Anatomy of Goat Ear

Presented to: Dr.Zeeshan AkbarPresented By: 14-Arid-2022 FAiSAL SHAHZAD SOMROOPMAS

THE EAR

The ear or organ of hearing (Organon auditus) consists of three natural divisions.1. External.2. Middle.3. Internal.

THE EXTERNAL EAR

The external ear differs considerably in size, thickness, and position. It may be carried vertically, inclined inward, or hang downward. It is relatively wide and is little curved except at the base.

The external ear (Auris externa) comprises1. The auricula, a funnel-like organ which collects the sound

waves, together with its muscles; and2. The external acoustic meatus, which conveys these waves

to the tympanic membrane, the partition which separates the canal from the cavity of the middle ear.

CONT….

• The auricula or pinna is attached by its base around the external acoustic process in such a manner as to be freely movable. • In the following description it will be assumed that the

opening is directed outward and that the long axis is practically vertical. • It has

Two surfaces Two borders A base An apex.

CONT….

The convex surface or dorsum (Dorsum auriculae) faces medially and is widest in its middle part; its lower part is almost circular in curvature, while above it narrows and flattens.

The concave surface (Scapha) is the reverse of the dorsum; it presents several ridges which subside toward the apex.

The anterior border is sinuous; it is largely convex, but becomes concave near the apex. It divides below into two diverging parts (Crura helicis).

The posterior border is convex. The apex is flattened, pointed, and curved a little

forward. The base is strongly- convex. It is attached to the external

acoustic process of the petrous temporal bone, and around this there is a quantity of fat. The parotid gland overlaps it below and laterally.

The structure of the external ear comprises a framework of cartilages (which are chiefly elastic), the integument, and a complicated arrangement of muscles

CONT….

The conchal or auricular cartilage (Cartilago auricula) determines the shape of the ear its form can be made out in a general way without dissection, except below, where it is concealed by the muscles and the parotid gland.

The basal part is coiled so as to form a tube, which encloses the cavity of the concha (Cavum conchse). This part is funnel-shaped and curves outward and a little backward. Its medial surface is strongly convex, forming a prominence termed the eminentia conchae.

The lowest part of the medial margin bears a narrow, pointed prolongation, the styloid process.

The annular cartilage (Cartilago annularis) is a quadrilateral plate, curved to form about three-fourths of a ring; its ends are a little less than half an inch (ca. 1 cm.) apart medially and are united by elastic tissue. It embraces the external acoustic process and forms with the lower part of the conchal cartilage the cartilaginous part of the external acoustic meatus.

CONT….

The scutiform cartilage (Cartilago scutiformis s. Scutulum) is an irregular quadrilateral plate which lies on the temporal muscle in front of the base of the conchal cartilage.

The external acoustic meatus leads from the cavum conchse to the tympanic membrane. It does not continue the general direction of the cavity of the concha, but extends medially downward and slightly forward.

THE MIDDLE EAR

The middle ear (Auris media) comprises the tympanic cavity and its contents, the auditive or Eustachian tubes, and two remarkable diverticula of the latter, which are termed the guttural pouches.

The temipanic cavity (Cavum tympani) is a space in the tympanic and petrous parts of the temporal bone situated between the membrana tympani and the internal ear. It is an air-cavity, which is lined by mucous membrane, and communicates with the pharynx and the guttural pouches by the auditive or Eustachian tubes. It contains a chain of auditory ossicles by which the vibrations of the membrana tympani are transmitted to the internal ear.

The cavity consists of: (1) A main part or atrium, which lies immediately to the

medial side of the membrana tympani. (2) the recessus epitympanicus, situated above the level of

the membrane and containing the upper part of the malleus and the greater part of the incus.

(3) a relatively large ventral recess in the bulla ossea.

CONT….

The lateral, membranous wall (Paries membranacea) is formed largely by the thin membrana tympani, which closes the medial end of the external acoustic meatus, and thus forms the septum between the external and middle parts of the ear.

The external cutaneous layer (Stratinn cutaneum) is a prolongation of the lining of the external acoustic meatus.

The medial, labyrinthine wall of the tympanic cavity (Paries labyrinthica) separates it from the internal ear; it presents a number of special features.

Middle and Internal ear

THE INTERNAL EAR

The internal ear or labyrinth (Auris interna s. Labyrinthus) consists of two parts,

(1) A complex membranous sac, which supports the auditory cells and

the peripheral ramifications of the auditory nerve (2) a series of cavities in the petrous temporal bone, which encloses the membranous part.

The first is called the membranous labyrinth, and contains a fluid, the endolymph.

The second is the osseous labyrinth. The two are separated by the perilymphatic space, which is occupied by a fluid termed the perilymph.

CONT….

CONT….

CONT….

from the brain.

Sectioned cochlea

Schematic Illustration of middle & internal ear.

THANKS