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Lecture name: The Axial skeleton
Written By: Batool Ajaleen , Mariam Ababneh
& Marwa Abozoor
Edited By: Buthaina Almasaeed & Bushra Slaeem
Sphenoid Bone
Sphenoid bone articulates with 12 bones from cranial and facial bones(occipital
, vomer , ethmoid , frontal bone ,temporal , parietal , zygomatic , palatine )
- it’s a single bone .
- it’s the base of cranial bone
* structure : body , greater wing , lesser wing , pterygoid process
1- the body : lies at the center of the sphenoid bone and is almost completely
cubical in shape .
It contains sphenoid sinuse(‫ )جيوب‬which are separated by a septum meaning
that the body is essentialy hollow.
- body articulates with athmoid bone anteriorely .
*sella turcica : saddle shape depression .(‫ )تشبه السرج‬. Which is a superior
surface of the sphenoid body bony landmark .
- the parts of the sella turcica :
1- tuberculum sellae : anterior wall of the sella turcica
2- hypophyseal fossa : (the deepest part)
3-dorsum sallae : posterior wall of the sella turcica
2- greater wing :
extends from the sphenoid body in lateral superior and posterior direction
(curved lateral upward)
*the curved shape of the sphenoid bone is the reason why we can see a small
part of sphenoid when looking from right or left side .
Copyright 2009, John Wiley & Sons, Inc.
 Great wing contributes to the facial skeleton like :
1- The floor of middle cranial fossa .
2- posterior wall of the orbit .
* Greater wing formina :
ovale / spinosum / rotundom which has a large bundle of nerve that
branched into 3 smaller nerves :
( maxillary nerve / mandibular nerve /middle meningeal vessels)
*optic canal can be viewed from the anterior aspect and is in the
posterior of the eye orbit just middle to the superior orbital fissure and
also can be viewed from the posterior aspect
*the optic nerve extend from the posterior of the eye passes through
the optic canal to the brain .
3-lesser wings : arise from the anterior aspect of the sphenoid body
and it’s the superior part of the sphenoid bone , it separates the anterior
cranial fossa from the middle cranial fossa .
 fissure : is the elongated opening fossa .
4-pterygoid process : descends inferiorly from the points of junction on
between sphenoid body of the greater wing
 it has two parts : 1) medial pterygoid plate which supports the
posterior opening of the nasal cavity 2) lateral pterygoid plate is the
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& Sons, Inc. muscles.
site of origin of the medialCopyright
and 2009,
lateral
pterygoid
Sphenoid Bone
Ethmoid bone
Ethmoid bone : it takes its name from the sieve (‫غربال‬/‫)منخل‬on its surface.
Its shape is like L shape but inverted , located in the midline of the
anterior cranium
 it has two parts , the horizontal part (superior part) & the vertical part
(when I look from the front )
 it is located at the roof of the nasal cavity & between the two orbital
cavities .
 it contributes to medial wall of the orbit and forms part of the anterior
cranial fossa where it separates the nasal cavity into left & right side .
 the ethmoid one has three parts :
1) cribriform plate : roof of the nasal cavity and received into the
ethmodial notch of the frontal bone , it supports the olfactory bulb and is
perforated by foramina for the passage of the all factory nerve .
2) perpendicular plate : superior two-thirds of the nasal septum .
3) the ethmoid labyrinths : (lateral masses of the ethmoid bone and it’s
irregular in shape)
 medial sheets : upper lateral wall of the nasal cavity from which the
superior & middle conchae extends into the nasal cavity .
Copyright 2009, John Wiley & Sons, Inc.
 These lateral masses have an important role in the
inhaled air which warms it before it arrives the lungs.
 inferior conchae is separated from the ethmoid bone and
consider from the facial bone
superior and medial concha are parts of ethmoid bone
Copyright 2009, John Wiley & Sons, Inc.
Occipital Bones
Occipital bone :
at the base of the skull in the occipital bone there is a large
oval opening called the foramen magnum which allows the
passage of spinal cord .
It’s a flat bone
External occipital protuberance is sharpened area (‫)منطقة مدببة‬
and has two lines superior nuchal line and inferior nuchal line.
* the occipital bone located at the back and lower part of the
cranium is a trapezoid (‫ )شبه منحرف‬in shape and curved on it
self . It is pierced(‫ )مثقوب‬by a large oval called the foramen
magnum through which the cranial cavity communicates with
the vertebral canal.
Copyright 2009, John Wiley & Sons, Inc.
The occipital bone is composed of four parts :
1- squamous part :is the curved expanded plate located behind the
foramen magnum . (external/internal surfaces )
2- basilar part
3- jugular part .
4-lateral part.
* external surface features : superior nuchal line ,inferior nuchal line ,
median nuchal line .
* jugular process excavated in front by jugular notch , forming posterior
part of jugular foramen .
Copyright 2009, John Wiley & Sons, Inc.
Skull
Skull
Skull
Copyright 2009, John Wiley & Sons, Inc.
Skull
Skull
Skull
Skull
Skull
Skull
Skull (Facial Bones)

Nasal Bones
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
Form the bridge of the nose
Maxillae
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Form the upper jawbone
Form most of the hard palate
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Zygomatic Bones
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
Form a part of the medial wall of each orbit
Palatine Bones
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commonly called cheekbones, form the prominences of the
cheeks
Lacrimal Bones


Separates the nasal cavity from the oral cavity
Form the posterior portion of the hard palate
Inferior Nasal Conchae

Form a part of the inferior lateral wall of the nasal cavity
Skull (Facial Bones)

Vomer
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Mandible
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
Divides the interior of the nasal cavity into right and left sides
“Broken nose,” in most cases, refers to septal damage rather
than the nasal bones themselves
Orbits
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
Lower jawbone
The largest, strongest facial bone
The only movable skull bone
Nasal Septum


Forms the inferior portion of the nasal septum
Eye socket
Foramina

Openings for blood vessels , nerves , or ligaments of the skull
Skull

Unique Features of the Skull


Sutures


an immovable joint that holds most skull bones together
Paranasal Sinuses
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Sutures, Paranasal sinuses, Fontanels
Cavities within cranial and facial bones near the nasal cavity
Secretions produced by the mucous membranes which line the sinuses,
drain into the nasal cavity
Serve as resonating chambers that intensify and prolong sounds
Fontanels




Areas of unossified tissue
At birth, unossified tissue spaces, commonly called “soft spots” link the
cranial bones
Eventually, they are replaced with bone to become sutures
Provide flexibility to the fetal skull, allowing the skull to change shape as
it passes through the birth canal
#mandible :
single bone .. It’s the only movable bone in the skull.
It consists of :
curved horizontal portion called the body and vertical part
called Ramus
The mandible bone composed of two halfs Joined at the
midline at vertical symphysis
* there is a mandible notch(incomplete opening)
* it also articulates to the neurocranium via the temporal
bone forming the temporomanndibular joint (TMJ)
*from the internal side we can see the mandibular foramina
* the mandibular foramina nerve branched into smaller
nerves
* ‫في اشي بيسأل الدكتور عنه في الالب بالـ‬mandible bone
Copyright 2009, John Wiley & Sons, Inc.
- Hard palate consists of horizontal plate of palatine bone
and palatine process of maxilla.
The hard palate separate the oral cavity from the nasal
cavity
#nasal bone (‫)مكان ما بنحط النظارة‬
*orbital cavity is made of 7 bones ; 3 cranial and 4 facial .
(frontal , sphenoid , lacrimal , maxilla , palatine , zygomatic
)
‫**في نقطة عن عظم األطفال أول ما ينولد و كيف لما يكبر بلتحم‬
‫**في نقطة عن بنية العظم و انها فاضية من جوا عشان هيك ال‬
‫ خفيف‬skull
Copyright 2009, John Wiley & Sons, Inc.
Skull
Skull
Hyoid Bone



(U
shape )
Does not articulate with
any other bone(the ONLY)
Supports the tongue,
providing attachment
sites for some tongue
muscles and for
muscles of the neck and
pharynx
The hyoid bone also
helps to keep the larynx
(voice box) open at all
times
Vertebral Column


Also called the spine, backbone, or spinal
column
Functions to:
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


irregular bone
Protect the spinal cord
Support the head
Serve as a point of attachment for the ribs, pelvic
girdle, and muscles
The vertebral column is curved to varying
degrees in different locations



Curves increase the column strength
Help maintain balance in the upright position
Absorb shocks during walking, and help protect the
vertebrae from fracture
Vertebral Column
•
•
•
•
7 cervical vertebrae
12 thoracic vertebrae
5 lumbar vertebrae
5 fused sacral
vertebrae
• 4 fused coccygeal
vertebrae
Vertebral Column

Various conditions may exaggerate the normal
curves of the vertebral column
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Kyphosis
Lordosis
Scoliosis
Composed of a series of bones called vertebrae
(Adult=26)
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7 cervical are in the neck region
12 thoracic are posterior to the thoracic cavity
5 lumbar support the lower back
1 sacrum consists of five fused sacral vertebrae
1 coccyx consists of four fused coccygeal vertebrae
Vertebral Column
kyphosis
scoliosis
(vertebral column takes a
side position )
(over
exaggerated
areas )
lordosis
‫ للداخل‬lumbar ‫• انحناء بمنطقة الـ‬
. Kyphosis ‫ولكن غير مبالغ مثل‬
‫• بسبب وجود ثقل يشد العمود لألمام مثل‬
Pregnancy / obesity or
anything else …
Vertebral Column (Intervertebral Discs)


Found between the bodies of adjacent
vertebrae
Functions to:




Form strong joints
Permit various movements of the vertebral
column
Absorb vertical shock
Vertebrae typically consist of:



A Body (weight bearing)
A vertebral arch (surrounds the spinal cord)
Several processes (points of attachment for
muscles) (7 processes)
Vertebral Column
The vertebral arch encloses a very important
structure(spinal cord) to protect it from any damage.

The vertebral arch has an anterior & posterior part. The
anterior portion is majorly by the body & the posterior
portion is the two lamina.

* there is two horizontal transverse processes and they
lie approximately between pedicle and lamina .
‫ تكون‬lamina posteriorly ‫ مع الـ‬pedicle anteriorly ‫نقطة التقاء الـ‬
.transverse process ‫الـ‬
single spinous process ‫ يعطينا‬two lamina ‫التقاء الـ‬
”‫”لربط األجزاء مع بعضها و هي فكرة واردة كسؤال‬
Copyright 2009, John Wiley & Sons, Inc.
-


The function of the two transverse processes and the
spinous process is to hold the muscles of the back.
 we have Superior articular process and an inferior one.
-The superior one articulates with the superior articular
process of adjacent vertebrae.
- Inferior articular process articulates the vertebrae with the
inferior one . ) ‫(حتى يركبوا على بعض‬


So we have seven processes project from each typical
vertebra :
2 transverse
1 spinous
2 articular
2inferior
Copyright 2009, John Wiley & Sons, Inc.
Vertebral Column (Regions)

Cervical Region
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Thoracic Region
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Lumbar vertebrae (L1–L5)
Provide for the attachment of the large back muscles
Sacrum
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Thoracic vertebrae (T1–T12)
Articulate with the ribs
Lumbar Region


Cervical vertebrae (C1–C7)
The atlas (C1) is the first cervical vertebra
The axis (C2) is the second cervical vertebra
The sacrum is a triangular bone formed by the union of five sacral
vertebrae (S1–S5)
Serves as a strong foundation for the pelvic girdle
Coccyx


The coccyx, like the sacrum, is triangular in shape
It is formed by the fusion of usually four coccygeal vertebrae
Vertebral Column
How to distinguish between cervical/thoracic /lumbar :
1-cervical :
- it articulates with the skull ( occipital bone ).
- The smallest but its foramen is the largest (heart
or triangular shaped ).
- the vertebral arteries that supply the brain passes
through the cervical foramina .
- spinous process is often bifid .
- two transverse foramen appear ONLY in cervical
vertebrae .
Copyright 2009, John Wiley & Sons, Inc.
2-thoracic :
- It articulates with the superior and inferior vertebrae so do
the cervical and the lumbar BUT it is the ONLY kind that
articulates with ribs this special articulation happens in
two areas , on the body and on the transverse process.
- the rib articulates with the vertebrae in two areas one with
the body and one with the transverse process through a
smooth area called a facet.
- The spinous process is inclined downward
‫* و هذا مفيد في المختبر حيث عند وضعها على سطح مست ٍو فإنها لن تستقر لالسفل‬
‫كونها غير مستوية‬
- It is bigger than cervical and smaller than lumbar
Copyright 2009, John Wiley & Sons, Inc.
3-lumbar
:
-The largest.
-No transverse foramina and no facets because it
does not articulates with the ribs.
- )‫مستوية من األسفل (تستقر عند وضعها على سطح مست ٍو‬
- The spinous process is very thick and vertical.
Copyright 2009, John Wiley & Sons, Inc.
Atypical vertebrae
o
o
o
The first vertebrae in cervical (C1) is called Atlas : it
lacks the body, it takes the shape of a ring (extra
information: it lacks the spinous process) .
The second one (C2) is called Axis : it has a special
projection called Dens (odontoid process ) . "projecting
from its superior surface "
The vertebra prominens (C7) has the longest spinous
process of all cervical vertebrae. It is also non-bifid.
These features give rise to its name.
Copyright 2009, John Wiley & Sons, Inc.
Vertebral Column
Vertebral Column
Vertebral Column
Vertebral Column
4-The sacrum
:
- There is lines of fusion shown between the fused bones.
lateral sacral line ‫لزقوا مع بعض و عملوا‬transverse process ‫في‬median sacral line ‫ لما لزقوا مع بعض عملوا‬spinous process ‫و ال‬
) ‫(**الدكتورة كررت فكرة ربط األجزاء‬
-There is a notch in the body of vertebrae from upside and
downside constitute a foramen that a spinal nerve
coming from the spinal cord passes through it .
5-Coccyx :
- 3-5 vertebrae attached to each other.
Copyright 2009, John Wiley & Sons, Inc.
Thorax

Thoracic cage is formed by the:



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Sternum
Ribs
Costal cartilages
Thoracic vertebrae
Functions to:



Enclose and protect the organs in the thoracic
and abdominal cavities
Provide support for the bones of the upper
limbs
Play a role in breathing
Thorax

Sternum



Ribs


“Breastbone” located in the center of the
thoracic wall
Consists of the manubrium, body, xiphoid
process
Twelve pairs of ribs give structural support to
the sides of the thoracic cavity
Costal cartilages

Costal cartilages contribute to the elasticity of
the thoracic cage
The sternum :
1- thin flat bone at the midline of the thoracic cage consists
of three parts ( originally it consists of three bones but
when we grow it fuses to make one bone "sternum”.
2- The ribs don’t attach directly on the sternum. They attach
to the sternum through the cartilage.
If it was bone-bone attachment (fixed) the thorax won’t be
able to expand during breathing.
Copyright 2009, John Wiley & Sons, Inc.
Vertebral Column
Typical ribs :
1- contain a head that articulates the ribs with the thoracic
vertebrae, there is a constricted area under the head called
"neck".
""every head projection has a neck constriction .. near the
neck there is another projection called tubercle”.
2- The ribs articulate with the thoracic vertebrae in two
areas, the head with the body of vertebrae and the tubercle
with the transverse process.
3-When we look at the rib from inside we can see a line
called costal groove.
(Costal means rib in latin)
through the groove there is a veine ... artery .. Nerve that
pass  VAN
Copyright 2009, John Wiley & Sons, Inc.
Vertebral Column
Classifications of ribs :
1 – T / F / floating :
(1,2,3,4,5,6,7 ) true : the rib articulates to sternum with its own cartilage.
(8,9,10) false : the rib articulates the sternum indirectly by joining the 7th
cartilage .
(11,12) Floating : no articulation.
2- Typical / Atypical :
The declination of the ribs as its own surface (anterior & posterior ).
- typical : the rib articulates with the corresponding and the above
vertebrae . Contains the basic features of a rib like head , neck …
- atypical : have features that are not common to all the ribs.
- R 1 atypical : the shortest .. the thickest and the surface is superior
&inferior flatly
- R 2 atypical : the surface is superior& inferior not anterior & posterior
- R 3 4 5 6 7 8 9 typical articulation & surface.
- R10 atypical : articulates with 10 only
- R11 / 12 a typical .. don’t articulate with sternum .. No angle .. No
articulation with the upper .
Copyright 2009, John Wiley & Sons, Inc.
In other words :
Rib 1 is shorter and wider than the other ribs. It only has one facet on its head
for articulation with its corresponding vertebrae (there isn’t a thoracic vertebrae
above it).
Rib 2 is thinner and longer than rib 1, and has two articular facets on the head
as normal.
Rib 10 only has one facet – for articulation with its numerically corresponding
vertebrae.
Ribs 11 and 12 have no neck, and only contain one facet, which is for
articulation with their corresponding vertebrae.

‫ا‬
ُ
‫الصفرإذا شئت وأنت الّلمتناهي‬
‫أنت‬
Copyright 2009, John Wiley & Sons, Inc.
We have 12 ribs
1-7
8-10
11,12
3-9
1,2,11
,12
Copyright 2009, John Wiley & Sons, Inc.
THANK YOU 