Chapter 06
Lecture and
Animation Outline
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1
Chapter 6-Skeletal System
Functions
1. Support
2. Protect
3. Movement
4. Storage
5. Blood cell production
2
Components of Skeletal System
•
Bone
•
Cartilage:
reduce friction and model for bone formation
•
Tendons:
attach bone to muscle
•
Ligaments:
attach bone to bone
3
Background Information
• Bones, cartilage, tendons, and ligaments are
connective tissues.
• Proteoglycans:
- large polysaccharides attached to proteins
- part of ground substance
- store water
4
• Bone’s extracellular matrix is collagen and
minerals (flexible and able to bear weight)
• Cartilage’s extracellular matrix is collagen and
proteoglycans (good shock absorber)
• Tendons and ligaments’ extracellular matrix is
collagen (very tough)
5
Classification of Bones
• Based on shape:
long, short, flat, irregular
• Type of bone tissue:
compact and spongy (cancellous)
6
Bone Shapes
• Long:
- Ex. Femur, tibia, fibula
• Short:
– Ex. Carpals, tarsals,
phlanges
• Flat:
– Ex. Ribs, sternum, skull
• Irregular:
– Ex. Vertebrae and facial
7
Long Bone Structures
• Diaphysis:
– shaft
– compact bone
tissue (on outside)
• Epiphysis:
– ends
– spongy bone tissue
• Articular cartilage:
- covers epiphyses
- reduces friction
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Articular cartilage
Epiphysis
Epiphyseal plates
in juveniles
Spongy bone
Compact bone
Medullary cavity (contains
red marrow in juveniles and
yellow marrow in adults)
Diaphysis
Periosteum
Endosteum
Young bone
(a)
8
• Epiphyseal plate:
– site of growth
– between diaphysis
and epiphysis
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Articular cartilage
Epiphysis
Epiphyseal lines
in adults
Spongy bone
Compact bone
• Medullary cavity:
– center of diaphysis
– red or yellow
marrow
Medullary cavity (contains
red marrow in juveniles and
yellow marrow in adults)
Diaphysis
Periosteum
Endosteum
Adult bone
(b)
• Periosteum:
membrane around
bone’s outer surface
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Articular cartilage
Epiphysis
Epiphyseal plates
in juveniles
Spongy bone
• Endosteum:
membrane that lines
medullary cavity
Compact bone
Medullary cavity (contains
red marrow in juveniles and
yellow marrow in adults)
Diaphysis
Periosteum
Endosteum
Young bone
(a)
10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Articular cartilage
Epiphysis
Epiphyseal plates
in juveniles
Epiphyseal lines
in adults
Spongy bone
Compact bone
Medullary cavity (contains
red marrow in juveniles and
yellow marrow in adults)
Diaphysis
Diaphysis
Periosteum
Endosteum
Young bone
Adult bone
(a)
(b)
Osteons
(haversian systems)
Endosteum
Inner
layer
Periosteum
Outer
layer
Compact bone
Central canals
Spongy bone
with trabeculae
Connecting vessels
11
Medullary
cavity
(c)
Adult bone
Compact Bone Tissue
• Location:
outer part of diaphysis (long
bones) and thinner surfaces
of other bones
• Osteon:
- structural unit of compact
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Osteons
(haversian systems)
Endosteum
Inner
layer
Periosteum
Outer
layer
Compact bone
bone
- includes lamella, lacunae,
canaliculus, central canal,
osteocytes
• Lamella:
rings of bone matrix
Central canals
Spongy bone
with trabeculae
Connecting vessels
Medullary
cavity
(c)
Adult bone
12
• Lacunae:
spaces between lamella
• Canaliculus:
- tiny canals
- transport nutrients and
remove waste
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Osteons
(haversian systems)
Endosteum
Inner
layer
Periosteum
Outer
layer
Compact bone
Central canals
• Central canal:
- center of osteon
- contains blood vessels
Spongy bone
with trabeculae
Connecting vessels
Medullary
cavity
(c)
Adult bone
13
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Osteon
Concentric rings
of lamellae
Central canal
Osteon
Lamellae on
surface of bone
Lamellae
between osteons
Periosteum
Blood vessel within
the periosteum
Blood vessels
connecting to
a central canal
Blood vessels
within a central
(Haversian) canal
Canaliculi
LM 400x
(a)
Canaliculi
Lacunae
(b)
Blood vessel
connecting to
a central canal
between osteons
a: © Trent Stephens
Osteocytes in
lacunae
Spongy Bone Tissue
• Cancellous bone
• Location: epiphyses of long bones and center of other bones
• Trabeculae: interconnecting rods, spaces contain marrow
• No osteons
15
Bone Cells
• Osteocytes:
maintain bone matrix
• Osteoblasts:
build bone
• Osteoclasts:
carve bone
16
Bone Formation
• Ossification:
process of bone formation (occurs in utero)
• Osteoblast’s role:
- build bone
- after an osteoblast becomes surrounded by bone
matrix it becomes an osteocyte
17
• Ossification center:
where bone formation begins
• Primary ossification center:
- where bone 1st begins to appear
- forms diaphyses
• Secondary ossification center:
forms epiphyses
18
Intramembranous Ossification
• Bone formation within connective tissue
membranes
• Osteoblasts build bone
• Ex. Skull bones
19
Endochondral Ossification
• Bone formation inside cartilage
• Cartilage models are replaced by bone
• Ex. All bones (except skull)
21
Steps in Endochondral Ossification
1. Chondroblasts build a cartilage model, the
chrondroblasts become chondrocytes.
2. Cartilage model calcifies (hardens).
3. Osteoblasts invade calcified cartilage and a
primary ossification center forms diaphysis.
4. Secondary ossification centers form epiphysis.
5. Original cartilage model is almost completely
ossified and remaining cartilage is articular
cartilage.
22
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Femur
Patella
Epiphysis
Epiphyseal
plate
Diaphysis
(a)
Length of bone
increases.
1
Epiphyseal
plate
Chondrocytes
divide and enlarge.
2
3
Calcified cartilage
is replaced by bone.
Bone of
diaphysis
(b)
4
Epiphyseal side
1 New cartilage is
produced on
Thickness of
the epiphyseal side
epiphyseal
of the plate as the
plate remains
chondrocytes divide
unchanged.
and form stacks
of cells.
2 Chondrocytes
mature and
Bone is
enlarge.
added to
diaphysis.
3 Matrix is calcified,
and chondrocytes
die.
4 The cartilage on
the diaphyseal side
of the plate is
replaced by bone.
1
2
3
4
LM 400x
Diaphyseal side
(c)
(a): © Ed Reschke/Peter Arnold, Inc./ Photolibrary.com; (c): © Bio-Photo Assocs/Photo Researchers, Inc.
24
Bone Growth
• Infancy and youth:
- long bones lengthen at epiphyseal plate
- long bones widen by adding more lamella
• End of bone growth (in length):
epiphyseal plate is replaced by an epiphyseal line
25
Figure
6.2b
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27
Bone Remodeling
• What is it?
- removal of existing bone by osteoclasts and
deposition of new bone by osteoblasts
- occurs in all bones
- responsible for changes in bone shape, bone
repair, adjustment of bone to stress, and
calcium ion regulation
28
Bone Repair
1. Broken bone causes bleeding and a blood clot
forms.
2. Callus forms which is a fibrous network between
2 fragments.
3. Cartilage model forms first then, osteoblasts enter
the callus and form cancellous bone this
continues for 4-6 weeks after injury.
4. Cancellous bone is slowly remodeled to form
compact and cancellous bone.
29
Bone and Calcium Homeostasis
• Bone is a major storage site for calcium
• Movement of calcium in and out of bone helps
determine blood levels of calcium
• Calcium moves into bone as osteoblasts build
new bone
• Calcium move out of bone as osteoclasts break
down bone
• Calcium homeostasis is maintained by
parathyroid hormone (PTH) and calcitonin
31
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Decreased
blood Ca2+
1
5
Increased
blood Ca2+
Posterior aspect
of thyroid gland
Kidney
Parathyroid
glands
1 Decreased blood Ca2+ stimulates PTH
secretion from parathyroid glands.
Thyroid gland
2 PTH stimulates osteoclasts to break down
bone and release Ca2+ into the blood.
3 In the kidneys, PTH increases Ca2+
reabsorption from the urine. PTH also
stimulates active Vitamin D formation.
3
PTH
2
Stimulates
osteoclasts
Vitamin D
4
Bone
Osteoclasts
promote Ca2+
Ca2+
uptake from
bone.
Calcitonin
4 Vitamin D promotes Ca2+ absorption from
the small intestine into the blood.
6
Inhibits
osteoclasts
5 Increased blood Ca2+ stimulates calcitonin
secretion from the thyroid gland.
6 Calcitonin inhibits osteoclasts, which
allows for enhanced osteoblast uptake of
Ca2+ from the blood to deposit into bone.
Osteoblasts promote
Ca2+ deposition in bone.
Small intestine
Ca2+
Blood
Hematopoietic Tissue
• What is it?
tissue that makes blood cells
• Red marrow:
location of blood forming cells
• Yellow marrow:
mostly fat
33
• Location of hematopoietic tissue in newborns:
most bones (red marrow)
• Location of hematopoietic tissue in adults:
- red is replaced with yellow marrow
- red marrow is mainly in epiphyses of femur
and humerus
34
Bone Anatomy
• Foramen:
- hole
- Ex. Foramen magnum
• Fossa:
- depression
- Ex. Glenoid fossa
• Process:
- projection
- Ex. Mastoid process
35
• Condyle:
- smooth, rounded end
- Ex. Occipital condyle
• Meatus:
- canal-like passageway
- Ex. External auditory meatus
• Tubercle:
- lump of bone
- Ex. Greater tubercle
36
37
Axial Skeleton
• Mastoid process:
attached to neck muscles
• External auditory meatus:
ear canal
• Nasolacrimal canal:
- canal between nasal cavity and eye
- conducts tears
38
• Styloid process:
attachment site for tongue
• Mandibular fossa:
depression where lower jaw and skull
meet
• Glenoid fossa:
where humerus meets scapula
39
• Hard palate:
roof of mouth
• Foramen magnum:
hole where spinal cord joins brainstem
40
• Zygomatic:
cheek bone
• Mandible:
lower jaw
• Maxilla:
upper jaw
41
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Incisive fossa
Maxilla
Palatine process of maxillary bone
Horizontal plate of palatine bone
Inferior orbital fissure
Zygomatic bone
Sphenoid bone
Vomer
Foramen ovale
Foramen spinosum
Styloid process
Mandibular fossa
External auditory canal
Jugular foramen
Carotid canal
Occipital condyle
Mastoid process
Foramen magnum
Temporal bone
Occipital bone
Nuchal lines
Inferior view
45
Hard
palate
Vertebral Column
•
•
•
•
•
•
7 cervical vertebra
12 thoracic vertebra
5 lumbar vertebra
1 sacrum
1 coccyx
Atlas:
- 1st vertebra
- holds head
• Axis:
- 2nd vertebra
- rotates head
46
Functions of Vertebral Column
• Support
• Protect spinal cord
• Movement
50
Thoracic Cage
• Protects vital organs
• 12 pair of ribs
• Sternum:
breastbone
• True ribs:
attach directly to sternum by cartilage
• False ribs:
attach indirectly to sternum by cartilage
• Floating ribs:
not attached to sternum
51
Pectoral Girdle
• Scapula:
shoulder blade
• Clavicle:
collar bone
53
Upper Limb Bones
• Humerus:
upper limb
• Ulna:
forearm
• Radius:
forearm
• Carpals:
wrist
• Metacarpals:
hand
55
Pelvic Girdle
• Where lower limbs attach to body
• Pelvis:
includes pelvic girdle and coccyx
• Ischium:
inferior and posterior region
• Ilium:
most superior region
• Acetabulum:
hip socket (joint)
60
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Iliac crest
Articular surface
(area of
articulation
with sacrum)
Ilium
Iliac fossa
Pelvic brim
Greater
sciatic notch
Acetabulum
Ischium
Greater
sciatic notch
Pubis
Ischial spine
Ischial spine
Ischium
Pubic symphysis
Obturator foramen
Ischial tuberosity
(a)
Lateral view
(b)
Medial view
64
Lower Limb Bones
• Femur:
thigh
• Patella:
knee cap
• Tibia:
large lower leg
• Fibula:
small lower leg
65
• Tarsals:
ankle
• Metatarsals:
foot
• Phalanges:
toes and fingers
66
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Head
Head
Greater trochanter
Greater trochanter
Neck
Neck
Lesser trochanter
Linea aspera
Body (shaft) of femur
Medial
epicondyle
Lateral epicondyle
Intercondylar fossa
Lateral epicondyle
Patellar groove
(a)
(b)
Lateral condyle
Medial
condyle
Anterior view
Posterior view
Anterior
surface
68
Anterior view
71
Articulations
• What are they?
where 2 bones come together (joint)
• Synarthrosis:
- nonmovable joint
- Ex. skull
• Amphiarthrosis:
- slightly movable joint
- Ex. Between vertebrae
• Diarthrosis:
- freely movable joint
- Ex. knee, elbow, wrist
72
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Parietal
bone
Frontal
bone
Squamous
suture
Coronal
suture
Occipital
bone
Lambdoid
suture
Mastoid (posterolateral)
fontanel
Sphenoidal
(anterolateral)
fontanel
Temporal bone
(a)
Lateral view
Frontal bones
(not yet fused
into a single
bone)
Frontal
(anterior)
fontanel
Parietal
bone
Sagittal
suture
Occipital
(posterior)
fontanel
Occipital
bone
(b)
Superior view
73
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Bone
Synovial membrane
Blood vessel
Nerve
Fibrous part of joint
capsule
Joint
capsule
Bursa
Joint cavity (filled
with synovial fluid)
Articular
cartilage
Tendon
sheath
Tendon
Outer layer
Bone
Inner layer
Periosteum
74
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Class and Example
of Joint
Structures Joined
Movement
Plane
Acromioclavicular
Carpometacarpal
Acromion process of
scapula and clavicle
Carpals and metacarpals
2–5
Slight
Multiple axes as
a group
Slight
Slight
Slight
Slight
Slight
Costovertebral
Intercarpal
Intermetatarsal
Intertarsal
Intervertebral
Ribs and vertebrae
Between carpal bones
Between metatarsal bones
Between tarsal bones
Between articular processes of
adjacent vertebrae
Sacroiliac
Between sacrum and coxal bone
(complex joint with several
planes and synchondroses)
Slight
Tarsometatarsal
Tarsal bones and metatarsal
bones
Slight
Carpal and metacarpal
of thumb
Between carpal bones
Manubrium of sternum
and clavicle
Two axes
Hinge
Cubital (elbow)
Knee
Interphalangeal
Talocrural (ankle)
Humerus, ulna, and radius
Femur and tibia
Between phalanges
Talus, tibia, and fibula
One axis
One axis
One axis
Multiple axes;
one predominates
Pivot
Medial atlantoaxial
Proximal radioulnar
Distal radioulnar
Atlas and axis
Radius and ulna
Radius and ulna
Rotation
Rotation
Rotation
Ball-and-Socket
Coxal (hip)
Humeral (shoulder)
Coxal bone and femur
Scapula and humerus
Multiple axes
Multiple axes
Two axes
Two axes
Metatarsophalangeal (ball of foot)
Atlas and occipital bone
Metacarpal bones and
phalanges
Metatarsal bones and
phalanges
Radiocarpal (wrist)
Temporomandibular
Radius and carpal bones
Mandible and temporal bone
Multiple axes
Multiple axes;
one predominates
Plane
Saddle
Carpometacarpal
pollicis
Intercarpal
Sternoclavicular
Slight
Slight
Saddle
Hinge
Pivot
Ball-and-socket
Ellipsoid
Atlantooccipital
Metacarpophalangeal (knuckles)
Ellipsoid
Two axes
75
Types of Movement
•
•
•
•
•
Flexion: bending
Extension: straightening
Abduction: movement away from midline
Adduction: movement toward the midline
Pronation: rotation of the forearm with palms
down
• Supination: rotation of the forearm with palms up
• Rotation: movement of a structure about the long
axis
76
Effects of Aging on the Skeletal
System and Joints
1. Decrease Collagen Production
2. Loss of Bone Density
3. Degenerative Changes
79
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80