Axial Skeleton:The Skull
Slides by Vince Austin;
figures from Marieb & Hoehn 8th ed.;
modifications and some slides by W. Rose
Portions copyright Pearson Education
The Axial SkeletonEighty bones segregated into three regions
– Skull– Vertebral column– Bony thorax
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Figure 7.1 The human skeleton.
Skull
Thoracic cage(ribs andsternum)
(a) Anterior view
(b) Posterior view
Facial bonesCranium
Sacrum
Vertebralcolumn
Clavicle
Bones ofpectoralgirdle
Bones ofpelvic girdle
Upperlimb
ScapulaSternumRibHumerusVertebraRadiusUlnaCarpals
PhalangesMetacarpalsFemurPatella Lower
limbTibiaFibula
TarsalsMetatarsalsPhalanges
The SkullSkull Body’s most complex bony structureFormed by the cranium and facial bones Cranium – protects brain; site of attachment for head
and neck musclesFacial bones
– Framework for the face, sense organs, and teeth– Provide openings for passage of air and food– Anchor facial muscles of expression
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Figure 7.2a The skull: Cranial and facial divisions and fossae.Bones of cranium (cranial vault)
Lambdoidsuture
Facialbones
Squamoussuture
(a) Cranial and facial divisions of the skull
Coronalsuture
Anatomy of the CraniumEight cranial bones – two parietal, two
temporal, frontal, occipital, sphenoid, and ethmoid
Cranial bones thin and strong for their weight
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Figure 7.2b The skull: Cranial and facial divisons and fossae.
Anterior cranialfossa
Middle cranialfossa
Posterior cranialfossa
(b) Superior view of the cranial fossae
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Figure 7.2c The skull: Cranial and facial divisions and fossae.
Frontal lobeof cerebrum
Temporal lobeof cerebrumCerebellum
PosteriorMiddleAnterior
Cranialfossae
(c) Lateral view of cranial fossae showing thecontained brain regions
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Figure 7.3 Major cavities of the skull, frontal section.
Frontalsinus
Ethmoidsinuses
Orbit Orbit
Cranial cavity
Oralcavity
Maxillarysinus
Inferiornasalconcha
Maxilla
Mandible
Ethmoidbone
Frontalbone
Zygomaticbone
Vomer
Nasalcavity
Frontal BoneAnterior portion of the craniumArticulates posteriorly with the
parietal bones via the coronal suture
Major markings include: supraorbital margins, anterior cranial fossa, frontal sinuses (internal and lateral to the glabella)
Frontal Bone
Figure 7.2a
Parietal Bones and associated suturesForm most of the superior and lateral aspects of the skullCoronal, sagittal, lambdoid, squamous sutures
Figure 7.3a
Lambdoidsuture
Occipital bone
Occipitalcondyle
Mastoidprocess
Parietal bone
Sagittal suture
Sutural (Wormian) bone
Occipital Bone
Forms most of skull’s posterior wall and base
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Cranial cavity floor
Middle cranialfossa
Posteriorcranial fossa
Occipital bone
Foramen magnum (spinal cord)
Jugular foramen
Anterior cranial fossa
View
Temporal Bones
Form the inferolateral aspects of the skull and parts of the cranial floor
Divided into four major regions – squamous, tympanic, mastoid, and petrous
Major markings include: zygomatic, styloid, and mastoid processes, middle cranial fossa
Major openings include: external auditory meatus, internal auditory meatus, stylomastoid and jugular foramina, carotid canal
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Figure 7.8 Right temporal bone, lateral view
Mastoidregion
Externalacousticmeatus
Mastoidprocess
Styloid process
Tympanic region
Zygomatic process
Squamousregion
Sphenoid BoneButterfly-shaped bone that spans the width of
the middle cranial fossaForms the central wedge that articulates with all
other cranial bonesCentral body, greater wings, lesser wings, and
pterygoid processesMajor markings: sella turcica, hypophyseal
fossa, pterygoid processes, sphenoid sinuses, middle cranial fossa
Major openings include: optic canals, superior orbital fissure
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Figure 7.7a Cranial cavity floor
Hypophyseal fossaof sella turcica
Middle cranialfossa
Superior view of cranial interior
Frontal bone
Optic canal (cn 2)
Sphenoid Lesser wingGreater wing
View
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Figure 7.9 Sphenoid bone
Greaterwing
Hypophysealfossa ofsella turcica
Body of sphenoid
Superiororbital fissure (cn 3, 4, part5, 6)
Superior view
Body of sphenoid
Greaterwing
Superior orbitalfissure (cn 3,4, part5, 6)
Lesserwing
Pterygoidprocess
Posterior view
Optic canal (cn2)
Lesser wing
Ethmoid BoneDeepest skull bone; lies between the sphenoid
and nasal bonesForms most of the bony area between the nasal
cavity and the orbitsMajor markings include: cribriform plate, crista
galli, perpendicular plate, superior & middle nasal conchae, ethmoid sinuses
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Figure 7.10 Ethmoid bone
Orbitalplate
Ethmoidalair cells
Perpendicularplate Middle nasal concha
Cribriformplate
Olfactoryforamina
Crista galli
Left lateral mass
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Figure 7.7a Cranial cavity floor
Frontal bone
Olfactory foramina
Cribriform plateEthmoidbone Crista galli
Anterior cranial fossa
View
Facial BonesFourteen bonesOnly mandible and vomer are unpairedPaired bones: maxillae, zygomatics, nasals,
lacrimals, palatines, inferior conchae
MandibleLower jawbone; largest, strongest bone of faceMajor markings include: coronoid process, mandibular condyle,
alveolar margin, mandibular angle, mandibular and mental foramina
Maxillary BonesMedially fused bones make up upper jaw and central portion of
the facial skeletonFacial keystone bones that articulate with all other facial bones
except mandibleMajor markings include: palatine, frontal, and zygomatic
processes (artic. w/ respective bones), alveolar margins, maxillary sinuses
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Figure 7.11 Mandible and maxilla
CoronoidprocessMandibular foramen
Mental foramenRamus ofmandible
Mandibularcondyle
Body of mandible
Alveolar margin
Mandibleright lateral view
Temporomandibularjoint
Articulates withfrontal bone
Alveolarmargin
Maxilla, right lateral view
Orbitalsurface
Zygomaticprocess(cut)
Mandibular angle
Facial Bones
Zygomatic Bones - irregularly shaped bones (cheekbones), form prominences of cheeks and inferolateral margins of orbitsNasal bones – thin medially fused bones, form bridge of noseLacrimal bones – contribute to medial walls of orbits; contain lacrimal fossae which house lacrimal sacsPalatine bones – two bone plates, form portions of hard palate, posterolateral walls of nasal cavity, and small parts of orbitsVomer – plow-shaped bone, forms part of nasal septumInferior nasal conchae – paired, curved bones in nasal cavity, form part of lateral walls of nasal cavity
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Figure 7.4a Anterior aspect of skull
Parietal bone
Nasal boneSphenoid bone
Temporal boneEthmoid boneLacrimal boneZygomatic bone
MaxillaMandible
Mentalforamen
Frontal bone
Supraorbital marginSuperior orbitalfissure
Inferior orbitalfissure
Inferior nasal conchaVomer
Optic canal
Ethmoidbone
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Figure 7.5a Lateral aspect of skull, external view
Coronal suture Frontal bone
Sphenoid bone(greater wing)
Ethmoid bone
Lacrimal bone
Nasal bone
Zygomaticbone Maxilla
Alveolarmargins
MandibleMental foramen
Parietal bone
Lambdoidsuture
SquamoussutureOccipitalbone
External acousticmeatusMastoid processStyloid process
Mandibular condyle
Mandibular ramus
(a) External anatomy of the right side of the skull
Mandibular angle Coronoid process
Zygomaticprocess
Temporal bone
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Figure 7.5b Lateral aspect of skull, internal view
Parietal bone
Coronal sutureFrontal bone
Frontal sinus
Crista galliNasal boneSphenoid sinusEthmoid bone(perpendicular plate)Vomer
Maxilla
Mandible
Alveolar margins
LambdoidsutureOccipitalbone
Sella turcicaof sphenoidbone
Pterygoidprocess ofsphenoid boneMandibularforamenPalatine bone
SquamoussutureTemporalbone
Midsagittal section showing the internal anatomy of left half of skull
Sphenoid bone
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Figure 7.6a Inferior aspect of skull, mandible removed
Maxilla
Sphenoid bone(greater wing)
External acoustic meatus
Foramen magnum
Occipital condyle
Maxilla
Hardpalate
Zygomatic bone
Temporal bone(zygomatic process)
Vomer
Styloid process
Mastoid process
Temporal bone(petrous part)
Parietal bone
Palatine bone
Orbits
Bony cavities in which the eyes are firmly encased and cushioned by fatty tissue
Formed by parts of seven bones – frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, and ethmoid
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Orbits(cn 3,4,part5,6)
(cn 2)
maxilla
frontal
temporal
Nasal Cavity
Constructed of bone and hyaline cartilageRoof – formed by cribiform plate of ethmoidLateral walls – formed by superior and middle
conchae of ethmoid, perpendicular plate of palatine, and inferior nasal conchae
Floor – formed by palatine process of the maxillae and by palatine
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Nasal cavity: left lateral wall Nasal septum removed.
Maxillary bone(palatine process)
Palatine bone Palatine bone
Pterygoidprocess
SphenoidsinusSphenoid
bone
Frontal sinus
Superiornasal conchaMiddlenasal concha
Ethmoidbone
Inferior nasalconcha
Nasal bone
Superior, middle, andinferior meatus
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Vomer
Crista galliCribriformplate
Ethmoidbone
Frontalsinus
Nasal bone
Septal cartilage
Alveolar marginof maxilla
Perpendicularplate of ethmoid bone
Sella turcica
Sphenoid sinus
Palatinebone Palatine processof maxilla
Nasal cavity: Midline structures. Septum in place; note contributions of ethmoid bone, vomer, septal cartilage
Hardpalate
Paranasal Sinuses
Mucosa-lined, air-filled sacs found in five skull bones: frontal, sphenoid, ethmoid, and paired maxillary bones
Named for bones in which they resideAir enters paranasal sinuses from nasal cavityMucus drains into nasal cavity from paranasal
sinusesLighten skull; enhance resonance of the voice
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Figure 7.15 Paranasal sinuses.
Frontalsinus
Ethmoidalair cells(sinus)
Maxillarysinus
Sphenoidsinus
Frontalsinus
Ethmoidalair cells
Maxillarysinus
Sphenoidsinus
(a) Anterior aspect (b) Medial aspect
Hyoid BoneNot actually part of the skullLies just inferior to mandible in anterior neckOnly bone that does not articulate with another
boneAttachment point for neck muscles that raise and
lower larynx during swallowing and speech
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Anterior aspects of skull
Parietal bone
Nasal boneSphenoid bone
Temporal boneEthmoid boneLacrimal boneZygomatic bone
MaxillaMandible
Mentalforamen
Frontal bone
Supraorbital marginSuperior orbitalfissure
Inferior orbitalfissure
Inferior nasal conchaVomer
Optic canal
Ethmoidbone
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Coronal suture Frontal bone
Sphenoid bone(greater wing)
Ethmoid bone
Lacrimal bone
Lacrimal fossa
Nasal bone
Zygomaticbone Maxilla
Alveolarmargins
MandibleMental foramen
Parietal bone
Lambdoidsuture
SquamoussutureOccipitalbone
Mandibular ramus
Right side of skull
Mandibular angle Coronoid process
Zygomaticprocess
Temporal bone
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Parietal bone
Frontal bone
Frontal sinus
Crista galliNasal boneSphenoid sinusEthmoid bone
Vomer
Maxilla
Mandible
Alveolar margins
LambdoidsutureOccipitalbone
Sella turcicaof sphenoidbone Mandibular
foramenPalatine bone
Temporalbone
Internal anatomy of left half of skull (midsagittal section)
Maxilla
Sphenoid bone
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Figure 7.7a Cranial cavity floor
Hypophyseal fossaof sella turcica
Middle cranialfossa
Temporal bone
Posteriorcranial fossa
Parietal bone
Occipital bone
Foramen magnum
Frontal bone
Olfactory foramina
Optic canal
Hypoglossal canal
Cribriform plateEthmoidbone Crista galli
Sphenoid
Anterior cranial fossa
Lesser wingGreater wing
View
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Maxilla
Sphenoid bone(greater wing)
Carotid canal
Foramen magnum
Occipital condyle
Maxilla
Hardpalate
Zygomatic bone
Temporal bone(zygomatic process)
Vomer
Inferior view of skull (mandible removed)
Temporal bone
Parietal bone
Palatine bone