Download OMM06-ExternalOsteologyCranium

OMM #6
Wed, 08/13/03 3pm
Heath White, MSIV, PDF
J. Uxer for Kelly Thurmon
Page 1 of 6
I.
II.
External Osteology of the Cranium
Intro
A. General Information
 BE FAMILIAR WITH THE ARTICULATIONS!!
 Be sure to read the 1st 21 pages of Expanding the Osteopathic Concept as
this will reinforce what’s been taught in the lectures.
 Reference the power points to see pictures of where the bones/sutures are.
 This is a continuation of the 1pm lecture and is a tour of the cranial bones &
sutures to provide us with a mental picture of how they relate to each other.
B. Objectives
 Identify the component anatomy of the parts of the cranial mechanism.
 Describe how abnormal function of the anatomy can lead to pathologic
physiology.
The Tour
A. Nasion
 Is the spot between the eyes
 Junction of internasal and frontonasal sutures.
o (i.e. the junction of the 2 nasal bones and the frontal bone.
 Palpate the depression at the base of the nose and between each orbit.
B. Nasal Bones
 Are found inferior to the nasion
 Form the spine of the nose—bridge of the nose superior to the nasal
cartilage
 Articulations (6)
o Maxilla
o Nasal cartilage
o Frontals (2)
o Ethmoid
o Each other
C. Frontozygomatic Suture
 Moving back to the nasion, move laterally along the supraorbital ridge
where you can feel the supraorbital notch about midline of the orbit.
 Proceed laterally to the superiolateral portion of the orbit and feel the
frontozygomatic suture, a little suture.
D. Zygomatic Bones
 Prominence of cheek inferiolateral to orbit
 Forms portion of the orbit, zygomatic arch, and anterior wall of temporal
fossa.
 Articulations (5)
o Maxilla
OMM #6
Wed, 08/13/03 3pm
Heath White, MSIV, PDF
J. Uxer for Kelly Thurmon
Page 2 of 6
o Frontals
o Temporals
o Sphenoid
E. Zygomaticomaxillary Suture
 Continue inferior from the frontozygomatic suture along the lateral aspect of
the orbit and begin to move medially.
 At the medial inferior portion of the orbit, feel the zygomaticomaxillary
suture, which runs at about a 45° diagonal between the zygomatic and
maxillary bones.
F. Maxilla Bones
 Form the floor of orbits, roof of mouth—anterior 2/3 of palate, carries/holds
upper teeth, and nasal fossa inferiorly and laterally.
 Articulations (9)
o Frontals
o Nasals
o Lacrimal
o Ethmoid
o Palatines
o Inferior conchae
o Vomer
o Zygomae
o Each other
G. Maxillonasal Junction and Maxillofrontal Suture
 Continue medially (toward the nose) from the zygomaticomaxillary suture
to the medial border of the orbit
 Palpate the suture of the maxillonasal junction and the maxillofrontal suture,
which is superior to the maxillonasal junction.
 If you continue moving up the nose, you’re at the nasion.
H. Glabella
 This is an anatomic point. It is not a physiologic point and has no
associated function.
 At the nasion, move upward to the midline elevated point between the 2
supraorbital ridges of the frontal bone.
I. Frontal Bones
 Located superior to the glabella
 Originate as paired bones and ossify by 6 years of age.
 Falx cerebri encloses sagittal sinus
 Articulations
o Parietals (2)
OMM #6
Wed, 08/13/03 3pm
Heath White, MSIV, PDF
J. Uxer for Kelly Thurmon
Page 3 of 6
o
o
o
o
o
o
Sphenoid
Ethmoid
Lacrimal
Maxillae
Nasals (2)
Zygomae
J. Metopic Suture
 Moving superiorly from Glabella along the midline, feel the remnant of the
metopic suture either as a depression or a ridge.
 Remnants of metopic suture are found in about 10% of skulls.
 Some flexibility always present.
 Metopic ossification runs midline of what would be with the sagittal suture.
This metopic suture shows that the frontal bones are actually paired bones.
 Metopic suture goes to the bregma where the frontal bones end.
 Again, the falx cerebri runs posteriorly along the midline & encloses the
sagittal sinus.
K. Bregma
 Continue towards the vertex of the skull in the midline, and you will reach a
depression about 1/3 of the way posteriorly on the vertex.—Translation:
move about 1 – 2 ” behind the hair line (for most) and find a little
depression. This is the start of the sagittal suture.
 The bregma is the junction of the coronal & sagittal sutures.
 It’s a remnant of the anterior fontanelle from the fetal skull.
 It’s also the point that depresses in flexion and rises in extension.
L. Sagittal Suture
 Serrated median between the medial parietal borders.
 Move posterior to bregma along the midline to the junction of the
lambdoidal sutures (lambda).
 Move your fingers from side to side & palpate the contour of the serrated
suture.
M. Parietal Bones
 Located to the sides of the sagittal suture.
 Falx cerebri encloses the sagittal sinus which continues between the
parietals.
 Articulations (8)
o Parietals
o Frontals
o Occiput
o Sphenoid
o Temporals
OMM #6
Wed, 08/13/03 3pm
Heath White, MSIV, PDF
J. Uxer for Kelly Thurmon
Page 4 of 6


As the parietals rotate into external rotation, the sagittal suture will
depress a little & separate in the posterior portion as the lateral
portions flare laterally and superiorly.
Note the parietal eminences: these are ossification centers—ossification
begins here in the parietal bones.
N. Coronal Sutures
 At the bregma, palpate the coronal sutures bilaterally.
 These descend laterally from the bregma.
 Junction of posterior frontal margin with anterior borders of parietal bones,
descending laterally along cranial vault.
O. Pterion
 Location where the coronal sutures end.
 Is a major functional location for cranial techniques. It’s where you put
your 2nd finger in the vault hold, while your 5th (pinky) finger is on the
occiput.
 At the lateral portion of the coronal sutures, feel your fingers move
somewhat deeper as you palpate the region of the pterion.
 Pterion is formed by 1. frontal, 2. apical border of the greater sphenoid
wing, 3. parietal, and 4. temporal squama. (note: 4 articulations)
 This area works like a shutter on a camera. It twists and curls in on itself
under trauma and affects the 4 articulating bones. It’s prone to dysfunction
because of the interlocking articulation of sutures.
P. Sphenoid
 Found in the anterior inferior direction from the pterion.
 Forms anterior, middle & posterior cranial fossae; the temporal,
infratemporal and nasal fossae; and orbits.
 Greater and lesser wings. Can only palpate the greater wing—in front of
your ear on the temporals.
 Articulations (12)
o Occiput at SBS (spheno basilar symphysis)
o Temporals (2)
o Parietals (2)
o Frontals (2)
o Ethmoid
o Palatines (2)
o Vomer
o Zygomae
 Greater Wing of the Sphenoid Bone
o Anterior/inferior aspect of the pterion region
o Where the pad of the index finger is applied in the vault hold in cranial
diagnosis & treatment.
OMM #6
Wed, 08/13/03 3pm
Heath White, MSIV, PDF
J. Uxer for Kelly Thurmon
Page 5 of 6
Q. Temporal Bones
 Posterior to the sphenoid
 Remember the beveling of the temporal bone and the way it functions
with the parietal bone.
 Parts
o Squama
o Mastoid—does not develop until the end of the 1st year. At this time, the
child pulls back, pulls head up, and the pull of the sternocleidomastoid
muscle on the mastoid process lifts the chin. This muscle pulls down on
the mastoid process giving it an elongated shape. This is the shape that
ossifies because it’s along a line of stress, and according to Wolffe’s
Law, bone is laid down along lines of stress.
o Petrous—medial projection in base of skull and exit of Eustachian tube
 Articulations
o Occiput
o Parietals
o Sphenoid
o Zygomae
o Mandible
R. Asterion
 From pterion, move posteriorly along the suture between the temporal
squama & parietal bone.
 The course of this suture is hemicircular above the ear.
 At the posterior end of the temporoparetial suture is a short parietomastoid
suture.
 At the posterior end of the parietomastoid suture is the asterion.
 The asterion, pterion, bregma, and lambda, were fontanelles (6 total) in fetal
development. At birth, the asterion & pterion are closed. The bregma
(anterior fontanelle) remain open to accommodate movement through the
birth canal.
 Asterion is the junction of the parietal bone, the mastoid process of the
temporal bone, and the occipital bone.
 The palpating finger can feel a slight depression at the asterion.
 Asterion roughly corresponds to the area where the blade of one’s
eyeglasses rests.
 If you palpate inferior to the asterion along the occipitomastoid suture, you
will lose this suture in the soft tissues of the muscles attaching the head to
the neck. (This suture is tender if you press on it too hard.)
 This suture is critical for its relationship to the OA. If the OA’s out, it may
lock up the occiptomastoid suture.
S. Occiput
 Parts
OMM #6
Wed, 08/13/03 3pm
Heath White, MSIV, PDF
J. Uxer for Kelly Thurmon
Page 6 of 6


o Basilar
 SBS
 Condyles
 Foramen magnum
o Lateral masses
 Condyles
 Hypoglossal canal
 Groove for lateral sinus
 Foramen magnum
o Squama
 Superior & inferior nuchal lines
 Sagittal ridge for falx cerebri and cerebelli
 Horizontal ridge for tentorium and groves for transverse sinus
Articulations
o Parietals
o Temporals
o Sphenoid
o Atlas
Review the parts that started as membranous and as cartilaginous
T. Lambdoiddal Sutures
 From each asterion move medially & superiorly along the lambdoidal suture
to apex of suture, Lambda
 Joins posterior parietal borders to superior occipital margin, descending
laterally across cranial vault.
U. Lambda
 Junction of sagittal & lambdoidal sutures
 Lambdoidal sutures are often asymmetrical and can contain wormian bones.
Wormain bones, islands of bone, are present to account for movement. A
coup/counter-coup lesion causes wormian bone formation to preserve the
movement.
 Remnant site of posterior fontanelle