1. ANATOMY OF
EXTERNAL
AND
MIDDLE EAR
BY
K.S RAMA RAJU

2. EXTERNAL EAR:-
PINNA:-
 EMBRYOLOGY:PERIOD OF DEVLOPMENT=4th-6thwk OF INTRAUTERINE LIFE
 CONTRIBUTION ARCHES= 1st &2nd BRANCHIAL ARCHES
 1st ARCH=TRAGUS, 2nd ARCH=REST OF PINNA
 6 HILLOCKS ARE FORMED FROM CONDENSATION OF MESODERM OF 1st AND 2nd ARCHES
ANOMALIES:
 PRE AURICULAR SINUS
 ABNAORMAL SHAPES OF PINNA:
1. BAT EAR
2. WILDERMUTH'S EAR
3. MOZART'S EAR
 MICROTIA
 SYNOTIA
 MELOTIA

3. ANATOMY OF PINNA:
 FRAMEWORK : MADE OF YELLOW ELASTIC CARTILAGE EXCEPT LOBULE
 CYMBA CONCHA: BENEATH IT LIES MAC EWEN'S TRIANGLE,A LANDMARK FOR MASTOID ANTRUM
 INCISURA TERMINALIS
BETWEEN TRAGUS AND ANTERIOR CRUS OF HELIX
DEVOID OF CARTILAGE
SITE OF INCISION FOR ENDAURAL APPROACH
LIGAMENTS OF PINNA:
1. 2 EXTRINSIC LIGAMENTS:
2. INTRINSIC LIGAMENTS :
MUSCLES OF PINNA:
 3 EXTRINSIC MUSCLES
1. AURICULARIS ANTERIOR
2. AURICULARIS SUPERIOR
3. AURICULARIS POSTERIOR
4. THESE MUSCLES SUPLIED BY TEMPORAL & POSTERIOR AURICULAR BRANCH OF FACIAL NERVE

4. ARTERIAL SUPPLY OF PINNA: SUPPLIED BY
BRANCHES OF EXTERNAL CAROTID ARTERY
POSTERIOR AURICULAR ARTERY:
1. MEDIAL SURFACE (EXCEPT LOBULE)
2. CONCHA
3. MIDDLE AND LOWER PORTIONS OF
HELIX
4. LOWER PART OF ANTIHELIX
AURICULAR BRANCH OF SUPERFICIAL
TEMPORAL ARTERY:
1. UPPER PORTIONS OF HELIX AND
ANTIHELIX
2. TRIANGULAR FOSSA
3. TRAGUS
4. LOBULE

5. NERVE SUPPLY:
SENSORY INNERVATION FROM:
1. GREATER AURICULAR NERVE
2. LESSER OCCIPITAL NERVE
3. AURICULAR BRANCH OF VAGUS NERVE
4. AURICULO TEMPORAL NERVE
5. FACIAL NERVE

6. EXTERNAL AUDITORY MEATUS:
 EMBRYOLOGY:DEVLOPS FROM 1st BRANCHIAL CLEFT AT 16th EMBRYONIC WEEK
 CELLS PROLIFERATE FROM BOTTOM OF ECTODERMAL CLEFT TO FORM MEATAL
PLUG WHICH LATER RECANALISES STARTING FROM DEEPER PART
ANOMALIES:
1. COMPLETE ATRESIA
2. SHALLOW DEPRESSION OF CANAL
3. CHANGE IN THE CURVATURE
4. STENOSIS

7. ANATOMY OF E.A.C:
LENGTH =24mm
1. CARTILAGENOUS PART=8mm
2. BONY PART=16mm
 FISSURE OF SANTORINI:VERTICAL FISSURE IN THE ANTERIOR PART OF CARTILAGE OF EAC
THROUGH THIS THE PAROTID AND MASTOID INFECTION APPEARS IN THE CANAL &VICE VERSA
 ROOF OF E.A.C=SQUAMOUS TEMPORAL BONE
 MOST OF THE CANAL=TYMPANIC BONE
SUTURES:
 ANTERIOR TYMPANO SQUAMOUS SUTURE
 POSTERIOR TYMPANO MASTOID SUTURE
CONSTRICTIONS:
 JUNCTION BETWEEN CARTILAGE AND BONY PORTIONS
 ISTHMUS(5mm FROM T.M)
ANTERIOR RECESS:
 DEEP TO ISTHMUS,ANTERO-INFERIOR PART OF CANAL WALL DIPS FORWARDS FORMING RECESS WHICH IS
DIFFICULT TO SPOT

8. ARTERIAL SUPPLY OF E.A.C:
 ROOF AND ANTERIOR PART OF CANAL=AURICULAR BRANCH OF SUPERIOR TEMPORAL ARTERY
 POSTERIOR PORTION OF CANAL=AURICULAR BRANCH OF POSTERIOR AURICULAR ARTERY
NERVOUS SUPPLY:
 ANTERIOR WALL & ROOF=AURICULOTEMPORAL NERVE(V3)
 POSTERIOR WALL & FLOOR=AURICULAR BRANCH OF VAGUS
VEINS:
 EXTERNAL JUGULAR VIEN
 MAXILLARY VIEN
 PTERYGOID PLEXUS

9. TYMPANIC MEMBRANE:
EMBRYOLOGY:
 OUTER EPIDERMAL LAYER OF T.M=1st PHARYNGEAL
GROOVE(ECTODERM)
 MIDDLE FIBROUS LAYER=MESODERM
 INNER MUCOUS LAYER=1st BRANCHIAL POUCH(ENDODERM)

10. ANATOMY:
• PARS FLACCIDA=LESS STIF FDUE TO PRESENCE OF
SPARSE DISORGANISED FIBROUS TISSUE
• PARS TENSA-LARGE,STIFF,VIBRATING SURFACE OF
T.M

11. BLOOD SUPPLY OF T.M:
OUTER SURFACE OF T.M:
 DEEP AURICULAR BRANCH OF MAXILLARY ARTERY
INNER SURFACE OF T.M:
 ANTERIOR TYMPANIC BRANCH OF MAXILLARY ARTERY
 POSTERIOR TYMPANIC BRANCH OF STYLOMASTOID ARTERY
 INFERIOR TYMPANIC BRANCH OF ASCENDING PHARYNGEAL ARTERY
NERVE SUPPLY OF T.M:
 LATERAL SURFACE=
ANTERIOR PART=AURICULO TEMPORAL NERVE
POSTERIOR PART=VAGUS NERVE
 MEDIAL SURFACE=GLOSSOPHARYNGEAL NERVE

12. EMBRYOLOGY OF MIDDLE EAR:
PHARYNGEAL POUCH:-
PROXIMAL NARROW PART=EUSTACHIAN TUBE
DISTAL DILATED PART=
1.TYMPANIC CAVITY
2.ANTRUM
3. ATTIC
4.MASTOID AIR CELLS
OSSICLES=
1st ARCH CARTILAGE=1.HEAD OF MALLEUS
2.BODY OF INCUS
2nd ARCH CARTILAGE=1.HANDLE OF MALLEUS
2.LONG PROCESS OF INCUS
3.CRURA OF STAPES
OTIC CAPSULE=FOOT PLATE OF STAPES

13. COMPARTMENTS AND FOLDS OF
TYMPANIC CAVITY:
 ATTIC COMPARTMENT:
1. ANTERIOR COMPARTMENT
2. POSTERIOR COMPARTMENT
A) SUPERIOR INCUDAL SPACE
B) MEDIAL INCUDAL SPACE
 COMPARTMENT OF MESOTYMPANUM
1.ANTERIOR MALLEOLAR FOLD
2.POSTERIOR MALLEOLAR FOLD

14. TYMPANIC CAVITY(MIDDLE EAR):
DIVIDED IN TO 3 PARTS:
1. EPITYMPANUM (ATTIC)
2. MESOTYMPANUM
3. HYPOTYMPANUM

15. LATERAL WALL OF MIDDLE EAR:
 FORMED BY
1.BONY LATERAL WALL OF EPITYMPANUM-
SCUTUM-EROSION CAUSE TELLTALE
SIGN ON CT
2.TYMPANIC MEMBRANE
3.BONY LATERAL WALL OF HYPOTYMPANUM
 PETROTYMPANIC FISSURE:
RECIEVES:
1. ANTERIOR MALLEOLAR LIGAMENT
2. ANTERIOR TYMPANIC BRANCH OF
MAXILLARY ARTEY
 CANAL OF HUGIER:MEDIAL WALL OF
PETROTYMPANIC FISSURE THROUGH
WHICH CHORDA TYMPANI RUNS OUT
 COURSE OF CHORSA TYMPANI

16. ROOF OF THE MIDDLE EAR:
 TEGMEN TYMPANI: FORMED BY PETROUS AND
SQUAMOUS PORTION OF TEMPORAL BONE
 PETOSQUAMOUS SUTURE:ROUTE OF INFECTION IN
TO EXTRA DURAL SPACE IN CHILDREN

17. FLOOR OF MIDDLE EAR:
 FORMED BY :-PNEUMATISED BONE

SEPARATES FROM JUGULAR BULB

TYMPANIC BRANCH OF GLOSSOPHARYNGEAL
NERVE ENTERS AT JUNCTION BETWEEN FLOOR AND
MEDIAL WALL

18. MEDIAL WALL OF THE MIDDLE EAR:
THREE DEPRESSIONS:
1. OVAL WINDOW
2. ROUND WINDOW
3. SINUS TYMPANI
 FACIAL NERVE CANAL
 DOME OF THE LATERAL
SCC:-POSTERIOR AND
LATERAL TO FACIAL
CANAL

19. ANTERIOR WALL OF MIDDLE EAR:-
LOWER 1/3rd:- PLATE OF BONE COVERING
CAROTID ARTERY
MIDDLE 1/3rd:-
1.EUSTACHIAN TUBE
2.CANAL FOR TENSOR TYMPANI
UPPER 1/3rd:-HAS ANTERIOR EPITYMPANIC
SINUS ANTERIOR TO OSSICLE HEADS&CAN
HIDE CHOLESTEATOMA IN CANAL WALL
UP SURGERIES

20. POSTERIOR WALL:-
 ADITUS
 PROCESSUS PYRAMIDALIS
 VERTICAL PORTION OF FACIAL NERVE
 FACIAL RECESS (SUPRAPYRAMIDAL RECESS)
 SINUS TYMPANI (INFRA PYRAMIDAL RECESS)

21. MUCOSA OF TYMPANIC CAVITY:-
 MUCOUS SECRETING RESPORATORY CILIATED EPITHELIUM
 VENTILATION ROUTE FROM MESOTYMPANUM AND EPITYMPANUM
IS VIA TWO SMALL OPENINGS
1. ANTERIOR ISTHMUS TYMPANI
2. POSTERIOR ISTHMUS TYMPANI
PRUSSAK'S SPACE:-SITE FOR CHOLESTEATOMA LATERALLY=PARS
FLACCIDA
MEDIALLY = NECK OF MALLEUS
INFERIORLY=LATERAL PROCESS OF MALLEUS
SUPERIORLY=LATERAL MALLEOLAR FOLD

22. BLOOD SUPPLY OF MIDDLE EAR:-
 FROM BRANCHES OF :
1. MIDDLE MENINGEAL ARTERY
2. MAXILLARY ARTERY
3. ASCENDING PHARYNGEAL ARTERY
4. STYLOMASTOID BRANCH OF POSTERIOR AURICULAR
ARTERY
 NERVE SUPPLY:-SENSORY:-IXth CRANIAL NERVE THROUGH TYMPANIC
PLEXUS
 MOTOR:-
1. TENSOR TYMPANI=MANDIBULAR DIVISION OF Vth NERVE
2. STAPEDIUS=FACIAL NERVE

23. COMPONENTS OF TYMPANIC
CAVITY:
EAR OSSICLES:
 MALLEUS=HEAD,NECK,ANTERIOR
PROCESS,LATERAL PROCESS
,HANDLE
 INCUS=BODY,SHORT
PROCESS,LONG
PROCESS,LENTICULAR PROCESS
 STAPES=HEAD,NECK,ANTERIOR
CRURA,POSTERIOR CRURA,FOOT
PLATE
 LONG AXIS OF STAPES IS ALWAYS
HORIZONTAL

24. MUSCLES OF MIDDLE EAR:
1. TENSOR TYMPANI
2. STAPEDIUS:-SUPPLIED BY A BRANCH OF
MANDIBULAR NERVE
NERVES:
1. CHORDA TYMPANI
2. TYMPANIC PLEXUS

25. EUSTACHIAN TUBE ANATOMY:
2 PARTS
 BONY PART (12mm)
 CARTILAGENOUS PART(24mm)
 MUSCLES ATTACHED:
 TENSOR TYMPANI:
 N.S=MANDIBULAR NERVESEPARATES
TUBE FROM
 OTIC GANGLION
 MANDIBULAR NERVE
 CHORDA TYMPANI
 MIDDLE MENINGEAL ARTERY
 contd

26. CONTD:
2.SALPHINGO PHARYNGEUS:
3.LEVATOR PALATI
N.S FOR THESE MUSCLES=PHARYNGEAL PLEXUS
ARTERIAL SUPPLY OF TUBE:
1.ASCENDING PHARYNGEAL ARTERY
2.MIDDLE MENINGEAL ARTERY
NERVE SUPPLY OF TUBE:
1.PHARYNGEAL Br OF SPHENO PALATINE GANGLION=OSTIUM
2.NERVOUS SPINOSUS(Vc)=CARTILAGE PART
3.TYMPANIC PLEXUS=BONY PART

27. MASTOID AIR CELLS SYSTEM:
 MASTOID ANTRUM:
AIR FILLED SPACE WITHIN PETROUS
PART OF TEMPORAL BONE
 RELATIONS
 RIDGE FORMED BY DIGASTRIC MUSCLE IN THE MASTOID
LIES LATERAL TO SIGMOID SINUS AND FACIAL
NERVE(LANDMARK)
 MAC EWEN,S TRIANGLE
 PETROUS APEX
 GRADENIGO'S SYNDROME
 KOCHER'S SEPTUM