Chapter 7
The Skeletal System:The Axial Skeleton
• Axial Skeleton
– 80 bones
– lie along longitudinal
axis
– skull, hyoid, vertebrae,
ribs, sternum, ear
ossicles
Bone Surface Markings
• Surface features-- rough areas, grooves,
openings, process, knobs
• Specific functions
206
• Appendicular Skeleton
– 126 bones
– upper & lower limbs and
pelvic & pectoral girdles
7-1
The Skull (8 Cranial & 14 Facial bones)
Important Bony Words Table 6.1
J
o
i
n
t
s
7-2
• Foramen = opening
Depressions/openings
• Fossa = shallow depression
• Sulcus = groove
• Meatus = tubelike passageway or canal
• Fissure = slit through a bone
• Sinus = air filled space in bone
• Condyle = large, round protuberance
• Facet = smooth flat articular surface
• Head = Rounded articular projection
Extentions & Projections (Attachment points for CT)
• Trochanter = very large projection
• Tuberosity (tubercle) = large, rounded projection
• Epicondyle = projection above a condyle
• Spine = slender narrow process
• Crest = narrow ridge
7-3
Frontal Bone (1)
The 8 Cranial Bones
Frontal
Parietal (2) Sphenoid
Temporal (2)
Ethmoid
Occipital
7-4
• Forehead, roof of orbits, & anterior cranial
floor
• Supraorbital margin and frontal sinus
7-5
7-6
1
Temporal Bones (4 & 5)
Parietal (2 & 3)
• Temporal bone:
– zygomatic process
forms part of arch
– external auditory
meatus
– mastoid process
– mandibular fossa
– Styloid process
• Parietal
– sides & roof of
cranial cavity
7-7
Occipital bone (6)
7-8
Sphenoid bone (7)
• Occipital
bone
• foramen magnum
• occipital condyles
• External occipital
protuberance
• superior & inferior
nuchal lines
• At base of skull
• Pterygoid processes
7-9
7-10
Sphenoid from Superior View
• Lesser wing & greater wing
7-11
7-12
2
Ethmoid Bone (8)
Ethmoid bone
• Contain sinuses
• Superior & middle nasal concha or turbinates
Perpendicular plate is upper part of nasal septum
• Anterior cranial floor, medial wall of orbits,
lateral nasal walls & superior nasal septum
7-13
7-14
Sutures = immovable joints
•
•
•
•
Coronal suture: unites frontal and both parietal bones
Squamous suture: unites parietal and temporal bones
Lamboid suture: unites parietal and occipital bones
Sagittal suture: unites parietal bones
7-15
7-16
14 Facial Bones
Zygomatic
Process of
Temporal
bone
Nasal (2)
Maxillae (2)
Mandible (1)
Lacrimal (2)
Inferior nasal conchae (2)
Zygomatic (2)
Palatine (2)
Vomer (1) 7-17
Temporal
Process of
Zygomatic
bone
7-18
3
Nasal
Mandible (1)
•
•
•
•
Condylar process (mandibular condyle)
Coronoid processes
Alveolar processes for lower teeth
Mandibular & mental foramen
7-19
7-20
Details of the orbit (eye socket)
Paranasal Sinuses
• Paired cavities in ethmoid, sphenoid, frontal
and maxillary
• Lined with mucous membranes and open into
nasal cavity
7-21
7-22
Paranasal Sinuses
Cranial fossa
On floor
of cranial
cavity
• Resonating chambers, lighten skull
• Sinusitis
Bless you
7-23
7-24
4
Hyoid Bone
Vertebral Column
• Backbone or spine built of
26 vertebrae
• Five vertebral regions
– cervical vertebrae (7) in
the neck
– thoracic vertebrae ( 12 )
in the thorax
– lumbar vertebrae ( 5 ) in
the low back region
– sacrum (5-fused)
– coccyx (4-fused)
7-25
7-26
Typical Vertebrae: 3 Bony
Parts
Intervertebral Discs
(process)
• absorbs vertical shock
• Permit movement of V. column
• Fibrocartilagenous ring with a pulpy center
1. Body
– weight
bearing
2. Vertebral arch
– pedicles
– laminae
• Vertebral
foramen
3. Processes (7)
– 2 transverse
– 1 spinous
– 4 articular
7-27
Intervertebral Foramen & Spinal Canal
7-28
Cervical Vertebrae (C1-C7)
• 1st and 2nd
cervical vertebrae
are unique
– atlas & axis
• Spinal canal = all vertebral foramen together
• Intervertebral foramen are 2 vertebral notches
together
7-29
7-30
5
Atlas & Axis (C1-C2)
Cervical Vertebrae (C1-C7)
•
•
•
•
C3 – C7
Smaller
Larger canal
Transverse
processes shorter
- transverse foramen
for vertebral artery
• Bifid spinous
process
• Atlas -- ring of bone, superior facets for occipital condyles
– nodding movement “yes”
• Axis -- pivotal movement “no”
7-31
7-32
Lumbar Vertebrae
L1 - L5
Thoracic Vertebrae
(T1-T12)
• Strongest &
largest
• Short thick
spinous &
transverse
processes
– back
musculature
• Longer transverse &
spinous processes
• Facets or demifacets
on body for head of
rib
• Facets on transverse
processes (T1-T10)
for tubercle of rib
7-33
7-34
Coccyx
Sacrum
• Union of 4 vertebrae (Co1 - Co4) by age 30
• Union of 5 vertebrae (S1 - S5) by age 30
7-35
7-36
6
Normal Curves of the Vertebral Column
Abnormal curves of the vertebral column
7-37
7-38
Thorax – The Chest
Thoracic Cage: Thorax – The Chest
– Bony cage
flattened from
front to back
1. Sternum
(breastbone)
2. Ribs
3. Costal cartilages
4. Thoracic vertebrae.
Ribs
– 1-7 are true ribs
(vertebrosternal)
– 8-12 are false ribs
8-10
vertebrochondral
– 11-12 are floating
7-39
Sternum
7-40
Ribs
• Manubrium
1st & 2nd ribs
clavicular notch
• Body
Costal
cartilages of
2-10 ribs
• Xiphoid process
7-41
• Increase in length
from ribs 1-7,
thereafter
decreasing
• Head and tubercle
articulate with
facets
Intercostal spaces
contain intercostal
muscles
7-42
7
Rib Articulation
• Tubercle articulates with transverse process
• Head articulates with vertebral bodies
7-43
8