Chapter 7 Lecture B Facial Bones

By: Colin Everhart

This slide is showing the temporal bone in there are 2 temporal bones the word temporal bone comes from the Latin word meaning the passage of time. This is a lot of time where the appearence of gray hairs start to form for the first time what are the important parts of this bone that you should know is the zygomatic process and the zygomatic process is where the temporal bone is going to meet the zygomatic bone.

The zygomatic process is actually not on the zygomatic bone.

Sometimes that can be a little confusing.

I've highlighted the structures you need to know in the previous lecture video and I'll do the same thing here.

Chapter 7   Lecture B Facial Bones

Again you need to be able to identify the zygomatic process you probably will in lab too again it depends on exactly who you have as your lab instructor and together the zygomatic process where it meets the zygomatic bone is going to form zygomatic arch and you also need to know the mandibular fossa which is where the mandible mandibular condilel is going to actually form a joint you need to know the mastoid process which is going to be posterior to the external acoustic or external auditory canal or meatus both mean the same thing as well as the styloid process here now again the zygomatic arch itself is going to be where the zygomatic process is going to meet the zygomatic bone so this whole region right here would be the zygomatic arch other important structures that you should know are things like the jugular foramen the jugular foramen is going to be the area where the jugular vein is going to pass through and then there's also the carotid canal and the carotid canal as you would imagine by the name is going to be where the carotid artery is going to pass through and you can see both these on the inferior surface of the skull.

You could see them on some of the other diagrams that are found in your chapter our next important bone is the sphenoid bone and the sphenoid bone kinda looks almost like a bat I like to think of this as the batman bone.

Looks kinda like a bat it also is a specific bone because specifically important one because it thought of as the keystone of the cranium and what. This means is that this sphenoid bone is going to pass and cover the very base of the entire cranium and span the entire with the cranium and there is a couple important parts and the sphenoid bone there is a greater wing and a lesser wing and the greater wing is going to be more lateral to the lesser wing.

We can see the greater wing here and you saw it labeled on some the other diagrams also the lesser wing is located here some of other important structures to know are the hypotheseal fossa of the sella turcica know you can just know that it's called the sella turcica which is an important part the sphenoid bone and I'll highlight the lesser wing and the greater wing. This is the posterior view at the bottom of this slide and then some the other important parts of this bone are the optic canal the optic canal would be where one of the cranial nerve passes through and it's the cranial nerve that actually goes from the eye back to the brain.

Where the optic nerve will pass cranial nerve two.

That's an important opening to know and then there are some other openings you don't need to know those again that may be different from lab but in lecture you are not responsible for them our next slide is showing the ethmoid bone and the ethmoid bone has kind of a complex shape it kinda looks almost like a a cube and it has the cribriform plate the cribriform plate is located right here it's kind of on the superior surface of the ethmoid bone and the very center the cribriform plate is a region that sticks up superiorly called the crista ghali the bottom of the ethmoid bone there is a region called the perpendicular plate which you'll be able to see it in the skull especially in lab and on some of the diagrams and also you can see the middle nasal concha.

The inferior nasal concha is not part of the ethmoid bone when we take a look at the skull over on the left side of this figure you could actually see the perpendicular plate at the tip of this arrow.

It's actually seen with in the nasal cavity itself.

The cribriformplate helps to form the roof of the nasal cavity and the floor of the interior cranial fossa and there are receptors in the nasal cavity located in this area then there's the crista ghalli which is the triangular process that is sticking up of the cribriform plate the perpendicular plate is going to project inferiorly into the superior part the nasal septum and then extending medially from the lateral masses are these nasal conchi.

The ethmoid plate the ethmoid bone is a very important on bone to make sure that you take a look at in lab and again it's kind of a more distinct looking bone and one just one quick note about the crista ghalli the crista ghalli is actually going to be attaching to the outermost layer of the brain and this outermost layer is called the your dura mater our next slide showing the facial bones so we've gone over the eighth cranial bones now for the facial bones there are 14 of them and these 14 bones only the mandible and the vomer are unpaired.

As you can see from this diagram the rest of them are going to be paired.

Again only the mandible and the former are on pair the rest of them are all going to be paired and as a rule the facial skeleton of man is much more elongated than that of women.

Let's go through the mandible first and the mandible is shown on this diagram the mandible is our lower jaw bones kindof a u shaped bone it's the largest strongest bone of our face and some of the important structures that you should know here are one of the joints which is called the temporomandibular joint as we'll learn in Chapter 8 joints are named for the bones that are going to mete or articulate and this happens where the mandibular condyle the condylar process is going articulate with the mandibular fossa of the temporal bone you should also know the mandibular foramen which you can see on the medial the inside of the jaw the alveolar process which is the process where the teeth are going to form joints the mental foramen the body of the mandible and the Ramus of the mandible.

The mandibular body is going to anchor the lower teeth superior border the alveolar process contains the socket.

Dental sockets and then the mental foramen again a foramen is one of these openings that you learn about in Chapter six and a foramen is in this case is the opening along blood vessels and nerves to pass to the skin of the chin the next slide is showing the maxillary bones or the maxillae.

The term maxillae are going to be plural again they are paired up.

Just because the mandible is by itself don't think that's the same thing for the maxilla there are two maxilla bones and they're are fused medially they form upper jaw the central portion of the facial skeleton and the maxillae are going to carry the upper teeth in there alveolar processes which forms the joints and.

We can see the alveolar process is here there's also the palatine processes which you can't actually see on this diagram you would have to look at a superior view the maxillae in order to see the palatine processes we also have the zygomatic process which you saw on another diagram as well.

Again make sure that you're aware of the palatine process the palatine processes and there is an additional suture which is actually going to going to form a joint between these two maxillae.

That would be the median palatine suture our next facial bone is going to be the zygomatic bone commonly called the cheekbone and again you can see zygomatic bone located right here articulates with the zygomatic process of the temporal bone which we looked at earlier and the zygomatic bones are gonna form the prominence in the cheek that that we know.

Well then there's also the nasal bone and again there are two nasal bones forming the bridge of the nose they articulate with the frontal bone superiorly the maxillary bone laterally and the perpendicular plate of the ethmoid posteriorly there's also going to be hyaline cartilage that's attached to the external nose and a little kinda memory trick to help you remember some of these bones if we start with the most medial bone we have the nasal bone and then we have the maxillary bone then we have the lacrimal bone and the ethmoid.

Again if we start medially and we move in a lateral direction and NMLE these letters will help you remember these four bones moving from medial to lateral.

Again we have N the nasal bone the maxillary bone the lacrimal bone then we have the ethmoid bone.

Even though again these diagrams are kind of in color you want to make sure that you're looking at the skulls in lab as well because those are not going to be in color unfortunately.

The next facial bone is the lacrimal bone the lacrimal bone is going to be where the tear ducts are located the lacrimal sack and there's really no specific bony landmarks to be aware of for the lacrimal bone just knowing that we have two of them and they are facial bones then we have the palatine bones which you actually can't see on this view we have to look at this slide to see the palatine bones notice there is the suture called the median palatine suture which I mentioned on a previous slide which is going to connect both palatine bones and then the next bone is an unpaired bone and it would be the vomer bone you can only really see the vomer bone from the an anterior view.

On this view we can actually see the vomer notice the vomer is going to be directly inferior to the ethmoid bone and the ethmoid bone has the middle nasal concha as well as the perpendicular plate then the inferior nasal concha they are thin curved bones in the nasal cavity they project medially from the lateral walls in the nasal cavity and they are just inferior to the ethmoid bone.

The inferior nasal concha each of these are also separate bones as well and you can see these on this next diagram here we can see the ethmoid bone with the superior nasal concha middle nasal concha and then separately is inferior nasal concha nasal bone and then the maxillary bone with the palatine process shown. This is another view where the concha are actually removed.

You can see the nasal bone the perpendicular plate of the ethmoid and then the vomer right below it now when we think about the orbits and the nasal cavity these are formed from many several bones it's really amazing how many of these bones are actually going to be responsible for the orbits and the nasal cavity.

You should be aware of the ones that form the orbits orbits are bony cavities where the eyes are going to be firmly encased cushioned by a lot of fatty tissue the muscles that move the eyes and the tear producing lacrimal glands are gonna be housed in these areas but the walls of the orbit are formed by parts of seven bones and the seven bones are going to include the frontal bone they're going to include the sphenoid bone the zygomatic bone you can see the frontal bone here the sphenoid bone the zygomatic bone we also have the maxilla bone. This is another view of the zygomatic bone here and we have the maxilla bone specifically palatine bone as well the lacrimal and also the ethmoid bone.

Seven bones in total are going to be responsible for making up the orbit of the eye.

Quite a few bones the nasal cavity is going to be constructed of bone and hyaline cartilage roof of the nasal cavities formed by the cribriform plates of the ethmoid which we can kinda see in this view and the depressions under the cover of the conchi are the lateral walls called meatuses there's a superior middle and inferior meatus and we can see those labeled at the top the slide superior middle and inferior meatuses and then the next slide is showing the paranasal sinuses the paranasal sinuses there are four of them and there's five skull bones the frontal sphenoid ethmoid and paired maxillary bones and these are all going to contain mucosa associated.

There is mucosa that is lining these specific sinuses.

There is mucosa lined and they are air filled sinuses and these are all called paranasal sinuses because they cluster around the nasal cavity they're small openings that connect the sinuses to the nasal cavity.

It kinda acts two-way streets air enters the sinuses and enters the sinuses from the nasal cavity mucus is formed by the sinus mucosa draining into the nasal cavity.

There can be mucus that drains into the nasal cavity what we know as post nasal drip not too much fun around this time the year mucosa of the sinuses also help to warm and humidify the inspired air that we breathe in they also lighten the skull.

One of their functions is to lighten the skull and also the mucosa of the sinuses can warm and humidified the air you will learn more about sinuses when you get to the respiratory system next semester but again it's a two-way street.

Air is going to enter the sinus mucus can also drain into the nasal cavity but you need to be able to recognize these different sinuses.

You may have a diagram on the test where you are labeling them we have the pair of frontal sinuses the ethmoid sinuses the sphenoid sinuses and the maxillary sinuses and if we look at a side view again we see the same four sinuses from the medial aspect the next slide showing the hyoid bone and though it's not really part of the skull it's kinda lie just inferior to the mandible and the anterior neck and is unique because it's the only bone of the body that does not articulate directly with another bone does not articulate directly with another bone.

Instead it's going to have certain ligaments these are called the stylohoid ligaments they're going to be connected to the styloid processes of the temporal bones.

Those were two items that you need to learn on the previous slide bony landmarks and these parts the hyoid bone is gonna raise and lower during swallowing and speech and one kinda interesting fact about hyoid bone is if the hyoid bone is broken then the medical examiner knows that the person was strangled.

It would be very difficult to break the hyoid bone.

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