MANUAL OF HISTOLOGY. 



til age, which gives the name to the anterior part of the tube 

 that stands in connection with the pharynx, is in the form of 

 a hook (Fig. 159, 2), with its short end directed downward and 

 inward. At the bend of the hook the opposing surfaces of car- 

 tilage cannot quite apply themselves to each other, and there 

 is thus left a little air-space between them, which Ruedinger 

 has termed the safety- tube (Fig. 159, 9). The cartilage is of the 

 hyaline variety, with small cells, which are much smaller and 

 more numerous at the periphery, thus forming a sort of peri- 



Fio. 159. Transverse section of Eustachian tube and surrounding parts : 1, median cartilaginous plate ; 

 2, lateral cartilaginous hook : 3, muscnlus dilator tubae ; 4, musculus levator veli palatini ; 5. fibro-carti- 

 lago basilaris : 6 and 7, acinous glands ; 8, deposit of fat in the lateral wall : 9, safety-tube ; 10, accessory 

 fissure ; 11, fold of the mucous membrane ; 12, adjacent tissues. Ruedinger. 



chondrium. The cartilage is joined to the osseous portion by 

 a narrow band of fibro-cartilage. 



The musculus dilator tubse (Fig. 159, 3), which goes to form 

 the membranous (muscular) portion of the tube, is joined to 

 the short end of the hook along the whole length of the carti- 

 laginous portion. The muscle is of the striped variety, and is 

 inserted into the perichondrium by means of a very short, flat 

 tendon. 



The entire tube is lined with a mucous membrane (Fig. 159, 

 11), continuous at one end with that of the pharynx, and at the 



