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The Axial Skeleton
 Forms the longitudinal axis of the body
 Divided into three parts
1. Skull
2. Vertebral column
3. Bony thorax
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Figure 5.8a The human skeleton.
Skull
Cranium
Facial bones
Clavicle
Thoracic
cage
(ribs and
sternum)
Vertebral
column
Sacrum
Scapula
Sternum
Rib
Humerus
Vertebra
Radius
Ulna
Carpals
Phalanges
Metacarpals
Femur
Patella
Tibia
Fibula
(a) Anterior view
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Tarsals
Metatarsals
Phalanges
Figure 5.8b The human skeleton.
Cranium
Bones of
pectoral
girdle
Clavicle
Scapula
Rib
Humerus
Vertebra
Radius
Ulna
Carpals
Upper
limb
Bones of
pelvic
girdle
Phalanges
Metacarpals
Femur
Lower
limb
Tibia
Fibula
(b) Posterior view
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Concept Link
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The Skull
 Two sets of bones
1. Cranium bones enclose the brain
2. Facial bones
 Hold eyes in anterior position
 Allow facial muscles to express feelings
 Bones are joined by sutures
 Only the mandible is attached by a freely movable
joint
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The Skull
 8 cranial bones protect the brain
1.
2.
3.
4.
5–6.
7–8.
Frontal bone
Occipital bone
Ethmoid bone
Sphenoid bone
Parietal bones (pair)
Temporal bones (pair)
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The Skull
 There are 14 facial bones. All are paired except for
the single mandible and vomer.
1–2.
3–4.
5–6.
7–8.
9–10.
11–12.
13.
14.
Maxillae
Zygomatics
Palatines
Nasals
Lacrimals
Inferior nasal conchae
Mandible
Vomer
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Figure 5.9 Human skull, lateral view.
Coronal suture
Frontal bone
Parietal bone
Sphenoid bone
Temporal bone
Ethmoid bone
Lambdoid suture
Lacrimal bone
Squamous suture
Occipital bone
Nasal bone
Zygomatic process
Zygomatic bone
Maxilla
External acoustic
meatus
Mastoid process
Alveolar processes
Styloid process
Mandibular ramus
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Mandible (body)
Mental foramen
Figure 5.10 Human skull, superior view (top of cranium removed).
Frontal bone
Sphenoid
bone
Cribriform plate Ethmoid
Crista galli
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 5.11 Human skull, inferior view (mandible removed).
Maxilla
(palatine process)
Hard
palate Palatine bone
Zygomatic bone
Temporal bone
(zygomatic process)
Maxilla
Sphenoid bone
(greater wing)
Foramen ovale
Vomer
Mandibular fossa
Carotid canal
Styloid process
Mastoid process
Temporal bone
Jugular foramen
Occipital condyle
Parietal bone
Foramen magnum
Occipital bone
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Figure 5.12 Human skull, anterior view.
Coronal suture
Frontal bone
Parietal bone
Nasal bone
Sphenoid bone
Ethmoid bone
Lacrimal bone
Zygomatic bone
Maxilla
Superior orbital
fissure
Optic canal
Temporal bone
Middle nasal concha
of ethmoid bone
Inferior nasal concha
Vomer
Mandible
Alveolar processes
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Paranasal Sinuses
 Hollow portions of bones surrounding the nasal
cavity
 Functions of paranasal sinuses
 Lighten the skull
 Amplify sounds made as we speak
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Figure 5.13a Paranasal sinuses.
Frontal sinus
Ethmoid sinus
Sphenoidal
sinus
Maxillary
sinus
(a) Anterior view
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Figure 5.13b Paranasal sinuses.
Frontal sinus
Ethmoid sinus
Sphenoidal
sinus
Maxillary
sinus
(b) Medial view
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The Hyoid Bone
 Closely related to mandible and temporal bones
 The only bone that does not articulate with another
bone
 Serves as a movable base for the tongue
 Aids in swallowing and speech
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Figure 5.14 Anatomical location and structure of the hyoid bone.
Greater horn
Lesser horn
Body
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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 are 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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Figure 5.15a The fetal skull.
Frontal bone
Anterior
fontanel
Parietal
bone
Posterior fontanel
(a)
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Occipital
bone
Figure 5.15b The fetal skull.
Parietal bone
Posterior
fontanel
Occipital
bone
Mastoid
fontanel
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Anterior fontanel
Sphenoidal
fontanel
Frontal
bone
Temporal bone
Vertebral Column (Spine)
 Vertebral column provides axial support
 Extends from skull to the pelvis
 26 single vertebral bones are separated by
intervertebral discs
 7 cervical vertebrae are in the neck
 12 thoracic vertebrae are in the chest region
 5 lumbar vertebrae are associated with the lower
back
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Vertebral Column (Spine)
 9 vertebrae fuse to form two composite bones
 Sacrum formed by the fusion of 5 vertebrae
 Coccyx (tailbone) formed by the fusion of 3 to 5
vertebrae
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Figure 5.16 The vertebral column.
Anterior
1st cervical vertebra
(atlas)
2nd cervical vertebra
(axis)
Posterior
Cervical curvature (concave)
7 vertebrae, C1 – C7
1st thoracic vertebra
Transverse process
Spinous process
Thoracic curvature (convex)
12 vertebrae, T1 – T12
Intervertebral disc
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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Vertebral Column (Spine)
 Primary curvatures
 Spinal curvatures of the thoracic and sacral regions
 Present from birth
 Form a C-shaped curvature as in newborns
 Secondary curvatures
 Spinal curvatures of the cervical and lumbar regions
 Develop after birth
 Form an S-shaped curvature as in adults
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Figure 5.17 The C-shaped spine typical of a newborn.
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Figure 5.18 Abnormal spinal curvatures.
(a) Scoliosis
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(b) Kyphosis
(c) Lordosis
Vertebral Column (Spine)
 Parts of a typical vertebra
 Body (centrum)
 Vertebral arch
 Pedicle
 Lamina
 Vertebral foramen
 Transverse processes
 Spinous process
 Superior and inferior articular processes
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Figure 5.19 A typical vertebra, superior view.
Posterior
Vertebral
arch
Lamina
Transverse
process
Spinous
process
Superior
articular
process
and
facet
Pedicle
Vertebral
foramen
Body
Anterior
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Figure 5.20a Regional characteristics of vertebrae.
(a) ATLAS AND AXIS
Transverse
process
Posterior
arch
Anterior arch
Superior view of atlas (C1)
Transverse
process
Spinous process
Facet on
superior
articular
process
Dens
Body
Superior view of axis (C2)
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Figure 5.20b Regional characteristics of vertebrae.
(b) TYPICAL CERVICAL VERTEBRAE
Spinous process
Vertebral
foramen
Facet on
superior
articular
process
Superior view
Superior articular
process
Spinous
process
Transverse
process
Body
Transverse
process
Facet on inferior
articular process
Right lateral view
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Figure 5.20c Regional characteristics of vertebrae.
(c) THORACIC VERTEBRAE
Spinous process
Vertebral
Transverse
foramen
process
Facet on
superior
Facet
articular
for rib
process
Body
Facet on Superior view
superior
Body
articular
process
Facet on
Costal facet
transverse
Spinous
for rib
process
process
Right lateral view
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Figure 5.20d Regional characteristics of vertebrae.
(d) LUMBAR VERTEBRAE
Spinous process
Vertebral
Transverse
foramen
process
Facet on
superior
articular
process
Body
Superior view
Superior
articular
process
Spinous
process
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Body
Facet on inferior
articular process
Right lateral view
Figure 5.21 Sacrum and coccyx, posterior view.
Sacral
canal
Ala
Superior Auricular
articular surface
process
Body
Median
sacral
crest
Sacrum
Posterior
sacral
foramina
Coccyx
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Sacral
hiatus
The Bony Thorax
 Forms a cage to protect major organs
 Consists of three parts
1. Sternum
2. Ribs
 True ribs (pairs 1–7)
 False ribs (pairs 8–12)
 Floating ribs (pairs 11–12)
3. Thoracic vertebrae
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Figure 5.22a The bony thorax (thoracic cage).
T1 vertebra
Jugular notch
Clavicular notch
Manubrium
Sternal angle
Body
Xiphisternal
joint
Xiphoid
process
True
ribs
(1–7)
False
ribs
(8–12)
L1
vertebra
(a)
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Floating
ribs (11, 12)
Intercostal
spaces
Costal cartilage
Sternum
Figure 5.22b The bony thorax (thoracic cage).
T2
T3
T4
Jugular
notch
Sternal
angle
Heart
T9
(b)
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Xiphisternal
joint
The Appendicular Skeleton
 Composed of 126 bones
 Limbs (appendages)
 Pectoral girdle
 Pelvic girdle
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Figure 5.8a The human skeleton.
Skull
Cranium
Facial bones
Clavicle
Thoracic
cage
(ribs and
sternum)
Vertebral
column
Sacrum
Scapula
Sternum
Rib
Humerus
Vertebra
Radius
Ulna
Carpals
Phalanges
Metacarpals
Femur
Patella
Tibia
Fibula
(a) Anterior view
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Tarsals
Metatarsals
Phalanges
Figure 5.8b The human skeleton.
Cranium
Bones of
pectoral
girdle
Clavicle
Scapula
Rib
Humerus
Vertebra
Radius
Ulna
Carpals
Upper
limb
Bones of
pelvic
girdle
Phalanges
Metacarpals
Femur
Lower
limb
Tibia
Fibula
(b) Posterior view
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The Pectoral (Shoulder) Girdle
 Composed of two bones that attach the upper limb
to the axial skeletal
1. Scapula
2. Clavicle
 Pectoral girdle (2)
 Light, poorly reinforced girdle
 Allows the upper limb a great deal of freedom
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Figure 5.23a Bones of the shoulder girdle.
Acromioclavicular joint
Clavicle
Scapula
(a) Articulated right shoulder (pectoral)
girdle showing the relationship to
bones of the thorax and sternum
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Figure 5.23b Bones of the shoulder girdle.
Sternal
(medial)
end
Posterior
Acromial
(lateral) end
Superior view
Acromial end
Anterior
Anterior
Sternal end
Posterior
Inferior view
(b) Right clavicle, superior and
inferior views
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Figure 5.23c Bones of the shoulder girdle.
Coracoid process
Suprascapular notch
Superior
angle
Spine
Acromion
Glenoid cavity
at lateral angle
Medial
border
Lateral border
(c) Right scapula, posterior aspect
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Figure 5.23d Bones of the shoulder girdle.
Acromion
Suprascapular notch
Superior border
Superior
angle
Coracoid
process
Glenoid
cavity
Lateral
(axillary)
border
Medial
(vertebral)
border
Inferior angle
(d) Right scapula, anterior aspect
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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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Figure 5.24a Bones of the right arm and forearm.
Greater
tubercle
Lesser
tubercle
Head of
humerus
Anatomical
neck
Intertubercular
sulcus
Deltoid
tuberosity
(a)
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Radial
fossa
Coronoid
fossa
Medial
epicondyle
Capitulum
Trochlea
Figure 5.24b Bones of the right arm and forearm.
Head of
humerus
Anatomical
neck
Surgical
neck
Radial
groove
Deltoid
tuberosity
Medial
epicondyle
(b) Trochlea
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Olecranon
fossa
Lateral
epicondyle
Bones of the Upper Limbs
 The forearm has two bones
1. Ulna—medial bone in anatomical position
 Proximal end articulation
 Coronoid process and olecranon articulate with the
humerus
2. Radius—lateral bone in anatomical position
 Proximal end articulation
 Head articulates with the capitulum of the humerus
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Figure 5.24c Bones of the right arm and forearm.
Trochlear
notch
Olecranon
Head
Neck
Radial
tuberosity
Coronoid
process
Proximal
radioulnar
joint
Radius
Ulna
Interosseous
membrane
(c)
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Radial
styloid
process
Ulnar
styloid
process
Distal
radioulnar joint
Bones of the Upper Limbs
 Hand
 Carpals—wrist
 8 bones arranged in two rows of 4 bones in each
hand
 Metacarpals—palm
 5 per hand
 Phalanges—fingers and thumb
 14 phalanges in each hand
 In each finger, there are 3 bones
 In the thumb, there are only 2 bones
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Figure 5.25 Bones of the right hand, anterior view.
Distal
Phalanges
(fingers)
Middle
Proximal
Metacarpals
(palm)
Carpals
(wrist)
4
3
2
5
1
Hamate
Trapezium
Pisiform
Triquetrum
Trapezoid
Scaphoid
Capitate
Lunate
Ulna
Radius
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Bones of the Pelvic Girdle
 Formed by 2 coxal (ossa coxae) bones
 Composed of three pairs of fused bones
1. Ilium
2. Ischium
3. 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
 Pelvis protects several organs
 Reproductive organs
 Urinary bladder
 Part of the large intestine
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Figure 5.26a The bony pelvis.
Iliac crest
Sacroiliac
joint
Ilium
Coxal bone
(or hip bone)
Sacrum
Pubis
Pelvic brim
Coccyx
Ischial spine
Acetabulum
Ischium
(a)
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Pubic symphysis
Pubic arch
Figure 5.26b The bony pelvis.
Ilium
Ala
Posterior
superior
iliac spine
Posterior
inferior
iliac spine
Greater sciatic
notch
Ischial body
Iliac crest
Anterior superior
iliac spine
Anterior inferior
iliac spine
Acetabulum
Body of pubis
Ischial spine
Pubis
Ischial
tuberosity
Ischium
(b) Ischial ramus
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Inferior pubic
ramus
Obturator
foramen
Gender Differences of the Pelvis
 The female’s pelvis:
 Inlet is larger and more circular
 Pelvis as a whole is shallower, and the bones are
lighter and thinner
 Ilia flare more laterally
 Sacrum is shorter and less curved
 Ischial spines are shorter and farther apart; thus, the
outlet is larger
 Pubic arch is more rounded because the angle of the
pubic arch is greater
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Figure 5.26c The bony pelvis.
False pelvis
Inlet of
true
pelvis
Pelvic brim
Pubic arch
)
(less than 90°
False pelvis
Inlet of
true
pelvis
Pelvic brim
(c)
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Pubic arch
)
(more than 90°
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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Figure 5.27a Bones of the right thigh and leg.
Neck
Head
Intertrochanteric
line
Lateral
condyle
Patellar
surface
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(a)
Lesser
trochanter
Figure 5.27b Bones of the right thigh and leg.
Greater
trochanter
Head
Lesser
trochanter
Intertrochanteric
crest
Gluteal
tuberosity
Intercondylar
fossa
Medial
condyle
(b)
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Lateral
condyle
Bones of the Lower Limbs
 The lower leg has two bones
1. Tibia—shinbone; larger and medially oriented
 Proximal end articulation
 Medial and lateral condyles articulate with the femur to
form the knee joint
2. Fibula—thin and sticklike; lateral to the tibia
 Has no role in forming the knee joint
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Figure 5.27c Bones of the right thigh and leg.
Intercondylar
eminence
Medial
condyle
Lateral
condyle
Head
Tibial
tuberosity
Proximal
tibiofibular
joint
Interosseous
membrane
Anterior
border
Fibula
Tibia
Distal
tibiofibular
joint
Lateral
malleolus
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(c)
Medial
malleolus
Bones of the Lower Limbs
 The foot
 Tarsals—7 bones
 Two largest tarsals
 Calcaneus (heel bone)
 Talus
 Metatarsals—5 bones form the sole of
the foot
 Phalanges—14 bones form the toes
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Figure 5.28 Bones of the right foot, superior view.
Phalanges:
Distal
Middle
Proximal
Tarsals:
Medial
cuneiform
Intermediate
cuneiform
Navicular
Metatarsals
Tarsals:
Lateral
cuneiform
Cuboid
Talus
Calcaneus
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Arches of the Foot
 Bones of the foot are arranged to form three strong
arches
 Two longitudinal
 One transverse
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Figure 5.29 Arches of the foot.
Medial longitudinal arch
Transverse arch
Lateral longitudinal
arch
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Joints
 Joints are articulations
 Two or more bones meet
 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 movable joints
 Diarthroses
 Freely movable joints
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Structural Classification of Joints
 Fibrous joints
 Generally immovable
 Cartilaginous joints
 Immovable or slightly movable
 Synovial joints
 Freely movable
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Concept Link
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Fibrous Joints
 Bones united by fibrous tissue
 Types
 Sutures
 Immobile
 Syndesmoses
 Allow more movement than sutures but still immobile
 Example: Distal end of tibia and fibula
 Gomphosis
 Immobile
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Figure 5.30a Types of joints.
Fibrous joints
(a) Suture
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Fibrous
connective
tissue
Figure 5.30b Types of joints.
Fibrous joints
Tibia
Fibula
Fibrous
connective
tissue
(b) Syndesmosis
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Cartilaginous Joints
 Bones connected by fibrocartilage
 Types
 Synchrondrosis
 Immobile
 Symphysis
 Slightly movable
 Example: Pubic symphysis, intervertebral joints
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Figure 5.30c Types of joints.
Cartilaginous joints
First rib
Hyaline
cartilage
Sternum
(c) Synchondrosis
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Figure 5.30d Types of joints.
Cartilaginous joints
Vertebrae
Fibrocartilage
(d) Symphysis
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Figure 5.30e Types of joints.
Cartilaginous joints
Pubis
Fibrocartilage
(e) Symphysis
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Synovial Joints
 Articulating bones are separated by a joint cavity
 Synovial fluid is found in the joint cavity
 Four distinguishing features of synovial joints
1.
2.
3.
4.
Articular cartilage
Articular capsule
Joint cavity
Reinforcing ligaments
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Figure 5.30f Types of joints.
Synovial joints
Scapula
Articular
capsule
Articular (hyaline)
cartilage
Humerus
(f) Multiaxial joint
(shoulder joint)
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Figure 5.30g Types of joints.
Synovial joints
Humerus
Articular (hyaline)
cartilage
Articular capsule
Radius
Ulna
(g) Uniaxial joint
(elbow joint)
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Figure 5.30h Types of joints.
Synovial joints
Ulna
Radius
Carpals
Articular
capsule
(h) Biaxial joint
(intercarpal joints of hand)
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Synovial Joints
 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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Synovial Joints
 Types of synovial joints based on shape:
 Plane joint
 Hinge joint
 Pivot joint
 Condylar joint
 Saddle joint
 Ball-and-socket joint
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Figure 5.31 General structure of a synovial joint.
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 5.32a Types of synovial joints.
Nonaxial
Uniaxial
Biaxial
Multiaxial
(f)
(a) Plane joint
(b)
(c)
(a)
(e)
(d)
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Figure 5.32b Types of synovial joints.
Humerus
Ulna
Nonaxial
Uniaxial
Biaxial
Multiaxial
(f)
(b)
(c)
(a)
(e)
(d)
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(b) Hinge
joint
Figure 5.32c Types of synovial joints.
Nonaxial
Uniaxial
Biaxial
Multiaxial
Ulna
Radius
(f)
(c) Pivot joint
(b)
(c)
(a)
(e)
(d)
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Figure 5.32d Types of synovial joints.
Nonaxial
Uniaxial
Biaxial
Multiaxial
(f)
(b)
(c)
(a)
(e)
(d)
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Metacarpal
Phalanx
(d) Condylar joint
Figure 5.32e Types of synovial joints.
Carpal
Metacarpal #1
Nonaxial
Uniaxial
Biaxial
Multiaxial
(f)
(e) Saddle joint
(b)
(c)
(a)
(e)
(d)
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Figure 5.32f Types of synovial joints.
Nonaxial
Uniaxial
Biaxial
Multiaxial
(f)
Head of
humerus
(b)
(c)
Scapula
(f) Ball-and-socket joint
(a)
(e)
(d)
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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 (OA)
 Most common chronic arthritis
 Probably related to normal aging processes
 Rheumatoid arthritis (RA)
 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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Figure 5.33 X-ray image of a hand deformed by rheumatoid arthritis.
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Clinical Forms of Arthritis
 Gouty arthritis (gout)
 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
 Fontanels
 Allow brain growth and ease birth passage
 Present in the skull at birth
 Completely replaced with bone within 2 years after
birth
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Developmental Aspects of the Skeletal System
 Growth of cranium after birth is related to brain
growth
 Increase in size of the facial skeleton follows tooth
development and enlargement of the respiratory
passageways.
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Figure 5.34 Ossification centers in the skeleton of a 12-week-old fetus are indicated by the darker areas. Lighter regions are still fibrous or cartilaginous.
Frontal
bone
of skull
Mandible
Parietal
bone
Occipita
bone
Clavicle
Scapula
Radius
Ulna
Humerus
Femur
Tibia
Ribs
Vertebra
Hip bone
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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 Differences in the growth rates for some parts of the body compared to others determine body proportions.
Human newborn
(a)
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Human adult
Figure 5.35b Differences in the growth rates for some parts of the body compared to others determine body proportions.
Newborn
(b)
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2 yrs.
5 yrs.
15 yrs.
Adult
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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Figure 5.18 Abnormal spinal curvatures.
(a) Scoliosis
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(b) Kyphosis
(c) Lordosis
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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Figure 5.36 Osteoporosis.
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Figure 5.37 Vertebral collapse due to osteoporosis.
Age 40
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Age 60
Age 70