Transcript Chapter 7: The Axial Skeleton

Unit
2
Support and Movement
Fundamentals of
Anatomy & Physiology
Frederic H. Martini
PowerPoint® Lecture Slides prepared by
Professor Albia Dugger, Miami–Dade College, Miami, FL
Professor Robert R. Speed, Ph.D., Wallace Community College, Dothan, AL
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Chapter 7:
The Axial Skeleton
What are the bones of the axial
skeleton, their structures, and
functions?
Structures of Bones

Articulations:


Marks:


contacts with other bones
areas of muscle and ligament attachment
Foraminae:

openings for nerves and blood vessels
The Axial Skeleton
PLAY
3D Peel-Away of Whole Axial Skeleton
Figure 7–1a
The Axial Skeleton *
Figure 7–1b
The Axial Skeleton

The axial skeleton:


forms the longitudinal axis of the body
has 80 bones
Bones of the Axial Skeleton

The skull:


8 cranial bones
14 facial bones
Bones of the Axial Skeleton

Bones associated with the skull:


6 auditory ossicles
the hyoid bone
Bones of the Axial Skeleton

The vertebral column:



24 vertebrae
the sacrum
the coccyx
Bones of the Axial Skeleton

The thoracic cage:


24 ribs
the sternum
Functions of the Axial Skeleton


Supports and protects organs in body
cavities
Attaches to muscles of:



head, neck, and trunk
respiration
appendicular skeleton
The Skull

The skull protects:



the brain
entrances to respiratory system
entrance to digestive system
The Skull
PLAY
The Adult Skull
Figure 7–2
The Skull

Has 22 bones:

8 cranial bones:


form the braincase or cranium
14 facial bones:

protect and support entrances to digestive and
respiratory tracts
Cranial Bones


Enclose the cranial cavity
Which contains the brain:

and its fluids, blood vessels, nerves, and
membranes
The Facial Bones

Superficial facial bones:


for muscle attachment
Deep facial bones:


separate the oral and nasal cavities
form the nasal septum
Sinuses

Cavities which decrease the weight of the
skull:


lined with mucus membranes
protect the entrances of the respiratory system
Sutures

The immovable joints of the skull
Figure 7–3a, b
Sutures
Figure 7–3c
Sutures
Figure 7–3d, e
The 4 Major Sutures
1.
2.
3.
4.
Lambdoid suture
Coronal suture
Sagittal suture
Squamous suture
Lambdoid Suture


Separates occipital from parietal bones
May contain sutural bones
Coronal Suture


Attaches frontal bone to parietal bones
The calvaria:

consists of occipital, parietal, and frontal bones
Sagittal Suture


Between the parietal bones
From lambdoid suture to coronal suture
Squamous Sutures

Form boundaries between temporal bones
and parietal bones
What are the bones of the
cranium, and the significance of
their markings?
Cranial Bones

The 8 cranial bones
Figure 7–4a, b
The Cranial Bones






Occipital bone
Frontal bone
Sphenoid
Ethmoid
Parietal bones
Temporal bones
The Occipital Bone
Figure 7–5a
The Parietal Bones
Figure 7–5b
The Frontal Bone
Figure 7–6
The Temporal Bones
Figure 7–7
The Sphenoid
Figure 7–8
The Ethmoid
Figure 7–9
What are the bones of the face,
and the significance of their
markings?
The Maxillary Bones

The largest facial bones
Figure 7–10a
The Palatine Bones
Figure 7–10b,c
What are the structures and
functions of the nasal complex?
The Small Bones of the Face
Figure 7–11
Functions of the Inferior
Nasal Conchae



To create air turbulence in the nasal cavity
To increase the epithelial surface area
To warm and humidify inhaled air
Functions of the Lacrimal Bones


The smallest facial bones
Form part of the medial wall of the orbit
The Mandible
Figure 7–12a,b
The Hyoid Bone
Figure 7–12c
Functions of the Hyoid Bone


Supports the larynx
Attaches muscles of the larynx, pharynx,
and tongue
The Orbital Complex

Portions of 7 cranial and facial bones
Figure 7–13
The Orbital Complex

Forms the eye sockets (orbits):




frontal bone (roof)
maxillary bone (floor)
maxillary, lacrimal and ethmoid bones (orbital rim
and medial wall)
sphenoid and palatine bones
The Nasal Complex

Bones of the nasal cavities and
paranasal sinuses
Figure 7–14
What are the functions of
paranasal sinuses?
Paranasal Sinuses

Air-filled chambers connected to the nasal
cavities:


lighten skull bones
provide mucous epithelium (flushes nasal
cavities)
What are the differences
between the skulls of infants,
children, and adults?
The Infant Skull
Figure 7–15
The Infant Skull



Grows rapidly
Is large compared to the body
Has many ossification centers
The Infant Skull

Fusion is not complete at birth:



2 frontal bones
4 occipital bones
several sphenoid and temporal elements
Fontanels



Are areas of fibrous connective tissue (soft
spots)
Cover unfused sutures in the infant skull
Allow the skull to flex during birth
The 4 Fontanels

Anterior fontanel:


frontal, sagittal, and coronal sutures
Occipital fontanel:

lambdoid and sagittal sutures
The 4 Fontanels

Sphenoidal fontanels:


squamous and coronal sutures
Mastoid fontanel:

squamous and lambdoid sutures
What are the vertebral regions,
the curvatures of the vertebral
column, and their functions?
The Vertebral Column

The spine or vertebral column:


protects the spinal cord
supports the head and body
Regions and Curves of the
Vertebral Column

26 bones:

PLAY
The Vertebral Column
24 vertebrae, the
sacrum, and coccyx
Figure 7–16
Regions of the Vertebral Column





Cervical (C)
Thoracic (T)
Lumbar (L)
Sacral (S)
Coccygeal (Co)
Vertebrae of the
Vertebral Column

The neck:


The upper back:



7 cervical vertebrae
12 thoracic vertebrae
each articulate with one or more pairs of ribs
The lower back:

5 lumbar vertebrae
The Sacrum and Coccyx


The 5th lumbar vertebra articulates with the
sacrum
The sacrum articulates with the coccyx
4 Curvatures of the
Vertebral Column
1.
2.
3.
4.
Cervical curve
Thoracic curve
Lumbar curve
Sacral curve
Primary Curves

Thoracic and sacral curves:


are called primary curves (present during fetal
development)
or accommodation curves (accommodate
internal organs)
Secondary Curves

Lumbar and cervical curves:


are called secondary curves (appear after birth)
or compensation curves (shift body weight for
upright posture)
What are the structures and
functions of each vertebral
group?
Structure of a Vertebra
Figure 7–17a,b
The Vertebral Arch
Figure 7–17c
Vertebral Foraminae

Intervertebral foraminae:



gaps between pedicles of adjacent vertebrae
for nerve connections to spinal cord
Vertebral canal:


formed by vertebral foraminae
encloses the spinal cord
The Vertebral Canal
Figure 7–17d,e
Intervertebral Discs



Are pads of fibrocartilage
Separate the vertebral bodies
Absorb shocks
Vertebral Regions
Figure 7–16
Vertebral Regions

Vertebrae are numbered:



by region, from top to bottom
C1 articulates with skull, L5 with sacrum
Vertebrae of each region:

have characteristics determined by functions
The Cervical Vertebrae
PLAY
3D Rotation of Cervical Vertebrae
Figure7–18a, b
The Cervical Vertebrae
Figure7–18c, d
Characteristics of Cervical
Vertebrae (4 of 6)

Atlas (C1):



articulates with occiptal condyles of skull
has no body or spinous process
has a large, round foramen within anterior and
posterior arches
Characteristics of Cervical
Vertebrae (5 of 6)

Axis (C2):




supports the atlas
has heavy spinous process
to attach muscles of head and neck
Axis and atlas bodies fuse during
development to form the dens
Whiplash

Whiplash:

a traumatic dislocation of cervical vertebrae
The Thoracic Vertebrae
PLAY
3D Rotation of Thoracic Vertebrae
Figure 7–19a
The Thoracic Vertebrae
Figure 7–19b, c
The Lumbar Vertebrae
PLAY
3D Rotation of Lumbar Vertebrae
Figure 7–20a
The Lumbar Vertebrae
Figure 7–20b, c
Characteristics of Lumbar
Vertebrae (1 of 3)

Lumbar vertebrae (L1–L5):





largest vertebrae
oval-shaped bodies
thicker bodies than T1–T12
no costal or transverse costal facets
triangular vertebral foramen
Comparing Vertebrae
Table 7–2
The Sacrum and Coccyx
PLAY
3D Rotation of Sacrum and Coccyx
Figure 7–21
Characteristics of the Sacrum
(1 of 3)

The sacrum:


is curved, more in males than in females
protects reproductive, urinary, and digestive
organs
Characteristics of the Sacrum
(2 of 3)

Attaches:


the axial skeleton to pelvic girdle of appendicular
skeleton
broad muscles that move the thigh
Characteristics of the Sacrum
(3 of 3)

The adult sacrum:



consists of 5 fused sacral vertebrae
fuses between puberty and ages 25–30
leaving transverse lines
Characteristics of the Coccyx

The coccyx:


attaches ligaments and a constricting muscle of
the anus
Mature coccyx:

consists of 3 to 5 fused coccygeal vertebrae
What is the significance of
articulations between ribs,
thoracic vertebrae, and
sternum?
The Thoracic Cage

The skeleton of the chest:


supports the thoracic cavity
Consists of:



thoracic vertebrae
ribs
sternum (breastbone)
The Rib Cage

Formed of ribs and sternum
Figure 7–22a
Articulations of Ribs and Vertebrae
Figure 7–22b
Functions of the Thoracic Cage

Protects organs of the thoracic cavity:

heart, lungs, and thymus
The Ribs
Figure 7–23
Functions of Ribs

Ribs:



are flexible
are mobile
can absorb shock
Functions of Ribs

Rib movements (breathing):


affect width and depth of thoracic cage
changing its volume
Ribs

Ribs (costae):

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
are 12 pairs of long, curved, flat bones
extending from the thoracic vertebrae
Ribs are divided into 2 types:


true ribs
false ribs
True Ribs

Ribs 1–7 (true ribs)


vertebrosternal ribs
connected to the sternum by costal cartilages
False Ribs

Ribs 8–12 (false ribs):

do not attach directly to the sternum
Types of False Ribs

Vertebrochondral ribs (ribs 8–10):



fuse together
merge with cartilage before reaching the
sternum
Floating or vertebral ribs (ribs 11–12):


connect only to the vertebrae
have no connection with the sternum
The Sternum

The sternum:


a flat bone
in the midline of the thoracic wall
3 Parts of the Sternum
1.
2.
3.
The manubrium
The sternal body
The xiphoid process
The Manubrium

The manubrium:





the superior portion of sternum
broad, triangular shape
articulates with collarbones (clavicles)
articulates with cartilages of 1st rib pair
has a jugular notch between clavicular
articulations
The Sternal Body

The sternal body:



is tongue-shaped
attaches to the manubrium
attaches to costal cartilages of ribs 2–7
The Xiphoid Process

The xiphoid process:



is the smallest part of the sternum
attaches to the sternal body
attaches to diaphragm and rectus abdominis
muscles
Development of the Xiphoid

The xiphoid process:


is the last part of sternum to fuse
can easily be broken away
KEY CONCEPT

The axial skeleton:


Vertebrae:


protects the brain, spinal cord, and visceral
organs of the chest
conduct body weight to the lower limbs
Lower vertebrae are larger and stronger:

because they bear more weight