There are observed attached to the utricle and saccule small calcareous bodies, called otolithes, or otoconia.

The arteries of the tympanum enter it in the following manner: A small branch from the middle meningeal passes through the hiatus Fallopii; another from the internal maxillary enters it through the Glaserian fissure; a third one comes from the stylo-mastoid, and gets in at the lower end of the aqueduct of Fallopius; it receives branches through the Eustachian tube from the ascending pharyngeal or inferior palatine arteries; the internal carotid also sends a twig into it through a small foramen from the carotid canal.

The artery to supply the labyrinth passes through the meatus auditorius internus. It sometimes comes from the superior cerebellar, and sometimes from the basilar. At the bottom of the meatus it divides into a vestibular and a cochlear branch.

The nerves connected with the middle and internal ear are derived from several sources. There are four which enter the petrous bone; one of these terminates in the labyrinth; the other three pass through the bone, traversing in their course the tympanum. The portio dura and portio mollis enter it through the meatus auditorius internus; the former leaves it through the foramen stylo-mastoideum; the latter is distributed to the labyrinth. The vidian enters through the hiatus Fallopii, and makes its exit as the chorda tympani, through a small aperture near the Glaserian fissure. Jacobson's branch of the glosso-pharyngeal passes through a small foramen situated between the jugular fossa and carotid foramen, and leaves the bone as the superficial petrosal branch of Jacobson, just below the hiatus Fallopii to go to the otic ganglion.

The PORTIO MOLLIS, Fig. 44 (15, 16, 17), at the bottom of the meatus divides into two branches, one for the cochlea and one for the vestibule and semicircular canals. The anterior or cochlear division passes through by a number of filaments the perforated base of the modiolus, and thus enters its osseous canals, from which the filaments enter nearly at right angles the space between the lamella of the lamina spiralis, to terminate in a delicate nervous membrane in the form of papillæ.

The posterior or vestibular division separates into three fasci

culi; the superior of which enters the vestibule to expand on the utricle and on the ampullæ of the superior vertical and

A VIEW OF THE LABYRINTH IN AN INVERTED POSITION, LAID OPEN SO AS TO SHOW THE DISTRIBUTION OF THE NERVES.-1, 2, 3. The cochlea laid open in its fullest extent, so as to show the lamina spiralis. The figures are placed on the two turns and and a half. 4, 5, 6. The remains of the parietes of the cochlea. 7, 8. The vestibule. 9, 10. Superior canal. 11, 12. Inferior canal. 13. The external canal. 14. The semicircular membranous canals. 15, 16, 17. The auditory nerve in its course to the labyrinth.

horizontal membranous semicircular canals; the middle passes through the macula cribrosa to expand on the saccule; the inferior enters the posterior part of the vestibule to go to the ampulla of the posterior vertical membranous canal.

The PORTIO DURA leaves the meatus and enters the aqueduct of Fallopius, passes forwards and outwards to communicate with the hiatus Fallopii, where it is joined by the vidian nerve, and presents a ganglionic enlargement; it then passes backwards and downwards over the fenestra ovalis to reach the foramen stylo-mastoideum. In its course through the tympanum it passes from the upper and anterior part of the inner wall to the lower and inner part of the posterior wall. It is connected by one or two filaments to the portio mollis.

The VIDIAN, after passing through the hiatus Fallopii, joins the portio dura and accompanies it through the tympanum and a short distance into the stylo-mastoid canal,

then leaves it, returns by a bony canal into the tympanum, and goes forwards between the handle of the malleus and long process of the incus, to a small foramen close by the Glaserian fissure. After leaving the portio dura, it is called the chorda tympani.

The NERVE OF JACOBSON, from the glosso-pharyngeal, enters the tympanum just below the promontory, and after giving off the following branches leaves it through an osseous canal in the upper and anterior part near the hiatus Fallopii:

Fig. 45.

A

A DRAWING OF THE TYMPANIC NERVE FROM BRESCHET'S WORK ON THE EAR.-A. Squamous part of temporal bone. B, B. Petrous portion of same. c. Lower maxillary nerve. D. Internal carotid artery. a. Tensor tympani muscle. 1. Carotid plexus. 2. Otie ganglion. 3. Glosso-pharyngeal nerve. 4. Tympanic nerve. 5. Branches to carotid plexus. 6. Branch to fenestra rotunda. 7. Branch to fenestra ovalis. 8. Branch to join the large superficial petrosal nerve. 9. Small superficial petrosal nerve. 10. Nerve to tensor tympani muscle. 11. Facial nerve. 12. Chorda tympani. 13. Petrous ganglion of the glosso-pharyngeal. 14. Branch to the membrane lining the Eustachian tube.

One branch enters the carotid canal to join the sympathetic; another joins the vidian in the hiatus Fallopii; a third goes to the Eustachian tube; a fourth to the fenestra ovalis, and a fifth to the fenestra rotunda. By a division of this nerve into

filaments, and these filaments reuniting, the tympanic plexus is formed. Before entering the tympanum, Jacobson's nerve is connected by filaments with the pneumogastric and facial nerves. This nerve joins the superficial petrosal branch of Jacobson, and thus forms a communication between the ganglion of the glosso-pharyngeal and the otic ganglion.

SECT. X.-DISSECTION OF THE NOSE.

The nose is the organ of smell; it affords to the lungs an external communication which is constantly open for the transmission of air; it furnishes a passage or common outlet to several cavities lined by mucous membrane; it also contributes essentially to the perfection of the voice. It occupies a central position in the facial portion of the head. It has on each side of it the orbit above and the antrum Highmori below, and extends from the floor of the cranial cavity above to the roof of the mouth below. It opens anteriorly upon the face, and posteriorly into the upper part of the pharynx. It is divided into two compartments called the nasal fosse, which are separated by an osseo-cartilaginous septum.

The term nose is more commonly applied to that portion which projects upon the face. The structure of the lower and most prominent portion of this is cartilaginous, while the upper part is osseous. The muscles, vessels, and nerves of the nose have already been described.

The bones are the nasal and the nasal processes of the superior maxillæ.

The cartilages, or fibro-cartilages, form the framework of the movable part of the nose. They furnish a structure of sufficient firmness to preserve the anterior nares patent, while their mobility is a protection against injury, and allows the nostrils to be closed or expanded.

These cartilages consist of the septal or middle, and two lateral upon each side, a superior and inferior, or alar.

The middle cartilage, Fig. 46 (4), forms the anterior septum of the nasal fossæ. The columna is the septum between the anterior nares. This cartilage is of an irregular triangular shape; its centre is not so thick as the margins, and is frequently inclined to one side or the other. Its upper and posterior border is attached to the vertical lamella of the

Fig. 46.

ethmoid, and its posterior inferior border is received between the edges of the vomer and the palatine processes of the superior maxilla; its anterior border is connected to the nasal suture and to the two inferior lateral cartilages. It sometimes projects backwards between the ethmoidal lamella and the vomer to the rostrum of the sphenoid bone.

The superior lateral cartilage, Fig. 47 (1), on each side is attached above to the lower border of the nasal bone, posteriorly to the nasal process of the superior maxilla, below to the inferior lateral cartilage of the same side, and in the median line to the septal cartilage; the two cartilages are not directly attached to each other at their anterior margins. The anterior margin is thicker than the posterior. They are of a triangular shape. Fig. 47.

Outer part of the lower

TRILS FROM BELOW.-2. lateral cartilages. 2. Inner part of the same. 4. Lower edge of the cartilage of the septum.

The inferior lateral or

Fig. 48.