Head And Neck Anatomy- Parts of the Skull (Part 1)

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					#lect 1 : the skull 1

#8 feb

***

introduction

This course is the head and neck. Of course,it is anatomy course. I will give all the
lecture of this course to you. I am the coordinator of this course.

This course is very important to you as a dentist. Much more than histology.
So,you need TO PAY MORE ATTENTION for this course. In fact,I would not
allowed you to miss any lecture,therefore I will take attendance. The attendance
will be taken next sunday . I will post the seat number soon ensyallah. You are
not allowed to miss more than 10 % of the lecture without excuses and 20% with
excuses. If not,you will be deprived from the exam.

The purpose of the lectures is to provide you the complete picture of the
skull,the head and neck,the structure,the surface landmarks, and the components
of those structure. It is in order for you to be able to practice with it in the future.
There will be 3 exam ; 1st,2nd and the final exam. The lab is separated from the
theory and it is one credit hour. (you can read the syllabus by yourself in e-
learning). The slide in hard copy form will be given to the CR. He will be incharged
to distribute it to you. I will not post it at e-learning.

So, I will start the course by describing the skull first. Then,the vertebrae. You had
already learned the thoracic,lumbar,sacral and coccygeal right? This semester
you will learn the cervical vertebrae since they are located in the neck. Of course
there are processes and muscle in the neck. The neck itself is divided into
triangles ; anterior and posterior.

Then you will have to be familiar with the radiographs of the head and neck.
There are different regions on the face,depression as well as the deep regions .
there are temporal,infratemporal fossa,temporal palatine fossa,nose,nasal
cavity,internasal sinuses,oral cavity,larynx and trachea,pharynx. Of course you will
have to learn about the anatomical of the head and neck,the orbit of the eye,the
ear and its location in the part of the skull ( temporal bone),the lymphatic
drainage of the head and neck. Finally,I will teach you the embryology of the head
and neck ( the development of the skull,face,head and neck). -everything stated in
syllabus-



The recommended text for theory is clinical anatomy by snell. For the lab is
grant’s anatomy.

If you want to be excellent in this course , try to study it gradually ; lecture by
lecture because you already studied gross anatomy before. You know,there are so
many structures. Try to develop the skill. not only memorize,try to tie the
information together



***

Slide 2

So,let’s start with the skull. This the view of the skull. As you can see, the skull is
composed of many bones. Some of them are paired while the other are not. So
we start here,you can see this bone here. It is called the frontal bone. The frontal
bone is the concave bone. Then you have these two bones here,the nasal bones.
There is suture in between called the internasal suture. I explained suture later
because its too early to talk about suture. So,first you have frontal bone which is
the concave bone. Nasal bone forming the bridge of the nose. You have here
,maxilla that holds the upper teeth and zygomatic bones here which form the
prominence of the cheek and mandible which form the lower jaw holding the
lower teeth. These cavity are is called orbit of the eye and it have two parts.



***

Slide 3.
This is another view of the skull (lateral). the previous we talked about is the
anterior. This is lateral view.Laterally you can see again the frontal bone : concave
bone.

This bone here is called the parietal bone . you can see it occupies the top of the
head. Just below the parietal bone on each side,there are temporal bone.
Posteriorly you can see occipital bone. Now,here you have mandible (also termed
lower jaw),maxillae(also termed upper jaw), zygoma (also termed zygomatic
bone) and the nose.

***
Slide 4-6

There are 14 bones making up the skull. some of them are paired and the rest of
the other are not paired.

    The paired bones : parietal,temporal,zygomatic,maxillae,nasal
     bones,lacrimal,palatine and inferior conchae.
    The unpaired bone : frontal,occipital,sphenoid,ethmois,vomer and
     mandible.

When I said paired bones,it means two bones. One on each side,left and right.
Unpaired/single bones means only one bone. The bones making up the skull can
be divided into two groups.



   1) Bones that form the cranial cavity
   2) Bones that form the face and nasal cavity


The cranial cavity is the cavity that encloses the brain.so,it’s a cavity and brain
occupies that cavity. The cranial cavity composed of 8 bones.only 2 bones are
paired (parietal & temporal)and the rest are single bones
(frontal,occipital,sphenoid and ethmoid).
***

Slide 7

This slide shows the view of cranial cavity and here is where the brain rest. You
have here the frontal bone and here in the midline (also termed median site) is
occupied by the ethmoid bone. Then you have sphenoid,parietal and temporal
bone. Posteriorly ,you have occipital bone.

Facial bones : zygomatic bones,maxillae,nasal bones,lacrimal,vomer,palatine
bones,inferior conchae and mandible)

***

Slide 8-9

There are 14 bones making up the face and nasal cavity. Only 2 bones are
unpaired (vomer & mandible) and the rest are paired (zygomatic
bones,maxillae,nasal bones,lacrimal bones,palatine bones and inferior conchae).
So,this is face and nasal cavity. So,you have first the nasal bone,two
maxilla,zygomatic bone,and the mandible.

 In nasal cavity there are inferior conchae and vomer. If internal conchae is here
(right)another one is here (left). Since they are called inferior conchae,we assume
that there are superior conchae. With this case,there are superior conchae which
we cannot see here. There are the middle conchae. Superior and middle conchae
do not belong to the same bone as inferior conchae. The inferior conchae
constitute bones by themselves,single bone. meanwhile,the superior and middle
conchae are part of another bones which is called as ethmoid bone.

***

Slide 10

This mid sagittal view show the 3 conchae ; superior & middle as part of ethmoid
bone and inferior conchae.
Q : about inferior conchae

A : it is a part of itself,a bone by itself.there are two.here(right) and here(left)

Do you know what mid sagittal plane? It is very important to know different of
planes. I assume that you were already familiar with the planes because you can
never study anatomy or understand or at least imagine the different structure
without understanding the planes.

Whenever you say sagittal plane,sagittal plane is the vertical plane that separate
left side and right side. mid means in the midline. So,mid sagittal is a vertical
plane in the midline that separate left side and right side. Whenever this vertical
plane is not in the midline it is called para-saggital plane. Now,there is another
vertical plane called coronal (also termed frontal ) plane. Coronal (frontal) is also
vertical plane. It separates the anterior part from posterior part. Finally,
transverse (also termed horizontal ) plane. It means cross sections.This plane
separate superior and inferior planes.

    Sagittal plane – vertical plane that separate left side and right side
    Mid sagittal plane - vertical plane in the midline that separate left side and
     right side
    Coronal plane – vertical planes that separates the anterior part and
     posterior part
    Transverse plane – horizontal plane that separates the superior(upper)and
     inferior(lower) part


***

Slide 11-13



Now,sutures. Skull is composed of many different bones. However these bones
meet with each other and therefore they need to articulate or join with each
other. That is what the suture do. The sutures articulate the bones of the skull
together. They are of fibrous type,so they are fibrous joints called synchrondoses.
The fibrous joint mean that the articulating surfaces of the bone are covered by
fibrous tissue or joined by fibrous tissue. It allow very little amount of movement,
that is why the skull is fix. Imagine that the joint of the bone is synovial joint
which has wide range of movement,so it will move by itself. That would be
ridiculous right? ;0

There are important suture which are the sagittal,coronal and the lambdoid. The
majority of other suture are named or signitive by the bones that are joined by
the sutures.

This is the view of the skull showing for different suture. This is frontal
bone,parietal bone(the top of the skull),the occipital bone (posterior),the
temporal bone. Between the frontal and parietal bone you have this coronal
suture. It is not hard to be remembered becaused coronal means divide posterior
and anterior. It is a suture that is located anteriorly.

Posteriorly,between parietal and occipital bone,you have lambdoid suture. Now,
between the two parietal bones you have the sagittal suture. So,this is the
superior view of the skull which contain parietal and occipital bone. So,here
between the frontal and two parietal bone,we have coronal suture. Joining the
two parietal bones is sagittal suture. Separating the parietal bones or joining the
parietal bone with the occipital bones is the lambdoid suture.



There are many landmarks that you need to know or points that have name here.
The point at the junction of coronal and sagittal suture is called bregma. At the
junction of sagittal and lambdoid suture you have this point here called lambda
point.

Now,I will talked to you about each view of the skull.any question?

Q : how the biopsy of the skull is done
A : we talked about this after class. I explained it to you
***

Slide 14-15

I will talk to you about each of view of the skull. There will be more details to
talked about. Anteriorly,the bones that can be seen are frontal bone,nasal bone
and maxilla. The maxilla is composed of a body and four surfaces. The body
contain the maxillary sinus. Sinus is just cavity contained within the bone. There
are many surfaces of the body named according to what they contribute to or
where is their location. So, you have the nasal surface,orbital
surface,infratemporal surface and anterior surface. you have zygomatic
process,frontal process,palatine process. This 3 processes are named according
to the bones to which the maxillary body joined them.

You have the alveolar process which contain the teeth and there is alveolar
process in maxilla as well as mandible because both of these have the teeth.
Then, you have the intermaxillary suture between the two maxilla. Zygomatic
bone have 2 procesess from frontal and temporal and there is mandible
composed of horizontal body,2 vertical rami (singular ; ramus) and condylar
process,composed of the head and neck



***

Slide 16-18

Here the internal surface of the mandible. I will show you each of this in the
figure. This is the anterior view of the skull. Here you have the frontal bone.
Frontal bone forms the supraorbital margin. Supra means above so it’s the upper
margin of the orbit. In median 1/3,you can see this notch or foramen the having
the same name as the margin,so it is supraorbital notch or supraorbital foramen.
Then, you can imagine the eyebrows are here right? At the location of the
eyebrow,you have superciliary arches. You have one superciliary arch here(right)
and another one here (left). They are on the frontal bone.Between the two
superciliary arches,there is median elevation called the glabella.
This is frontal bone.

You have the maxilla here composed of the body with 4 surfaces. You have nasal
surface forming the lateral wall of the nasal cavity. You have the orbital surface
forming the floor of the orbit. You have anterior surface having the infraorbital
foramen and there is a fourth surface you cannot see here called the
infratemporal surface which form the anterior wall of infratemporal fossa. You
will see this surface in a few minutes whenever I talk to you about the
infratemporal fossa.

You have here the alveolar process contain the teeth. Here you have zygomatic
bone forming the prominence of the cheek. you have this bone one here (right)
and here (left). You can see this process extending superiorly to articulate with
the frontal bone,therefore it is called the frontal process. You have this process
extending laterally to articulate with the temporal bone and therefore it is called
temporal process which participate in forming zygomatic arch together with
zygomatic process of temporal bone.

Now,the processes of the maxilla. You have frontal processes extending upward
to articulate with the frontal bone. The zygomatic process extending laterally to
articulate with the zygomatic bone. There is palatine process which you cannot
see here. It is forming the floor or the major part of floor of the neck. The palatine
process extend horizontally to articulate with the palatine process with the other
maxilla, forming the nasal part of the hard part.

You have here the vomer. Do you remember the nasal septum I talked to you
about in the nasal cavity in the histology? The vomer points the inferior posterior
part of the nasal septum. And here you have inferior conchae.

Here,of course this is again infraorbital foramen in the anterior surface. Here is
mandible. This is here palatine procees and this is another one of the maxilla.

Here is mandible. The mandible composed of horizontal body and two vertical
rami. You have condylar process here(right) and another one here (left) which is
composed of head . the head participate in forming the tempomandibular joint
which is very important to you. You have here in the body externally,can you see
in the median area here,in the midline? This is call symphysis menti. It just the
region in the mandible and can only can be seen externally. Any question?

Q : about the nasal septum. (not so clear)
A : well,it is just about anatomical deviation. That why there is a deviation of size
of nasal aperture or nasal cavity.
Q : would it affect any of the sutures ? (the rest of other question not so clear)
A : they are not articulate. They just projecting into nasal cavity.


Now the triangular of symphysis menti is called mental protuberance.
Protuberance means protrusion. Symphysis menti in the middle and mental
protuberance.

Then you have mental foramen. I think you already familiar with the names of
teeth. The mental foramen is below second premolar. You have a line that is
oblique extending from the mental protruberance . This line is called oblique line.
So here is the oblique line. Symphysis menti,mental protruberance,mental
foramen and oblique line. This is on the body of the mandible,the external
surface.

Now,on the ramus of the mandible,this upper quarter of the ramus is called the
mandibular notch. Anterior to it is coronoid process. Posterior to it is condylar
process composed of head and neck. On the internal surface of the mandible you
have a small protrusion called genial tubercle or mental spine. Externally,opposite
to mental spine is symphysis menti.



You have a ridge here extending upward and backward. This is call the mylohyoid
line. Inferior to is a fossa called the submandibular fossa. Again, genial tubercle or
mental spine behind the symphysis menti. Mylohyoid line extending upward and
backward,inferior to it is submandibular fossa. All of this features are the internal
surface of the mandible.
On the ramus of the mandible,internally in the middle of the ramus,you can see
this foramen called mandibular foramen. This mandibular foramen leads to
mandibular canal within the bone. So,within the ramus (the canal )of the
mandible extending and continuing into the body. Medially,you have protrusion
here called the lingula. Extending from the lingula to the submandibular fossa is a
mylohyoid groove. Again, on the internal surface of the ramus you have
mandibular foramen in the middle of the ramus leading to mandibular canal.
Medial,from the lingula to submandibular fossa is the mylohyoid groove.

Now the only thing left on the mandible is this fossa. There is one fossa on each
side of symphysis menti but on the base. This fossa is called digastric fossa.



***

Slide 19-21

There are 2 orbits that can be seen anteriorly on the skull. The orbit has 4 margins
: supraorbital,lateral,infraorbital and medial margins. These margins are formed
by bones.

The orbit has walls since it is a cavity. It has superior,inferior,lateral and medial
wall. So, this is the orbit and you have this,supraorbital margin formed by frontal
bone. In the middle third of supraorbital margin,you can see supraorbital foramen
or notch. Laterally there are frontal bone and zygomatic bone. These two bones
articulate with each other by processses. This process called zygomatic process of
frontal bone. This is frontal process of zygomatic bone. So, both processes
forming the lateral margin of the orbit.

Inferiorly,the infraorbital margin is formed by the zygomatic bone and maxilla.
Medially,the medial margin is formed by the maxilla,frontal bone and lacrimal.
So,those are the margin not the wall. Again, supraorbital margin is formed by the
frontal bone and we have supraorbital foramen in the middle third. Lateral
margin is formed by zygomatic process of frontal bone and frontal process of
zygomatic bone. The infraorbital margin is formed by zygomatic bone and maxilla.
Finally,the medial margin is formed by maxilla,lacrimal and frontal bones. So ,this
is the just margin.

The wall however are these. For example this is the superior wall or roof,this is
lateral wall,this is inferior wall or the floor and this is medial wall. As you can see
the superior wall is formed by the frontal bone. This part of the frontal bone that
form the superior wall or roof of the orbit is called the orbital plate of frontal
bone. Then,in addition to orbital plate of the frontal you have lesser wing of
sphenoid. Both of these form the superior wall or roof of the orbit.

This is the lesser wing of sphenoid bone. This is one group of lesser wing (right)
and this is another one (left). Between these two groups you have this canal
called the optic canal.

Laterally, lateral wall is form by the zygomatic bone and the greater wing of the
sphenoid.

So,till now you know that there are two parts of the sphenoid,lesser wing
(participating forming the superior wall or roof)and greater wing (participating
forming the lateral). Inferior wall is formed by zygomatic bone and then part of
the maxilla which is call the orbital plate. This floor is also formed by this orbital
plate of palatine wall. This is the greater wing of the sphenoid. this is the orbital
plate of maxilla and this is orbital plate of palatine bone.

Between the greater wing of sphenoid above and orbital plate of maxilla and the
palatine bone,you have here inferior orbital fissure. Between greater wing and
lesser wing of sphenoid you have superior orbital fissure.

The medial wall is formed by ethmoid bone,lacrimal bone and frontal process of
the maxilla. There is another bone that you cannot see here that is sphenoid
bone. So, a small portion of the body of sphenoid bone also contribute to the
formation of medial wall of the orbit. By the way, I’m intending to say things twice
so that you can remember things well.
Again,the orbit has 4 walls ;

   1. Superior wall - form by orbital plate of frontal bone and lesser wing of
      sphenoid. Between two groups of lesser wing there is optic canal
   2. Lateral wall – form by zygomatic bone and greater wing of sphenoid.
      Between greater wing and lesser wing of sphenoid bone you have superior
      orbital fissure.
   3. Inferior wall – form by zygomatic bone,orbital plate of maxilla and in
      addition,the orbital plate of palatine.
   4. Medial – form by orbital plate of ethmoid,lacrimal bone and frontal process
      of maxilla and a small portion of the body of sphenoid bone.

On the orbit,on the medial margin of the orbit,you have anterior lacrimal crest
and posterior lacrimal crest. The anterior lacrimal crest is located on the frontal
process of the maxilla and the posterior process is located on the lacrimal bone.
Between these two crests you has this fossa for lacrimal sac. This fossa leads to
the nasal lacrimal canal.



                                      THE END

				
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