Download Bones, Part 1: The Axial Skeleton

PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
7
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 1
Bones, Part 1:
The Axial
Skeleton
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
The Skeleton

Consists of
 Bones, cartilage, joints, and ligaments

Composed of 206 named bones grouped into two
divisions
 Axial skeleton (80 bones)
 Appendicular skeleton (126 bones)
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The Axial Skeleton


Formed from 80
named bones
Consists of skull,
vertebral column,
and bony thorax
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Figure 7.1a
The Axial Skeleton
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Figure 7.1b
Bone Markings



Projections that provide attachment for muscles
and ligaments
Projections that help form joints
Depressions and openings for passage of nerves
and blood vessels
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The Skull

Formed by cranial and facial bones
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Figure 7.2a
The Cranium

The cranium serves to
 Enclose brain
 Provide attachment sites for some head and neck
muscles
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The Face

Facial bones serve to
 Form framework of the face
 Form cavities for the sense organs of sight, taste,
and smell
 Provide openings for the passage of air and food
 Hold the teeth in place
 Anchor muscles of the face
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Overview of Skull Geography



Facial bones form anterior aspect
Cranium is divided into cranial vault and the base
Internally, prominent bony ridges divide skull into
distinct fossae
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Overview of Skull Geography

The skull contains smaller cavities
 Middle and inner ear cavities – in lateral aspect of
cranial base
 Nasal cavity – lies in and posterior to the nose
 Orbits – house the eyeballs
 Air-filled sinuses – occur in several bones around
the nasal cavity
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Overview of Skull Geography

The skull contains approximately 85 named
openings
 Foramina, canals, and fissures
 Provide openings for important structures
 Spinal cord
 Blood vessels serving the brain
 12 pairs of cranial nerves
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Cranial Bones

Formed from eight large bones
 Paired bones include
 Temporal bones
 Parietal bones
 Unpaired bones include
 Frontal bone
 Occipital bone
 Sphenoid bone
 Ethmoid bone
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Frontal Bones




Forms the forehead and roofs of the orbits
Forms superciliary arches
Internally, it contributes to the anterior cranial
fossa
Contains frontal sinuses
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Parietal Bones and Sutures


Parietal bones form superior and lateral parts of
skull
Four sutures of the cranium
 Coronal suture – runs in the coronal plane
 Located where parietal bones meet the frontal bone
 Squamous suture – occurs where each parietal
bone meets a temporal bone inferiorly
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Parietal Bones and Sutures

Sutures of the cranium (continued)
 Sagittal suture – occurs where right and left
parietal bones meet superiorly
 Lambdoid suture – occurs where the parietal
bones meet the occipital bone posteriorly
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Sutural Bones



Small bones that occur within sutures
Irregular in shape, size, and location
Not all people have sutural bones
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The Skull – Posterior View
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Figure 7.2b
Occipital Bone




Forms the posterior portion of the cranium and
cranial base
Articulates with the temporal bones and parietal
bones
Forms the posterior cranial fossa
Foramen magnum located at its base
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Occipital Bone

Features and structures
 Occipital condyles
 Hypoglossal foramen
 External occipital protuberance
 Superior nuchal lines
 Inferior nuchal lines
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Inferior Aspect of the Skull
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Figure 7.4a
Temporal Bones



Lie inferior to parietal bones
Form the inferolateral portion of the skull
Term “temporal”
 Comes from Latin word for time

Specific regions of temporal bone
 Squamous, temporal, petrous, and mastoid regions
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Lateral Aspect of the Skull
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Figure 7.3a
The Temporal Bone
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Figure 7.5
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
7
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 2
Bones, Part 1:
The Axial
Skeleton
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
The Sphenoid Bone




Spans the width of the cranial floor
Resembles a butterfly or bat
Consists of a body and three pairs of processes
Contains five important openings
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The Sphenoid Bone
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Figure 7.6a
The Sphenoid Bone
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Figure 7.6b
The Ethmoid Bone


Lies between nasal and sphenoid bones
Forms most of the medial bony region between the
nasal cavity and orbits
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The Ethmoid Bone
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Figure 7.7
Bones of the Skull
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Table 7.1 (1 of 2)
Facial Bones

Unpaired bones

Paired bones
 Mandible and vomer
 Maxillae
 Zygomatic bones
 Nasal bones
 Lacrimal bones
 Palatine bones
 Inferior nasal conchae
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Mandible


The lower jawbone is the largest and strongest
facial bone
Composed of two main parts
 Horizontal body
 Two upright rami
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Mandible
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Figure 7.8a
Maxillary Bones



Articulate with all other facial bones except the
mandible
Contain maxillary sinuses – largest paranasal
sinuses
Forms part of the inferior orbital fissure
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Maxillary Bones
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Figure 7.8b
Maxillary Bones
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Figure 7.4a
Other Bones of the Face

Zygomatic bones
 Form lateral wall of orbits

Nasal bones
 Form bridge of nose

Lacrimal bones
 Located in the medial orbital walls

Palatine bones
 Complete the posterior part of the hard palate
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Other Bones of the Face

Vomer
 Forms the inferior part of the nasal septum

Inferior nasal conchae
 Thin, curved bones that project medially form the
lateral walls of the nasal cavity
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Facial Bones
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Table 7.1 (2 of 2)
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
7
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 3
Bones, Part 1:
The Axial
Skeleton
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Bones of the Face
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7.2a
Special Parts of the Skull




Orbits
Nasal cavity
Paranasal sinuses
Hyoid bone
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Nasal Cavity
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Figure 7.9a
Nasal Septum
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Figure 7.9b
Orbits
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Figure 7.10b
Paranasal Sinuses

Air-filled sinuses are located within
 Frontal bone
 Ethmoid bone
 Sphenoid bone
 Maxillary bones


Lined with mucous membrane
Serve to lighten the skull
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Paranasal Sinuses
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Figure 7.11a, b
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
7
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 4
Bones, Part 1:
The Axial
Skeleton
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
The Hyoid Bone



Lies inferior to the
mandible
The only bone with
no direct
articulation with
any other bone
Acts as a movable
base for the tongue
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Figure 7.12
The Vertebral Column



Formed from 26 bones in the adult
Transmits weight of trunk to the lower limbs
Surrounds and protects the spinal cord
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The Vertebral Column


Serves as attachment sites for muscles of the neck
and back
Held in place by ligaments
 Anterior and posterior longitudinal ligaments
 Ligamentum flavum
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The Vertebral Column
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Figure 7.13
Intervertebral Discs




Cushion-like pads between vertebrae
Act as shock absorbers
Compose about 25% of height of vertebral column
Composed of
 Nucleus pulposus and annulus fibrosis
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Intervertebral Discs

Nucleus pulposus
 The gelatinous inner sphere of intervertebral disc
 Enables spine to absorb compressive stresses
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Intervertebral Discs

Annulus fibrosis
 An outer collar of ligaments and fibrocartilage
 Contains the nucleus pulposus
 Functions to bind vertebrae together, resist tension
on the spine, and absorb compressive forces
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Ligaments and Intervertebral Discs
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Figure 7.14a
Herniated Disc


May be caused by
trauma to the spine
Aging is also a
contributing factor
 Nucleus pulposes
loses cushioning
properties
 Anulus fibrosis
weakens
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Figure 7.14c
Regions and Normal Curvatures


Vertebral column is about 70 cm (28 inches)
Vertebral column is divided into five major
regions
 Cervical vertebrae
 7 vertebrae of the neck region
 Thoracic vertebrae
 12 vertebrae of the thoracic region
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Regions and Normal Curvatures

Vertebral column is divided into five major
regions (continued)
 Lumbar vertebrae
 5 vertebrae of the lower back
 Sacrum
 Inferior to lumbar vertebrae
 Articulates with coxal bones
 Coccyx
 Most inferior region of the vertebral column
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Regions and Normal Curvatures

Four distinct curvatures give vertebral column an
S-shape
 Cervical and lumbar curvature
 Are concave posteriorly
 Thoracic and sacral curvatures
 Are convex posteriorly

Curvatures increase the resilience of the spine
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Regions and Normal Curvatures
PLAY
Spine (vertical)
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Figure 7.13
General Structure of Vertebrae
PLAY
Spine (horizontal)
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Figure 7.15
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
7
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 5
Bones, Part 1:
The Axial
Skeleton
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Regions Vertebral Characteristics


Specific regions of the spine perform specific
functions
Types of movement that occur between vertebrae
 Flexion and extension
 Lateral flexion
 Rotation in the long axis
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Cervical Vertebrae


Seven cervical vertebrae (C1 – C7) – smallest and
lightest vertebrae
C3 – C7 are typical cervical vertebrae
 Body is wider laterally
 Spinous processes are short and bifid (except C7)
 Vertebral foramen are large and triangular
 Transverse processes contain transverse foramina
 Superior articular facets face superoposteriorly
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Cervical Vertebrae
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Table 7.2a
Cervical Vertebrae
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Figure 7.17a
The Atlas



C1 is termed the atlas
Lacks a body and spinous process
Supports the skull
 Superior articular facets receive the occipital
condyles

Allows flexion and extension of neck
 Nodding the head “yes”
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The Atlas
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Figure 7.16a
The Atlas
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Figure 7.16b
The Axis


Has a body and spinous process
Dens (odontoid process) projects superiorly
 Formed from fusion of the body of the atlas with
the axis
 Acts as a pivot for rotation of the atlas and skull
 Participates in rotating the head from side to side
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The Axis
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Figure 7.16c
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
7
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 6
Bones, Part 1:
The Axial
Skeleton
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Thoracic Vertebrae (T1 – T12)



All articulate with ribs
Have heart-shaped bodies from the superior view
Each side of the body of T1 – T10 bears demifacts
for articulation with ribs
 T1 has a full facet for the first rib
 T10 – T12 only have a single facet
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Thoracic Vertebrae
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Table 7.2b
Thoracic Vertebrae





Spinous processes are long and point inferiorly
Vertebral foramen are circular
Transverse processes articulate with tubercles of
ribs
Superior articular facets point posteriorly
Inferior articular processes point anteriorly
 Allows rotation and prevents flexion and extension
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Lumbar Vertebrae (L1 – L5)






Bodies are thick and robust
Transverse processes are thin and tapered
Spinous processes are thick, blunt, and point
posteriorly
Vertebral foramina are triangular
Superior and inferior articular facets directly
medially
Allows flexion and extension – rotation prevented
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Lumbar Vertebrae
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Table 7.2c
Lumbar Vertebrae
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Figure 7.17c
Sacrum (S1 – S5)






Shapes the posterior wall of pelvis
Formed from 5 fused vertebrae
Superior surface articulates with L5
Inferiorly articulates with coccyx
Sacral promontory
 Where the first sacral vertebrae bulges into pelvic
cavity
Center of gravity is 1 cm posterior to sacral
promontory
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Sacrum

Sacral foramina
 Ventral foramina
 Passage for ventral rami of sacral spinal nerves
 Dorsal foramina
 Passage for dorsal rami of sacral spinal nerves
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Sacrum
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Figure 7.18a, b
Coccyx



Is the “tailbone”
Formed from 3 – 5 fused vertebrae
Offers only slight support to pelvic organs
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
7
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 7
Bones, Part 1:
The Axial
Skeleton
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Bony Thorax


Forms the framework of the chest
Components of the bony thorax
 Thoracic vertebrae – posteriorly
 Ribs – laterally
 Sternum and costal cartilage – anteriorly



Protects thoracic organs
Supports shoulder girdle and upper limbs
Provides attachment sites for muscles
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The Bony Thorax
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Figure 7.19a
The Bony Thorax
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Figure 7.19b
Sternum

Formed from three sections
 Manubrium – superior section
 Articulates with medial end of clavicles
 Body – bulk of sternum
 Sides are notched at articulations for costal cartilage
of ribs 2–7
 Xiphoid process – inferior end of sternum
 Ossifies around age 40
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Sternum

Anatomical landmarks
 Jugular notch
 Central indentation at superior border of the
manubrium
 Sternal angle
 A horizontal ridge where the manubrium joins the
body
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Ribs

All ribs attach to vertebral column posteriorly
 True ribs - superior seven pairs of ribs
 Attach to sternum by costal cartilage
 False ribs – inferior five pairs of ribs
 Ribs 11–12 are known as floating ribs
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Ribs
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Figure 7.20a
Ribs
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Figure 7.20b
Disorders of the Axial Skeleton

Abnormal spinal curvatures
 Scoliosis – an abnormal lateral curvature
 Kyphosis – an exaggerated thoracic curvature
 Lordosis – an accentuated lumbar curvature –
“swayback”

Stenosis of the lumbar spine
 A narrowing of the vertebral canal
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The Axial Skeleton Throughout Life



Membrane bones begin to ossify in second month
of development
Bone tissue grows outward from ossification
centers
Fontanels
 Unossified remnants of membranes
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Fontanels
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Figure 7.21a
Fontanels
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Figure 7.21b
The Axial Skeleton Throughout Life


Many bones of the face and skull form by
intramembranous ossification
Endochondral bones of the skull
 Occipital bone
 Sphenoid
 Ethmoid bones
 Parts of the temporal bone
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The Axial Skeleton Throughout Life

Curvatures of the vertebral column
 Primary curvatures – thoracic and sacral
curvatures
 An infant's spine is C-shaped at birth
 Secondary curvatures – cervical and lumbar
curvatures
 Develop when a baby begins to walk
 Redistributes weight of the upper body over the
lower limbs
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The Axial Skeleton Throughout Life

Aging of the axial skeleton
 Water content of the intervertebral discs decreases
 By age 55, loss of a few centimeters in height is
common
 Thorax becomes more rigid
 Bones lose mass with age
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