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Chapter 8
Lecture
Outline
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1
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Overview of the Skeleton

Regions of the skeleton
• axial skeleton = central axis
• appendicular skeleton = limbs and
girdles

Number of bones
• 206 in typical adult skeleton


varies with development of sesamoid bones
(patella)
Classification of ossicles on the ear
2
Surface Features of Bones
3
Axial and Appendicular Skeleton

Axial skeleton in
tan
• skull, vertebrae,
sternum, ribs,
sacrum and hyoid

Appendicular
skeleton in green
•
•
•
•
pectoral girdle
upper extremity
pelvic girdle
lower extremity
4
Major Skull Cavities
5
The Skull



22 bones joined together by sutures
Cranial bones surround cranial cavity
Facial bones support teeth and form
nasal cavity and orbit
6
Cranial Fossa

3 basins that comprise the cranial floor or base
• anterior fossa holds the frontal lobe of the brain
• middle fossa holds the temporal lobes of the
brain
• posterior fossa contains the cerebellum
7
Frontal Bone



Forms forehead and
part of the roof of
the cranium
Forms roof of the
orbit
Contains frontal
sinus
8
Parietal Bone



Temporal lines
Cranial roof and part
of its lateral walls
Bordered by 4
sutures
Temporal lines of
temporalis muscle
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Temporal Bone

Lateral wall and part
of floor of cranial
cavity





zygomatic process
mandibular fossa and
TMJ
external auditory
meatus
styloid process
mastoid process
10
Petrous Portion of Temporal Bone


Part of cranial floor
Houses middle and
inner ear cavities
• internal auditory meatus
11
Right Temporal Bone
12
Openings in Temporal Bone

Carotid canal

Jugular foramen
• Created by temporal
and occipital bone
“joint”
13
Occipital Bone




Foramen magnum holds
spinal cord
Skull rests on atlas at
occipital condyles
External occipital
protuberance for nuchal
ligament
Nuchal lines mark neck
muscles
14
Sphenoid Bone

Lesser wing

Greater wing


Body of sphenoid
Medial and lateral
pterygoid processes
15
Sphenoid Bone

Body of the sphenoid
• sella turcica contains
hypophyseal fossa
• houses pituitary gland

Lesser wing
• optic foramen

Greater wing
Foramen ovale
16
Sphenoid Bone

Sphenoid
sinus
17
Ethmoid Bone





Lateral walls and roof
nasal cavity
Cribriform plate and crista
galli
Ethmoid air cells form
ethmoid sinus
Perpendicular plate forms
part of nasal septum
Concha (turbinates) on
lateral wall
18
Ethmoid Bone


Superior and middle
concha
Perpendicular plate of
nasal septum
19
Maxillary Bones

Forms upper jaw
• alveolar processes are bony points
between teeth
• alveolar sockets hold teeth

Forms inferomedial wall of orbit
• infraorbital foramen

Forms anterior 2/3’s
of hard palate
• incisive foramen
• cleft palate
20
Locations of Paranasal Sinuses


Maxillary sinus fills maxillae bone
Other bones containing sinuses are frontal,
ethmoid and sphenoid.
21
Palatine Bones




L-shaped bone
Posterior 1/3 of the
hard palate
Part of lateral nasal
wall
Part of the orbital
floor
22
Zygomatic Bones


Forms angles of the
cheekbones and
part of lateral orbital
wall
Zygomatic arch is
formed from
temporal process of
zygomatic bone and
zygomatic process
of temporal bone
23
Lacrimal Bones


Form part of medial
wall of each orbit
Lacrimal fossa
24
Nasal Bones


Forms bridge of
nose and supports
cartilages of nose
Often fractured by
blow to the nose
25
Inferior Nasal Conchae


A separate bone
Not part of
ethmoid like the
superior and
middle concha or
turbinates
26
Vomer


Inferior half of the
nasal septum
Supports cartilage
of nasal septum
27
Mandible

Only movable bone
• TMJ joint between mandibular fossa
and condyloid process



Attachment of muscles of
mastication
Mandibular foramen
Mental foramen
28
Ramus, Angle and Body of
Mandible
29
Bones Associated With Skull

Auditory ossicles
• malleus, incus, and
stapes

Hyoid bone
• suspended from
styloid process of
skull by muscle
and ligament
30
Skull in Infancy and Childhood

Spaces between
unfused bones called
fontanels
• filled with fibrous
membrane
• allow shifting of bones
during birth and growth
of brain

Skull reaches adult size
by 8 or 9
31
The Vertebral Column


33 vertebrae and
intervertebral discs of
fibrocartilage
Five vertebral groups
•
•
•
•
•
7 cervical in the neck
12 thoracic in the chest
5 lumbar in lower back
5 fused sacral
4 fused coccygeal
32
Newborn Spinal Curvature


Spine exhibits one
continuous Cshaped curve
Known as primary
curvature
33
Adult Spinal Curvatures


S-shaped vertebral
column with 4
curvatures
Secondary curvatures
develop after birth
• lifting head as it begins
to crawl develops
cervical curvature
• walking upright
develops lumbar
curvature
34
Abnormal Spinal Curvatures




From disease,
posture, paralysis
or congenital defect
Scoliosis from lack
of proper
development of one
vertebrae
Kyphosis is from
osteoporosis
Lordosis is from
weak abdominal
muscles
35
General Structure of Vertebra



Body
Vertebral foramen
form vertebral canal
Neural arch
• 2 lamina
• 2 pedicles

Processes
• spinous, transverse
and articular
36
Intervertebral Foramen and Discs

Intervertebral
foramen
• passageway for nerves

Intervertebral discs
• bind vertebrae
together
• absorb shock
• gelatinous nucleus
pulposus surrounded
by anulus fibrosus
(ring of fibrocartilage)
37
Typical Cervical Vertebrae



Small body and larger vertebral foramen
Transverse process short with transverse
foramen for protection of vertebral arteries
Bifid or forked spinous process in C2 to C6
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The Unique Atlas and Axis

Atlas (C1) supports the
skull
• ring surrounding large
vertebral foramen



anterior and posterior arch
no vertebral body
Axis (C2)
• dens or odontoid process is
held in place inside the
vertebral foramen of the
atlas by ligaments
39
Atlas and Axis Articulation
40
Typical Thoracic Vertebrae

Larger body than cervical but smaller than lumbar
Spinous processes pointed and angled downward

Rib attachment

• costal facets on vertebral body and at ends of transverse
processes for articulation of ribs
41
Lumbar Vertebrae


Thick, stout body and blunt, squarish
spinous process
Superior articular processes face medially
• lumbar region resistant to twisting movements
42
Sacrum (Anterior View)


5 sacral vertebrae
fuse by age 26
Ala and Sacral
prominence
43
Sacrum (Posterior View)



Median sacral crest
Lateral sacral crest
Posterior sacral
foramina
44
Coccyx

Single, small bone
• 4 vertebrae fused by 30
• Co1 to Co4

Fractured by fall or
during childbirth
45
Thoracic Cage



Consists of thoracic
vertebrae, sternum and
ribs
Protects many organs
Rhythmically expanded
by respiratory muscles
to draw air into the
lungs
46
Rib Structure
Tubercle
Head

Flat blade called a shaft
• inferior margin has costal
groove for nerves and vessels


Proximal head and tubercle
are connected by neck
Articulation
• head with body of vertebrae
• tubercle with transverse
process
47
Numbered Rib Articulations
48
True and False Ribs


True ribs (1 to 7)
attach to sternum
with hyaline
cartilage
False ribs (8-12)
• 11-12 are floating
and not attached to
sternum

12 pairs of ribs in
both sexes
49
Pectoral Girdle



Attaches upper extremity to the body
Scapula and clavicle
Clavicle attaches medially to the
sternum and laterally to the scapula
• sternoclavicular joint
• acromioclavicular joint

Scapula articulates with the humerus
• humeroscapular or shoulder joint
• easily dislocated due to loose
attachment
50
Clavicle


S-shaped bone, flattened dorsoventrally
Sternal end rounded -- acromial end flattened
51
Scapula



Coracoid process = muscle attachment
Subscapular, infraspinous and supraspinous fossa
Glenoid fossa = socket for head of humerus
52
Scapular Features
53
Upper Limb




Brachium (arm) = humerus
Antebrachium (forearm) = radius
and ulna (radius on thumb side)
Carpus (wrist) = 8 small bones(2
rows)
Manus (hand) = 19 bones(2 groups)
• 5 metacarpals in palm
• 14 phalanges in fingers
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Humerus






Anatomical neck
Greater and lesser tubercles
and deltoid tuberosity
Intertubercular groove holds
biceps tendon
Trochlea articulates with ulna
Olecranon fossa holds
olecranon process of ulna
Forearm muscles attach to
medial and lateral
epicondyles
55
Ulna and Radius

Radius
• head

articulates with capitulum
• radial tuberosity

Ulna
• olecranon and trochlear
notch

Interosseous membrane
• ligament attaches radius to
ulna along interosseous
margin of each bone
56
Carpal Bones

Form wrist

2 rows
• proximal row =
scaphoid, lunate,
triquetrum and
pisiform
• distal row =
trapezium, trapezoid,
capitate and hamate
57
Metacarpals and Phalanges


Phalanges are
bones of the
fingers
Metacarpals are
bones of the palm
58
Sesamoid Bone
59
Pelvic Girdle



Girdle = 2 hip bones
Pelvis = girdle and sacrum
Anteriorly, pubic bones are
joined by pad of
fibrocartilage to form pubic
symphysis
60
Pelvic Inlet and Outlet

False and true pelvis separated at pelvic
brim
61
Os Coxae (Hip Bone)


Acetabulum is hip joint
socket
Ilium
• iliac crest and iliac fossa

Pubis
• body, superior and inferior
ramus

Ischium
• ischial spine
• ischial ramus joins inferior
pubic
ramus
62
Comparison of Male and
Female


Female lighter, shallower pubic arch( >100 degrees),
and pubic inlet round or oval
Male heavier, upper pelvis nearly vertical,
coccyx more vertical, and pelvic inlet heart-shaped
63
Femur and Patella (Kneecap)

Nearly spherical head and
constricted neck
• ligament to fovea capitis




Greater and lesser
trochanters
Posterior ridge called linea
aspera
Medial and lateral condyles
and epicondyles found
distally
Patella = triangular
sesamoid
64
Tibia

Broad superior head
with 2 flat articular
surfaces

medial and lateral condyles
• roughened anterior
surface palpated below
patella
(tibial tuberosity)
• distal expansion = medial
65
malleolus
Fibula




Does not bear any
body weight
Head = proximal
end
Lateral malleolus =
distal expansion
Joined to tibia by
interosseous
membrane
66
The Ankle and Foot


Tarsal bones are shaped and
arranged differently from carpal
bones due to load-bearing role of
the ankle
Talus is most superior tarsal bone
• forms ankle joint with tibia and
fibula
• sits upon calcaneus and articulates
with navicular


Calcaneus forms heel (achilles
tendon)
Distal row of tarsal bones
• cuboid, medial, intermediate and
lateral cuneiforms
67
The Foot


Remaining bones of foot
are similar in name and
arrangement to the hand
Metatarsal I is proximal to
the great toe (hallux)
• base, shaft and head

Phalanges
• 2 in great toe

proximal and distal
• 3 in all other toes

proximal, middle and distal
68