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Anatomy Made
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part #1
‫هذا الملف يشمل تفريغ المحاضرة الثانية لعون‬
‫ وحتى األخير‬11 ‫بدءا من الصفحة‬
Done By :MohamedA. Diabat
Edited by Awn Academic team
The Axial Skeleton
 The
axial skeleton consist of 80 Bones ,
segregated to :1. The Skull
2. Vertebral coloumn
3. Thorax
The Skull
1.The Skull
 Body’s
most complex bony structure
 Consist
mainly of two groups of bones :
1. The cranium bones :- More posterior and
superior ,designed for the protection of the brain
and site of attachment for head and neck muscles.
Cranial bones are thin flat bones ,Remarkibly
strong for their weight.
2. Facial bones :- more anterior and inferior
 The
◦
◦
◦
◦
cranial bones consist of :-
2 Parietal bones
2 Temporal bones
one Frontal bones
one Occipital bone :- can be seen from lateral and
posterior aspect ,but most of it is seen from
superior and inferior aspect of the base of the
skull.
◦ Sphenoid bone , can be seen from the superior &
inferior aspects of the base of the skull, Laterally,
we can only see the greater wing of sphenoid
◦ Ethmoid bone :- can be seen from the anterior
aspect of the skull and from the superior when we
look from the inferior aspect of the base of skull.
Facial
bones
1.Supply the framework of the face, the
sense organs, and the teeth
2. Provide openings for the passage of
air and food.
3. Anchor the facial muscles of
expression.
Neonatal Skull
 Is
the skull formed during intrauterine life
and persists till the age of 3-4 years.
 C haracterized by fontanels which are gaps
between the bones of the skull covered by
connective tissue.
 In the course of delivery,these fontanels will
allow easier delivery by overlapping.
*Has the same number of bone in adult skull, but
not mature yet.
Neonatal fontanel
◦ In the lateral view of neonatal skull,you can
see:
◦ The sphenoidal fontanel :- Occurs at the
junction of frontal bone,the squamous part of
the temporal bone,the parietal bone and the
greater wing of sphenoid bone.
◦ Mastoid fontanel :- occur at the junction
between occipital bone,the parietal bone and
the mastoid portion of the temporal bone.
 At
the superior view of the skull there is :-
◦ Anterior Fontanel :- At the junction
between the frontal bone and 2 parietal bones.
◦ Posterior fontanel :- which occurs at the
junction between the two parietal bones & the
occipital bone.
The importance of fontanels in
some clinical aspects
 Normally,they must be flat.
 If you
see a bulging fontanel,then this
means that this baby has an increase in
the intra-cranial pressure which might
be caused by the accumulation of the
intra-cranial fluid.
 Whereas,if you see a depressed
fontanel ,then this means loss of fluid
and dehydration.
 All
of these fontanels will close after birth
but in different periods, as follows:
1. Usually the posterior and mastoid
fontanels close at the age of 6 months.
2. The sphenoidal fontanel usually closes at
the age of 9 months.
3. The anterior fontanel usually closes
after 1 year and sometimes persists until 2
years old and thus It’s the biggest and
major fontanel of the neonatal skull.
 After
3-4 years,the bones will ligate
together and form immovable joints
called sutures,and they are like
intercalated bones.
Coronal suture
Between parietal bones and frontal bone.
Sagittal suture
Between right and left parietal bones.
Lambdoid suture
Between parietal bones and occipital bone.
Squamous suture
Between parietal and temporal bones.
• Also, we have :
1- a mastoid suture
2- a sphenoid suture or a
sphenotemporal suture (between
sphenoid bone and the squamous
portion of temporal bone) .
In addition to the previous sutures,there are very small sutures called
Sphenoid sutures.
Frontal bone
Frontal bone &
occipital bone are
L-shaped bones.
Articulates posterior with
the parietal bones via the
coronal suture
Major markings include the
supra-orbital margins, the
anterior cranial fosse, and the
frontal sinuses (internal and
lateral to the glabella)
The roof of the
orbital cavity is
made of the
horizontal aspect of
the frontal bone.
Forms the anterior
portion of the cranium
(the roof ).
Also, We can't see it from the
inferior border of the skull
 Frontal
bone is mainly two parts:
◦ Frontal squama of the frontal bone.
◦ An indented part(Horizantel) near the
top of the orbital cavity.
 Has
two important Process :-
◦ Zygomatic process, that goes to Zygomatic
bone , and it’s lateral.
◦ Maxillary process, goes to the maxilla and it’s
medial.
 There is a suture between frontal bone and
maxilla called frontomaxillary or frontonasal
suture
 REMEMBER
◦ It is important to differentiate between the
zygomatic process of the frontal bone &
the frontal process of the zygomatic
bone.
The first one is a part of the frontal bone
whereas the second one is a part of the
zygomatic bone.But both of them are ligated
to each other.
◦ The same goes for the maxillary process of
the frontal bone and the frontal process
of maxilla.
 Supraorbital margin is important clinically ,
WH Y ?!
◦ Because it has the Supraorbital notch and
there is a Supraorbital nerve passes through
this notch.This nerve is the most
superficial nerve in the body.
◦ This nerver is important in HYS syndrome
(hysteria) ,In this syndrome the patient (
usually females) come performing the act of
unconsciousness.So you press on the nerve
and suddenly he will feel the pain and awake.
also a Supraorbital foramen in
which usually a Supraorbital artery
passes through.
 Sometimes, the supraorbital nerve goes
through the supraorbital foramen. But
most of the times, it goes through the
notch not the foramen.
 there’s
is a smooth and depressed area in the
middle aspect between the two maxillary
processes of the frontal bone.
 From the superior view of Frontal bone,you
can see that the transverse portion of the
frontal bone is divided by the presence of the
ethmoid bone (cribriform plate and crista
galli) in the middle.
 You can see that the cribriform plate is
perforated,why ?!
◦ Because Post-ganglionic axons of the
olfactory nerves go through the cribriform
plate and perforate it
 Glabella
Lateral View of the skull
 The
greater wing of the sphenoid
bone is seen in the lateral view of the
skull and is a very important part,because
medial to it there is an artery called
middle meningeal artery.
 Accidents in this side of skull is very
dangerous ,because its relatively thin and
fractures may lead to cut in the Middle
MeningealArtery which may lead to intracranial hemorrhage.
Sphenoid bone is called the
keystone bone of the cranium
By its greater wing, it ligates the
frontal, parietal and squamous
portion of the temporal bone.
And in the middle,it ligates the frontal,
occipital and temporal bone.
Parietal bones
 Parietal
bones are two flat bones
that :◦ Ligated to each other in the middle by
Sagittal suture.
◦ Ligated to Frontal bone anteriorly by
coronal suture.
◦ Ligated to Occipital bones posteriorly by
Lambdoid suture.
◦ Ligated to Temporal bone laterally by
Squamous suture
◦ Also, we have Parietosphenoidal
suture with sphenoid
 Each Parietal
bone usually has one line
or two (pointed by arrows in next
picture).
 These
lines provide the insertion for
Temporalis muscle and the lateral
aspect of fronto-occipitalis muscle.
Temporal Bone
 In
the lateral view,you can see the ear
which is made of the temporal bone.
 Temporal bone has three parts :1. Squama of the temporal bone,thin and
flat.
2. Mastoid Portion,posterior and inferior.
Within this portion, there’s a process called
Mastoid process which is characterized
by the presence of air cells.
Air cells which are found in the mastoid
process are emptiness through the bone and
have two main functions:
1. To reduce the weight of the skull.
2. Important for the resonance of the voice
and thus clarifying the voice.
Anterior to mastoid process there is Styloid
process,(pen-shaped process) which is
important for the insertion of many muscles
such as stylohyoid muscle.
3.
Petrous part of the temporal bone
(The arrow in 2ND picture)
- this portion cannot be seen laterally. It is a
triangular elevation of the temporal bone
that goes toward the medial line.
External auditory meatus
(external acoustic meatus)
 An opening between mastoid
process and
styloid process.
 The portal to the middle ear.
 Ends in what’s called the tympanic
membrane.From there on, there will be the
middle and the inner ear.
 This portion of the bone continues toward
the medial line and there it’s called the petrous
part of the temporal bone.
 External ear is made of a cartilaginous
structure and external auditory meatus.
 To
see the middle and the inner ear you
have to remove the petrous portion of
the temporal bone.
 The temporomandibular joint is formed
by the temporal bone and the mandible.
The temporal bone provides what’s called
mandibular fossa.
 Anterior to temperomandibular joint.You
can see the zygmoatic process of the
temporal bone which goes to articulate
with the temporal process of the
zygomatic bone to form the zygomatic
arch.
Zygomatic arch forms the cheeks which are beauty
characteristic of humans.
Posterior view of the Skull
 The posterior
view is occupied by the parietal
bones.
 T he occipital bone is an L-shaped bone like
the frontal bone.I.e.,it has a portion that’s
horizontal and another one that’s posterior.
 The posterior potion is smooth except in the
inferior aspect of this portion, you can see two
lines which are more prominent than the
lines present in the lateral aspect of the
parietal bone.These lines are the superior
and inferior nuchal lines. They provide
insertions for the muscles of the neck and back.
 These
lines goes to the middle and then
they form a protuberance (a smooth
elevation) called external occipital
protuberance.
 This
protuberance is an important
landmark for the middle of spinous
processes of the cervical bones and
used in anesthesia,surgery & dissection.
 T he
two horizontal portions of the
frontal bone are not fused << This
allows the ethmoid bone to be seen from
the superior aspect.
 Actually,you will not be able to see the
cribriform plate in real life,because
lateral to crista galli,you will see the
olfactory bulbs.After you remove
the olfactory bulbs and all their
innervations, you can see the perforated
cribriform plate.
 Crista
galli is the upper portion of
the perpendicular plate of ethmoid
bone which goes down to form the nasal
septum.