816 DIRECTIONS FOR LABORATORY WORK 



malleus; membrana flaccida (Shrapnell's membrane)? and cutaneous 

 layer, mucous layer, and intermediate radial and circular collagen fibers. 

 Sketch (396). Sketch (397) h.p. a small segment of the tympanic 

 membrane near the umbo. Function of tympanic membrane ? Relation 

 to the auditory ossicles? Structure of the ossicles? Relation of tym- 

 panum to the mastoid 'cells'? to the auditory tube? 



(2) THE AUDITORY TUBE (Eustachian Tube). Study a stained 

 transverse section of the cartilaginous portion of the tuba auditiva. 

 Note character of the lining epithelium, and the fibro-cartilagiiious 

 wall. Relation of cartilage plate to medial and lateral surfaces, and to 

 the tensor and levator palati muscles. Sketch (398). Function of the 

 auditory tube ? Position and significance of the tubal tonsil ? Function 

 of the musculus tensor palati in relation to the auditory tube? 



(C) THE INTERNAL EAR 



(1) VESTIBULE (Utriculus and Sacculus). Study a stained sec- 

 tion of the wall of the utricle or saccule through the macula. Note char- 

 acter of the lining epithelium. Sketch h.p. (399) a segment of the 

 macula. Function of the otolithic membrane? 



(2) SEMICIRCULAR DUCTS (Canals). Study h.p. a stained trans- 

 verse section of a membraneous semicircular duct. Compare with 

 a section through the ampulla. Sketch segments of the lining epithe- 

 lium (400), and of the crista ampulla? acustica including the overlying 

 cupola (401). 



(3) COCHLEA. Study l.p. a stained axial section of the cochlea 

 of some mammal (cat; rabbit). Sketch a complete vertical section of 

 a turn of the cochlea (402). Identify and label all the included parts. 

 Function of the vestibular (Reissner's) membrane? tectorial membrane? 

 basilar membrane ? Shambaugh's glands ? the stria vascularis ? vas prom- 

 inens ? 



Make h.p. sketch (403) of the spiral organ (of Corti), identifying 

 the various cells involved. 



Study an injected specimen of the caf s cochlea. Diagram (404) the 

 blood supply of a turn of the cochlea. 



Describe the nerve supply of the membraneous labyrinth, of the in- 

 ternal ear. Where is the internal acoustic meatus? Function of the 

 utriculus? sacculus? semicircular canals? cochlea? 



