[Music] tympanic membrane the tympanic membrane or eardrum is a thin semi-transparent membrane which separates the external from the middle ear in its try laminar oval and as 0.1 millimeters think it is about eight to ten millimeters in diameter and it's positioned obliquely at at acute angle of around 55 degrees the membrane forms a fibrocartilaginous ring that is attached to the tympanic plate subdivisions the tympanic membrane is divided into two parts pars tenza and parcel asada tensa forms most of the tympanic membrane is thickened in its periphery to form a fibrocartilaginous rim called the annulus tympanic as' the fibrocartilaginous rim presents a notch above from the margins of the knotch the anterior and posterior malleolus folds extend to gain attachment to the lateral process of the malleus the handle of the malleus is firmly attached to the inner surface of the parts tensa pars Placida this is also known as shrapnel membrane it is a small triangular region above the lateral process of the malleus between the anterior and posterior malleolus folds this part is thin Lacs and appears pink in color surfaces the tympanic membrane presents with a lateral and medial surface the ladle surface of the tympanic membrane is concave towards the Miatas and is directed downwards forwards and laterally the medial surface is convex and bulges into the middle ear the point of maximum convexity is known as the UM bow when the tympanic membrane is illuminated on inspection the concavity of the membrane produces a cone of light radiating from the UM bow over the anterior inferior quadrant it receives the attachment of the handle of the malleus up to the center of the membrane structure the tympanic membrane is divided into three layers outer cuticular layer it is lined by hairless keratinized squamous epithelium intermediate fibers layer this consists of an outer radiating and inner circular layer of fibers the radiating fibers radiate from the handle of the malleus the circular fibers are present more in the periphery inner mucosal layer it is lined by a single layer of ciliated columnar epithelium blood supply the outer surface is supplied by the deep auricular artery a branch of the first part of the maxillary artery so the inner surface is supplied by the anterior tympanic artery a branch of the first part of the maxillary artery and the posterior to Manek artery a branch of the stylo mastoid artery venous drainage veins from the outer surface drink into the external jugular vein veins from the inner surface join in to the transverse sinus and the pterygoid venous plexus nerve supply the anterior half of the lateral surface is innervated by the auricular temporal nerve the posterior half of the later surface is innervated by the auricular branch of the vagus nerve the medial surface is innervated by the tympanic branch of the glossopharyngeal nerve via the tympanic plexus development the tympanic membrane develops from the two bow tympanic recess first ectodermal cleft and the intervening mesoderm the chiba tympanic recess is formed by the union of the first and part of the second Ferengi allow a this that opposes the first ectodermal cleft with mesoderm lying in between hence the tympanic membrane consists from superficial to deep a three layers and are derived from octo derm mesoderm and endoderm these three layers correspond to the following three layers for the tympanic membrane cuticular layer which is derived from ectoderm intermediate layer which is derived from mesoderm and the mucous layer which is arrived from endoderm clinical correlation examination of the tympanic membrane inspection of the tympanic membrane with an otoscope provides significant information about the condition of the middle ear the color curvature presence of lesions and position of the malleus are features of significance when the tympanic membrane is illuminated for examination a cone of light is reflected in the anterior inferior quadrant of the membrane from the Ambo which marks the attachment of the handle of the malleus since the membrane is semi translucent the following structures line deep to it are visible handle of the malleus as a yellow streak extending from the Ambo upwards and forwards lateral process of the malleus as a white prominence in the upper part of the street of the handle of the malleus long processes of the incus as white streaks behind and parallel to the upper part of the handle of the malleus a cone of light at the five o'clock position in the anterior inferior quadrant clinically the tympanic membrane is divided into four quadrants by means of two imaginary lines passing through the UM bow one is drawn along the handle of the malleus and the other at a right angle to it through the UM bow perforation of the tympanic membrane may occur due to an external injury or infection of the middle ear known as otitis media sometimes an incision is given in the tympanic membrane known as myringotomy to drain the pus from the middle ear the incision is usually given in the posterior inferior quadrant to avoid injury to the court attempt any nerve which crosses the inner aspect of the membrane in its upper part