Transcript Document

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky
The Skeleton
Part A
Human Anatomy & Physiology, Sixth Edition
Elaine N. Marieb
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7
The Skeleton
 The skeleton (“dried up body” or mummy)
 It is strong, yet light, and almost perfectly adapted
for the protective, locomotor and manipulative
functions it perform
 Composed of bones, cartilages, joints and ligaments,
accounts for about 20% of body mass.
 The skeleton is divided into Axial and Appendicular
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The Axial Skeleton
 This part of skeleton supports the head, neck and
trunk and it protects the brain, spinal cord and the
organs in the thorax
 Eighty bones segregated into three regions
 1.- Skull
 2.- Vertebral column
 3.- Bony thorax
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The Skull
 The skull, the body’s most complex bony structure,
is formed by the cranium and facial bones
 Cranium – protects the brain and is the site of
attachment for head and neck muscles
 Facial bones
 Supply the framework of the face, the sense organs,
and the teeth
 Provide openings for the passage of air and food
 Anchor the facial muscles of expression
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Anatomy of the Cranium
 The cranium can be divided in :
1.- cranial vault (calvaria)
2.- cranial base (floor)
 Eight cranial bones – two parietal, two temporal,
frontal, occipital, sphenoid, and ethmoid
 Cranial bones are thin and remarkably strong for
their weight
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Frontal Bone
 Forms the anterior portion of the cranium
 Articulates posteriorly with the parietal bones via
the coronal suture
 The most anterior part of the frontal bone is the
vertical frontal squama, commonly called the
forehead
 Major markings include the supraorbital margins,
the anterior cranial fossa, and the frontal sinuses
(internal and lateral to the glabella)
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Skull: Anterior View
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Figure 7.2a
Skull: Posterior View
Figure 7.2b
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Parietal Bones and Major Associated Sutures
 They are curved, rectangular bones. Form most of
the superior and lateral aspects of the skull
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Figure 7.3a
Parietal Bones and Major Associated Sutures
 Four sutures mark the articulations of the parietal
bones
 1.- Coronal suture – articulation between parietal
bones and frontal bone anteriorly
 2.- Sagittal suture – where right and left parietal
bones meet superiorly
 3.- Lambdoid suture – where parietal bones meet
the occipital bone posteriorly
 4.- Squamosal or squamous suture – where parietal
and temporal bones meet
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Occipital Bone and Its Major Markings
 It articulates anteriorly with
the paired parietal and
temporal bones via the
lambdoid and
occipitomastoid sutures.
 It also joins with the
sphenoid bone in the cranial
floor via a plate called the
pharingeal tubercule.
 Forms most of skull’s
posterior wall and base
 Major markings include the
posterior cranial fossa,
foramen magnum, occipital
condyles, and the
hypoglossal canal
Figure 7.2b
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Occipital Bone and Its Major Markings
Internally, the occipital bone forms the walls of the posterior
cranial fossa which supports, the cerebellum of the brain.
The foramen magnum
connect the brain with
the spinal cord
Figure 7.4b
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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 the zygomatic, styloid, and
mastoid processes, and the mandibular and middle
cranial fossae
 Major openings include the stylomastoid and jugular
foramina, the external and internal auditory
meatuses, and the carotid canal
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Temporal Bones
• Between the styloid and
mastoid processes exist the
stylomastoid foramen that
allow cranial nerve VII to
leave the skull.
• The mastoid region of the
temporal bone exhibits the
conspicuous mastoid
process, an anchoring site
for some neck muscles
Figure 7.5
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Homeostatic Imbalance
 The mastoid process is full of air cavities, “the
mastoid sinuses or “air cells”. Because it position
behind the middle ear cavity (high risk area for
infections spreading from the throat) put it at risk for
infection itself.
 A mastoid sinus infection is difficult to treat
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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
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Sphenoid Bone
Figure 7.6a, b
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Ethmoid Bone
 Like the temporal and sphenoid bones, the ethmoid
bone has a complex shape
 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
 Major markings include the cribriform plate, crista
galli, perpendicular plate, nasal conchae, and the
ethmoid sinuses
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Ethmoid Bone
Allow the olfatory nerves to
pass from the smell receptors
in the nasal cavites to the brain
Figure 7.7
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Wormian Bones (sutural bones)
 Tiny irregularly shaped bones that appear within
sutures more often in the lambdoid suture.
Structurally unimportant.
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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
 As a rule the facial skeleton of men is more
elongated than that the women, therefore, women’s
faces tend to be rounder and less angular
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Mandible and Its Markings
 The U-shaped mandible (lower jawbone) is the
largest, strongest bone of the face
 It has a body , which forms the chin, and two
upright rami (branches)
 Its major markings include the coronoid process,
mandibular condyle, the alveolar margin, and the
mandibular and mental foramina
 Each ramus meets the body posteriorly at a
mandibular angle
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Mandible and Its Markings
Figure 7.8a
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Maxillary Bones (or maxillae)
 Medially fused bones that make up the upper jaw
and the central portion of the facial skeleton
 Facial keystone bones that articulate with all other
facial bones except the mandible
 Their major markings include palatine, frontal, and
zygomatic processes, the alveolar margins, inferior
orbital fissure, and the maxillary sinuses
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Maxillary Bone
The anterior nasal spine allows the infraorbital
nerve and artery to reach the face
Figure 7.8b
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Zygomatic Bones
 Irregularly shaped bones (cheekbones) that form the
prominences of the cheeks and the inferolateral
margins of the orbits
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Other Facial Bones
 Nasal bones – thin medially fused bones that form
the bridge of the nose
 Lacrimal bones (fingernail shaped) – contribute to
the medial walls of the orbit and contain a deep
groove called the lacrimal fossa that houses the
lacrimal sac
 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
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Other Facial Bones
 Vomer – plow-shaped bone that forms part of the
nasal septum
 Inferior nasal conchae – paired, thin-curved bones in
the nasal cavity that form part of the lateral walls of
the nasal cavity. They are the largest of the three
pairs of conchae.
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Anterior Aspects of the Skull
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Figure 7.2a
Posterior Aspects of the Skull
Figure 7.2b
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External Lateral Aspects of the Skull
Figure 7.3a
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Midsagittal Lateral Aspects of the Skull
Figure 7.3b
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Inferior Portion of the Skull
Figure 7.4a
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Inferior Portion of the Skull
Figure 7.4b
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