Transcript Osteology of the Face and Skull, Scalp Layers and Jaw

Chris Evans
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Understand basic osteology of the skull with
attention to the facial skeleton
Interpret x-rays of the facial skeleton
Explain the movements of the
temperomandibular joint
Describe the layers of the scalp
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Understand the osteology of the skull with
attention to the facial skeleton
Interpret x-rays of the facial skeleton
Explain the movements of the
temperomandibular joint
Describe the layers of the scalp
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22 bones join to form the skull
◦ 8 pairs and 6 individuals
◦ Divided into neurocranium and viscerocranium
◦ Sometimes sutural bones present
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Bones of the cranium join together at sutures
– immobile fibrous joints with a small degree
of elasticity
o
Mandible joins to temporal bone via the synovial
temperomandibular joint
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The neurocranium
covers the brain
Split into the cranial
base (supports brain)
and the calvaria
(dome like protective
roof)
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The viscerocranium
comprises the facial
bones
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Neurocranium
consists of frontal
bone, ethmoid,
sphenoid, temporal
bone x2, parietal
bone x2 and the
occipital bone.
Calveria - Upper
domed part of
cranium which forms
the roof of the
cranial cavity
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Nuchal lines
points of
attachment
for scalp,
neck muscles
and
ligamentum
nuchae
External occipital
protuberance
Superior nuchal line
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Cranial base
supports
the brain
Split into
anterior,
middle and
posterior
sections
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Note anterior
position of
sphenoid
Occipital and
temporal
bones
extend far
underneath
cranial cavity
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Consists of
mandible,
ethmoid, vomer,
maxilla x2, inferior
nasal concha x2,
zygomatic x2,
palatine x2, nasal
x2 and lacrimal x2
Superior orbital
margin
Glabella
Nasion
Sphenoid bone
Nasal bone
Ethmoid bone
Lacrimal bone
Zygomatic bone
Inferior nasal concha
Vomer
Maxilla
Mandible
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Zygomatic
bone and
temporal bone
form
zygomatic arch
(cheekbone)
Squamous part of temporal bone
Zygomatic bone
Mastoid process
Tympanic part of temporal bone
Styloid process
Temporal process of zygomatic bone
Zygomatic process of temporal bone
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Contributes to
the hard palate
(roof of oral
cavity)
Squamous suture
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At birth, the
bregma and
lambda are
missing, as the
sutures are not
fully formed
This leaves soft
spots in the skull
- fontanelles
Bregma
Lambda
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Pterion – ‘H’ shaped
junction formed by the
frontal, parietal,
sphenoid and temporal
bones
The bone here is thin,
and overlies the anterior
branch of middle
meningeal artery
Trauma here can tear the
artery, resulting in life
threatening haematoma
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Understand the osteology of the skull with
attention to the facial skeleton
Interpret x-rays of the facial skeleton
Explain the movements of the
temperomandibular joint
Describe the layers of the scalp




Understand the osteology of the skull with
attention to the facial skeleton
Interpret x-rays of the facial skeleton
Explain the movements of the
temperomandibular joint
Describe the layers of the scalp
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Condylar process
consists of head and
neck of mandible
Masseter attachment
Head of mandible
forms
temperomandibular
Lateral pterygoid attachment
joint with articular
tubercle of temporal
bone
Medial pterygoid attachment
Temporalis
attachment
Mylohyoid attachment
Geniohyoid
attachment
Digastric attachment
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The temporal fossa on the
lateral cranium is filled by
the temporalis muscle
The infratemporal fossa is
medial to the ramus of the
mandible and lateral to the
lateral pterygoid plate, and
contains the pterygoid
muscles
The two fossae
communicate by the space
medial to the zygomatic
arch
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Route of
communication
between
temporal and
infratemporal
fossae
Lateral plate of pterygoid
process of sphenoid bone
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Temperomandibular
joint allows opening
and closing of mouth
and side to side
movements
Synovial joint is
unusual – joint is
divided by an articular
disk
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Masseter – main muscle
for chewing
◦ Zygomatic arch to lateral
surface of ramus of
mandible
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Temporalis – accessory
muscle for chewing,
retracts mandible
◦ Temporal fossa to
coronoid process and
anterior margin of ramus
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Medial pterygoids
◦ Deep head from
medial surface of
lateral pterygoid
plate
◦ Superficial head
from maxilla
◦ elevate mandible
and perform side to
side movements
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Lateral pterygoids
◦ Upper head from
roof of infratemporal
fossa (sphenoid) to
neck of manible
◦ Lower head from
lateral surface of
lateral pterygoid
plate
◦ Protrude mandible
and perform side to
side movements
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Digastric – anterior belly from
digastric fossa on mandible to
hyoid, posterior belly from
mastoid process to hyoid
◦ Depresses mandible
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Mylohyoid – mylohyoid line on
mandible to hyoid bone
◦ Depresses mandible, supports
floor of oral cavity
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Geniohyoid – inferior mental
spine on mandible to hyoid
bone
◦ Depresses mandible
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When pterygoids
on only one side
contract, the
mandible moves
to the opposite
side
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Understand the osteology of the skull with
attention to the facial skeleton
Interpret x-rays of the facial skeleton
Explain the movements of the
temperomandibular joint
Describe the layers of the scalp
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Covers the neurocranium
from superior nuchal line
posteriorally to supraorbital margin
anteriorally
Laterally extends to the
zygomatic arches
Aponeurotic layer serves
as attachemnt point for
occipitofrontalis
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Top 3 layers form a single
unit – the ‘scalp proper’,
which moves freely over the
loose connective tissue
Loose connective tissue
layer ‘danger area’ as blood
and pus can move easily
through it – infection can
spread into cranial cavity
through emissary veins
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Skin contains many sebaceous glands and
hair follicles
Connective tissue (dense) contains nerve and
blood vessel supply to scalp
Aponeurotic layer serves as the attachment
point for occipitofrontalis muscle bellies
Loose connective tissue allows free movement
of the scalp proper, possible infection site
Pericranium is attached firmly to the calveria,
continuous with fibrous tissue in sutures
Sagittal section
A
P
Skin
Aponeurosis
Bone
Frontal belly of occipitofrontalis
inserts into skin around
eyebrows. Infection can
consequently spread to eyes and
nose from scalp – ‘black eyes’
Occipital belly of
occipitofrontalis inserts into the
occipital bone- infection cannot
spread down the neck
Finally…