Download The Skeletal System

5
The Skeletal System
Yong Jeong, MD, PhD
Department of Bio and Brain Engineering
The Skeletal System
•Parts of the skeletal system
•Bones (skeleton)
•Joints
•Cartilages
•Ligaments
•Two subdivisions of the skeleton
•Axial skeleton
•Appendicular skeleton
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1
Functions of Bones
• Support the body
• Protect soft organs
• Skull and vertebrae for brain and spinal cord
• Rib cage for thoracic cavity organs
• Allow movement due to attached skeletal muscles
• Store minerals and fats
• Calcium and phosphorus
• Fat in the internal marrow cavity
• Blood cell formation (hematopoiesis)
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Bones of the Human Body
•The adult skeleton has 206 bones
•Two basic types of bone tissue
•Compact bone
•Homogeneous
•Spongy bone
•Small needle-like pieces of bone
•Many open spaces
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Spongy
bone
Compact
bone
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Figure 5.1
Classification of Bones on the Basis of
Shape
•Bones are classified as:
•Long
•Short
•Flat
•Irregular
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Classification of Bones
•Long bones
• Typically longer than they are wide
• Shaft with heads situated at both ends
• Contain mostly compact bone
• All of the bones of the limbs (except wrist,
ankle, and kneecap bones)
• Example:
• Femur
• Humerus
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Figure 5.2a
4
Classification of Bones
•Short bones
•Generally cube-shaped
•Contain mostly spongy bone
•Includes bones of the wrist and ankle
•Sesamoid bones are a type of short bone
which form within tendons (patella)
•Example:
•Carpals
•Tarsals
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Figure 5.2d
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Classification of Bones
•Flat bones
•Thin, flattened, and usually curved
•Two thin layers of compact bone surround a
layer of spongy bone
•Example:
•Skull
•Ribs
•Sternum
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Classification of Bones
•Irregular bones
•Irregular shape
•Do not fit into other bone classification
categories
•Example:
•Vertebrae
•Hip bones
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Figure 5.2b
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Anatomy of a Long Bone
•Diaphysis
•Shaft
•Composed of compact bone
•Epiphysis
•Ends of the bone
•Composed mostly of spongy bone
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Articular
cartilage
Proximal
epiphysis
Diaphysis
Spongy bone
Epiphyseal
line
Periosteum
Compact bone
Medullary
cavity (lined
by endosteum)
Distal
epiphysis
(a)
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Figure 5.3a
8
Anatomy of a Long Bone
•Periosteum
•Outside covering of the diaphysis
•Fibrous connective tissue membrane
•Perforating (Sharpey’s) fibers
•Secure periosteum to underlying bone
•Arteries
•Supply bone cells with nutrients
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Endosteum
Yellow
bone marrow
Compact bone
Periosteum
Perforating
(Sharpey’s)
fibers
Nutrient
arteries
(c)
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Figure 5.3c
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Anatomy of a Long Bone
•Articular cartilage
•Covers the external surface of the epiphyses
•Made of hyaline cartilage
•Decreases friction at joint surfaces
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Articular
cartilage
Compact bone
Spongy bone
(b)
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Figure 5.3b
10
Anatomy of a Long Bone
•Epiphyseal plate
•Flat plate of hyaline cartilage seen in young,
growing bone
•Epiphyseal line
•Remnant of the epiphyseal plate
•Seen in adult bones
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Articular
cartilage
Proximal
epiphysis
Diaphysis
Spongy bone
Epiphyseal
line
Periosteum
Compact bone
Medullary
cavity (lined
by endosteum)
Distal
epiphysis
(a)
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Figure 5.3a
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Anatomy of a Long Bone
•Marrow (medullary) cavity
•Cavity inside of the shaft
•Contains yellow marrow (mostly fat) in
adults
•Contains red marrow for blood cell formation
in infants
•In adults, red marrow is situated in cavities of
spongy bone and epiphyses of some long
bones
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Bone Markings
• Surface features of bones
• Sites of attachments for muscles, tendons, and
ligaments
• Passages for nerves and blood vessels
• Categories of bone markings
• Projections or processes—grow out from the bone
surface
• Terms often begin with “T”
• Depressions or cavities—indentations
• Terms often begin with “F”
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Microscopic Anatomy of Compact Bone
•Osteon (Haversian system)
•A unit of bone containing central canal and
matrix rings
•Central (Haversian) canal
•Opening in the center of an osteon
•Carries blood vessels and nerves
•Perforating (Volkmann’s) canal
•Canal perpendicular to the central canal
•Carries blood vessels and nerves
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Osteon
(Haversian system)
Lamellae
Blood vessel continues into
medullary cavity containing marrow
Spongy bone
Perforating
fibers
Compact
bone
Periosteal
blood vessel
Periosteum
(a)
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Central (Haversian) canal
Perforating
(Volkmann’s) canal
Blood vessel
Figure 5.4a
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Microscopic Anatomy of Bone
•Lacunae
•Cavities containing bone cells (osteocytes)
•Arranged in concentric rings called lamellae
•Lamellae
•Rings around the central canal
•Sites of lacunae
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Osteon
Lamella
Osteocyte
Lacuna
Canaliculus
(b)
Lacuna
(c) Central
canal
Interstitial
lamellae
Central (Haversian) canal
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Figure 5.4b
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Microscopic Anatomy of Bone
•Canaliculi
•Tiny canals
•Radiate from the central canal to lacunae
•Form a transport system connecting all bone
cells to a nutrient supply
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Lamella
Osteocyte
(b)
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Canaliculus
Lacuna
Central (Haversian) canal
Figure 5.4b
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Formation of the Human Skeleton
•In embryos, the skeleton is primarily hyaline
cartilage
•During development, much of this cartilage is
replaced by bone
•Cartilage remains in isolated areas
•Bridge of the nose
•Parts of ribs
•Joints
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Bone Growth (Ossification)
•Epiphyseal plates allow for lengthwise growth
of long bones during childhood
•New cartilage is continuously formed
•Older cartilage becomes ossified
•Cartilage is broken down
•Enclosed cartilage is digested away,
opening up a medullary cavity
•Bone replaces cartilage through the action
of osteoblasts
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Bone Growth (Ossification)
•Bones are remodeled and lengthened until
growth stops
•Bones are remodeled in response to two
factors
•Blood calcium levels
•Pull of gravity and muscles on the
skeleton
•Bones grow in width (called appositional
growth)
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Articular
cartilage
Hyaline
cartilage
Spongy
bone
New center of
bone growth
New bone
forming
Epiphyseal
plate
cartilage
Growth
in bone
width
Medullary
cavity
Bone starting
to replace
cartilage
Growth
in bone
length
New bone
forming
Bone collar
Hyaline
cartilage
model
In an embryo
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Invading
blood
vessels
Epiphyseal
plate cartilage
In a fetus
In a child
Figure 5.5
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Bone growth
Bone grows in
length because:
1 Cartilage
grows here.
2 Cartilage
is replaced
by bone here.
3 Cartilage
grows here.
4 Cartilage
is replaced by
bone here.
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Bone remodeling
Growing shaft is
remodeled as:
Articular cartilage
Epiphyseal plate
1 Bone is
resorbed here.
2 Bone is added
by appositional
growth here.
3 Bone is
resorbed here.
Figure 5.6
Types of Bone Cells
•Osteocytes—mature bone cells
•Osteoblasts—bone-forming cells
•Osteoclasts—giant bone-destroying cells
•Break down bone matrix for remodeling and
release of calcium in response to
parathyroid hormone
•Bone remodeling is performed by both
osteoblasts and osteoclasts
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Bone Fractures
•Fracture—break in a bone
•Types of bone fractures
•Closed (simple) fracture—break that does
not penetrate the skin
•Open (compound) fracture—broken bone
penetrates through the skin
•Bone fractures are treated by reduction and
immobilization
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Common Types of Fractures
Table 5.2
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Repair of Bone Fractures
•Hematoma (blood-filled swelling) is formed
•Break is splinted by fibrocartilage to form a
callus
•Fibrocartilage callus is replaced by a bony
callus
•Bony callus is remodeled to form a permanent
patch
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Hematoma
External
callus
New
blood
vessels
Internal
callus
(fibrous
tissue and
cartilage)
1 Hematoma
forms.
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Bony
callus of
spongy
bone
Healed
fracture
Spongy
bone
trabecula
2 Fibrocartilage
callus forms.
3 Bony callus
forms.
4 Bone remodeling
occurs.
Figure 5.7, step 4
20
The Axial Skeleton
•Forms the longitudinal axis of the body
•Divided into three parts
•Skull
•Vertebral column
•Bony thorax
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Cranium
Skull
Facial bones
Clavicle
Thoracic cage
(ribs and
sternum)
Scapula
Sternum
Rib
Humerus
Vertebral
column
Vertebra
Radius
Ulna
Sacrum
Carpals
Phalanges
Metacarpals
Femur
Patella
Tibia
Fibula
Tarsals
Metatarsals
Phalanges
(a) Anterior view
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Figure 5.8a
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Cranium
Bones of
pectoral
girdle
Clavicle
Scapula
Upper
limb
Rib
Humerus
Vertebra
Radius
Ulna
Carpals
Bones
of
pelvic
girdle
Phalanges
Metacarpals
Femur
Lower
limb
Tibia
Fibula
(b) Posterior view
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Figure 5.8b
The Skull
•Two sets of bones
•Cranium
•Facial bones
•Bones are joined by sutures
•Only the mandible is attached by a freely
movable joint
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Coronal suture
Frontal bone
Parietal bone
Sphenoid bone
Temporal bone
Ethmoid bone
Lambdoid
suture
Lacrimal bone
Squamous suture
Nasal bone
Occipital bone
Zygomatic bone
Zygomatic process
Maxilla
External acoustic meatus
Mastoid process
Alveolar
processes
Styloid process
Mandible (body)
Mental foramen
Mandibular ramus
Figure 5.9
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Frontal bone
Sphenoid
bone
Cribriform plate
Crista galli
Ethmoid
bone
Optic canal
Sella turcica
Foramen ovale
Temporal bone
Jugular foramen
Internal
acoustic meatus
Parietal bone
Occipital bone
Foramen magnum
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Figure 5.10
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Maxilla
Hard (palatine process)
palate
Palatine bone
Maxilla
Zygomatic bone
Sphenoid bone
(greater wing)
Temporal bone
(zygomatic process)
Foramen ovale
Vomer
Mandibular fossa
Carotid canal
Styloid process
Jugular foramen
Mastoid process
Temporal bone
Occipital condyle
Parietal bone
Foramen magnum
Occipital bone
Figure 5.11
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Coronal suture
Frontal bone
Parietal bone
Nasal bone
Superior orbital fissure
Sphenoid bone
Ethmoid bone
Lacrimal bone
Optic canal
Temporal bone
Zygomatic bone
Middle nasal concha
of ethmoid bone
Maxilla
Inferior nasal concha
Vomer
Mandible
Alveolar processes
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Figure 5.12
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Paranasal Sinuses
•Hollow portions of bones surrounding the
nasal cavity
•Functions of paranasal sinuses
•Lighten the skull
•Give resonance and amplification to voice
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Frontal sinus
Ethmoid sinus
Sphenoidal sinus
Maxillary sinus
(a) Anterior view
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Figure 5.13a
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Frontal sinus
Ethmoid sinus
Sphenoidal sinus
Maxillary sinus
(b) Medial view
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Figure 5.13b
The Hyoid Bone
•The only bone that does not articulate with
another bone
•Serves as a moveable base for the tongue
•Aids in swallowing and speech
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Greater horn
Lesser horn
Body
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Figure 5.14
The Fetal Skull
•The fetal skull is large compared to the infant’s
total body length
•Fetal skull is 1/4 body length compared to
adult skull which is 1/8 body length
•Fontanels—fibrous membranes connecting
the cranial bones
•Allow skull compression during birth
•Allow the brain to grow during later
pregnancy and infancy
•Convert to bone within 24 months after birth
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Anterior
fontanel
Frontal bone
Parietal
bone
Posterior fontanel
Occipital
bone
(a)
Figure 5.15a
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Parietal bone
Posterior
fontanel
Occipital
bone
Mastoid
fontanel
Anterior fontanel
Sphenoidal
fontanel
Frontal
bone
Temporal bone
(b)
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Figure 5.15b
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The Vertebral Column
•Each vertebrae is given a name according to
its location
•There are 24 single vertebral bones
separated by intervertebral discs
•Seven cervical vertebrae are in the neck
•Twelve thoracic vertebrae are in the chest
region
•Five lumbar vertebrae are associated with
the lower back
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The Vertebral Column
•Nine vertebrae fuse to form two composite
bones
•Sacrum
•Coccyx
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Anterior
1st cervical
vertebra (atlas)
2nd cervical
vertebra (axis)
1st thoracic
vertebra
Transverse
process
Spinous
process
Intervertebral
disc
Posterior
Cervical curvature
(concave)
7 vertebrae,
C1 – C7
Thoracic curvature
(convex)
12 vertebrae,
T1 – T12
Intervertebral
foramen
1st lumbar
vertebra
Lumbar curvature
(concave)
5 vertebrae,
L1 – L5
Sacral curvature
(convex)
5 fused vertebrae
Coccyx
4 fused vertebrae
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Figure 5.16
The Vertebral Column
•Primary curvatures are the spinal curvatures
of the thoracic and sacral regions
•Present from birth
•Form a C-shaped curvature as in newborns
•Secondary curvatures are the spinal
curvatures of the cervical and lumbar regions
•Develop after birth
•Form an S-shaped curvature as in adults
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Figure 5.18
A Typical Vertebrae
•Body
•Vertebral arch
•Pedicle
•Lamina
•Vertebral foramen
•Transverse processes
•Spinous process
•Superior and inferior articular processes
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Posterior
Vertebral
arch
Lamina
Transverse
process
Spinous
process
Superior
articular
process
and
facet
Pedicle
Vertebral
foramen
Body
Anterior
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Figure 5.19
(a) ATLAS AND AXIS
Transverse
process
Posterior
arch
Anterior
arch
Superior view of atlas (C1)
Transverse
process
Dens
Body
Spinous
process
Facet on
superior
articular
process
Superior view of axis (C2)
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Figure 5.20a
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(b) TYPICAL CERVICAL VERTEBRAE
Facet on superior
articular process
Spinous
process
Vertebral
foramen
Transverse
process
Superior view
Superior
articular
process
Spinous
process
Body
Transverse
process
Facet on inferior
articular process
Right lateral view
Figure 5.20b
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(c) THORACIC VERTEBRAE
Spinous process
Transverse
process
Vertebral
foramen
Facet
for rib
Facet on
superior
articular
process
Body
Superior view
Facet on
superior
articular
process
Facet on
transverse
process
Body
Spinous
process
Costal facet
for rib
Right lateral view
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Figure 5.20c
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(d) LUMBAR VERTEBRAE
Spinous process
Vertebral
foramen
Transverse
process
Facet on
superior
articular
process
Body
Superior view
Body
Superior
articular
process
Spinous
process
Facet on inferior
articular process
Right lateral view
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Figure 5.20d
Sacrum and Coccyx
•Sacrum
•Formed by the fusion of five vertebrae
•Coccyx
•Formed from the fusion of three to five
vertebrae
•“Tailbone,” or remnant of a tail that other
vertebrates have
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Ala
Sacral
canal
Superior Auricular
articular surface
process
Body
Sacrum
Coccyx
Median
sacral
crest
Posterior
sacral
foramina
Sacral
hiatus
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Figure 5.21
The Bony Thorax
•Forms a cage to protect major organs
•Consists of three parts
•Sternum
•Ribs
•True ribs (pairs 1–7)
•False ribs (pairs 8–12)
•Floating ribs (pairs 11–12)
•Thoracic vertebrae
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T1 vertebra
Jugular notch
Clavicular notch
Manubrium
Sternal angle
Body
Xiphisternal
joint
Xiphoid
process
True
ribs
(1 –7)
Sternum
False
ribs
(8–12)
L1
Vertebra
Floating
ribs (11, 12)
(a)
Intercostal
spaces
Costal cartilage
Figure 5.22a
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T2
T3
T4
Jugular
notch
Sternal
angle
Heart
T9
Xiphisternal
joint
(b)
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Figure 5.22b
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The Appendicular Skeleton
•Composed of 126 bones
•Limbs (appendages)
•Pectoral girdle
•Pelvic girdle
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Cranium
Skull
Facial bones
Clavicle
Thoracic cage
(ribs and
sternum)
Scapula
Sternum
Rib
Humerus
Vertebral
column
Vertebra
Radius
Ulna
Sacrum
Carpals
Phalanges
Metacarpals
Femur
Patella
Tibia
Fibula
Tarsals
Metatarsals
Phalanges
(a) Anterior view
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Figure 5.8a
37
Cranium
Bones of
pectoral
girdle
Clavicle
Scapula
Upper
limb
Rib
Humerus
Vertebra
Radius
Ulna
Carpals
Bones
of
pelvic
girdle
Phalanges
Metacarpals
Femur
Lower
limb
Tibia
Fibula
(b) Posterior view
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Figure 5.8b
The Pectoral (Shoulder) Girdle
•Composed of two bones
•Clavicle—collarbone
•Articulates with the sternum medially and
with the scapula laterally
•Scapula—shoulder blade
•Articulates with the clavicle at the
acromioclavicular joint
•Articulates with the arm bone at the
glenoid cavity
•These bones allow the upper limb to have
exceptionally free movement
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38
Acromioclavicular Clavicle
joint
Scapula
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(a) Articulated right shoulder (pectoral) girdle
showing the relationship to bones of the
thorax and sternum
Figure 5.23a
Posterior
Sternal (medial)
end
Acromial (lateral)
end
Anterior
Superior view
Acromial end
Sternal end
Anterior
Posterior
Inferior view
(b) Right clavicle, superior and inferior views
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Figure 5.23b
39
Suprascapular notch
Coracoid process
Superior
angle
Acromion
Glenoid cavity
at lateral angle
Spine
Medial
border
Lateral border
(c) Right scapula, posterior aspect
Figure 5.23c
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Acromion
Coracoid
process
Suprascapular notch
Superior border
Superior
angle
Glenoid
cavity
Lateral
(axillary)
border
Medial
(vertebral)
border
Inferior angle
(d) Right scapula, anterior aspect
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Figure 5.23d
40
Bones of the Upper Limbs
•Humerus
•Forms the arm
•Single bone
•Proximal end articulation
•Head articulates with the glenoid cavity of
the scapula
•Distal end articulation
•Trochlea and capitulum articulate with the
bones of the forearm
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Greater
tubercle
Lesser
tubercle
Head of
humerus
Anatomical neck
Head of
humerus
Anatomical
neck
Intertubercular
sulcus
Radial
groove
Deltoid
tuberosity
Deltoid
tuberosity
Radial
fossa
Coronoid
fossa
Capitulum
(a)
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Surgical
neck
Medial
epicondyle
Trochlea
Medial
epicondyle
Trochlea
(b)
Olecranon
fossa
Lateral
epicondyle
Figure 5.24a
41
Bones of the Upper Limbs
•The forearm has two bones
•Ulna—medial bone in anatomical position
•Proximal end articulation
• Coronoid process and olecranon
articulate with the humerus
•Radius—lateral bone in anatomical position
•Proximal end articulation
• Head articulates with the capitulum of
the humerus
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Trochlear notch
Olecranon
Head
Neck
Radial
tuberosity
Coronoid
process
Proximal
radioulnar
joint
Radius
Ulna
Interosseous
membrane
Radial
styloid
process
(c)
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Ulnar styloid
process
Distal
radioulnar
joint
Figure 5.24c
42
Bones of the Upper Limbs
•Hand
•Carpals—wrist
•Eight bones arranged in two rows of four
bones in each hand
•Metacarpals—palm
•Five per hand
•Phalanges—fingers and thumb
•Fourteen phalanges in each hand
•In each finger, there are three bones
•In the thumb, there are only two bones
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Distal
Phalanges
(fingers)
Middle
Proximal
Metacarpals
(palm)
4
3
2
5
1
Trapezium
Hamate
Trapezoid
Carpals Pisiform
(wrist) Triquetrum
Scaphoid
Capitate
Lunate
Ulna
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Radius
Figure 5.25
43
Bones of the Pelvic Girdle
•Formed by two coxal (ossa coxae) bones
•Composed of three pairs of fused bones
•Ilium
•Ischium
•Pubis
•Pelvic girdle = 2 coxal bones, sacrum
•Bony pelvis = 2 coxal bones, sacrum, coccyx
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Bones of the Pelvic Girdle
•The total weight of the upper body rests on the
pelvis
•It protects several organs
•Reproductive organs
•Urinary bladder
•Part of the large intestine
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44
lliac crest
Sacroiliac
joint
llium
Coxal bone
(or hip bone)
Sacrum
Pubis
Pelvic brim
Coccyx
Ischial spine
Acetabulum
Pubic symphysis
Ischium
Pubic arch
(a)
Figure 5.26a
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IIium
Ala
IIiac crest
Posterior
superior
iliac
spine
Anterior superior
iliac spine
Posterior
inferior
iliac spine
Anterior inferior
iliac spine
Greater sciatic
notch
Acetabulum
Ischial body
Body of pubis
Ischial spine
Pubis
Ischial
tuberosity
Ischium
Ischial ramus
(b)
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Inferior pubic
ramus
Obturator
foramen
Figure 5.26b
45
Gender Differences of the Pelvis
•The female inlet is larger and more circular
•The female pelvis as a whole is shallower, and
the bones are lighter and thinner
•The female ilia flare more laterally
•The female sacrum is shorter and less curved
•The female ischial spines are shorter and
farther apart; thus the outlet is larger
•The female pubic arch is more rounded
because the angle of the pubic arch is greater
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False pelvis
Inlet of
true
pelvis
Pelvic brim
Pubic arch
(less than 90°)
False pelvis
Inlet of
true
pelvis
Pelvic brim
Pubic arch
(more than 90°)
(c)
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Figure 5.26c
46
Bones of the Lower Limbs
•Femur—thigh bone
•The heaviest, strongest bone in the body
•Proximal end articulation
•Head articulates with the acetabulum of
the coxal (hip) bone
•Distal end articulation
•Lateral and medial condyles articulate
with the tibia in the lower leg
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Neck
Head
Head
Intertrochanteric
line
Lesser trochanter
Lesser trochanter
Gluteal tuberosity
Intercondylar
fossa
Medial
condyle
Lateral
condyle
Greater
trochanter
Intertrochanteric
crest
Lateral
condyle
Patellar
surface
(a)
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(b)
Figure 5.27a
47
Bones of the Lower Limbs
•The lower leg has two bones
•Tibia—Shinbone; larger and medially
oriented
•Proximal end articulation
• Medial and lateral condyles articulate
with the femur to form the knee joint
•Fibula—Thin and sticklike; lateral to the tibia
•Has no role in forming the knee joint
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Intercondylar
eminence
Medial
condyle
Tibial
tuberosity
Lateral
condyle
Head
Proximal
tibiofibular
joint
Interosseous
membrane
Anterior
border
Fibula
Tibia
Distal
tibiofibular
joint
Medial
malleolus
Lateral
malleolus
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(c)
Figure 5.27c
48
Bones of the Lower Limbs
•The foot
•Tarsals—seven bones
•Two largest tarsals
• Calcaneus (heel bone)
• Talus
•Metatarsals—five bones form the sole of
the foot
•Phalanges—fourteen bones form the toes
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Phalanges:
Distal
Middle
Proximal
Tarsals:
Medial
cuneiform
Intermediate
cuneiform
Navicular
Metatarsals
Tarsals:
Lateral
cuneiform
Cuboid
Talus
Calcaneus
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Figure 5.28
49
Arches of the Foot
•Bones of the foot are arranged to form three
strong arches
•Two longitudinal
•One transverse
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Medial longitudinal arch
Transverse arch
Lateral longitudinal
arch
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Figure 5.29
50
Joints
•Articulations of bones
•Functions of joints
•Hold bones together
•Allow for mobility
•Two ways joints are classified
•Functionally
•Structurally
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Functional Classification of Joints
•Synarthroses
•Immovable joints
•Amphiarthroses
•Slightly moveable joints
•Diarthroses
•Freely moveable joints
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51
Structural Classification of Joints
•Fibrous joints
•Generally immovable
•Cartilaginous joints
•Immovable or slightly moveable
•Synovial joints
•Freely moveable
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Fibrous Joints
•Bones united by collagenic fibers
•Types
• Sutures
• Immobile
• Syndesmoses
• Allows more movement than sutures but
still immobile
• Example: Distal end of tibia and fibula
• Gomphosis
• Immobile
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Fibrous joints
Fibrous joints
Fibrous
connective
tissue
(a) Suture
Tibia
Fibula
Fibrous
connective
tissue
(b) Syndesmosis
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Figure 5.30a
Cartilaginous Joints
•Bones connected by cartilage
•Types
•Synchrondrosis
•Immobile
•Symphysis
•Slightly movable
•Example: Pubic symphysis, intervertebral
joints
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Cartilaginous joints
First rib
Hyaline
cartilage
Sternum
(c) Synchondrosis
Figure 5.30c
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Cartilaginous joints
Vertebrae
Fibrocartilage
(d) Symphysis
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Figure 5.30d
54
Cartilaginous joints
Pubis
Fibrocartilage
(e) Symphysis
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Figure 5.30e
Synovial Joints
•Articulating bones are separated by a joint
cavity
•Synovial fluid is found in the joint cavity
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55
Synovial joints
Scapula
Articular
capsule
Articular
(hyaline)
cartilage
Humerus
(f) Multiaxial joint
(shoulder joint)
Figure 5.30f
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Synovial joints
Humerus
Articular
(hyaline)
cartilage
Articular
capsule
Radius
(g) Uniaxial joint
(elbow joint)
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Ulna
Figure 5.30g
56
Synovial joints
Ulna
Radius
Articular
capsule
Carpals
(h) Biaxial joint
(intercarpal joints of hand)
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Figure 5.30h
Features of Synovial Joints
•Articular cartilage (hyaline cartilage) covers
the ends of bones
•Articular capsule encloses joint surfaces and
lined with synovial membrane
•Joint cavity is filled with synovial fluid
•Reinforcing ligaments
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57
Structures Associated with the Synovial
Joint
•Bursae—flattened fibrous sacs
•Lined with synovial membranes
•Filled with synovial fluid
•Not actually part of the joint
•Tendon sheath
•Elongated bursa that wraps around a tendon
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Acromion of
scapula
Ligament
Joint cavity
containing
synovial fluid
Bursa
Ligament
Articular
(hyaline)
cartilage
Tendon
sheath
Synovial membrane
Fibrous layer of the
articular capsule
Tendon of
biceps muscle
Humerus
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Figure 5.31
58
Nonaxial
Uniaxial
Biaxial
Multiaxial
(a) Plane joint
(a)
Figure 5.32a
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Nonaxial
Uniaxial
Biaxial
Multiaxial
(b)
Humerus
Ulna
(b) Hinge joint
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Figure 5.32b
59
Nonaxial
Uniaxial
Biaxial
Multiaxial
Ulna
Radius
(c)
(c) Pivot joint
Figure 5.32c
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Nonaxial
Uniaxial
Biaxial
Multiaxial
(d)
Metacarpal
Phalanx
(d) Condylar joint
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Figure 5.32d
60
Nonaxial
Uniaxial
Biaxial
Multiaxial
Carpal
Metacarpal #1
(e)
(e) Saddle joint
Figure 5.32e
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Nonaxial
Uniaxial
Biaxial
Multiaxial
(f)
Head of
humerus
Scapula
(f) Ball-and-socket joint
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Figure 5.32f
61
Inflammatory Conditions Associated
with Joints
•Bursitis—inflammation of a bursa usually
caused by a blow or friction
•Tendonitis—inflammation of tendon sheaths
•Arthritis—inflammatory or degenerative
diseases of joints
•Over 100 different types
•The most widespread crippling disease in
the United States
•Initial symptoms: pain, stiffness, swelling of
the joint
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Clinical Forms of Arthritis
•Osteoarthritis
•Most common chronic arthritis
•Probably related to normal aging processes
•Rheumatoid arthritis
•An autoimmune disease—the immune
system attacks the joints
•Symptoms begin with bilateral inflammation
of certain joints
•Often leads to deformities
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Clinical Forms of Arthritis
•Gouty arthritis
•Inflammation of joints is caused by a
deposition of uric acid crystals from the
blood
•Can usually be controlled with diet
•More common in men
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Developmental Aspects of the Skeletal
System
•At birth, the skull bones are incomplete
•Bones are joined by fibrous membranes called
fontanels
•Fontanels are completely replaced with bone
within two years after birth
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Parietal
bone
Frontal
bone
of skull
Mandible
Occipital
bone
Clavicle
Scapula
Radius
Ulna
Humerus
Femur
Tibia
Ribs
Vertebra
Hip bone
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Figure 5.34
Skeletal Changes Throughout Life
•Fetus
•Long bones are formed of hyaline cartilage
•Flat bones begin as fibrous membranes
•Flat and long bone models are converted to
bone
•Birth
•Fontanels remain until around age 2
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Skeletal Changes Throughout Life
•Adolescence
•Epiphyseal plates become ossified and long
bone growth ends
•Size of cranium in relationship to body
•2 years old—skull is larger in proportion to
the body compared to that of an adult
•8 or 9 years old—skull is near adult size and
proportion
•Between ages 6 and 11, the face grows out
from the skull
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Figure 5.35a
65
© 2012 Pearson Education, Inc.
Figure 5.35b
Skeletal Changes Throughout Life
•Curvatures of the spine
•Primary curvatures are present at birth and
are convex posteriorly
•Secondary curvatures are associated with a
child’s later development and are convex
anteriorly
•Abnormal spinal curvatures (scoliosis and
lordosis) are often congenital
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66
© 2012 Pearson Education, Inc.
Figure 5.18
Skeletal Changes Throughout Life
•Osteoporosis
•Bone-thinning disease afflicting
•50 percent of women over age 65
•20 percent of men over age 70
•Disease makes bones fragile and bones can
easily fracture
•Vertebral collapse results in kyphosis (also
known as dowager’s hump)
•Estrogen aids in health and normal density
of a female skeleton
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© 2012 Pearson Education, Inc.
Figure 5.36
© 2012 Pearson Education, Inc.
Figure 5.37
68