INTRODUCTION:

It is a thin, translucent partition between the external acoustic meatus and the middle ear.
  • Shape: Oval Shaped.
  • Measurement: 9×10 mm
  • Location: It is placed obliquely at the angle of the 55° with the floor of the Meatus.

FEATURES:

The membrane has 2 Surfaces:-

Outer Surface:

  • It is free, concave and lined by a thin skin.

Inner Surface:

  • It provides attachment to the handle of the malleus.
  • It is convex.
  • At the tip of the handle of the malleus lies the point maximum convexity called UMBO.
  • The membrane is thickened at its circumference which is fixed to the tympanic membrane is lightly stretched called PARS TENSA.
  • The part between the two malleolar fold is loose is known as PARS flaccida.
  • It is crossed internally by chorda tympani. It is more liable to rupture.
  • The membrane is held tense by the inward pull of the tensor tympani muscle which is inserted into the upper end of the handle of malleus.

STRUCTURE:

The tympanic membrane is composed of the 3 types:-
  1. Outer cuticular layer of skin.
  2. Middle Fibrous layer: It is made up of Superficial radiating fibers and deep circular fibers. The Fibrous layer is replaced by loose areolar tissue in pars flaccida.
  3. Inner mucous layer: It is lined by the low ciliated columnar epithelium.

ARTERIAL SUPPLY:

  • The outer surface is supplied by AURICULAR branch of the maxillary artery.
  • The inner surface is supplied by the anterior and posterior tympanic artery.

VENOUS DRAINAGE:

  • Outer surface drains into the external jugular vein.
  • Inner surface drains into the transverse sinus.

LYMPHATIC DRAINAGE:

 It drains into preauricular and Retropharyngeal Lymph Nodes.

NERVE SUPPLY:

Outer surface:

  • Anteroinferior part:- supplied by Auriculotemporal nerve.
  • Anterosuperior part:- supplied by the temporal branch of the vagus nerve.

Inner surface:

  • It is supplied by tympanic branch.

APPLIED ANATOMY:

  1. Tympanic membrane perforation.
  2. Myringotomy:- In this, the membrane is incised to drain pus present in the middle ear.
  3. Myringectomy:- Removal of tympanic membrane.