102 



PRACTICAL ANATOMY. 



Describe tlic Eustachian tube. 



It conveys air from the pharynx to the middle ear. You may see the 

 pharyngeal orifice on the posterior wall of the pharynx, in line with the inferior 

 turbinated bone. You will find the tympanic orifice in the anterior wall of the 

 tympanum, forming the lower of the two compartments of the canalis musculo- 

 tubarius. This you will understand when you dissect the middle ear and the 

 petrous stage of the seventh nerve. The tube is an inch and a half long from 

 the posterior wall of the pharynx to the anterior wall of the tympanum. The tube 



FIG. 63. MUSCLES OF THE PHARYNX. 



I. Orbicularis oris. 2. Pterygo-maxillary ligament. 3. Mylo-hyoideus. 4. Os hyoides. 5. Tliyro- 

 hyoid ligament. 6. Pomum Adami. 7. Cricoid cartilage. 8. Trachea. 9. Tensor palati. 10. Levator 

 palati. II. Glosso-pharyngeal nerve. 12. Stylo-pharyngeus. 13. Superior laryngeal nerve and 

 artery. 14. External laryngeal nerve. 15. Crico-thyroideus. 16. Inferior laryngeal nerve. 17. 

 Esophagus. 



has a bony part in the petrous portion of the temporal bone one-half of an inch 

 long ; it has a fibro-cartilaginous part one inch long. 



Has the cartilaginous tube any practical importance as a guide in dissection ? 



Yes ; it projects between the origins of the levator palati and tensor palati. 



Give the origins of the levator palati and the tensor palati, and show their re- 

 lation to the Eiistac/iian tube. 



(i) The levator palati (Fig. 1 1) arises from the petrous part of the temporal 

 bone and from the lower margin of the Eustachian tube. This muscle you 

 find, then, behind the tube in dissecting, to the inner side. The tensor palati 

 (Fig. 1 1) arises from the spine of the greater ala of the sphenoid, from the 

 scaphoid fossa, and from the cartilage of the Eustachian tube, and is in relation 



