B

(1)     Basilar Papilla (synonym: Papilla of Huschke, spiral ganglion) The organ of corti.
(2)     Battle’s sign: Bruising occurring over the mastoid process . Characteristically associated with fractures of the middle cranial fossa.
(3)     Bezold’s abscess: is an abscess situated deep in the neck (behind { deep to} the sternocleidomastoid muscle) which occurs as a complication of Otitis media and associated with acute coalescent mastoiditis. Perforation of the medial aspect of the mastoid tip into the digastric groove produces a deep seated abscess in the neck. The carotid sheath, parapharyngeal space and the mediastinum may be involved in the process.
(4)     Bills Bar: is a vertical crest of bone in the fundus of the internal acoustic meatus. It is used as a landmark during translabyrinthine surgery. It is named after Dr William (Bill) Foutts House. Anterior to Bills Bar lies the facial nerve.
(5)     Bills Island: is an island of bone left behind on the sigmoid sinus to protect it from intraoperative trauma during the translabyrinthine approach to the cerebellopontine angle. Named for Dr William Foutts House.
(6)     Bills Tongue: It is the small piece of tumor from an acoustic neuroma said to resemble a tongue. It is seen between the inferior compartments during the translabyrinthine approach. Named after Dr William Foutts House.
(7)     Blue mantle of Manasse: is the uniform basophilic staining of bone deposit, particularly in the perivascular spaces typically seen in otosclerosis.
(8)     Blunting: is a term used to denote obliteration of the angle formed between the tympanic membrane and the anterior part of the external auditory canal. Blunting occasionally occurs following repair of anterior perforations of the tympanic membrane.
(9)     Brain Fungus: is a misnomer. It is not a fungus. It is a term to describe the herniation of the meninges with or without brain matter through a defect in the tegmen.
(10)     Breschets Hiatus: (synonym :helicotrema). Helicotrema is a space at the apex of the cochlea allowing communication between the scala vestibuli and the scala tympani.
(11) Bridge: is formed by the lateral wall of the aditus ad antrum. It is attached to the tegmen by the anterior buttress and to the facial ridge by the posterior buttress.
(12) Browns sign: When a vascular tumor (example: glomus) is situsted in the middle ear, blanching occurs as a response to pneumatic pressure applied with a b ulb attached to an otoscope or Siegles speculum. It is said to occur in some, not all cases.
(13) Buttress : Anterior Buttress: bone which connects the bridge to the tegmen.
Posterior buttress: Connects the bridge to the facial ridge. Below the posterior buttress lies the facial nerve, the lateral semicircular canal and the short process of the incus. The posterior buttress continues inferiorly as the facial ridge.

C
(1)     Canal of Contagno:Canal containing the inferior cochlear vein.
(2)     Capitulum (Latin for head): Capitulum Mallei (head of malleus). Capitulum Stapedius( Head of stapes).
(3)     Cerebellopontine (CP) angle:is a triangular space with its base towards the brainstem and its apex directed towards the petrous apex. Its boundaries are (a) Lateral: medial portion of the posterior surface of the temporal bone with its dural covering. Medial: The Brainstem (pons). Posterior: Anterior surface of the cerebellum and the flocculus. Superior: Trigeminal nerve. Inferior: 9, 10, 11, 12 cranial nerves. The CP angle contains the 7th and 8th cranial nerves.
(4)     Citelli’s abscess (synonym : zygomatic abscess of citelli): It is a complication of otitis media in which an abscess forms in the preaural region over the root of the zygoma. This occurs when the zygoma is extensively pneumatized.
(5)     Citelli’s sinodural angle: it is the sinodural angle between the middle fossa superiorly and the posterior cranial fossa and sigmoid sinus posteriorly. It marks the position of the superior petrosal sinus at the junction of the dura of the middle and posterior cranial fossa.
(6)     Coalescent mastoiditis: is a Complication of Otitis Media where small individual cells of the mastoid coalesce into larger cavities filled with pus under pressure. This causes the septae of the various aircells to demineralize causing individual cells to disappear leading to multiple pockets of pus. In extreme circumstances the mastoid can become one large pus filled cavity.
(7)     Cochlea: This is the bony housing of the organ for hearing. It resembles a shell of a snail. Its base is directed towards the bottom of the Internal Auditory Canal and its long axis runs outward, slightly forward and downward from base to apex. It coils for 2 and ¾ turns, a length of approximately 35mm around a central bony axis known as the modiolus which forms the inner wall of the bony canal of the cochlea. The basal turn of the cochlea protrudes into the middle ear and is known as the promontory.
(8)     Cochleariformis processus: is a bony projection that cradles the tendon of the tensor tympani as it extends to the neck of the malleus. It also serves as a landmark to identify the horizontal portion of the facial nerve. The word “cochleariformis” is derived from the latin meaning “spoon shaped” unlike the word “cochlea’’ which in latin means resembling a “snails shell”.
(9)     Cog: is a bony ridge that hangs from the tegmen anterior to the head of the malleus. The cog lies immediately above and slightly posterior to the cochleariformis process. It serves to divide the anterior epitympanum from the remainder of the epitympanum. It also serves as a landmark in identifying the horizontal portion of the facial nerve. Posterior to the cog lies the head of the malleus
(10)     Cone of light: is seen in the anteroinferior part of the pars tensa of the tympanic membrane as a gleaming cone. . This cone of light is caused by the reflection of the incidental rays of light that strikes the tympanic membrane perpendicularly. Absence of the cone of light or multiple cones of light are indicative of a shift of the tympanic membrane, likely due to an underlying pathology in the middle ear.
(11)     Corti, organ of: is the sense organ of hearing and it is set upon the basilar membrane throughout the entire cochlea. It consists of sensory cells with hairs , supporting cells and the tectorial membrane. It is named after Alfonso Corti who described it
(12)     Corti, tunnel of: is a triangular channel, also known as the inner tunnel which is formed by the heads of the inner and outer pillar cells.
(13)     Cortilymph: is fluid in the tunnel of corti, the space of nuel, the outer stunnel and the spaces around the hair cells. This fluid is now believed to be perilymph.
(14)     Cribrose: (latin:- a sieve, a strainer): Macula cribrosa inferior is the small cribrose area deep in the singular canal that transmits the fibers of the posterior ampullary nerve.
Macula cribrosa media is the perforated area at the posteromedial aspect of the fundus of the internal auditory canal and transmits the fibers of the saccular nerve
The superior semi-circular canal ampulla specifically the Macula cribrosa superior is used as a landmark for the lateral end of the internal auditory canal during translabyhrinthine surgery. The macula cribrosa transmits nerve fibers to the utricle and ampullae of the superior and lateral semi-circular canals. Also known as Mikes dot in honor of Michael E Glasscock III.
(15)     Crista: is special sensory neuroepithelium found in the ampullae of the labhyrinth and comprises 3 basic structures, (i) Sensory neural cells containing hairs on the free surface, (ii) supporting cells and (iii) gelatinous substance lying on the hairs and is compose mostly of mucopolysaccharides.
(16)     Crista falciformis: is a transverse crest in the internal auditory canal dividing it into superior and inferior compartments
(17)     Crus commune: is the common duct formed by the superior and posterior semi-circular canals as their non sampullated ends enter the vestibule.

D
(1)     Diplaacusis: is a distortion of pitch sensation. If a pure tone is perceived to sound as though 2 tones were being introduced in combination, it is known as monoaural diplacusis. If the pitch is different from that perceived by the normal ear, is known as binaural diplacusis and is characteristically seen in edndolymphatic hydrops. Echo diplacusis occurs when a pure tone is heard a fraction of a second later and can occur in serous labyrinthitis.
(2)     Donaldson’s line; is an imaginary line extending from the lateral semicircular canal bisecting the perpendicular formed by the posterior semicircular canal. This helps locate the superior limit of the endolymphatic sac. The endolymphatic is typically located in the dura of the posterior fossa medial to the sigmoid sinus inferior to Donaldsons line. This is a general guide to the location of the endolymphatic sac and it varies with periaqueductal pneumartization.
(3)     Dorello’s canal{ The 6th cranial nerve (abducens nerve) runs through a canal of dura between the petrous apex and the sphenoid bone and this is known as Dorello’s canal. The inferior petrosal sinus also passes through this canal to reach the cavernous sinus.

E
(1)     Epitympanum (synonym : Attic): It is located in the middle ear just behind the pars flaccida.
Its boundaries are:
Medial: Petrous apex, the facial nerve and the geniculate ganglion.
Superior: Tegmen tympani.
Lateral: Scutum Pars Flaccida.
Inferior : Tympanic diaphragm
Anterior: The petrous apex, The middle cranial fossa and in well pneumatised bones the root of the zygoma. Posterior Aditus ad antrum.
Contents of the epitympanum: Head of the malleus, body of the incus and their associated ligaments and folds.
The epitympanum is divided into Anterior and Posterior compartments. The compartment anterior to the cog is known as the anterior epitympanic recess and the space behind is the posterior epitympanic recess. The head of the malleus and the body of the incus lie in the posterior epitympanic recess. The anterior epitympanic recess does not contain any of the ossicles. When viewing the tympanic membrane from the external auditory canal, the epitympanum is that portion of the middle ear that lies above the level of the short process of the malleus.
Communications: The epitympanum communicates with the mesotympanum through the isthmus tympani anticus and the isthmus tympani posticus. These openings breach the tympanic diaphragm. The epitympanum also communicates with the mastoid via the aditus ad antrum.

(2)     Eustachian tube: (synonym : pharyngotympanic tube)Named after Bartolomeus Eustachias (1520 – 1574). It consists of 2 parts, a lateral bony part and a medial cartilaginous part. In the adult it is approximately 3.75cms long. The bony part constitutes one third of its length and the cartilagenous the remaining 2/3 . The bony part makes an angle of approximately 400with the horizontal. It is widest at its opening in the middle ear and narrowest at its junction with the cartilaginous part. The cartilaginous part does NOT form a 3600 ring being deficient superiorly. It makes an angle of 1600 with the bony part. The tensor palatii muscle is responsible for opening the cartilaginous part of the eustachian tube which is closed at rest.

F
(1)     Facial recess: (Synoynm: posterior recess, suprapyramidal recess, Lateral facial recess, lateral tympanic recess): it is a depression of variable depth in the posterior wall of the middle ear. It is a term described by William F House and James Sheehy to delineate the area bounded

1. Superior by the fossa Incudis,
2. Inferior laterally: Chorda tympani
3. Medially: Facial nerve.
   It is through the recess that the middle ear can be entered from behind through a surgery termed posterior tympanotomy. The bone that separates the mastoid from the middle ear during a posterior tympanotomy is termed the “tympanomastoid septum”.The facial recess has the shape of a triangle.

(2)     Facial ridge: is the posterior portion of the bony part of the external auditory canal lying over the second genu / vertical segment of the facial nerve. It is a descriptive term and as yet not accepted by the physicians in general.
(3)     Fallopian canal ( synonym facial nerve canal): is a canal which houses the facial nerve in the middle ear.
(4)     Fissulae ante fenestram: is an irregular ribbon of connective tissue that extends through the bony otic capsule from the vestibule just anterior to the oval window (ante fenestram) to the tympanic cavity near the processus cochleariformis. The tissue in the fenestra is continuous with the perilymphatic connective tissue mesh in the labyrinth at one end and with the subepithelial connective tissue in the middle ear at the other end. It has a predilection to be involved by otosclerosis.
(5)     Fossa Mastoidea (synonym: Cribriform area of the mastoid): is a shallow depression about a centimeter posterior to the spine of Henle, the cortex of which is perforated by numerous blood vessels especially in the infant and child.
(6)     Fossula fenestrae cochleae (synonym: cochlear fossa, round window niche): it lies posteroinferior to the promontory. The subiculum lies superiorly.. It is the site of the round window which is closed by the round window membrane.
(7)     Fossulae fenestra vestibuli ( synonym: Huguier's sinus ,fossa of the oval window, stapes niche): Its limits lie bounded superiorly by the facial nerve and inferiorly by the ponticulus.
(8)     Fossula post fenestram: is a connective tissue tract that lies just behind the oval window. It resembles the fissula ante fenestram.

G
(1)     Ganglion: Clusters of neurones outside the central nervous system. Corti’s ganglion : synonym : Acoustic ganglion
Gasserian ganglion, semilunar ganglion: synonym: Trigeminal ganglion.
Scarpa’s Ganglion : synonym: Vestibular ganglion.

(2)     Glasserian Fissure; (Synonym ; petrotympanic suture) is situated in the protympanum. Through this suture passes the anterior tympanic artery (branch of the internal maxillary artery) as it gains access to the middle ear. The Glasserian fissure lies just below the bony opening of the eustachian tube in the middle ear.
(3)     Gradenigo’s syndrome: is a triad of symptoms consisting of (1) pain behind the eye, (2) 6th (abducens) cranial nerve palsy and otorrhea.. These are manifestations of apical petrositis.
(4)    Greisingers syndrome: consists of edema over the posterior aspect of the mastoid (postauricular region) due to thrombosis of the mastoid emissary veins. This usually precedes sigmoid sinus thrombosis and can occur as a complication of otitis media.

H
(1)     Habenula arcuate: is the inner portion of the cochlear basilar membrane.
(2)     Habenula perforata (synonym: Foramina nervosa limbus laminae spiralis): is the opening in the tympanic lip of the limbus permitting the passage of the cochlear nerve fibers.
(3)     Hamulus cochleae: is the osseous spiral lamina that projects beyond the apex of the modiolus. (4)     Hard Angle (synonym: Solid angle): is the solid bone medial to the antrum in the angle formed by the three semicircular canals.
(5)     Helicotrema (synonym; Breschets hiatus): Helicotrema is a space at the apex of the cochlea allowing communication between the scala vestibuli and the scala tympani.
(6)     Helix:is the most peripheral arc of the free margin of the auricle that starts near the tragus.
(7)     Henle (Spine of Henle) {synonym: supremeatal spine): The upper posterior angle of the external auditory canal is marked by a small bony spine. It is an important landmark and is used in Mac Ewen’s triangle to locate the mastoid antrum.
(8)     Henneberts sign: is a positive fistula sign that can be elicited in the presence of a normal tympanic membrane and in the absence of middle ear disease and is due to a lax annular ligament of the stapedial footplate. This sign is seen in syphilis.
(9)     Hiatus canalis facialis: is a dehiscence in the middle cranial fossa that transmits the greater superficial petrosal nerve.
(10)     Hillocks of His: are the 6 developmental hillocks of the auricle that are derived from the 1st and 2nd branchial arches.
(11)     Hitselbergers sign: is anesthesia of the posterior wall of the external auditory canal, seen in acoustic schwannomas. Named after Dr William Hitselberger.
(12)     Huguier (Canal of Huguier) {synonym : iter chordae anterius): is a canal that begins in the medial end of the petrotympanic (Glasserian)fissure through which the chorda tympani exits after it has traversed through the tympanic cavity.
(13)     Huschke (foramen of Huschke) (synonym: foramen tympanicum):: In infants opposing spurs of growing bone on the ventral aspect of the bony external auditory canal fuse, dividing the original external auditory canal causing it too get located superiorly and an inferiorly situated channel that is known as the foramen of Huschke. The foramen closes during late childhood. It is a developmental defect in the antero-inferior aspect of the bony external auditory meatus. The foramen is located at the antero-inferior aspect of the external auditory canal and lies posteromedial to the temporomandibular joint.
(14)     Hypotympanum: is that portion of the middle ear situated below an imaginary line drawn below the lowest part of the circumference of the pars tensa. It is an irregular bony groove. The hypotympanum forms the roof over the jugular bulb. On occasion the jugular bulb can be dehiscent allowing the uncovered jugular bulb to protrude into the middle ear.
(15)     Hyrtles fissure (synonym: tympanomeningeal hiatus): it begins in the hypotympanaum, just below the round window and extends to the posterior cranial fossa. Hyrtl's fissure is a transient anatomic landmark in the developing fetal petrous temporal bone. It closes by the process of gradual ossification around the 24th week of gestation. On occasion it can persist and can be the cause of a perilabyrinthine cerebrospinal fluid fistula in the child.

I
(1)     Incisura terminalis: a cleft devoid of cartilage and is located in the superior aspect of the cartilaginous portion of the external auditory canal. This defect is used to make the endaural incision without the risk of incising the cartilage. This cleft separates the crus of the helix from the tragus and continues up to the bony part of the external auditory canal.
(2)     Infrapyramidal recess (synonym: sinus tympani):Is a space located posteriorly in the middle ear cavity, lying medial to the vertical segment of the facial nerve.

Superior: round window niche, ponticulus, lateral semicircular canal
Inferior: subiculum, round window niche, styloid eminence and jugular wall.
Medial: bony labyrinth.
Posterior: posterior semicircular canal.
Lateral: pyramidal eminence and the vertical part of the facial nerve. Its significance is that diseases like cholesteatoma may reside in this area and can go undetected.
(3)     Inlay technique: is a term used to denote the positioning of the graft that is used to repair a perforation of the tympanic membrane, when the graft is placed medial to the fibrous layer of the tympanic membrane.
(4)     Intact canal wall technique: is a term that was initially used during mastoidectomy to denote that the natural posterior bony part of the external auditory canal had been preserved (not lowered or removed). It has now come to also include reconstruction of the posterior bony part of the external canal.
(5)     Isthmus tympani anticus / Isthmus tympani posticus: are openings situated in the tympanic diaphragm which allow the epitympanum and mesotympanum to communicate with each other.
(6)     Iter chordae anterior / Iter chordae posterior: openings through which the chorda tympani gains access into the middle ear and exits the middle ear.

J
(1)     Jacobson’s nerve(synonym: tympanic nerve): it is the tympanic branch of the glossopharyngeal (Xth cranial nerve) nerve. It runs across the promontory in the middle ear.
(2)     Jugular Bulb:The jugular bulb is the dilatation of the internal jugular vein. There are 2 jugular bulbs. The jugular vein begins at the jugular foramen. At the origin of the internal jugular vein lies the superior jugular bulb which is situated just below the hypotympanum. The inferior jugular bulb lies at the termination of the jugular vein where it unites with the subclavian vein to form the brachiocephalic vein.

K
(1)     Koerners septum (synonym: petrosquamosal lamina): This is a bony partition which divides the mastoid into a lateral squamous and medial petrous section. It is sometimes encountered when approaching the mastoid antrum.. It may be mistaken for the floor of the antrum. It lacks the landmarks of the antrum such as the lateral semicircular canal.

L
(1)     Lateralization: A term used to describe the outward(lateral) drift of the graft used to repair a perforation of the tympanic membrane.
(2)     Lateral Sinus: It begins from the external occipital protuberance and extends horizontally forward in the posterior attachment of the tentorium as far as the mastoid process and then curves downwards and medially in a deep groove on the inner wall of the mastoid process as the sigmoid sinus.
(3)     Lenticular process (synonym: os orbiculare, sylvian apophysis): is the part of the long process of the incus which articulates with the capitulum (head) of the stapes.
(4)     Lilli- Crowe test: it is a test to decide which sigmoid sinus is blocked. When one sigmoid sinus is occluded by thrombus, compression of the opposite normal jugular vein will produce dilatation of the retinal veins and this will be seen on retinoscopy. Compression of the thrombosed side alone will fail to elicit this response.
(5)     Limbus laminae spiralis ossea (synonym: Limbus of the spiral osseous lamina): is the fibroepithelial mound to which are attached the tectorial and Reissners membranes.

M
(1)     Mac Ewens Triangle: It is a triangle formed on the lateral most surface of the temporal bone. The base of the triangle is formed by the suprameatal crest which is formed by the posterior extension of the upper border of the root of the zygoma. A tangent passing through the spine of Henle to reach the suprameatal crest so that it forms an angle of almost450 below the horizontal forms the other side. A perpendicular is dropped from the suprameatal crest to reach the spine of Henle forms the third side. This triangle is used to locate the mastoid antrum. The mastoid antrum lies at justover half an inch (1.5cms) deep to Mac Ewens triangle.
(2)     Masking: Prevention of the non test ear from participating in an audiological test is known as masking. Commonly “white noise” is administered to the non test ear while the audiological is being carried out. This is an attempt to ensure that the ear under audiological evaluation is tested alone without the participation of the contralateral ear in the test.
(3)     Mastoid process: The term mastoid is derived grom the Greek meaning resembles a breast. There is no actual mastoid process present at birth. It is believed that as the child grows the sternocleidomastoid muscle pulls on it causing it to form.
(4)     Medialization: A term used to describe the medial drift of the graft that was used to repair the perforation of the tympanic membrane.
(5)     Mesotympanum: is that portion of the middle ear that lies between an imaginary horizontal plane from the superior to the inferior edges of the pars tensa. It contains the stapes, long process of the incus, long process of the malleus, the round and oval windows.
(6)     Middle ear cavity(Synonym: tympanic cavity) : It has the shape of a biconcave disc. It measures approximately 15mm in height, 123mm in width. The middle ear cavity is further divided into the epitympanum, the mesotympanum, the protympanum and the hypotympanum. It has lateral, medial, anterior and posterior walls.
The lateral limits : formed by the scutum.
Medial: Petrous bone, the lateral semicircular canal, the basal turn of the cochlea, and the facial nerve.
Superior(roof): Tegmen tympani.
Floor: the jugular bulb and its bony covering.
The anterior wall has 4 openings.
From superior to inferior:-

1. The canal of Huguier (iter chorda anterior).through which the chorda tympani exits the middle ear
2. The canal for the tensor tympani
3. The tympanic orifice of the eustachian tube
4. The Glasserian fissure: through which passes the tympanic artery.
   The posterior wall presents from superior to inferior:-
   (a)aditis ad antrum, (b) the pyramid of the stapedius tendon, (c) Facial nerve and its recess along with the sinus tympani
   The contents of the middle ear are the three ossicles, the tensor tympani and the stapedius muscles, the chorda tympani and the tympanic plexus of nerves.

(7)     Middle ear cleft : The middle ear cleft consists of (i) The Eustachian tube, (ii) the middle ear cavity, (iii) the aditus ad antrum, (iv) the pneumatic system of the temporal bone.
(8)     Mike’s dot: The superior semicircular canal ampulla, specifically the macula cribrosa superior is used as a landmark for the lateral end of the internal auditory canal. This transmits the nerve fibers to the utricle and ampulla of the lateral and superior semicircular canals. Named after Michael E Glasscock III.
(9)     Modiolus: it is the central conical shaped central pillar in the cochlea around which the turns of the cochlear are wrapped. It is made up of spongy bone. The neurovascular (The cochlear nerve, and spiral ganglion) bundle passes through the modiolus.
(10)     Morgagni (foramen of Margagni: {synonym: singular canal, foramen singulae, solitary canal): It is the canal for the posterior ampullary nerve

N
(1)     Nuel ( spaces of Nuel): these are spaces between the processes of the phalangeal cells in the organ of corti.

O
(1)     Obersteiner- Redlich zone.(synonym: glial schwann sheath junction):is the transition zone between peripheral myelin and oligodendrital myelin of the cranial nerves. This site shows predilection for acoustic neuroma formation.
(2)     Olivicochlear bundle (synonym: Rasmussens bundle): are efferent nerve fibers passing from neurons in the region of the olive to the cochlear.
(3)     Onlay: A term used to describe the technique of positioning the graft that is used to repair a defect of the tympanic membrane, lateral to the middle fibrous layer of the tympanic membrane.
(4)     Oorts anastomosis (synonym: vestibular cochlear anastam osis:: is the anastomosis between the saccular branch of the inferior vestibular nerve and the cochlear nerve.
(5)     Ostman (pad of fat): is the adipose tissue found between the lateral aspect of the fibrocartilaginous part of the eustachian tube and the tensor veli palatini.
(6)     Otic Capsule: is the bony and rigid outer wall of the inner ear. This is located in the temporal bone. It has three components: the vestibule, semicircular canals, and cochlea. . They contain a clear fluid, the perilymph. The otic capsule develops from the mesenchyme that is differentiating in to embryonal cartilage (precartilage). Eventually the otic capsule becomes the petrous portion of the temporal bone. By the 8th week the mesenchyme condensation has formed a cartilagenous model of the otic capsule. A total of 14 centers of ossification eventually arise and fuse to complete the ossification of the otic capsule. Three layers of bone emerge from the ossification of the cartilaginous otic capsule. They are from outer to inner (i) periosteal bone, (ii) enchondral bone, (iii) endosteal bone.
(7)     Otic hydrocephalus:is a complication of otitis media. Raised intracranial tension, headaches, 6th (abducens) cranial nerve palsy, vomiting, papilledema are present. No brain abscesses are present but the symptoms are likely to be caused by a mild non purulent or localised meningeal inflammation as a complication of otitis media. This meningeal inflammation may have resulted in either an increased production or decreased absorption of cerebrospinal fluid resulting in hydrocephalus.
(8)     Otoconia: are the bio crystals of the otolithic organ. They are composed of calcium carbonate. They are located in the utricle and saccule. They are essential for us to sense linear acceleration and gravity’s pull.
(9)     Otic placode is: a thickening of the ectoderm on the outer surface of the human developing embryo. The ear develops. The ear, including the organ of hearing and balance that is the vestibular system and the auditory system, develops from the otic placode around the third week of development. About the fourth week of gestation , the otic placode invaginates into the mesenchyme adjacent to the rhombencephalon and forms the otic pit. The otic pit then pinches off from the surface ectoderm and forms the otic vesicle.

P
(1)     Paracusis Willisi: is the phenomenon of hearing better in the presence of background (ambient) sound. In this situation the conversational voice is raised above the level of the ambient sound and thus also above the threshold of hearing of the patient suffering from a conductive hearing loss. This causes to appreciate an apparent improvement in hearing.
(2)     Pars flaccida (synonym: shrapnells membrane): is the smaller upper part of the tympanic membrane. It is devoid of the middle layer of radiate and circular collagenous tissue that is found in the pars tensa. The pars flaccida does not have an annulus and lies above the lateral process of the malleus between the notch of Rivinus and the anterior and posterior malleal folds.
(3)     Pars tensa : it forms the larger part of the tympanic membrane. It is situated below the pars flaccida. It is lodged by way of the annulus into the sulcus in the tympanic plate of the temporal bone. It has an umbo which is located at the center of the pars tensa.The umbo marks the attachment of the tip of the handle of malleus. The pars tensa has 3 layers, they are from lateral to medial (i) Epithelial layer, (ii) fibrous layer, (iii) Mucosal layer.
On histopathology the layers consists (from lateral to medial) of (a) Stratum corneum, (b)stratum granulosum, (c) stratum spinosum,(d) stratum basalae, ( e) the basal lamina, (f ) subepithelial connective tissue layer, (g) radiate collagenous layer, (h ) circular collagenous layer , ( I ) submucosal layer, (j ) basal lamina and finally the (k)mucosal layer.
The handle of malleus is enveloped by the pars tensa in the middle layer.
(4)     Perilymphatic duct (synonym: periotic duct): is the membranous tube within the cochlear aqueduct.
(5)     Perilymph gusher: is the profuse flow of perilymph the moment the vestibule is opened due to the abnormal patency of the cochlear duct.This complication is occasionally seen during stapedectomy.
(6)     Perilymphatic (periotic) labyrinth: comprises the fluid tissue space interposed between the membranous otic (endolymphatic) labyrinth and its bony covering, the otic capsule. The perilymphatic cistern of the vestibule, the scala tympani, scala vestibuli, perilymphatic spaces of the semicircular canals , the fissula ante fenestram, the fossula post fenestram and the periotic duct are all considered part of the perilymphatic labyrinth.
(7)     Ponticulus; is the bony bridge that extends from the posterior wall of the middle ear near the base of the pyramidal eminence to the promontory and forms the superior boundary of the sinus tympani.
(8)     Porus acousticus: is the inlet of the medial aspect of the internal auditory canal (IAC) and is located on the posterior intracranial surface of the temporal bone. The 7th and 8th cranial nerves pass through the porus acousticus to enter the IAC. The porus acousticus is situated at the junction of the inner and middle third of the temporal bone and lies closer to the superior margin.
(9)     Promontory: is the basal turn of the cochlea which presents as a characteristic bulge in the mesotympanum of the middle ear.
(10)     Protympanum: is situated in the mesotympanum of the middle ear cavity. It lies anterior to an imaginary line drawn from the anterior mrgin of the tympanic annulus. It leads to the tympanic orifice of the eustachian tube.
(11)     Prussack’s space ( synonym: superior recess of the tympanic membrane): is a small space lying in between the neck of the malleus medially and the pars flaccida laterally. Below it is bounded by the short (lateral) of the malleus and above by the fibers of the lateral malleolar fold. Posteriorly it communicates with the aditus. Inferiorly Prussacks space is bounded by the anterior and posterior malleolar folds.
(12)     Pyramid: is a bony prominence situated in the posterior wall of the mesotympanum. The stapedius muscle arises from it. Behind it lies the facial nerve and above it lies the facial recess and below it lies the sinus tympani.

R
(1)     Randfassernetz of Held: is that portion of the tectorial membrane that blankets the organ of corti.
(2)     Recessus ellipticus: the medial wall of the vestibule presents a posterior area known as the recessus ellipticus to which the utricle is attached.
(3)     Recessus sphericus: The medial wall of the vestibule presents an anterior area known as the recessus sphericus which lodges the saccule.
(4)     Reicherts Bar: cartilaginous and osseous remnants of Reicherts cartilage.
(5)     Reicherts canal: is the ductus reuniens.
(6)     Reicherts cartilage: is the 2nd branchial arch cartilage.
(7)     Reissners membrane (synonym: membrana vestibularis pars vestibularis ductus cochlearis): is the membrane that forms the anterior wall of the cochear duct. It separates the scala media from the scala vestibuli.
(8)     Ring sign: On a contrast enhanced computed tomographic scan, the brain abscess appears as a hypodense area surrounded by an enhancing ring which is encased by increased vascularity due to inflammation and hence the name ‘ring sign’.
(9)     Rivinus, (notch of Rivinus): is a superiorly situated deficiency in the tympanic ring. The pars flaccida is attached to it superiorly. It is bounded anteriorly and posteriorly at the junction where the annulus sweeps toward the malleus to become the anterior and posterior malleolar ligaments.
(10)     Rosenmuller( fossa of Rosenmuller) {synonym: pharyngeal recess): is a recess situated in the nasopharynx posterior to the Taurus tubarius which is known as the prominence of the eustachian tube.
(11)     Rosenthal (canal of Rosenthal)(synonym: spiral canal of the modiolus) :are canals situated in the modiolus for the spiral ganglion.

S
(1)     Santorini’s fissures: are 2 fissures in the cartilage of the auricle. They are vertical fissures located in the anterior part of the external auditory canal cartilage in isthmus (the bony-cartilaginous junction).They allow communication between the external auditory canal and that of the area around the parotid. Named for Giovanni Domenico Santorini
(2)     Scalae: are three compartments (scalae) in the cochlea , (1) scala vestibuli, (2) scala Media, (3) scala tympani. The scala media contains endolymph and ends in a blind sac. The scala media contains the organ of corti, the hair cells and other neural structures responsible for hearing. The scala media is separated from the scala vestibuli by Reissners membrane. While the scala tympani is separated from the scala media by the basilar membrane.
The scala vestibuli and scala tymoani contain perilymph and communicate with each other via the helicotrema.
(3)     Scarpa’s ganglion:is the peripheral ganglion of th vestibular system of the 8 th nerve.
(4)     Schwartzed’s sign:is a pale ‘flamingo’glow that can be seen emanating from behind the tympanic membrane in patients suffering from active otosclerosis. The pink glow is due to increased vascularity indicative of an active otosclerotic focus. Schwartze’s sign when positive is considered by many to be a contraindication for surgery.
(5)     Scutum (synonym: scutum of Leidy, lateral epitympanic bony wall): is the part of the squamous portion of the temporal bone that forms the lateral wall of the epitympanic recess.
(6)     Shrapnells membrane (synonym: pars flaccida); is the smaller upper part of the tympanic membrane. It is devoid of the middle layer of radiate and circular collagenous tissue that is found in the pars tensa. The pars flaccida does not have an annulus and lies above the lateral process of the malleus between the notch of Rivinus and the anterior and posterior malleolar folds.
(7)     Sigmoid sinus: the sigmoid sinus forms the posterior boundary of the mastoid bone. It is a continuation of the lateral sinus. The sigmoid sinus begins superiorly when the lateral sinus reaches the temporal bone to curve downwards in a groove of the mastoid process. The sigmoid sinus ends in the jugular bulb which is situated just below the hypotympanum.
(8)     Singular canal{synonym: foramen singulae, solitary canal, foramen of Morgagni): It is the canal for the posterior ampullary nerve
(9)     Sinodural angle (synonym sinodural angle of Citelli, Citelli’s angle)) is the angle between the middle cranial fossa (tegmen antri) superiorly and the posterior cranial fossa and sigmoid sinus posteriorly. It marks the location of the superior petrosal sinus at the junction of the duraof the middle and posterior cranial fossa
(10)     Sinus tympani: is a space located posteriorly in the middle ear cavity lying medial to the vertical segment of the facial nerve.
Superior: round window niche, ponticulus, lateral semicircular canal
Inferior: subiculum, round window niche, styloid eminence and jugular wall.
Medial: bony labyrinth.
Posterior: posterior semicircular canal.
Lateral: pyramidal eminence and the vertical part of the facial nerve. Its significance is that diseases like cholesteatoma may reside in this area and can go undetected.
(11)     Solid angle (synonym; hard angle) is the solid bone medial to the antrum in the angle formed by the three semicircular canals.
(12)     Stria vascularis: is the highly specialized and vascular spiral structure located on the internal surface of the spiral ligament in the scala media.
(13)     Subiculum: is a ridge of bone inferior and posterior to the round window. The subiculum forms the inferior limit of the sinus tympani.

T
(1)     Tegmen Antri (synonym: tegmen mastoideum): is the roof of the mastoid separating the middle cranial fossa and its contents from the mastoid antrum.
(2)     Tegmen tympanum: is the roof of the middle ear cavity separating the middle cranial fossa and its contents from the middle ear.
(3)     Temporal bone: This is the bone that houses the organ for hearing and balance. The temporal bone has 5 components, the petrous, squamous, mastoid, tympanic bone and the styloid process. It has 2 striated muscles, the tensor tympani and the stapedius muscle. 2 major blood vessels , The internal carotid and the sigmoid sinus / jugular vein. It has several passages that connect the temporal bone to external structures like the eustachian tube. The facial nerve traverses through the temporal bone
(4)     Tentorium Cerebelli: is the layer of dura mater that serves as a roof for the cerebellum and also acts as the floor for the occipital lobes of the cerebrum.
(5)     Tobey Ayer Test: In unilateral sigmoid sinus thrombosis pressure on the jugular vein on the normal side produces a quick rise in cerebrospinal fluid pressure equivalent to compressing both jugular veins in a normal subject. Compression of the thrombosed jugular vein fails to produce a rise in CSF pressure. When a lumbar puncture has been performed in a patient with suspected jugular vein thrombosis observation of the changes in CSF pressure while performing this maneuveur explained above, helps determine which jugular vein is thrombosed. This test is also termed the Queckenstedt test when it is used to determine spinal canal stenosis.
(6)     Tractus spiralis foraminosus (synonym: tractus tegmentaliscentralis) : is the area on the medial wall of the vestibule through which passes the cochlear nerve from the internal auditory meatus to the cochlea.
(7)     Trautmanns triangle: is formed posteriorly by the sigmoid sinus, superiorly by the superior petrosal sinus and the tegmen and anteriorly by the posterior semicircular canal. This triangle identifies the location of the posterior fossa dura.
(8)     Tulio phenomenon: consists of vertigo and nystagmus on exposure to high intensity acoustic stimuli and is an indication of a fistula in the bony wall of the semicircular canals. It seems to occur only in the presence of an intact tympanic membrane with an intact ossicular chain.
(9)     Tympanic diaphragm: is a series of mucosal folds and suspensory ligaments. It separates the mesotympanum from the epitympanum. The components of the diaphragm are (1) The head of the malleus, (2) The body of the incus, (3) lateral and medial malleolar folds (4) tensor tympani folds, (5) posterior incudal ligament and (6) lateral and medial malleolar folds. Only 2 passages breach the diaphragm. They are the anterior and posterior isthmuses. It is via these openings that the mesotympanum communicates with the epitympanum.
(10)     Tymanic membrane ( TM .) :forms the lateral wall of the middle ear cavity. It consists of 2 parts , the pars tensa and the pars flaccida. It lies obliquely in the external auditory canal. The handle of the malleus right up its tip is included in the umbo ( latin for the boss of a shield). A vertical and horizontal line passing through the tip of the handle of the malleus divides the pars tensa into 4 quadrants, anterosuperior, anterinferior, posterosuperior and posteroinferior. The nerve supply of the medial aspect of the tympanic membrane is from the tympanic plexus. The auriculotemporal nerve (from the 5th cranial nerve) supplies the anterior part of the lateral aspect of the TM while the auricular branch of the vagus supplies the posterior quadrant of the lateral aspect of the TM.
(11)     Tympanomastoid fissure: is situated in the posterior inferior aspect of the bony part of the external auditory canal. It represents fusion between the mastoid and tympanic parts of the temporal bone. It transmits the auricular branch of the vagus (Arnold’s ) nerve.
(12)     Tympanomeatal angle: The tympanic membrane is placed obliquely in the external auditory canal. The posterior quadrant of the tympanic membrane is more lateral than the anterior quadrant. The angle that the anterior quadrant of the tympanic membrane makes with the bony part of the external auditory canal is called the tympanomeatal angle.

U
(1)     Umbo: is situated in the pars tensa of the tympanic membrane. It is the center of the slight concavity. It marks the attachment of the tip of the handle of the malleus. It is also the center through which passes an imaginary line which divides the tympanic membrane (pars tensa) into 4 quadrants. Umbo means boss of a shield in latin.
(2)     Utriculo-endolymohatic valve of Bast: is a valve characterised as a thickened portion of the utricle. It functionally separates the utricle from the dilated proximal part of the endolymphatic sac.

V
(1)     Voits anastomosis: is a small nerve that leaves the superior division of the vestibular nerve to anastamose with the saccule.
(2)     Volkmans canals: are canals in bone other than Haversian canals which allow blood vessels to pass through.
(3)     Von Troltsch (spaces of Von Troltsch):consists of 2 spaces.. (1) The anterior spaced. It lies between the anterior malleolar fold and that part of the tympanic membrane anterior to the handle of the malleus. (2) The posterior space lies between the posterior malleolar fold and that part of the tympanic membrane posterior to the handle of malleus.

W
(1)     Wrisburg (anastomosis of Wrisberg); is the anastomosis seen between the 7 th cranial nerve and the nervus intermedius.

Z
(1)     Zygomatic abscess of Citelli: is a complication that can occur in otitis medi\a in which an abscess forms in the preaural region over the root of the zygoma.