TUL E \rr.K\.\L .ifor.sy/r MBATUS 10.51 



Ligaments and muscles. The auricle is attached to the side of the head by the 

 skin, by the continuity of its cartilage with that of the acoustic meatu.-. and by certain 

 extrinsic ligaments and muscles. Three ligament.- may be distinguished in the con- 

 nective tissue: The anterior ligament, stretching from the xygoma to the helix 

 and tragus; the superior ligament, from the superior margin of the bony external 

 acoustic meatus to the spine of the helix; and the posterior ligament, from the mas- 

 toid process to the eminence of the concha. There are also three extrinsic muscles, 

 the anterior, superior, and posterior auricular (see p. 3315, fig. 306). Six intrinsic 

 muscles are distinguished. These are poorly marked in man and vary much in de- 

 velopment. Upon the lateral surface (fig. 746) the helicis major stretches from the 

 spine of the helix to the vent ral superior margin of the helix; the helicis minor over- 

 lies the cms helicis; the tragicus runs vertically upon the tragus: and the anti- 

 tragicus stretches from the antitragus to the cauda helicis. I'pon the medial sur- 

 face (fig. 746) the transversus auriculae stretches between the eminences of 

 concha and scapha,andthe obliquus Ijetween the eminences of the concha and the 

 triangular fossa. 



VESSELS AND NERVES 



The arteries are the auricular liranch of the posterior auricular and the anterior auricular 

 branches of the superficial temporal (pp. 5'Jti :md 527). The veins are the anterior auricular vein 

 of the posterior facial (temporal) and the auricular branches of the posterior auricular (pp. 648 

 and 649). The latter sometimes join tin- transverse (lateral) sinus through the mastoid emissary 

 vein. The lymphatics empty into the anterior and posterior auricular lymph-nodes (p. 707). 

 The sensory nerves of the auricle are the branches of the great auricular, small occipital (p. 913, 

 fig. 708), and auriculo-temporal (p. 971, fig. 708). The muscles are supplied by the posterior auric- 

 ular branch of the facial (p. 977, fig. 705). 



VARIATIONS 



There are many variations in the size, shape, and conformation of the auricle and in the 

 cephalo-auriculiir angle. These are associated not only with differences in sex, age, and race, 

 but are also found in individuals of the same family. 



THE EXTERNAL ACOUSTIC MEATUS 



The external acoustic (auditory) meatus extends medially and somewhat ven- 

 trally from the concha to the tympanic membrane (fig. 747). It is about twenty- 

 five mm. (1 in.) long, and, owing to the obliquity of the tympanic membrane, its 

 ventral and inferior wall is slightly longer t han the dorsal and superior. It consists of 

 a lateral cartilaginous and a medial osseous portion. The canal describes an 

 S-shaped curve in both horizontal and vertical directions, and is convex ventrally and 

 inferiority towards its auricular end, and concave vent rally and inferiorly towards its 

 tympanic end. The irregularly elliptical lumen has its long axis vertical at the auric- 

 ular, but nearly horizontal at its tympanic end, and it is constricted at about its 

 centre, and also near the tympanum. 



Relations. The anterior irall is in relation with the condyle of the mandible 

 medially, and with the parotid gland laterally; the inferior wall is closely bound to 

 the parotid gland ; and the posterior wall of the bony part is separated by only a 

 thin plate of bone from the mastoid cells. The superior tea// is separated at its 

 medial end by a thin plate of bone from the epitympanic recess, and laterally a thicker 

 layer of bone separates it from the cranial cavity. 



Structure of the meatus. The walls of the meatus are formed laterally of 

 fibro-cartilage and medially of bone. The cartilage is folded upon itself to form a 

 groove, the deficient and dorsal part of which is completed by dense connective tissue. 

 the groove l>eing thus converted into a canal. Medially, the cartilage forms about 

 one-third of the circumference; laterally, two-thirds. Two fissures or incimms 

 (incisures of S<nitai-in>) usually occur in its anterior wall (fig. 746). Laterally the 

 cartilage is directly continuous with the cartilage of the auricle and medially it 

 firmly connected with the lateral lip of the osseous portion. The osseous portion 

 forms slightly more than half the canal, and is formed by the tympanic portion of the 

 temporal bone: it is described in connection with that bone (p. 63). 



The skin of the meatus forms a continuous covering for the canal and tympanic 

 membrane. It is thick in the cartilaginous, but very thin in the bony, part of the 

 meatus, especially near the tympanic end. where it is tightly bound to the periosteum. 



