2o8 THE POCKET ANATOMY 



stylo- and palato-pharyngei muscles, prolonged upwards into 

 superior cornu, which passes up wards, backwards, and inwards, 

 having lateral thyro-hyoid ligament attached to tip ; and 

 downwards into inferior cornu, shorter, passing downwards, 

 forwards, and inwards, presenting on inner surface a small 

 facet to articulate with cricoid. 



The cricoid cartilage : shaped like signet ring, deep behind 

 and shallow in front. 



Outer surface: anterior half gives attachment to crico- 

 thyroid muscles, and behind this to part of inferior con- 

 strictor. Posterior half, broad and thick, presents ridge in 

 middle line for attachment of some longitudinal fibres of 

 oesophagus ; on each side of ridge, a depression giving attach- 

 ment to the crico-arytenoideus posticus, and external to this 

 a small facet for articulation with inferior cornu of thyroid. 



Inner surface : smooth, lined with mucous membrane. 



Superior border : inclines from the front, upwards and back- 

 wards, gives attachment anteriorly and laterally to crico- 

 thyroid membrane and crico-arytenoideus lateralis. Presents 

 posteriorly in mid-line a notch, on each side of which is a 

 facet for articulation with arytenoid cartilage. 



Inferior border: horizontal, connected with ist ring of 

 trachea by intervening membrane. 



Arytenoid cartilages : are two small pyramidal cartilages, 

 articulating with posterior part of upper border of cricoid. 



Antero-external surface : convex and rough, receives attach- 

 ment of thyro-arytenoideus muscle and false vocal cord. At 

 upper end is a tubercle for superior thyro-arytenoid ligament, 

 and below an oblique ridge. 



Posterior surface : hollowed for attachment of arytenoideus 

 muscle. 



Internal surface : narrow and smooth, covered with mucous 

 membrane. 



Base : has concave facet on under surface for articulation 

 with cricoid cartilage, and prolonged into three angles. 



External or muscular process : short and prominent, gives 

 attachment to lateral and posterior crico-arytenoid muscles. 



Anterior or vocal process : long and pointed, gives attach- 

 ment to true vocal cord. 



Internal : rounded. 



Apex : looks backwards and inwards, surmounted by the 

 cartilage of Santorini. 



Cartilages of Santorini or cornicula laryngis : two small 

 cartilages- of conical shape, each attached to the apex of an 

 arytenoid cartilage, and giving attachment to the aryteno- 

 epiglottidean fold. 



