 Hello everybody, today we will be talking on temporal bone CT. Temporal bone consists of five osteos parts namely the peatress, quamus, mastoid, tympanic and stoiline. The auditory apparatus consists of external ear, middle ear, inner ear. In middle ear we will be looking at hypotempanum, mesotempanum, epitempanum, all the six walls of the middle ear, the ossicles. In the inner ear we will be looking at the oscious labyrinth. Critical structures in relation to the temporal bone are the nerves and the vascular structures. The structures situated within or in close relation to the temporal bone are at risk of injury in cases of temporal bone trauma. Let's start with the axial anatomy. I have stack of images to learn the anatomy. We are going from down up and this is a magnified or retargeted, magnified view of the right ear. As you go from down up, you are seeing the part of the mandible that is a remus, the styloid process and the mastoid tip. You are going up, this is the styloid process, the head of the mandible, mastoid bone, you are the mastoid air cells are not pneumatized. As you go up, you will see the external auditory canal, the membranous part and the bony wall of the external auditory canal. Immediately here to the tympanic membrane you are seeing part of the hypotempanum, here you are seeing the internal carotid artery, the internal jugular bulb, all the jugular bulb, the TM joint and do not forget to see these two holes that is a foremen ovale, foremen spinosum, hypotempanum, internal carotid artery, this is a jugular bulb which is not high riding and is not dehesin. Anteriorly you will see the eustachian tube, eustachian tube here. The first structure to meet in the inner ear is going to be your basal tone of the cochlea. Now one more structure that you should look at is this canal which is the cochlear aqueduct. Remember it is in the lower cuts in the same orientation as that of the internal auditory canal but it is much lower down. Again this is nothing but the internal carotid artery going up, basal tone of the cochlea, basal turn, this is the round window. Now you are looking at the mesotempanic part of the middle ear. You will start seeing the ossicles. Now anteriorly you already saw the eustachian tube. Our structure here is the tensitempanic. You will see two parallel lines, the handle of the malleus, the long process of the incus. Now after the basal turn in the higher cut you will start seeing more of cochlea, the apical turn, part of the middle turn and posteriorly you will start seeing the semicircular canal. Now posteriorly here sits the sigmoid sinus. So this is the bony part of the sigmoid plate. You go a little higher, you will see two dots now. Malleus, lengthy form process of incus and this is the step piece. So naturally this area becomes the area of the oval window. Now posterior wall of the middle ear, you will see this alphabet W. This is the facial nerve recess, this is the pyramidal eminence and this is the sinus tympani. Now inner ear structures, cochlea. So this is seen as a stack of coins, apical turn and the middle turn. This is part of the vestibule. This area, the bone ear is important. This is the area of fistula antifinistrum. In cases where the patient has definitely a hearing loss, conductive or mixed type and the CT looks normal, look at this area fistula antifinistrum. This area is part of the vestibular aqueduct. This is part of the posterior sinus canal. So higher you will see the vestibule, you will see part of the oval window, part of the internal artery canal and we are in the lower sections of the internal artery canal. So this is the cochlear nerve aperture. Remember seventh nerve is higher, seven up, cochlear nerve is down. So this is the opening of the entry of the cochlear nerves or cochlear nerve aperture. This is the vestibular nerve opening going to the vestibule. Part of the vestibule is seen still in the epitome panem but we are not at the ice cream cone appearance. This is the malleus incus. Always remember malleus is anterior, incus is posterior. This is the epitome panem. The vestibular aqueduct is better seen. This is just a part of lateral sinusoid canal. This is the posterior sinusoid canal. Now this is the epitome panem with the ice cream cone appearance of the occipal head of the malleus. Short process of the incus and part of the body of the incus. So this is incus, the cone is the incus and the ice cream ball is the malleus. This forms a figure of eight epitome panem, a diatis toadantrum and mastoidantrum. Sometimes you will see this thick bony septum called the coinus septum. Now inner ear structures that you can see is internal artery canal, part of the cochlea, posterior knee is the vestibule, lateral sinusoid canal, posterior sinusoid canal part. It's a vestibular aqueduct and this is the horizontal portion of the facial nerve which goes under the lateral semiscellular canal which you will appreciate on the coronal. Now higher cuts, this is the good part of the internal acoustic canal. The medial most part is called as porous acousticus. Now laterally in the internal artery canal you will see this hair in bend appearance. This is the labyrinthine portion of the facial nerve. This is the genu of the facial nerve and this is the horizontal or tympanic segment of the facial nerve. We are still in the epitome panem. Now only a part of ice cream cone is seen of the ossicles. Again figure of eight is very well seen. Mastoidantrum, coinus septum, a diatis toadantrum epitome panem and in the inner ear you will see the vestibule, lateral semiscellular canal part, posterior semiscellular canal. This is again part of the lateral, the posterior as you go higher you will see that this is the part of the superior semiscellular canal. So this is the petrus bone that you finished on axial section. So this forms a triangle like structure. Now from here we will see the still images and just recapitulate our anatomy. Going from down up again for an oval, for a spinosome. This blue arrow shows the jugular spine. You should look at it when you are suspecting glomus juculari tumor. This is your jugular bulb. This is showing the sigmoid plate. These are the mastoid air cells. These are the mastoid trabacule. This is a TM joint. A section above it shows you the internal carotid artery. This is the part of the middle ear anteriorly will be your eustachian tube. This gray structure here is a tensor tympanide. This is the external artery canal. Jugular bulb. Interestingly in this case there is a focal dehiscence that is absence of bony wall of the jugular bulb. So this patient can present with tinnitus as this is directly seen in the middle ear in the region of the hypotropanide. Now you have the inner ear structures, the basal turn of the cochlea. The red arrow shows the round window niche, vestibular aqueduct, cochlear aqueduct, eustachian tube with the tensor tympanide area. This structure, magnified image shows you the stack of the coin that is cochlea, vestibular aqueduct. This is the region of the mesotmpanum because you can see most of the ossicles here, part of the malleus, lentiform process of incurs, head of the stapes. Here you are seeing the W. Blue arrow shows the sinus tympanide. This bony spike is the pyramidal evidence gives attachment to the stepedius tendon and laterally this is the facial nerve recess. Section ahead above shows you the internal artery canal, vestibule, horizontal portion of the facial nerve. The figure of eight is better seen here with the epitmpanum consisting of the ossicle head of the malleus, part of the body and short process of incurs, a diatostoid anterum, mastoid anterum, coenuse septum, vestibule, lateral semisimucanal, posterior semisimucanal, internal artery canal, middle turn of the cochlea. Section above this is the better appreciation of internal artery canal with the facial nerve, the hairpin, labyrinthine portion, genu, tympanic portion. This is the crystal falsiform is better appreciated on coronal. This is part of the ice cream, remaining part of the ice cream cone. So you are above this section. So epitmpanum, adiatostoid anterum and part of the mastoid anterum. These are the limbs of the superior semisimucanal. Now let's go on to the coronal stack of epiges going from front to back. You will see the TM joint. This is the internal carotid artery. These are the mastoid air cells with a trabacule and this is the external artery canal, the superior wall, the inferior wall. This is the scutum attachment for the tympanic membrane. This is the head of the malleus. This is the anterior process attached to the tympanic membrane. This air column is the trusac space. The inner ear structures that you are going to see is the cochlea, apical turn, middle turn. This is the entire middle ear epitmpanum, mesotempanum, hypotempanum. As you go one section posteriorly, you will see the apical turn, middle turn and you should look at this structure. This is the facial nerve. Now this is the ossicle. If you trace that ossicle, this is the part of the malleus and this is the incus. So you have to identify the malleus, the incus and this is you've just finished the cochlea, the chucklea that I call and you're going to start with the basal turn but at this level you have to look laterally and superiorly. You will see this makes eye appearance. This is the facial nerve. This is the labyrinthine segment and this is the tympanic again labyrinthine portion and the tympanic portion. This is the scutum, rusac space, hypotempanum, epitempanum. Roof of the middle ear is the tegment tympani, roof of the mastoid air cells is tegment mastoidium. This is the styloid process. You are at the jugular bulb here. Now this ossicle is the incus. This is part of the stepis. Now this is the basal turn of the cochlea, promontory. This is the area of the oval window. This is the facial nerve. This is part of the internal acoustic canal with Christa falsiformis. So this is the internal auditric canal. This is the medial part is here. This is a porous acousticus internal auditric canal with the Christa falsiformis dividing to superior part and inferior part. So here will be your cochlear nerve. This will be the seven up that is seventh nerve. This part of the inner ear is important forming a mermaid tail is the basal turn of the cochlea. This is the promontory. This area is the vestibule, the chest and the abdomen of the mermaid and the central is the oval window. The hands in the ballerina pose are the semi-silver canals, superior semi-silver canal, lateral semi-silver canal and this area here is the facial nerve. You are still at the tegment tympani going posteriorly lateral semi-silver canal part of the oval window and if you observe this structure this is the round window. You go posteriorly. You will start still seeing the semi-silver canal and this is a posterior semi-silver canal and this structure which you see immediately this is the hypoglycemic canal. This is the mastoid tip and these are the mastoid air cells. So again you are still seeing the posterior semi-silver canal. Let's see the still images. Tegment tympani, scutum, the air column is the rousac space, head of the malleus in the epitome panum. So this is the entire middle ear. You are not really appreciating the hypotempanum much here. So I told you the chakli that is the cochlea, apical turn, middle turn and go superiorly and laterally you will see the snake side, labyrinthine portion, tympanic portion. Left ear, exonotri canal, middle ear, cedar, cochlea like a swirl or like a snail, apical turn, middle turn, the snake side, labyrinthine portion medially, tympanic portion laterally. This is the tegment tympani. Here the most important area as I told you before the mermaid medially is the internal artery canal, crystal falsiformis, this is the basal turn, romontri, oval window, vestibule, superior semisemical canal, lateral semisemical canal, facial nerve, this entire thing is the middle ear, epitempanum, mesotempanum, hypotempanum, exonotri canal, scutum. This is the lentiform process of the incus. The right here just to show you vestibule, here is the vestibule red arrow points towards the basal turn, a lateral semisemical canal, superior is not very well seen, internal artery canal, scutum. As you go posteriorly I showed you the from the mermaid, the basal turn, the tail of the mermaid you go posteriorly and you will see the hole here of air containing area which is the round window. So this is the oval window, round window, superior semisemical canal, lateral semisemical canal, facial nerve and as you go posteriorly you will see this area, this is the vertical portion of the facial nerve and it comes out of the stylo mastoid for a man. For ENT surgeons the medial wall of the middle ear is very important and actually what you see from down up is the area of the promontory because this is the basal turn, this is the area of the oval window and you also want to see the lateral semisemical canal but it is better seen on the coronal, promontory with the basal turn of the cochlea, oval window, lateral semisemical canal and the facial nerve. I want to stress upon a point here sometimes there is a bony bump here above the superior semisemical canal, it is nothing but the arcuate eminence. A slide or two on ossicles, head of the malleus, so this is the malleus, this is the anterior process, this is the handle, this is the incus, body, short process, long process and lentiform process. So this head sits here and we actually cut, you will see the ice cream cone, head of the malleus, body, part of the body and short process. This is head of the stepes, the crure and the foot plate or the base which sits at the oval window. So these are the two parallel line, handle of the malleus and part of the incus, a section above will show you malleus, lentiform process of the incus and this is the stepes. So this naturally is the area of the oval window. Again to show you this is the area of fistula antifenestrum. In the higher cuts where you are in the epitmpanum you will see this ice cream cone, head of the malleus, short process of the incus is this and part of the body, so part of the body short process. Ossicular chain on coronal anatomy, this is the malleus, this is the incus, this is the area of the stepes and the base or the foot plate of the stepes and in this patient I purposely kept this abnormal area, abnormal slide where there is ossification of the area of the oval window. So there is no oval window proper like you saw it on the other section but I wanted to show you the stepes very well. So the base is absolutely adherent and there is bony plate there in the region of the oval window. So this concludes our anatomy of the temporal bone. Thank you.