MEATUS AUDITORIUS. 457 



(he concha by a fissure which is closed in the entire ear by ligamentous 

 fibres ; it is firmly attached at its termination to the processus auditorius. 



The Ligaments of the external ear are those which attach the pinna to 

 the side of the head, viz. the anterior, posterior, and ligament of the 

 tragus ; and those of the fibro- cartilage, which serve to preserve its folds 

 and connect the opposite margins of the fissures. The latter are two in 

 number, the ligament between the concha and the processus caudatus, and 

 the broad ligament which extends from the upper margin of the fibre-car- 

 tilage of the tragus to the helix, and completes the meatus. 



The proper Muscles of the pinna are the 



Major helicis, 

 Minor helicis, 

 Tragicus, 

 Antitragicus, 

 Transversus auriculae. 



The Major helicis is a narrow band of muscular fibres situated upon the 

 anterior border of the helix, just above the tragus. 



The Minor helicis is placed upon the posterior border of the helix, at 

 its commencement in the fossa of the concha. 



The Tragicus is a thin quadrilateral layer of muscular fibres, situated 

 upon the tragus. 



The Antitragicus arises from the antitragus, and is inserted into the 

 posterior extremity, or processus caudatus of the helix. 



The Transversus auricula, partly tendinous and partly muscular, ex- 

 tends transversely from the convexity of the concha to that of the helix, 

 on the posterior surface of the pinna. 



These muscles are rudimentary in the human ear, and deserve only the 

 title of muscles in the ears of animals. Two other muscles are described 

 by Mr. Tod,* the obliquus auris and contractor meatus, or trago-helicus. 



The MEATUS AUDITORIUS is a canal, partly cartilaginous and partly os- 

 seous, about an inch in length, which extends inwards and a little forwards 

 from the concha to the tympanum. It is narrower in the middle than at 

 each extremity, forms an oval cylinder, the long diameter being vertical, 

 and is slightly curved upon itself, the concavity looking downwards. 



It is lined by an extremely thin pouch of epithelium, whichj when with- 

 drawn after maceration, preserves the form of the meatus. Some stiff 

 short hairs are also found in its interior, which stretch across the tube, and 

 prevent the ingress of insects and dust. In the substance of its lining 

 membrane are a number of ceruminous glands , which secrete the wax of 

 the ear. 



Vessels and Nerves. The pinna is plentifully supplied with arteries; 

 by the anterior auricular from the temporal, and by the posterior auricular 

 from the external carotid. 



Its Newes are derived from the anterior auricular of the fifth, the pos- 

 terior auricular of the facial, and the auricularis magnus of the cervical 

 plexus. 



"The Anatomy and Physiology of the Organ of Hearing," by David Tod, 1832 



39 



