 

 without cilia on the lower cords ; on the epiglottis the epithelium 

 is ciliated in the lower half. 



Numerous racemose glands are connected with the mucous mem- 

 brane of the larynx ; and the orifices will be seen on the surface, 

 especially at the posterior aspect of the epiglottis. In the edge of 

 the aryteno-epiglottidean fold there is a little swelling occasioned by 

 a mass of subjacent glands (arytenoid) ; and along the upper vocal 

 cord lies another set. None exist over the true vocal cords, but 

 close to those bands is the collection of the sacculus laryngis, which 

 moistens the ventricle and the lower vocal cord. 



Dissection of nerves and vessels. The termination of the laryngeal 

 nerves may be dissected on the left side of the larynx. For this 

 purpose the half of the thyroid is to be disarticulated from the 

 cricoid cartilage, care being taken of the recurrent nerve, which lies 

 close behind the joint between the two. The trachea and larynx 

 should be fastened clown with pins ; and after the thyroid has been 

 drawn away from the cricoid cartilage, the recurrent laryngeal nerve 

 can be traced over the side of the latter cartilage to the muscles of 

 the larynx and the mucous membrane of the pharynx. 



Afterwards the superior laryngeal nerve is found as it pierces the 

 thyro-hyoid membrane, and branches of it are to be followed to the 

 mucous membrane of the larynx and pharynx. Two communications 

 are to be looked for between the laryngeal nerves ; one is beneath the 

 thyroid cartilage, the other in the mucous membrane of the pharynx. 



An artery accompanies each nerve, and its offsets are to be dis- 

 sected at the same time as the nerve. 



