240 A. G. POHLMAN 



The drum, in addition, receives strengthening fibers from defi- 

 nite elastic hgaments which may well be named the drum-tubal 

 ligaments; these will be discussed after the general structure of 

 the columella has been considered, because they are definitely 

 related to the columella, both in position and in function. 



MTS LA 



Fig. 3 Section through the length of the cokimellar recess of a twenty-day 

 chick; resorcin-fuchsin stain. C , columella; CSL, columellar-squamosal ligament; 

 F, fibrous tube of external canal; LA, ligamentum annulare; MD, musculus digas- 

 tricus; MT, membrana tympani; MTS, membrana tympani secundaria; T, 

 tympanum; TT, tendon of tensor tympani. 



COLUMELLAR APPARATUS 



The strut responsible for the prominence of the drum in the 

 external auditory canal is the columellar apparatus, which 

 demands a careful consideration and which may be divided into 

 two segments, a medial bony columella proper and a lateral 

 cartilaginous extracolumella. 



The bony columella has been likened to the mammalian stapes 

 with a long stalk attached to it. It begins medially at the 

 margin of the fenestra vestibuli as a flattened bony plate, the 

 columellar foot-plate, which rapidly decreases in size to form a 



