Download The Axial skeleton

The Axial skeleton
1 For higher quality , refer to slide 44 (anatomy 1) file.
This illustration shows the inferior view of the skull , if you want to study each
bone of the skull –the systematic studying- , you will see the maxilla , zygomatic ,
frontal , sphenoid , temporal , occipital and all their parts that can be viewed from the
inferior aspect. For example; if we are studying the temporal bone you can see the
petrous part , also the lateral part can be viewed , the external acoustic meatus , the
mandibular fossa1, the zygomatic process, styloid process , mastoid process , the
carotid canal that we saw it before within the petrous part , the mastoid notch for the
digastrics muscle(not important now) . In the occipital bone , you can see the
pharyngeal tubercle within the basilar part or the body , the glossopharyngeal canal
(hypoglossal) .
1
Why it's mandibular fossa not mandibular facet ? because it's an articular structure , facet
can also have articular surface but they are named according to their sizes .
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2 higher quality in slide 45 .
Here, it's very important to know all
these openings from this superior
view as well as from the inferior view,
because most of these openings can
be visualized from both views except
some of them like the carotid canal
(seen from the inferior view).
There are structures pass through
each opening, there are many
cranial nerves pass through these
openings (olfactory, optic,
glossopharyngeal).
Many structures pass through the
Jugular foramen including the
glossopharyngeal nerve , the
inferior petrousal sinus which will
form the jugular artery , vagus nerve
, accessory nerve ,sigmoid sinus
and posterior meningeal artery .
This illustration is beyond what we need to memorize, the dr will provide us with an
easier handout for the openings and their structures.
Here , the midsagittal section of the skull , it will passes through the midline.
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It will show us the ethmoid bone (perpendicular plate), as we said before the
Frontal bone have the anterior squamous part and a very thin horizontal part ,
beside the horizontal part there are small holes this is the Cribriform plate
(part of the ethmoid ). Also, there is the Crista galli which is continuation of
the perpendicular plate of the ethmoid.
We can see the Sphenoid bone its body and the Sella turcica ,dorsum sellae
and within that area there are sinuses . you can see the greater and lesser
wings of the sphenoid and there is the groove for the middle meningeal
artery which is dangerous area in lateral trauma of the head .
Notice: the foramen magnum ( head of arrow) , the squamous part of the
temporal bone, the vomer which articulate with the anterio-inferior aspect of
the sphenoid body .
The roof of the mouth composed of the palatine bone and the palatine
process of the maxilla , anterior you can see the alveolar processes of the
maxilla .the maxilla goes up to meet a process from the frontal bone in the
middle . And there the nasal bones which is a separate bones (they are two).
You can see the mandible with the alveolar processes and the teeth
embedded in it.
The facial bones are: Maxillae–Zygomatics–Nasals-Lacrimals–Palatines–
Inferior conchae.
(important)*6
The inferior chonchae is separate bone while the superior and middle
chonchae are parts from ethmoid bone.
The dr mentioned all the bones and added:
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*The medial wall of the nose formed by the vomer which articulates with the
inferior portion of the perpendicular plate of ethmoid.
*The lacrimal bones are not visualized here because they form the medial wall
of the orbit.
The Maxilla
The maxilla located in the middle of the face , the maxilla composed of two
fused bones in the midline so considered as one bone.
The process: any
elevation or migration
from the body of a
bone, which articulates
tightly with another
bone without joint (no
articular surface or
ligament) .
 Superior of the maxilla there is process articulates with two bones ,
widely with the nasal bone and so called the nasal process , and a sharp
margin (teeth like ) articulates with the frontal bone. The zygomatic
process is very thick process. So the maxilla has 4 processes two with
frontal and another two with zygomatic.
(important)
 The maxilla forms the border and walls of the orbit , and with the nasal
bone forms the nasal cavity , the nasal opening (external nares) is made
only by the medial border of the maxilla which ends anterio-inferior by the
nasal spine. Inferior to the spine you can see the alveolar elevations which
contains openings for teeth embedded in it.
 Posterior in this alveolar process there is rounded protrusion called
tuberosity.
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 In the posterior aspect of the body , inferior to zygomatic process there
is a line through this line there is a canal which is called perforating
posterior dental canal.
 The maxilla has two faces:
1-the superior face is oblique surface which is the orbital surface seen only
from the orbit.
2-the anterio-lateral surface is smooth surface.
 Inferior and anterior to the zygomatic process there is depression called
canine fossa.
This is the inferior view, you can see the palatine process of the maxilla almost
separated by a sulcus , sometimes it could be opened in a genetical disorder
called cleft palate resulted from failure of fusion along the line from the
incisive foramen until the palatine bone.
The horizontal plate of the palatine bone articulates with the posterior
palatine process of the maxilla, the lateral of palatine there are pterygoid
plates which come in contact with the inferior of the sphenoid.
The palatine nerve passes through the greater palatine foramen which is
located Medial to the maxilla tuberosity.
In a medial view of the maxilla you can
see the roof of the mouth, the floor of
the nose and the maxillary sinus
which is the biggest sinus participate in
resonance of the sound.
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Important: the palatine process of the maxillary and the palatine bone
is forming two things: the roof of the mouth and the floor of the nose.
The palatine
The palatine bone composed of vertical plate and
horizontal plate. It has many processes serve as
attachment for many muscles in the pharyngeal and
tongue. There are many depressions in the lateral wall of
the nasal cavity. Smokers have accumulation of mucous
in these depressions and this is dangerous.
The zygomatic
The zygomatic bone is a very smooth bone, it has 3 processes: frontal process
, temporal process and anteriorly maxillary process . The zygomaticofacial
foramen is in the middle of this bone.
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The Mandible
The mandible is not from the facial bones, it articulates with the temporal
bone posteriorly. It has two parts: vertical parts called rami(plural of ramus)
and horizontal part the body which is U-shaped . The mandibular angle is
where the ramus meets the body of mandible, it's easily palpated .The ramus
is very smooth in the lateral aspect, it has three borders:
 Anterior border: very smooth and rounded.
 Posterior border: Sharper than the anterior.
 Superior border: it has a notch; this notch is called the mandibular
notch. Anterior to the notch there is the coronoid process of the
mandible. Posterior to the notch there is articular surface or process
which is mandibular condyle, it has head (enter the articulation with
the mandibular fossa), neck and body.
The masseter muscle is inserted in the posterior margin of the mandible , and
it will take insertion again from the lateral smooth surface of the body, the
lateral surface has ridges to provide the attachment .
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The body of the mandible has a superior margin and inferior margin, the
inferior margin is important because:
1- it's palpable.
2- The facial artery passes there in the middle between the mandibular angle
and the chin, its pulsation can be felt here.
The alveolar processes are same like in the maxilla.
In the medial surface, you can see the mandibular foramen, it's limited
superior and anterior by a ridge called the lingula of the mandibular ramus.
Inferior to the mandibular foramen there is the mylohyoid groove, where the
mylohyoid muscle originates from2.
Continue to the medial aspect of the body of the mandible, there is the
mylohyoid line continues along the ramus to the body and divides the body to
submandibular fossa and sublingual fossa and their glands reside in these
fossae.
In The anteriolateral surface, there is mental foramen. Anterior to the
foramen there is the mental tubercle, it's deeper in some people and it
resulted from fusion of two bones like in the maxilla.
"SORRY FOR ANY POSSIBLE MISTAKE, YOUR COLLEAGUE: Mohammad Zaher Khrais "
The mylohyoid muscle originates from the mylohyoid line not groove- according to wiki-
2
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