Dr. sona MCV HOSPITAL POLLACHI ANATOMY OF MIDDLE EAR Dr. sona MCV HOSPITAL POLLACHI

MIDDLE EAR CLEFT EUSTACHIAN TUBE,MIDDLE EAR CAVITY, ADITUS, ANTRUM, MASTOID AIR CELLS.

EUSTACHIAN TUBE AUDITORY OR PHARYNGO TYMPANIC TUBE CONNECTS NASOPHARYNX WITH TYMPANIC CAVITY ADULT- 36mm LONG AND RUNS DOWNWARDS, FORWARDS AND MEDIALLY FROM ITS TYMPANIC END, FORMING AN ANGLE OF 45* WITH THE HORIZONTAL

2 PARTS- BONY AND FIBROCARTILAGINOUS BONY PART- POSTERO LATERAL, 1/3RD FIBROCARTILAGINOUS PART- ANTERO MEDIAL 2/3RD 2 PARTS MEET AT ISTHMUS- NARROWEST PART OF THE TUBE

TYMPANIC END- 5X2cm; situated in anterior wall of middle ear, a little above the level of floor. PHARYNGEAL END- slit like, vertically. Cartilage at this end raises an elevation called torus tubarius situated in lateral wall of of nasopharynx, 1-1.25cm behind posterior end of inferior turbinate.

MUSCLES RELATED TO EUSTACHIAN TUBE TENSOR VELI PALATINI- DILATOR TUBAE LEVATOR VELI PALATINI SALPINGO PHARYNGEUS ELASTIN HINGE OSTMANN’S PAD OF FAT

LINING OF THE EUSTACHIAN TUBE PSEUDO STRATIFIED CILIATED COLUMNAR EPITHELIUM INTERSPERSED WITH MUCOUS SECRETING GOBLET CELLS. SUBMUCOSA- RICH IN SEROMUCINOUS GLANDS CILA BEAT IN DIRECTION OF NASOPHARYNX

DIFFERENCES BETWEEN INFANT AND ADULT EUSTACHIAN TUBE LENGTH DIRECTION ANGULATION AT ISTHMUS BONY VERSUS CARTILAGINOUS PART TUBAL CARTILAGE DENSITY OF ELASTIN AT THE HINGE OSTMANN’S PAD OF FAT

BLOOD SUPPLY RAMUS MENINGEUS ACCESSORIUS ARTERY OF PTERYGOID CANAL ASCENDING PHARYNGEAL ARTERY VENOUS DRAINAGE- PTERYGOID PLEXUS NERVE SUPPLY- TYMPANIC PLEXUS AND SPHENOPALTINE GANGLION

FUNCTIONS VENTILATION AND REGULATION OF MIDDLE EAR PRESSURE PREVENTS REFLUX OF NASOPHARYNGEAL SECRETIONS CLEARANCE OF MIDDLE EAR SECRETIONS

TYMPANIC CAVITY BICONCAVE DISC VERTICAL -15mm ANTERO-POSTERIOR -13mm TRANSVERSE – 6mm at upper part,2mm at the centre, 4mm at the lower part

Epitympanu m (attic)‏ Mesotympanu m Hypotympanu m

TYMPANIC CAVITY ROOF- TEGMEN TYMPANI FLOOR- ANTERIOR WALL- CANAL OF HUGUIER (CHORDA TYMPANI) CANAL FOR TENSOR TYMPANI TYMPANIC ORIFICE FOR ET THE GLASERIAN FISSURE (TYMPANIC ARTERY AND ANTERIOR LIGAMENT OF MALLEUS)

POSTERIOR WALL – PYRAMID- TENDON OF STAPEDIUS ADITUS- FACIAL RECESS/ POSTERIOR SINUS- MEDIALLY VIIth NERVE, LATERALLY CHORDA TYMPANI NERVE, ABOVE FOSSA INCUDIS SINUS TYMPANI- SUBICULUM BELOW AND PONTICULUS ABOVE

MEDIAL WALL- PROMONTARY- BASAL COIL OF COCHLEA OVAL WINDOW ROUND WINDOW CANAL FOR FACIAL NERVE PROMINENCE OF LATERAL SEMICIRCULAR CANAL PROCESSUS COCHLEARIFORMIS- LEVEL OF GENU OF FACIALNERVE

LATERAL WALL TYMPANIC MEMBRANE AND BONY OUTER ATTIC WAL CALLED SCUTUM

CONTENTS OF MIDDLE EAR CAVITY OSSICLES MALLEUS- HEAD,NECK,HANDLE,LATERAL AND ANTERIOR PROCESS INCUS- BODY, SHORT PROCESS, LONG PROCESS STAPES- HEAD,NECK,ANTERIOR AND POSTERIOR CRURA AND FOOT PLATE

Malleus

Incus

Stapes

INTRA TYMPANIC MUSCLES TENSOR TYMPANI-ATTACHES TO NECK OF MALLEUS AND TENSES TM STAPEDIUS- ATTACHES TO NECK OF STAPES AND HELPS TO DAMPEN VERY LOUD SOUNDS

TYMPANIC PLEXUS LIES ON PROMONTARY TYMPANIC BRANCH OF GLOSSOPHARYNGEAL NERVE AND SYMPATHETIC FIBRES FROM PLEXUS AROUND INTERNAL CAROTID ARTERY CHORDA TYMPANI NERVE

MUCOUS MEMBRANE CILIATED COLUMNAR IN ANTERIOR AND INFERIOR PART, CUBOIDAL IN POSTERIOR PART. EPITYMPANUM AND MASTOID AIR CELLS LINED BY FLAT NONCILIATED EPITHELIUM

BLOOD SUPPLY SUPERIOR- SUPERFICIAL PETROSAL, SUPERIOR TYMPANIC,RAMUS NUTRICIA INCUDOMALLEI INFERIOR- INFERIOR TYMPANIC BRANCH OF ASCENDING PHARYNGEAL ARTERY ANTERIOR- ANTERIOR TYMPANIC BRANCH OF INTERNAL MAXILLARY ARTERY;RAMUS TYMPANICI BRANCH OF INTRNAL CAROTID ARTERY POSTERIOR-POSTERIOR TYMPANIC BRANCH OF STYLOMASTOID ARTERY

VEINS DRAIN INTO ;PTERYGOID VENOUS PLEXUS LYMPHATICS DRAIN INTO RETROPHARYNGEAL AND PAROTID NODES NERVE SUPPLY- TYMPANIC BRANCH OF IXTH CRANIAL NERVE(JACOBSON’S NERVE)

MASTOID ADITUS AD ANTRUM- BONY PROMINENCE OF HORIZONTAL CANAL LIES ON ITS MEDIAL SIDE WHILE FOSSA INCUDIS LIES LATERALLY. FACIAL NERVE COURSES JUST BELOW THE ADITUS

MASTOD ANTRUM AIR CHAMBER IN TEMPORAL BONE, LINED BY FLATTENED SQUAMOUS CELLS ROOF- TEGMEN ANTRI ANTERIOR- OPENING OF ADITUS AD ANTRUM MEDIAL- POSTERIOR AND HORIZONTAL SEMICIRCULAR CANALS LATERAL- SUPRA MEATAL(MACEWEN’S) TRIANGLE [1.5cm DEEP]

MAST0ID PROCESS LIES BEHIND TYMPANIC PORTION OF TEMPORAL BONE BONE CORTEX WITH HONEYCOMB OF AIRCELLS UNDERNEATH 1. WELL PNEUMATISED OR CELLULAR 2. DIPLOETIC 3. SCLEROTC OR ACELLULAR

ARTERIAL SUPPLY- POSTERIOR TYMPANIC ARTERY FROM STYLOMASTOID BRANCH OF POSTERIOR AURICULAR ARTERY VEINS-MASTOID EMISSARY VEIN, POSTERIOR AURICULAR VEIN AND SIGMOID SINUS

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