Download The Skeleton

The Skeleton
Chapter 7
Part A
The Skeleton
• Skeleton = Greek for ‘dried up
body’ or ‘mummy’
• Composed of bones, cartilages,
joints, and ligaments
– Mostly bone
– Ligaments connects bones and
reinforces joints
The Skeleton
• About 20% of body mass
– 160 pound person would have about
30 pound skeleton
• Classified into 2 parts
– Axial and Appendicular
The Axial Skeleton
• 80 bones in 3 regions
– Skull
– Vertebral column
– Bony thorax
• Supports the head, neck, trunk
• Protects the brain, spinal cord,
and the organs in the thorax
The Axial Skeleton
Axial
Skeleton
in Green
Figure 5.6
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.20b
The Skull
• Most complex structure
– 22 bones – mostly flat
• Two sets of bones
– Cranium
– Facial bones
The Skull
• Bones are joined by sutures
– Except mandible
• Sutures are interlocking joints –
saw-toothed or serrated
appearance
• Only the mandible is attached by a
freely movable joint
The Skull
•
•
•
•
•
Major skull sutures are
Coronal
Sagittal
Squamous
Lambdoid
The Skull
• Cranial bones or cranium
– Protects brain
– Site of attachment for head
and neck muscles
The Skull
• Facial bones
– Framework for face
– Cavities for special sense organs
of sight taste and smell
– Openings for air and food passage
– Secure teeth
– Anchor facial muscles of
expression
Anatomy of the Cranium
•
•
•
•
•
•
•
•
Eight cranial bones –
two Parietal
two Temporal
Frontal
Occipital
Sphenoid
Ethmoid
Cranial bones are thin and
remarkably strong for their weight
Frontal Bone
• Forms the anterior
portion of the
cranium
• Articulates
posteriorly with
the parietal bones
via the coronal
suture
• In yellow
Frontal Bone
• Major markings
– Frontal squama (forehead)
– supraorbital margins
– Supraorbital foramen
– the anterior cranial fossa
– the frontal sinuses
– glabulla
Parietal Bones
• Two curved retangular bones that
form most of the superior and
lateral aspects of skull
• In
Green
Parietal Bones and Major
Associated Sutures
• Four sutures mark the articulations
of the parietal bones
– Coronal suture – articulation
between parietal bones and
frontal bone anteriorly
– Sagittal suture – where right and
left parietal bones meet
superiorly
Parietal Bones and Major
Associated Sutures
• Four sutures mark the articulations
of the parietal bones
– Lambdoid suture – where parietal
bones meet the occipital bone
posteriorly
– Squamosal or squamous suture –
where parietal and temporal
bones meet
Skull: Posterior View
Parietal
bones
in
maroon
Figure 7.2b
Occipital Bone
• Forms most of
skull’s
posterior wall
and base
• Occiptal bone
in brown
Figure 7.2b
Occipital Bone
• Forms most of
skull’s posterior
wall and base
• Major markings
– Posterior cranial
fossa (inside)
– Foramen magnum
– Occipital condyles
– Hypoglossal canal
– External occipital
protuberance (you
can feel this)
Figure 7.2b
Human Skull, Inferior View
Figure 5.9
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.24
Temporal Bones
• Temple and
temporal are
latin words for
‘time’
– Gray hair
usually
appears first
at the
temples
• Divided into four major
regions
– Squamous
– Tympanic
• Ear drum
– Mastoid
– Petrous
• Contributes to the
cranial base
• Houses middle and
inner ear cavities
Temporal
Bones
Human Skull, Inferior View
Figure 5.9
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.24
Temporal Bones
• Major markings
– Zygomatic process
(squamous region)
• Zygomatic
process meets
zygomatic bone
of face – you can
feel this – your
cheek bone
Temporal Bones
• Major markings
– Styloid process
(needle like
projection in the
tympanic region)
Temporal Bones
• Major markings
– Mastoid process
(felt as a lump
posterior to the
ear)
– Mandibular fossae
– Middle cranial
fossae ( in Petrous
region)
Temporal Bones
• Major openings
– stylomastoid
foramina
– jugular
foramina
– external and
internal
auditory
meatuses (ear
canal)
– carotid canal
Sphenoid Bone
• Butterfly-shaped bone that spans the
width of the middle cranial fossa
• Forms the central wedge that articulates
with all other cranial bones
• Consists of a central body, greater wings,
lesser wings, and pterygoid processes
• Major markings: the sella turcica,
hypophyseal fossa, and the pterygoid
processes
• Major openings include the foramina
rotundum, ovale, and spinosum; the optic
canals; and the superior orbital fissure
Human Skull, Superior View
Sphenoid
Bone in
pink
Figure 5.8
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.23
Sphenoid Bone
Figure 7.6a, b
Ethmoid Bone
• Most deep of the
skull bones; lies
between the
sphenoid and nasal
bones
• Forms most of the
bony area
between the nasal
cavity and the
orbits
Ethmoid Bone
• Major markings
– cribriform plate
– crista galli
– perpendicular
plate
– nasal conchae
– ethmoid sinuses
Human Skull, Superior View
Figure 5.8
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.23
Human Skull, Inferior View
Figure 5.9
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.24
Wormian Bones
• Also called sutural bones
• Tiny irregularly shaped bones that
appear within sutures
• Structurally unimportant
• Not all skulls exhibit them
Facial Bones
Facial Bones
• Fourteen bones of which only the
mandible and vomer are unpaired
• The paired bones are the maxillae,
zygomatics, nasals, lacrimals,
palatines, and inferior conchae
• Usually facial bones of men are
more elongated than of women
Mandible and Its Markings
• The
mandible
(lower
jawbone) is
the
largest,
strongest
bone of
the face
Mandible and Its Markings
• Its major
markings include
the coronoid
process,
mandibular
condyle, the
alveolar margin,
and the
mandibular and
mental foramina
Mandible and Its Markings
• Dentists
inject
Novocain
into the
mandibular
foramina to
numb teeth
Maxillary Bones
• Medially fused bones that make up the
upper jaw and the central portion of the
facial skeleton
Maxillary Bones
• Facial keystone bones that articulate
with all other facial bones except the
mandible
Maxillary Bones
• Their major markings include palatine,
frontal, and zygomatic processes, the
alveolar margins, inferior orbital fissure, and
the maxillary sinuses
Zygomatic Bones
• Irregularly
shaped bones
(cheekbones)
that form the
prominences
of the cheeks
and the
inferolateral
margins of
the orbits
In Teal
Other Facial Bones
• Nasal
bones –
thin
medially
fused
bones that
form the
bridge of
the nose
Other Facial Bones
• Lacrimal bones –
contribute to
the medial walls
of the orbit and
contain a deep
groove called
the lacrimal
fossa that
houses the
lacrimal sac
Other Facial Bones
• Palatine bones –
two bone plates
that form
portions of the
hard palate, the
posterolateral
walls of the
nasal cavity,
and a small part
of the orbits
Other Facial Bones
• Vomer –
plowshaped
bone that
forms
part of
the nasal
septum
Other Facial Bones
• Inferior nasal
conchae –
paired, curved
bones in the
nasal cavity
that form part
of the lateral
walls of the
nasal cavity
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
Orbits
Figure 7.9b
Nasal Cavity
• Constructed of bone and hyaline
cartilage
• Roof – formed by the cribriform plate
of the ethmoid
Nasal Cavity
• Lateral walls – formed by the superior
and middle conchae of the ethmoid, the
perpendicular plate of the palatine, and
the inferior nasal conchae
• Floor – formed by palatine process of
the maxillae and palatine bone
Paranasal Sinuses
 Hollow portions of bones
surrounding the nasal cavity
Figure 5.10
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.25a
Paranasal Sinuses
• Mucosa-lined, air-filled sacs found in
five skull bones – the frontal, sphenoid,
ethmoid, and paired maxillary bones
Paranasal Sinuses
• Air enters the paranasal sinuses from
the nasal cavity and mucus drains into
the nasal cavity from the sinuses
Paranasal Sinuses
• Lighten the skull and enhance the
resonance of the voice and amplifies
Figure 7.11
Hyoid Bone
• Not actually part of the skull, but lies
just inferior to the mandible in the
anterior neck
• Only bone of the body that does not
articulate directly with another bone
• Attachment point for neck muscles that
raise and lower the larynx during
swallowing and speech
The Hyoid Bone
 The only bone
that does not
articulate with
another bone
 Serves as a
moveable base for
the tongue
Figure 5.12
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.26
The Fetal Skull
 The fetal skull
is large
compared to
the infants
total body
length
Figure 5.13
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.27a
The Fetal Skull
 Fontanelles –
fibrous membranes
connecting the
cranial bones
Allow the brain
to grow
Convert to bone
within 24 months
after birth
Figure 5.13
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.27b
Quiz – Next time!
Complete study guide
Pages 143 - 150
Skull: Anterior View
Figure 7.2a
Parietal Bones and Major Associated Sutures
• Form most of the superior and lateral
aspects of the skull
Figure 7.3a
Occipital Bone and Its Major
Markings
Figure 7.4b
Anterior Aspects of the Skull
Figure 7.2a
Posterior Aspects of the Skull
Figure 7.2b
External Lateral Aspects of
the Skull
Figure 7.3a
Midsagittal Lateral Aspects of
the Skull
Figure 7.3b
Inferior Portion of the Skull
Figure 7.4a
Inferior Portion of the Skull
Figure 7.4b
Quiz – Next time!
Complete study guide