. Anatomy of the cat. Cats; Mammals. THE SKULL 2,2, the external auditory meatus is a nearly dorsoventral groove, which, when the bone is articulated, forms a part of the boundary of the stylomastoid foramen (Fig. 22, J); just ventrad of this groove is a pit (/•) which lodges the tip of the tympanohyal bone. Craniad the bone is produced into a short spine, the styli- form process (^7), which lies in a horizontal groove in the ventral surface of the basisphenoid. Laterad of this spine is a groove for the tuba auditiva or Eustachian tube. The medial surface (Fig. 24) presents in the middle near
. Anatomy of the cat. Cats; Mammals. THE SKULL 2,2, the external auditory meatus is a nearly dorsoventral groove, which, when the bone is articulated, forms a part of the boundary of the stylomastoid foramen (Fig. 22, J); just ventrad of this groove is a pit (/•) which lodges the tip of the tympanohyal bone. Craniad the bone is produced into a short spine, the styli- form process (^7), which lies in a horizontal groove in the ventral surface of the basisphenoid. Laterad of this spine is a groove for the tuba auditiva or Eustachian tube. The medial surface (Fig. 24) presents in the middle near its ventral margin a short triangular spine which lies in the natural state against the ventral surface of the basilar portion of the occipital. Caudad of this spine the surface is marked by two or three vertical parallel grooves (Fig. 23, ;//). They indicate the portion of the bone which bounds the jugu- ^, ^ ... ri('. 24. — Tympanic lar foramen, and are possibly impressions of Bulla, Isolated, the ninth, tenth, and eleventh nerves. Mkoial Surkace. ;' inner end of audi- Ihe dorsal two-tlnrds of the medial tory meatus;/^ partition surface is lacking in the disarticulated bulla ^li^i'l'"g tympanic cav. '^ _ ity; c, styliiorni process. (Fig. 24), so that the cavity of the bone is exposed. This opening is in the natural state closed by the petrous bone. The caudal end is rough where it is overlaid by the jugular process. On the inner surface of the tympanic bulla is seen the thick- ened margin of the inner end of the auditory meatus (Fig. 24, a). To it is attached the membrana tympana. In the median dorsal line this margin is notched for the reception of the incus and head of the malleus. From the lateral wall of the cavity at the line of junction of the ectotympanic and ento- tympanic a thin bony partition {b) rises. It runs almost directly mediad; is concave dorsally and divides the tj^mpanic cavity into two chambers. The Petrous Portion (Fig. 23, b, and Fig. 25
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Keywords: ., bookcentury1900, bookcollect, booksubjectcats, booksubjectmammals
