Hello everyone Today we are going to discuss about temporal bone Now these are a pair of irregular bones Forming part of the lateral wall of the skull over here you can see This is the teritorry of temporal bone As well as they form part of the interior And Part of base of the skull over here you can see So if you see it from inside in the interior particularly part of middle cranial fossa And posterior cranial fossa this portion belongs to the temporal bone In front lies greater wing of sphenoid And behind there lies occipital bone in between temporal bones there lies body of sphenoid So this is the teritorry of temporal bones And over here in the norma lateralis also you can see part of the temporal bone So this is the left temporal bone I have and if you correlate it with the articulated skull See this is how it looks like from norma lateralis If you see it from inside see this This is how it looks like This is how it is oriented So this is the teritorry of temporal bone Now let's see individual parts so first is the squamous part This is a flat translucent bony plate you can see over here with a zygomatic process So this is squamous part which is forming part of the temporal fossa in Norma lateralis Posterior to that is a mastoid part you can see over here And It forms a mastoid process Over here you can see so this is mastoid part The third is a triangular tympanic plate or tympanic part you can see here That contributes in formation of the mandibular fossa and external acoustic meatus you can see here This is the tympanic part The fourth and most important one is the petrous part here you can see That forms part of the middle and posterior cranial fossa And that lodges middle and internal ear here you can see this is petrous part of the temporal bone And 5 one is styloid process or styloid part of the temporal bone you can see here This is a long slender bony process Which is directed downward forward and medially So this is styloid process and styloid part of the temporal bone So by and last there are five parts squamous part, mastoid part, tympanic part, the petrous part Okay and last one is the styloid part of the temporal bone Now let's see individual Parts in detail So first is the squamous part of the temporal bone over here you can see This has got an outer surface And inner surface you can see over here And two borders the superior border over here you can see Which is having convexity upward and an antero inferior border this one So these are the parts of Squamous temporal bone Now let's see first the outer surface or external surface Now this is forming part of temporal fossa in norma lateralis So if you correlate with the articulated skull this is the outer surface of squamous part of the temporal bone Now posteriorly it is limited by a crest this is termed as Supra mastoid Crest This you can see over here And this Crest will provide attachment to temporal fascia Whereas the outer surface along with the other parts origin to temporalis muscle Now as we discussed the squamous part of the temporal bone is continuous behind with mastoid part of the temporal bone And the junction between these two part is an imaginary line Which is basically a suture which gets fused Which is situated approximately 1.5 cm behind this Supra mastoid Crest Somewhere over here and this portion is providing attachment to occipital belly of occipital frontalis And auricularis posterior muscle Sometimes you may find a suture between these two Now this portion of the squamous temporal will form roof and upper half of posterior wall of external acoustic meatus The rest of the boundaries are formed by tympanic plate So here you can see this is roof and this is the upper half of the posterior wall This is contributed by squamous temporal bone Now if you draw an tangent passing from postero aspect of the external acoustic metatus like this So between supramastoid crest this tangent And poster Superior margin of external acoustic Meatus like this There is formation of a triangle over here you can see This is termed as macewen triangle or Supra meatal triangle And approximately 12 to 15 mm deep there lies tympanic antrum or mastoid antrum So that much thickness of the bone is there over here Now at the time of birth the bone is just 2 mm in thickness And the thickness increases approximately at the rate of 1 mm per year till it achieves adult size that is 12 to 15 mm Now antro inferiorly over here sometimes you may see a bony spicule Related to this triangle this is termed as suprameatal spine over here you can see there is a bony spicule Now in front of external acoustic meatus The external surface of the squamous temporal will form a zygomatic process over here you can see Now this will articulate with corresponding temporal process of zygomatic bone And together they form zygomatic Arch
Let me show you the same in articulated skull So over here you can see this is the external surface of squamous temporal And that is giving a zygomatic process Which will articulate with the temporal process of zygomatic bone This is zygomatic bone and this is its temporal process together they fuse And they form a continuous zygomatic Arch Now let me show you the same in separate bone So this is left zygomatic bone And this is its temporal process Now the temporal process of zygomatic bone will articulate with The zygomatic process of temporal bone both are having a serrated margin
like this they fuse And they form a complete zygomatic Arch Now looking at the zygomatic process of temporal bone It has has got an outer surface an inner surface Upper border and lower border The initial formation of this zygomatic process will show a concave upper surface Which is lodged by tendon of temporalis And then it shows formation of zygomatic process with upper and lower border,
outer and inner surfaces The distal end is serrated and that we have discussed it will merge with Or it will join with corresponding temporal process of zygomatic bone Now the outer surface is subcutaneous The upper border laterally provides attachment to Galea Aponeurotica Whereas medially it provides attachment to temporal fascia The lower border will provide origin to Masseter muscle and that origin also extends to the inner surface Now if you see the inferior aspect of zygomatic process It will split to form an anterior route and a posterior route Now at the junction there is a tubercle which is called as tubercle at the root of zygoma Now this tubercle will provide attachment to lateral ligament of temporal mandibular joint Now basically temporal mandibular joint will be form over here in relation to this mandibular fossa Which is bounded in front by anterior
route And laterally by posterior route Now the anterior route itself will form an articular tubercal Which will take part in formation of temporal mandibular joint Which will also related to head of the mandible Posterior to this Anor route there is a depressed area this is termed as mandibular fora Which will come in contact with head of the mandible Now the posterior route most posteriorly It will form sometimes a bony Elevation over here in this case you can see this is termed as post-glenoid tubercle Now in quadrupeds this tubercle is very much prominent And that will prevent posterior dislocation of head of the mandible Which will be related somewhere over here But in human it is regress So over here this is the posterior route This is post glenoid tubercle Now The upper border of posterior route over here you can see This is posterior route so this is its upper border Now upper border of posterior route is continuous as Supra mastoid Crest That we already discussed Whereas The upper border of posterior root in front is continuous as upper border of zygomatic process So this is basically the posterior root of zygoma Or zygomatic process Now talking about mandibular fossa this entire region is the mandibular fossa Which has got an anterior articular area And posterior non-articular area let me connect head of the mandible with it And that will give you a better idea So this is mandible, this is its ramus coronoid process And condyloid process, this is head Now this head along with the mandibular fossa Will form The temporal mandibular joint Basically there lies a fibrocartilagenous disc in between that will Divide the joint cavity into upper and lower compartment But over here you can see the head of the mandible will Lodge in the anterior Articular area of the mandibular fossa along with this articular tubercle like this See over here The head also comes in contact with the articular tubercle The posterior part of this mandibular fossa is contributed by this tympanic plate And that is non articular Basically it is related with the parotid gland or here lies the part of parotid gland So all around this articular area of mandibular fossa will provide attachment to Joint capsule So that is about external surface of squamous part of the temporal bone Now let's see the internal surface or cerebral surface over here you can see Now this will form part of the lateral boundary of middle cranial fossa See over here in articulated skull you can clearly make out Now this is the cerebral surface of squamous part of the temporal bone over here you can see It is having multiple irregular bony markings Which are produced by reciprocal bony markings on the Temporal lobe of the brain over here there lies temporal lobe Plus it may show certain vascular markings Which are produced by anterior and posterior branches of middle meningeal vessels Now below this cerebral surface will merge with the anterior surface of petrous temporal bone Sometimes you may find a suture separating these two So this is regarding cerebral surface of squamous temporal Now the borders as I mentioned it has got a superior border which is convex upward Now this will articulate with the corresponding squamosal border of the parietal bone So let me show you the parietal bone So this is the parietal bone it has got outer surface and inner surface And this is its inferior border Now the inferior border In anterior part is related to the sphenoid In the middle part it is related to the squamous temporal bone And in posterior part it is related to master temporal bone So three different parts of the bones are related to it So what we are concerned here with the superior border of squamous temporal That will articulate with the middle part of this inferior border of Parietal bone like this Basically this borders are beveled And this beveled borders will fuse with each other will fix with each other like this This is how they join So in front this inferior border is related to the sphenoid over here you can see This is temporal bone, squamous part And this is the mastoid part of the temporal bone So this is how it gets fused Now second border of the squamous temporal is anteroinferior border over here you can see Now this will articulate with corresponding squamosal border of greater wing of sphenoid Let me join greater wing of sphenoid So this is sphenoid And in the midline you can see this is body Now above there are two lesser Wings you can see over here And this are the greater wing of sphenoid So this is left this is right greater wing, now Over here you can see this is the Squamosal border of Greater wing of sphenoid If you see it from laterally Now this will Join with anteroinferior border of The square temporal like this Okay And this Fusion you have seen in norma lateralis along with the frontal bone These four bones when they fuse together they form an edge shaped Suture which is term as pterion This is how the articulation takes place See this, the greater ring of sphenoid has joined with the Anteroinferior border of Squamous temporal So if you see the same thing in articulated skull this is the temporal This is part of the Parietal bone and this is greater wing of sphenoid So over here the line of fusion you can see between anteroinferior border of squamous temporal And squamosal border of greater wing of sphenoid see this So here there forms pterion Between frontal bone, parietal bone, squamous temporal and greater wing of sphenoid You can clearly make out the line of fusion So this is pterion So this is regarding squamous part of the temporal bone Now next is the mastoid part of the temporal bone Which is situated posterior to the squamous part And line of fusion is approximately 1.5 cm Behind this supramastoid crest somewhere over here that we already discussed So this is the teritorry of mastoid part of the temporal bone Now looking at its part it has got an outer surface See over here And which is continuous below as a mastoid process It has got an inner surface which is forming sigmoid sulcus Which lodges sigmoid sinus and it also forms part of the posterior cranial fossa it's lateral boundary So this is inner surface This is outer surface with mastoid process Plus it has got a posterior border And a superior border So these many parts are there for mastoid temporal Now the external surface is rough And below it is continuous as mastoid process Which is a bony prolongation Now basically this mastoid process its external aspect Provides attachment to sternocleidomastoid Now when the baby learns head holding At that time this mastoid process is formed because of pulling action of sternocleidomastoid Now other two muscles attach over here behind sternocleidomastoid are Splenius capitis and longissimus capitis So 3 muscles are attached over here along the external aspect of mastoid process Sternocleidomastoid, splenius capitis and longissimus capitis Now the inner surface of the mastoid temporal as we have discussed It will have a sigmoid sulcus Which will lodge sigmoid sinus over here you can see So part of the sigmoid sinus is formed by this inner surface of mastoid temporal Beyond This surface is continuous with posterior surface of petrous temporal bone This is posterior surface of petrous temporal Now this is the sigmoid sulcus And sometimes you may find opening of a foramen which is lodging Emissary vein and externally it opens Somewhere at the junction between mastoid and occipital So let me show you the same in the articulated skull So this is the mastoid process and here there will be the Suture between mastoid and occipital bone, that is occipital mastoid suture And over here you can see there is a foramen Which is called as mastoid foramen which will allow passage of an emissary vein That will communicate posterior auricular vein over here with the sigmoid sinus inside Additionally this foramen will also allow passage of meningeal branch of occipital artery So that is regarding inner surface of the mastoid temporal Now if you see the inner surface of mastoid process Which is situated just below The inner surface of this mastoid temporal over here just focus In this area there is a notch Now this Notch is termed as digastric notch Just because it is providing attachment to posterior belly of digastric Now just medial to that there is a groove Now this groove will lodge occipital artery So two important features are found along the inner aspect or inner surface of mastoid process One is digastric notch and another is the groove or occipital artery Now the borders of mastoid temporal as you know it has got a superior and a posterior border So the superior border as we have discussed it will articulate with the inferior border of parietal bone Let me join it again like this And together they form parietomastoid suture over here you can see Whereas the posterior border will articulate with the Corresponding border of occipital bone
let me join these two together again See this This is how they are joined So they form a, they form an occipital mastoid suture like this And over here the parietal bone will join with the occipital bone So there is a meeting point between parietal bone, occipital bone and The mastoid bone over here this is termed as asterion So this is regarding mastoid part of the temporal bone Now next is tympanic part of the temporal bone Now as you know it is a triangular bony plate over here you can see And it has got a superior border An inferior border A lateral border over here And two surfaces anterior And posterior Now looking at the superior border This is related to the mandibular fossa And mandibular fossa is part and parcel of squamous part of the temporal bone So between these two there are forms a fissure This is termed as squamo-tympanic fissure Between squamous part and tympanic part of the temporal bone So this is termed as squamo-tympanic fissure Now from the middle cranial fossa Lateral aspect of this anterior part of Petrous temporal this portion of bone is termed as tegmen tympani And it will send a downturn edge over here you can see So this portion or this bony plate of tegment tympani Will divide the initial squamo-tympanic fissure into Two sub fissures which are termed as Petro-squamous and petro-tympanic fissure The petro means it is a part and parcel of petrous temporal bone So the tegmen tympani is part of petrous temporal bone So the petrous temporal will divide the initial squamo-tympanic fissure into petro-squamous in front And petro-tympanic fissure behind Now medial aspect of the petro-tympanic fissure Will allow passage of three important structures namely Chorda tympani nerve which will come out from the middle ear cavity Second is anterior tympanic branch of maxillary artery Which will enter inside the middle ear cavity from infratemporal fossa And third is it will allow passage of anterior ligament of malleus So these three structures are related to medial aspect of this petro-tympanic fissure Now second border is inferior border, over here you can see Now it is related to inferior aspect of the petrous temporal bone See over here so this is the inferior border And along its course it will split to enclose this styloid process So that will form a sheath that covers styloid process So this is inferior border Okay and that is also receiving attachment of parotid fascia Now third is lateral border over here you can see And along with the posterior surface it will form Anterior wall, floor and lower half of posterior wall of external acoustic meatus Now this will complete the entire external acoustic meatus Which will provide attachment to cartilagenous part of external acoustic meatus Now posteriorly this lateral border will merge with this mastoid temporal And mastoid process and in between these two there is a fissure Over here you can see this is termed as tympano-mastoid fissure And this will allow passage of auricular branch of vagus So that is about lateral border Now let's see the surfaces So as you know it has got two surfaces anterior surface Now which is related to mandibular fossa And that will form non articular part of mandibular fossa And here there lies parotic gland between joint capsule and the anterior surface So if you join the head of the mandible like this This is anteriorly related to Joint capsule And in between these two there lies part of parotic gland Over here Now next is posterior surface as we have discussed along with the lateral border It will form anterior wall, floor and lower half of The posterior wall of external acoustic meatus Or the Bony part of external acoustic meatus And medial aspect of this posterior surface bears a sulcus That is termed as tympanic sulcus which will lodge tympanic membrane Now the entire tympanic plate is not completely developed at the time of birth And instead of it is observed in the form of a tympanic ring So this is regarding tympanic plate or tympanic part of the temporal bone Now next is and most important one is the petrous part of the temporal bone Which is pyramidal in shape and that has got a base Which will merge with the inner surface of squamous part and mastoid part Over here you can see this will be the base of petrous temporal Next it has got an apex which is blunt And that is directed forward medially and slightly upward Let me show you in articulated skull So this will be the base of petrous temporal Here will be the apex which is blunt and that is related to Body of sphenoid and part of the greater wing of sphenoid So here will be the apex, here will be the base Plus it has got three surfaces anterior surface Which will form part of middle cranial fossa Posterior surface that will form part of posterior cranial fossa And an inferior surface over here you can see So if you hold it like this here will be the anterior surface Here will be the posterior surface and below It will have inferior surface, so this is the inferior surface of petrous temporal Additionally it has got three borders Superior border between anterior and posterior surface And anterior border And a posterior border So by and large it has got a base An apex three surfaces anterior posterior and inferior plus three borders Superior, anterior and posterior borders Now regarding base that will merge with the inner surface of squamous temporal And mastoid temporal So this will be the base Next is the apex as you know it is blunt and it is directed forward, medially And slightly upward Now When you see it along with the articulated skull over here you can see It is related to body of sphenoid and somewhere over here will be The greater wing of the sphenoid, now together this will form a foramen Which has got a lacerated margin so that is termed as foramen lacerum Now in living foramen lacerum will lodge some cartilage And the apex of this petrous temporal will show opening of carotid canal over here you can see Now the carotid canal starts from the inferior surface of petrous temporal over here you can see And that will lodge petrous part of the internal carotid artery Which has got a curved course And that is found along with sympathetic plexus around So the internal carotid artery will enter inside the petrous temporal From its inferior surface and that will emerge out from the Apex And temporarily this internal carotid artery is observed Within the foramen lacerum and later on it will enter inside cavernous sinus Which will be seen somewhere over here Additionally the Apex of petrous temporal will provide attachment to a ligament That is termed as petrous sphenoidal ligament Now medially it is attached to the sphenoid Now this is the sphenoid, this is body of sphenoid And this is dorsum sellae On either side of that there is formation of posteroglenoid proces Now below to that there is a bony spicule you can see over here Now over here there is attachment of petrous sphenoidal ligament So if we join these two together It will give you a better idea So here they are joined and you can see over here This is that bony spicule On either side of dorsum sellae And this is apex of petrous temporal so here there is attachment of petro-sphenoidal ligament Now below to that just above the apex below to that ligament And just above the Apex there passes abducent nerve And here it pierces dura matter and finally it enters into cavernous sinus Which is situated on either side of body of sphenoid So the under surface of this ligament is intimately related to abducent nerve So that is regarding apex Now let's see the surfaces first comes the anterior surface Now just next to the apex anterior surface shows a trigeminal impression you can see over here There is a depressed area And There lodges trigeminal ganglion within a cave or within a pouch of dura matter That pouch is termed as trigeminal cave or cavum trigeminale And within that cave there lodges trigeminal ganglion Now this impression also indents Superior border Near the Apex you can see here there is a formation of a notch And this is related to motor and sensory route of trigeminal nerve Deep to to the attachment of tentorium cerebelli Now next to that trigeminal impression there is a depressed area you can appreciate over here Now that forms roof of internal acoustic meatus And next to that there is an elevated area Over here you can see This is termed as arcuate eminence and this is produced by underlying Superior semicircular Canal of internal ear So three structures related to the interior surface Trigeminal impression, a depressed area and arcuate eminence Now rest of the Interior surface Which is in relation to the internal surface of squamous temporal over here you can see This bony plate is termed as tegmen tympani Part of it we have already discussed So this is tegmen tympani And from behind forward it forms a continuous roof of Tympanic antrum Middle ear cavity and bony part of the auditory tube So these three structures are lying over here And there is a continuous bony roof formed by tegment tympani Now a down turnage of that tegmen tympani will divide the Squamo-tympanic fissure into petro-squamous and petro-tympanic fissure that we already discussed So here is a tegmen tympani Now In this region over here you can see there will be Tympanic cavity or middle ear cavity deep inside And this portion of tegmen tympani will form roof of middle ear cavity Now in that portion There are two hiatuses and groove you can see over here One is medial, one is lateral So medial one is for greater petrosal nerve and lateral one is for lesser petrosal nerve So this is termed as hiatus for greater petrosal nerve Which is continuous as a groove And this one is termed as hiatus for lesser petrosal nerve Both are found in the roof of middle cavity within tegment tympani Now the hiatus for greater petrosal nerve will allow passage for greater petrosal nerve Which is a branch of facial nerve and it will go towards foramen lacerum So if I join Sphenoid bone again You can better appreciate the hiatus reaching to the foramen lacerum So here you can see this is the hiatus and that will go towards foramen lacerum So the greater petrosal nerve which is piercing roof and that is a branch of facial nerve Will reach to the upper part of the foramen lacerum And over here as we have discussed there is carotid canal Which is surrounded by sympathetic plexus So there forms a deep petrosal nerve from the sympathetic nerves And the greater and deep petrosal nerve will join to form nerve to pterygoid canal or vidians nerve And that will pass through this pterygoid canal to reach to the Pterygopalatine fossa which is situated just in front on on the interior aspect of this canal over here Now second hiatus is for lesser petrosal nerve Now lesser petrosal nerve is a branch coming from tympanic plexus And tympanic plexus is formed over promontory Now promontory is an elevation Found over the medial wall of middle ear cavity So from the medial wall from tympanic plexus lesser petrosal nerve is formed That will pierce the roof which is formed by tegmen tympani And that will come out through this hiatus and will reach to Foramen ovale over here you can see that is another oval shaped foramen found in the greater wing of the sphenoid Over here you can see Now it will pass through that foramen ovale and will end up into o ganglion Which is found in the infratemporal fossa So that is about Hiatus and groove for lesser petrosal nerve Now as I mentioned it will form a continuous roof of tympanic antrum, tympanic cavity And bony part of the auditory tube Now if you see it from in front You will clearly appreciate two Canal over here you can see The upper one is Canal for tensor tympani And lower one is is the Bony part of the auditory tube So the upper Canal lodges tensor tympani muscle And the lower Canal forms bony part of the auditory tube Now next is posterior surface And the most important feature in the posterior surface is internal acoustic meatus It is 1 cm in depth and it is in line with the external acoustic meatus Now it will allow passage of three structures namely facial nerve Vestibulo-cochlear nerve and laybrinthine artery Now at its lateral end That meatus will be divided by a horizontal bony plate into upper and lower compartment Now let me explain that in a diagram So over here you can see this is left internal acoustic meatus like this And from this and from its medial end three structures will pass Vestibulo-cochlear, facial its motor and sensory route As well as Labrinthine artery So these structures will enter inside the internal acoustic meatus Which is approximately 1 cm And its lateral end will be divided by a horizontal Crest into upper and lower part So from the upper part from its anterior aspect There is facial canal through which the facial nerve will pass Whereas posterior part of the upper half is formed as Superior vestibular area Which allows passage of superior division of vestibular nerve In the lower half anterior aspect is showing a spiral shape multiple foramina That is termed as tractor spiralis foraminosus through which the cochlear nerve passes And posterior part in the lower compartment Is divided into two inferior vestibular area that will allow passage of Inferior division of vestibular nerve and most posteriorly there is a small foramen That is termed as foramenn singular That will allow a twig of vestibular nerve And that will supply ampula of posterior semicircular Canal So that is regarding internal acoustic meatus Now lateral to that there is a depressed area you can see here Which is indistinct in adults But it is very much pronounced in case of newborn Now this is termed as sub arcuate fossa it lodges some folds of dura matter and blood vessels Now below to that you will find an oblique sleet You can clearly appreciate over here Now this is termed as Aqueduct of vestibule and it lodges Saccus and Ductus Endolymphaticus which are filled with endolymph Now most laterally the posterior surface is continuous with the inner surface of the mastoid temporal And at the there is formation of sigmoid sulcus So this is regarding posterior surface Now next is the inferior surface here you can see Now this is left temporal so if you hold it like this And if you compare it with normal basalis this is how it looks like So in front this is the greater wing of sphenoid And this is squamous part of the temporal bone Over here you can see So here will be greater wing of sphenoid, this is the mandibular fossa of squamous part And posteriorly it is related to basio occiput And this jugular process of occipital bone Like this Okay So let's see the features So below the apex there is a quadrilateral area you can see over here Now this will provide attachment to levator veli palatini muscle This portion Now next to that there is carotid Canal And that will Lodge internal carotid artery with sympathetic plexus around That will run within the petrous temporal & come out from apex of petrous temporal That we already discussed Now next to this carotid canal there is a depressed area This is termed as jugular fossa and this will form interior wall of jugular foramen And basically this fossa will lodge superior bulb of internal jugular vein Now how the jugular foramen is formed let's see Let's connect it with the occipital bone Now this is occipital bone This is foramen magnum, this is squamous part of occipital bone And this is jugular process it also includes occipital condyles And over here there is an articular facet And medial to that articular facet there is a jugular Notch over here I'm talking about this portion so this will come in contact with the jugular fossa And together they form Jugular foramen, like this Okay So here there is formation of jugular foramen Anterior boundary is formed by jugular fossa of petrous temporal And posterior boundary is formed by the jugular Notch of jugular process Now this jugular foramen is divided into three compartment Medial, intermediate and lateral compartment So the medial compartment will allow passage of inferior petrosal sinus From the middle compartment there passes three cranial nerve 9,10th and 11th Plus meningeal branch of ascending phyringeal artery And lateral compartment will allow passage of internal jugular vein Now lateral to the notch this is an articular facet and behind to that there is a Groove You can appreciate it when I bring it closer see this there is a Groove Now this groove is nothing but terminal part of sigmoid sulcus Now we know sigmoid sulcus is contributed by medial surface of Mastoid temporal and if we join these two together you can clearly appreciate That groove which is found over jugular process is the terminal part of sigmoid sulcus you can see over here See this there is a continuous groove So initially it is contributed by the Mastoid temporal And its terminal part is contributed by this jugular And finally it forms the jugler foramen Now the lateral compartment lodges internal juglear vein So obviously over here The sigmoid sinus which is lodging in the sigmoid Sulcus will terminate into internal jugular vein So over here there is commencement of internal jugular vein Now as I mentioned there is a depressed area in jugular fossa This will lodge Superior bulb of internal jugular vein So this is about jugular fossa and there is a bony plate over here you can see Between carotid canal and jugular fossa Now here you can see a small foramen This is termed as tympanic canaliculus Which will allow passage of tympanic branch of glossopharyngeal nerve Now this Branch will enter deep inside into the middle ear cavity Where over promontory it will form tympanic plexus And a branch from tympanic plexus that is lesser petrosal nerve That will come out from this hiatus for lesser petrosal nerve that we already discussed So this is tanympic canaliculus Now if you closely observe this jugular fossa Along its lateral aspect over here you can see one to two small foramina These are termed as mastoid canaliculus And auricular branch of vagus will pass through it Now we already discussed that In relation to the lateral border of tympanic plate with the mastoid process There is formation of tympano mastoid fissure So from mastoid canaliculi over here the auricular branch of vagus will enter inside And through this tympano mastoid fissure the auricular branch of vagus will come out So this is mastoid canaliculus that is found in the lateral aspect of jugular fossa Now lateral to that jugular fossa There is an articular facet you can see over here Now this will articulate with corresponding articular facet Over jugular process of occipital bone Now let me show it again So this is jugular process and over here there is a corresponding articular facet Now these articular facets of petrous temporal And jugular process will join together by a primary cartilagenous joint And this is how these two bones are joined with each other Okay So here there is an articular facet for primary cartilagenous joint Now another thing to to observe in the inferior surface is There is formation of a notch in front of carotid canal Over here you can see there is a notch this is termed as pyramidal notch So that Notch you can appreciate from posterior surface And that is also observed from inferior surface this is pyramidal Notch Lodging inferior ganglion of glosso pharyngeal nerve At the apex of this Notch deep inside you can clearly appreciate a small foramen This is termed as cochlear canaliculus And aqueduct of cochlea will be lodge inside Now that is containing paralymph so through this cochlear canaliculus The paralymph comes in contact with sub arachnoid space which is having CSF So paralim is in connection with CSF through this cochlear canaliculus Now lateral to this jugular fossa Over here you can see this is inferior border of tympanic plate That we already discussed And that splits to enclose styloid process So that is all together a different part of the temporal bone This is styloid part of the temporal bone And this is Mastoid process So between mastoid process and styloid process there is a foramen you can see over here This is termed as stylo-mastoid foramen Now facial nerve will come out of it from the middle ear cavity And it will also allow passage of stylo-mastoid branch of posterior auricular artery So these two structures are passing through stylo-mastoid foramen So this is stylo-mastoid foramen It is lying deep to the mastoid process Now one important thing to understand over here is you know the mastered process develops at 2 years of age So before that The facial nerve which is emerging out from this foramen is exposed to the surface So any surgery which is done behind auricle over here The auricle will be over here & if a surgery is performed behind auricle in this area Care should be taken not to injure facial nerve So that is about inferior surface of petrous temporal bone Now let's see borders as you know there are three borders Superior, anterior and posterior border So the superior border will provide attachment to tentorium cerebelli And the attachment encloses Superior petrosal sinus So if you see it an articulated skull over here there will be attachment of tentorium cerebelli And that will enclose entire posterior cranial fossa And that will divide it into Supra tentorial and infratentorial compartment So here there will be superior petrosal sinus Now near the apex we already discussed there is a notch And that is lodging sensory and motor route of trigeminal nerve That Notch is a continuation of trigeminal impression So that is about Superior border Now let's see the anterior border Now anterior border over here is related to greater wing of sphenoid And between these two they form sulcus tube Which lodges cartilaginous part of auditory tube So let me join Sphenoid With the temporal bone Over here this is the greater wing of sphenoid and we are talking about this Posterior border of greater wing of sphenoid So if you join these two together and if you see it from below See this they are joined and if you see it from below The junction will form sulcus tubae And this will lodge cartilagenous part Now if you see from in front deep inside there is Bony part of the auditory tube That is formed by tegmen tympani that we already discussed And its continuity is in the form of sulcus tubae Which is lodging cartilagenous part of auditory tube So entire auditory tube will be found over here Now lateral aspect of the Interior border will merge with the inner surface of the squamous part of the temporal bone And the the line of fusion is sometimes observed in the form of suture And this is particularly the tegment tympani which is fused over here And that we already discussed that over here there forms a continuous roof And that lodges this bony part of the auditory tube And Canal for tensor tympani Now posterior border over here you can see medial it is related to basio occiput And laterally it is free & that forms part of jugular foramen that we already discussed So if we see its medial aspect Posterior border it is related to this basio occiput And over here at the junction it lodges inferior petrosal sinus Now inferior petrosal sinus in front is in connection with cavernous sinus And behind it opens into internal jugular vein So inferior petrosal sinus is considered as first tributary of internal jugular vein And over here you can see lateral aspect of this posterior border is free And that is in relation to formation of jugular foramen Now last part of temporal bone is styloid process or styloid part of the temporal bone It is developed from cartilage of second pharyngeal Arch And that is enclosed by splitting of inferior border of tympanic plate you can see here So it will be in relation to inferior surface of petrous temporal And with the inferior border of tympanic plate Now this styloid process is a long slender bony spicule approx. 2.5 cm in length And that is directed downward forward and medially Now it provides attachment to three muscles and two ligaments Namely Stylo-glossus, Stylohyoid and stylo-pharyngeal muscle And two ligaments Stylohyoid and stylo- mandibular So the stylohyoid process plus three muscles plus two ligaments together they are turned as styloid apparatus Now let's see attachment of the muscles over styloid process So first comes the Stylo glossus which is attached over here along the anterior aspect near the tip And that is supplied by hypoglossal nerve 2nd is stylohyoid which is attached along the posterior aspect midway between base And tip somewhere over here and that is applied by facial nerve And third is stylopharyngeus that is attached along the medial aspect near the base And that is supplied by glossopharyngeal nerve So the thing to remember is there are three muscles attached to Styloid process And all these three are supplied by three different nerves Now both the ligaments stylohyoid and stylomandibular They are attached to the tip, the stylohyoid is a derivative of second pharyngeal arch And stylomandibular ligament is formed by condensation of deep cervical fascia So the 3 muscles, 2 ligaments and styloid process are termed as styloid apparatus So that is about temporal bone Hope you understood well Thanks for watching