- 
702 THE ORGANS OF SENSE. 
Ligaments of the Pinna.—'he cartilage of the pinna is attached to the skull 
by two fibrous bands which form its extrinsic ligaments, viz.: (@) anterior, 
stretching from the zygoma to the 
spina helicis and tragus; and (0) 
posterior, passing from the eminentia 
pe viguus conch and upper wall of the meatus — 
i read. 
| Sulcus antihelicis : 
Milita teone transversus tO the mastoid process. Small liga- 
> Spina helicis mentous bands pass between individual 
parts of the pinna, and form what are 
Cartilage of termed its intrinsic hgaments. 
Foie a Muscles of the Pinna (Figs. 511, 
\ : terminalis 512)—The muscles of the pinna are 
Guidahelicse re rae divided into two groups, extrinsic and 
2 \Cartilage of Tntrinsic. The extrinsic muscles pass 
Fic, 512.—INNER SURFACE OF CARTILAGE eee rome une pinne ue he pace seu 
(onetnale naturalicway: and are described in the section upon 
Myology. The intrinsic muscles, on 
the other hand, are confined to the pinna and are six in number, four on its outer 
and two on its cranial aspect. 
(a) On the outer surface (Fig. 511)— 
1. M. helicis major, passing upwards from the spina helicis along the ascending 
part of the helix. 2. M. helicis minor, covering the crus helicis. 5. M. tragicus, 
quadrangular in shape, and consisting of fibres running vertically over the greater 
part of the tragus. Some of its fibres are prolonged upwards to the spina helicis 
and constitute the m. pyramidalis. 4. M. antitragicus, covering the antitragus and 
passing obliquely upwards and backwards as far as the antihelix and cauda helicis. 
(b) On the cranial surface (Fig. 512)— 
1. M. transversus auricule, consisting of scattered fibres, which stretch from 
the eminentia conche to the convexity of the helix. 2. M. obliquus auricule (Tod), 
comprising a few fasciculi, which run obliquely or vertically across the furrow corre- 
sponding with the crus antihelicis inferior. A small muscle, the stylo-auricularis, 
sometimes extends from the root of the styloid process to the cartilage of the 
meatus. 
Skin of the Pinna.—The skin covering the pinna is thin and smooth, and is 
prolonged inwards, in the form of a tube, as a lining to the external auditory 
meatus. It adheres firmly, on the outer surface of the pinna, to the subjacent 
perichondrium. Hairs are well developed on the tragus and antitragus, and also in 
the incisura intertragica, forming the barbula hirci, which guard the entrance to the 
concha. Soft downy hairs are found over the greater part of the pinna and point 
towards Darwin’s tubercle. Sebaceous glands, present on both surfaces of the pinna, 
are nost numerous in the concha and fossa triangularis. Sweat glands are found 
on both surfaces, but are much more numerous on the cranial aspect. 
Pontieulu 
Vessels of the Pinna.—The arteries for the pinna are derived—(a) from the superficial tem- 
poral, which sends two or three branches to the outer surface ; and (6) from the posterior auricular, 
which gives three or four branches to the cranial surface. From the latter, two sets of twigs are 
prolonged to the outer surface, one turning round the free margin of the helix and the other 
passing through small fissures in the cartilage. The veins from the outer surface open into the 
superficial temporal vein ; those from the cranial surface chiefly join the posterior auricular vein, 
but some communicate with the mastoid emissary vein. The lymphatics take three directions, 
viz.: (a) forwards to the preauricular gland in front of the tragus, (6) downwards to the parotid 
lymphatic glands, and (c) backwards to the highest of the mastoid lymphatic glands. 
Nerves of the Pinna.—The muscles of the pinna are supplied by the seventh cranial 
nerve. The skin receives its sensory nerves from—(a) the great auricular, which supplies 
nearly the whole of the cranial surface and sends filaments in company with the branches of 
the posterior auricular artery to the outer surface; (6) the auriculo-temporal, which supplies 
the tragus and ascending part of the helix; (ec) the small occipital, which sends a branch to the 
upper part of the cranial surface. | 
EXTERNAL AUDITORY MEATUS. | 
The external auditory meatus (meatus acusticus externus) (Figs. 513, 514) is | 
the passage leading inwards from the concha as far as the membrana tympani. Its. 
