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PowerPoint® Lecture Slides prepared by Janice Meeking, Mount Royal College

C H A P T E R

Copyright © 2010 Pearson Education, Inc.

7

The Skeleton: Part A


The Axial Skeleton

• Consists of 80 bones

• Three major regions• Skull

• Vertebral column

• Thoracic cage

Copyright © 2010 Pearson Education, Inc. Figure 7.1a

Skull

Thoracic cage(ribs andsternum)

(a) Anterior view

Facial bonesCranium

Sacrum

Vertebralcolumn

ClavicleScapulaSternumRibHumerusVertebraRadiusUlnaCarpals

PhalangesMetacarpalsFemurPatellaTibiaFibula

TarsalsMetatarsalsPhalanges


The Skull

• Two sets of bones

1. Cranial bones

• Enclose the brain in the cranial cavity

• Cranial vault (calvaria)

• Cranial base: anterior, middle, and posterior cranial fossae

• Provide sites of attachment for head and neck muscles


The Skull

2. Facial bones

• Framework of face

• Cavities for special sense organs for sight, taste, and smell

• Openings for air and food passage

• Sties of attachment for teeth and muscles of facial expression


Bone Markings: Depressions and Openings

• Meatus

• Canal-like passageway• Sinus

• Cavity within a bone• Fossa

• Shallow, basinlike depression

• Groove

• Furrow• Fissure

• Narrow, slitlike opening• Foramen

• Round or oval opening through a bone


Fontanels (soft spots) & Sutures • Cartilage and mesenchyme regions in the skull that will

eventually ossify by intramembranous bone formation

Physiologic Purposes

1. Allows rapid growth of the brain

2. Allows overlap of the skull bones during delivery

• Medical Usages

1. Allows determination of fetal head during delivery

2. Allows determination of the superior sagittal sinus during surgery for hydrocephalus

3. Assists in the determination of fetal age


Fontanels

• Anterior Fontanel – Largest Fontanel – closes 18 – 24 months after birth

• Posterior Fontanel – Closes 2 months after birth

• Anterolateral Fontanel – Closes 3 months after birth

• Posterolateral Fontanel – begins to close 1 – 2 months after birth and finishes closure at 12 months


Sutures• A suture is a type of fibrous joint which only occurs in

the skull (or "cranium"). They are bound together by Sharpey's fibers. A tiny amount of movement is permitted at sutures, which contributes to the compliance and elasticity of the skull.

• Frontal Suture – completely closes – if it persists it is termed the metopic suture• Coronal suture—between parietal bones and frontal bone • Sagittal suture—between right and left parietal bones • Lambdoid suture—between parietal bones and occipital

bone • Squamous (squamosal) sutures—between parietal and

temporal bones on each side of skull

http://en.wikipedia.org/wiki/Fibrous_joint

http://en.wikipedia.org/wiki/Sharpey's_fibres

http://en.wikipedia.org/wiki/Compliance_(physiology)

http://en.wikipedia.org/wiki/Elasticity_(physics)


Bones of cranium (cranial vault)

Lambdoidsuture

Facialbones

Squamoussuture

(a) Cranial and facial divisions of the skull

Coronalsuture


Coronal suture Frontal boneSphenoid bone(greater wing)Ethmoid boneLacrimal bone

Lacrimal fossa

Nasal boneZygomaticbone Maxilla

Alveolarmargins

MandibleMental foramen

Parietal bone

Lambdoidsuture

SquamoussutureOccipitalbone

OccipitomastoidsutureExternal acousticmeatusMastoid processStyloid process

Mandibular condyleMandibular notchMandibular ramus

(a) External anatomy of the right side of the skullMandibular angle Coronoid process

Zygomaticprocess

Temporal bone

Figure 7.5a


Cranial Bones

• Frontal bone

• Parietal bones (2)

• Occipital bone

• Temporal bones (2)

• Sphenoid bone

• Ethmoid bone


Frontal Bone

• Anterior portion of cranium

• Most of anterior cranial fossa

• Superior wall of orbits

• Contains air-filled frontal sinus


Parietal bone

Squamous part of frontal boneNasal boneSphenoid bone(greater wing)Temporal boneEthmoid boneLacrimal boneZygomatic bone

MaxillaMandible

Infraorbital foramen

Mentalforamen

(a) Anterior view Mandibular symphysis

Frontal boneGlabellaFrontonasal sutureSupraorbital foramen(notch)Supraorbital marginSuperior orbitalfissure

Inferior orbitalfissureMiddle nasalconcha

Inferior nasal conchaVomer

Optic canal

Perpendicularplate

Ethmoidbone

Copyright © 2010 Pearson Education, Inc. Figure 7.2b

Anterior cranialfossa

Middle cranialfossa

Posterior cranialfossa

(b) Superior view of the cranial fossae


Parietal Bones

• Superior and lateral aspects of cranial vault



Lacrimal fossa


Alveolarmargins


Parietal bone

Lambdoidsuture

SquamoussutureOccipitalbone




Zygomaticprocess

Temporal bone

Figure 7.5a


Anterior cranialfossa

Middle cranialfossa

Posterior cranialfossa

(b) Superior view of the cranial fossae


Ethmoid Bone

• Deepest skull bone

• Superior part of nasal septum, roof of nasal cavities

• Contributes to medial wall of orbits

Copyright © 2010 Pearson Education, Inc. Figure 7.10

Orbitalplate

Ethmoidalair cells Perpendicularplate Middle nasal concha

Cribriformplate

Olfactoryforamina

Crista galli

Left lateral mass


Parietal bone


MaxillaMandible


Mentalforamen





Optic canal

Perpendicularplate

Ethmoidbone


Figure 13.5a Location and function of cranial nerves. Frontal lobe

Temporal lobe

InfundibulumFacialnerve (VII)Vestibulo-cochlearnerve (VIII)Glossopharyngealnerve (IX)Vagus nerve (X)Accessory nerve (XI)Hypoglossal nerve (XII)

(a)

Filaments ofolfactory nerve (I)Olfactory bulbOlfactory tract

Optic chiasma

Optic nerve(II) Optic tractOculomotornerve (III)Trochlearnerve (IV) Trigeminalnerve (V) Abducensnerve (VI)

CerebellumMedullaoblongata


Figure 15.21 Olfactory receptors. Mitral cell(output cell)

Olfactorygland

Olfactorytract

Olfactoryepithelium

Filaments ofolfactory nerve

Cribriform plateof ethmoid bone

Lamina propriaconnective tissue

Basal cell

Supporting cellDendriteOlfactory cilia

Olfactory bulbGlomeruli

Axon

Olfactoryreceptor cell

Mucus

Route of inhaled aircontaining odor molecules

Olfactory tractOlfactory bulb

(a)

(b)

Nasalconchae

Route ofinhaled air

Olfactoryepithelium


Figure 15.21a Olfactory receptors.

Olfactory tractOlfactory bulb

(a)

Nasalconchae

Route ofinhaled air

Olfactoryepithelium


Sphenoid Bone

• Complex, bat-shaped bone

• Keystone bone• Articulates with all other cranial bones

• Three pairs of processes• Greater wings

• Lesser wings

• Pterygoid processes


Hypophyseal fossaof sella turcicaMiddle cranialfossaTemporal bone(petrous part)

Posteriorcranial fossa

Parietal bone

Occipital bone

Foramen magnum

(a) Superior view of the skull, calvaria removed

Frontal bone

Olfactory foramina

Optic canal

Foramen rotundumForamen ovaleForamen spinosum

Jugular foramenHypoglossal canal

Foramen lacerumInternal acousticmeatus

Cribriform plateEthmoidbone Crista galli

Sphenoid

Anterior cranial fossa

Lesser wingGreater wing

View


GreaterwingHypophysealfossa ofsella turcica

ForamenrotundumForamenovaleForamenspinosumBody of sphenoid

Superiororbital fissure

(a) Superior view

Optic canal Lesser wing


Body of sphenoid

Greaterwing

Superiororbitalfissure

Lesserwing

Pterygoidprocess

(b) Posterior view


Incisive fossa

Median palatine sutureIntermaxillary suture

Infraorbital foramenMaxillaSphenoid bone(greater wing)

Foramen ovale

Foramen lacerumCarotid canalExternal acoustic meatusStylomastoidforamenJugular foramen

Foramen magnum

Occipital condyle

Inferior nuchal line

Superior nuchal line

Foramen spinosum

Maxilla(palatine process)

Hardpalate

Zygomatic bone

Temporal bone(zygomatic process)

Mandibularfossa

Vomer

Styloid process

External occipital crestExternal occipitalprotuberance

(a) Inferior view of the skull (mandible removed)

Mastoid processTemporal bone(petrous part)

Pharyngeal tubercleof basilar region ofthe occipital boneParietal bone

Palatine bone(horizontal plate)


Temporal Bones

• Inferolateral aspects of skull and parts of cranial floor

• Four major regions• Squamous

• Tympanic

• Mastoid

• Petrous


Mastoidregion

Externalacousticmeatus

Mastoidprocess Styloid process

Tympanic regionMandibular fossaZygomatic process

Squamousregion


Incisive fossa



Foramen ovale


Foramen magnum

Occipital condyle



Foramen spinosum


Hardpalate

Zygomatic bone


Mandibularfossa

Vomer

Styloid process







Hypophyseal fossaof sella turcicaMiddle cranialfossaTemporal bone(petrous part)

Posteriorcranial fossa

Parietal bone

Occipital bone

Foramen magnum

(a) Superior view of the skull, calvaria removed

Frontal bone

Olfactory foramina

Optic canal

Foramen rotundumForamen ovaleForamen spinosum

Jugular foramenHypoglossal canal

Foramen lacerumInternal acousticmeatus

Cribriform plateEthmoidbone Crista galli

Sphenoid

Anterior cranial fossa

Lesser wingGreater wing

View


Occipital Bone

• Most of skull’s posterior wall and posterior cranial fossa

• Articulates with 1st vertebra

• Sites of attachment for the ligamentum nuchae and many neck and back muscles


Lambdoidsuture

Occipital bone


Externaloccipitalprotuberance

Suturalbone

Occipitomastoidsuture

(b) Posterior view

Occipitalcondyle

Externaloccipitalcrest

Inferiornuchalline

Mastoidprocess

Parietalbone

Sagittal suture


Incisive fossa



Foramen ovale


Foramen magnum

Occipital condyle



Foramen spinosum


Hardpalate

Zygomatic bone


Mandibularfossa

Vomer

Styloid process







Sutural Bones

• Tiny irregularly shaped bones that appear within sutures


Lambdoidsuture

Occipital bone


Externaloccipitalprotuberance

Suturalbone

Occipitomastoidsuture

(b) Posterior view

Occipitalcondyle

Externaloccipitalcrest

Inferiornuchalline

Mastoidprocess

Parietalbone

Sagittal suture


Facial Bones

• Mandible

• Maxillary bones (maxillae) (2)

• Zygomatic bones (2)

• Nasal bones (2)

• Lacrimal bones (2)

• Palatine bones (2)

• Vomer

• Inferior nasal conchae (2)


Mandible

• Lower jaw

• Largest, strongest bone of face

• Temporomandibular joint: only freely movable joint in skull


Coronoidprocess

Mandibular foramen

Mentalforamen

Mandibularangle

Ramusofmandible

Mandibularcondyle

Mandibular notch

Mandibular fossaof temporal bone

Body of mandible

Alveolarmargin

(a) Mandible, right lateral view

Temporomandibularjoint


Maxillary Bones

• Medially fused to form upper jaw and central portion of facial skeleton

• Keystone bones• Articulate with all other facial bones except

mandible


Frontal process

Articulates withfrontal bone

Anterior nasalspine

Infraorbitalforamen

Alveolarmargin

(b) Maxilla, right lateral view

Orbitalsurface Zygomaticprocess(cut)


Parietal bone


MaxillaMandible


Mentalforamen





Optic canal

Perpendicularplate

Ethmoidbone


Incisive fossa



Foramen ovale


Foramen magnum

Occipital condyle



Foramen spinosum


Hardpalate

Zygomatic bone


Mandibularfossa

Vomer

Styloid process







Zygomatic Bones

• Cheekbones

• Inferolateral margins of orbits


Parietal bone


MaxillaMandible


Mentalforamen





Optic canal

Perpendicularplate

Ethmoidbone


Nasal Bones and Lacrimal Bones

• Nasal bones• Form bridge of nose

• Lacrimal bones• In medial walls of orbits

• Lacrimal fossa houses lacrimal sac



Lacrimal fossa


Alveolarmargins


Parietal bone

LambdoidsutureSquamoussutureOccipitalbone




Zygomaticprocess

Temporal bone


Palatine Bones and Vomer

• Palatine bones

• Posterior one-third of hard palate

• Posterolateral walls of the nasal cavity

• Small part of the orbits

• Vomer

• Plow shaped

• Lower part of nasal septum


Incisive fossa



Foramen ovale


Foramen magnum

Occipital condyle



Foramen spinosum


Hardpalate

Zygomatic bone


Mandibularfossa

Vomer

Styloid process







Inferior Nasal Conchae

• Form part of lateral walls of nasal cavity


Maxillary bone(palatine process)

Palatine bone(perpendicular plate)


Pterygoidprocess

(a) Bones forming the left lateral wall of the nasal cavity (nasal septum removed)

SphenoidsinusSphenoid

bone

Anterior nasal spine

Frontal sinusSuperiornasal conchaMiddlenasal concha

Ethmoidbone

Inferior nasalconcha Nasal bone

Superior, middle, andinferior meatus


Orbits

• Encase eyes and lacrimal glands

• Sites of attachment for eye muscles

• Formed by parts of seven bones (next slide)


Roof of orbit

Medial wall

Supraorbital notch Optic canal

Floor of orbit

Nasal bone

Lateral wall of orbit

Zygomatic bone

Inferior orbital fissureInfraorbital groove


Superiororbital fissure

(b) Contribution of each of the seven bones forming the right orbit

• Lesser wing ofsphenoid bone• Orbital plate offrontal bone

• Zygomatic processof frontal bone• Greater wing ofsphenoid bone• Orbital surface ofzygomatic bone

• Sphenoid body• Orbital plateof ethmoid bone• Frontal processof maxilla• Lacrimal bone

• Orbital process ofpalatine bone• Orbital surface ofmaxillary bone• Zygomatic bone

Figure 7.13a


Nasal Cavity

• Roof, lateral walls, and floor formed by parts of four bones• Ethmoid• Palatine bones• Maxillary bones• Inferior nasal conchae

• Nasal septum of bone and hyaline cartilage• Ethmoid • Vomer • Anterior septal cartilage


Maxillary bone(palatine process)

Palatine bone(perpendicular plate)


Pterygoidprocess

(a) Bones forming the left lateral wall of the nasal cavity (nasal septum removed)

SphenoidsinusSphenoid

bone

Anterior nasal spine

Frontal sinusSuperiornasal conchaMiddlenasal concha

Ethmoidbone

Inferior nasalconcha Nasal bone

Superior, middle, andinferior meatus


Vomer

Crista galliCribriformplate

Ethmoidbone

Frontalsinus

Nasal bone

Septal cartilage

Alveolar marginof maxilla

Perpendicularplate of ethmoid bone

Sella turcica

Sphenoid sinus

Palatinebone Palatine processof maxilla

(b) Nasal cavity with septum in place showing the contributions of the ethmoid bone, the vomer, and septal cartilage

Hardpalate


Paranasal Sinuses

• Mucosa-lined, air-filled spaces

• Lighten the skull

• Enhance resonance of voice

• Found in frontal, sphenoid, ethmoid, and maxillary bones


Frontalsinus Ethmoidalair cells(sinus)

Maxillarysinus

Sphenoidsinus

FrontalsinusEthmoidalair cells

Maxillarysinus

Sphenoidsinus

(a) Anterior aspect (b) Medial aspect


Hyoid Bone

• Not a bone of the skull

• Does not articulate directly with another bone

• Site of attachment for muscles of swallowing and speech


Greater horn

Lesser horn

Body

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