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© 2012 Pearson Education, Inc.
The Skeletal System
• Parts of the skeletal system• Bones (skeleton)• Joints• Cartilages• Ligaments
• Two subdivisions of the skeleton• Axial skeleton• Appendicular skeleton
http://www.youtube.com/watch?v=8d-RBe8JBVs
© 2012 Pearson Education, Inc.
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)
© 2012 Pearson Education, Inc.
Bones of the Human Body• The adult skeleton has 206 bones• Two basic types of bone tissue
1. Compact bone
2. Spongy bone• Small needle-like pieces of bone
• Many open spaces
© 2012 Pearson Education, Inc.
Classification of Bones on the Basis of Shape
• Bones are classified as:• Long• Short• Flat• Irregular
© 2012 Pearson Education, Inc.
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 bones)
• Example:• Femur• Humerus
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Classification of Bones• Irregular bones
• Irregular shape• Do not fit into other bone classification categories
• Example:• Vertebrae • Hip bones
© 2012 Pearson Education, Inc.
Anatomy of a Long Bone• Diaphysis
• Shaft• Composed of compact bone
• Epiphysis • Ends of the bone
• Composed mostly of spongy bone
Figure 5.3a
Distalepiphysis
Diaphysis
Proximalepiphysis
Articularcartilage
Spongy bone
EpiphyseallinePeriosteum
Compact boneMedullarycavity (linedby endosteum)
(a)
http://www.youtube.com/watch?v=owlpf6zHgyw
© 2012 Pearson Education, Inc.
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
• http://www.youtube.com/watch?v=8A0rRIpjutY&feature=relmfu
© 2012 Pearson Education, Inc. Figure 5.3c
Yellowbone marrow
Compact bone
Perforating(Sharpey’s)fibers
Nutrientarteries
Periosteum
Endosteum
(c)
© 2012 Pearson Education, Inc. Figure 5.3b
Compact bone
Spongy bone
Articularcartilage
(b)
Anatomy of a Long Bone
• Articular cartilage• Covers the external surface of the epiphyses
• Made of cartilage
• Decreases friction at joint surfaces
© 2012 Pearson Education, Inc. Figure 5.3a
Distalepiphysis
Diaphysis
Proximalepiphysis
Articularcartilage
Spongy bone
EpiphyseallinePeriosteum
Compact boneMedullarycavity (linedby endosteum)
(a)
• Epiphyseal plate• Flat plate of
hyaline cartilage seen in young, growing bone
• Epiphyseal line• Remnant of
the epiphyseal plate
• Seen in adult bones
Anatomy of a Long Bone
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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”
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc. Figure 5.4a
CompactbonePeriostealblood vesselPeriosteum
Perforatingfibers
Central (Haversian) canal
Perforating(Volkmann’s) canalBlood vessel
Spongy bone
Blood vessel continues intomedullary cavity containing marrow
Lamellae
(a)
Osteon(Haversian system)
© 2012 Pearson Education, Inc.
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
•http://www.youtube.com/watch?v=cNdwwVCpld8&feature=relmfu
© 2012 Pearson Education, Inc. Figure 5.4b
Lamella
CanaliculusLacunaCentral (Haversian) canal
(b)
Osteocyte
© 2012 Pearson Education, Inc. Figure 5.4c
Osteon
Lacuna
Centralcanal
Interstitiallamellae
(c)
© 2012 Pearson Education, Inc.
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
•http://www.youtube.com/watch?v=CQhUINnTdZI&feature=relmfu
© 2012 Pearson Education, Inc. Figure 5.4b
Lamella
CanaliculusLacunaCentral (Haversian) canal
(b)
Osteocyte http://www.youtube.com/watch?v=ylmanEGjRuY&feature=relmfu
© 2012 Pearson Education, Inc.
Formation of the Human Skeleton
• In embryos, the skeleton is primarily hyaline cartilage
•During development, much of this cartilage is replaced by bone – called ossification
•Cartilage remains in isolated areas•Bridge of the nose•Parts of ribs•Joints
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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)
© 2012 Pearson Education, Inc. Figure 5.5
In a fetusIn an embryo
Bone collar
Hyalinecartilagemodel
Bone startingto replacecartilage
In a child
Medullarycavity
New center ofbone growth
Hyalinecartilage
Epiphysealplate cartilage
Growthin bonelength
New boneforming
Invadingbloodvessels
Epiphysealplatecartilage
Articularcartilage
Spongybone
New boneforming
Growthin bonewidth
http://www.youtube.com/watch?v=t5_3sNLtfxQ
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Common Types of Fractures
•Comminuted—bone breaks into many fragments
•Compression—bone is crushed•Depressed—broken bone portion is pressed inward
• Impacted—broken bone ends are forced into each other
•Spiral—ragged break occurs when excessive twisting forces are applied to a bone
•Greenstick—bone breaks incompletely
http://www.youtube.com/watch?v=c5Q5GPwAS4k
Setting a bone: http://www.youtube.com/watch?v=nQVihuOUQkU&feature=related
© 2012 Pearson Education, Inc.
Comminuted fracture
Compression fracture
© 2012 Pearson Education, Inc.
Depressed fracture
Impacted fracture
© 2012 Pearson Education, Inc.
Spiral fracture
Greenstick fracture
© 2012 Pearson Education, Inc. Figure 5.7
Internalcallus(fibroustissue andcartilage)
Hematomaforms.
Fibrocartilage callus forms.
Bony callus forms.
Bone remodeling occurs.
1 2 3 4
Hematoma
Bonycallus ofspongybone
Spongybonetrabecula
Newbloodvessels
Externalcallus
Healedfracture
Healing of bone fractures
© 2012 Pearson Education, Inc.
The Axial Skeleton
•Forms the longitudinal axis of the body•Divided into three parts
•Skull•Vertebral column•Bony thorax
© 2012 Pearson Education, Inc. Figure 5.8a(a) Anterior view
Phalanges
Metatarsals
Tarsals
Fibula
Tibia
Patella
Femur
Metacarpals
Phalanges
Carpals
UlnaRadius
Vertebra
Humerus
Rib
Sternum
Scapula
Clavicle
Facial bones
Cranium
Skull
Thoracic cage(ribs andsternum)
Vertebralcolumn
Sacrum
© 2012 Pearson Education, Inc. Figure 5.8b(b) Posterior view
Fibula
Tibia
Femur
Metacarpals
Phalanges
Carpals
RadiusUlna
Vertebra
Humerus
Rib
Scapula
Clavicle
Cranium
Bones ofpectoralgirdle
Upperlimb
Bones ofpelvicgirdle
Lowerlimb
© 2012 Pearson Education, Inc.
The Skull
•Two sets of bones•Cranium•Facial bones
•Bones are joined by sutures•Only the mandible is attached by a freely movable joint
© 2012 Pearson Education, Inc. Figure 5.9
Coronal suture
Parietal bone
Lambdoidsuture
Temporal bone
Squamous suture
Occipital bone
Zygomatic process
External acoustic meatus
Mastoid process
Styloid process
Mandibular ramus
Frontal bone
Sphenoid bone
Ethmoid bone
Lacrimal bone
Nasal bone
Zygomatic bone
Maxilla
Alveolarprocesses
Mandible (body)Mental foramen
© 2012 Pearson Education, Inc. Figure 5.10
Sphenoidbone
Temporal bone
Internalacoustic meatus
Parietal bone
Occipital bone
Foramen magnum
Jugular foramen
Foramen ovale
Sella turcica
Optic canal
Frontal bone
Cribriform plate
Crista galliEthmoidbone
© 2012 Pearson Education, Inc. Figure 5.12
Coronal suture
Parietal bone
Nasal bone
Sphenoid bone
Ethmoid bone
Lacrimal bone
Zygomatic bone
Maxilla
Mandible
Alveolar processes
Vomer
Inferior nasal concha
Middle nasal conchaof ethmoid bone
Temporal bone
Optic canal
Superior orbital fissure
Frontal bone
© 2012 Pearson Education, Inc.
Paranasal Sinuses
•Hollow portions of bones surrounding the nasal cavity
•Functions of paranasal sinuses•Lighten the skull•Give resonance and amplification to voice
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc. Figure 5.15a
Frontal bone
Parietalbone
(a)
Occipitalbone
Anteriorfontanel
Posterior fontanel
© 2012 Pearson Education, Inc. Figure 5.15b
Anterior fontanel
Frontalbone
SphenoidalfontanelParietal bone
Posteriorfontanel
OccipitalboneMastoidfontanel
Temporal bone
(b)
© 2012 Pearson Education, Inc.
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
•Nine vertebrae fuse to form two composite bones•Sacrum•Coccyx
© 2012 Pearson Education, Inc. Figure 5.16
Anterior Posterior1st cervicalvertebra (atlas)2nd cervical vertebra (axis)
Cervical curvature(concave)7 vertebrae,C1 – C7
1st thoracicvertebra
TransverseprocessSpinousprocess
Intervertebraldisc
Intervertebralforamen
Thoracic curvature(convex)12 vertebrae,T1 – T12
1st lumbarvertebra Lumbar curvature
(concave)5 vertebrae,L1 – L5
Sacral curvature(convex)5 fused vertebrae
Coccyx4 fused vertebrae
© 2012 Pearson Education, Inc. Figure 5.21
Superiorarticularprocess
AuricularsurfaceSacral
canalAla
Sacrum
Body
Mediansacralcrest
Posteriorsacralforamina
SacralhiatusCoccyx
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc. Figure 5.22a
T1 vertebraJugular notch
ManubriumSternal angleBodyXiphisternaljoint
Xiphoidprocess
Sternum
Intercostalspaces
Costal cartilageFloatingribs (11, 12)
Falseribs(8 –12)
Trueribs(1 –7)
L1 Vertebra
(a)
Clavicular notch
© 2012 Pearson Education, Inc. Figure 5.22b
T2
T3
T4
T9
Jugularnotch
Sternalangle
Heart
Xiphisternaljoint
(b)
© 2012 Pearson Education, Inc. Figure 5.8a(a) Anterior view
Phalanges
Metatarsals
Tarsals
Fibula
Tibia
Patella
Femur
Metacarpals
Phalanges
Carpals
UlnaRadius
Vertebra
Humerus
Rib
Sternum
Scapula
Clavicle
Facial bones
Cranium
Skull
Thoracic cage(ribs andsternum)
Vertebralcolumn
Sacrum
• Composed of 126 bones
• Limbs (appendages)
• Pectoral girdle• Pelvic girdle
The Appendicular Skeleton
© 2012 Pearson Education, Inc. Figure 5.8b(b) Posterior view
Fibula
Tibia
Femur
Metacarpals
Phalanges
Carpals
RadiusUlna
Vertebra
Humerus
Rib
Scapula
Clavicle
Cranium
Bones ofpectoralgirdle
Upperlimb
Bones ofpelvicgirdle
Lowerlimb
© 2012 Pearson Education, Inc. Figure 5.23a
Acromio- clavicularjoint
Scapula
(a) Articulated right shoulder (pectoral) girdle showing the relationship to bones of the thorax and sternum
Clavicle
© 2012 Pearson Education, Inc. Figure 5.25
Phalanges (fingers)
Distal
Middle
Proximal
Metacarpals (palm)
Carpals (wrist)
Hamate
Pisiform
Triquetrum
Lunate
UlnaRadius
Capitate
Scaphoid
Trapezoid
Trapezium
1
2345
© 2012 Pearson Education, Inc.
Bones of the Pelvic Girdle
•Formed by two coxal (ossa coxae) bones•Composed of three pairs of fused bones
• Ilium• Ischium•Pubis
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc. Figure 5.26a
Coxal bone (or hip bone)
llium
Pubis
Ischium
(a)
Pubic arch
Coccyx
Sacrum
lliac crest
Sacroiliac joint
Pelvic brim
Ischial spine
Acetabulum
Pubic symphysis
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc. Figure 5.26c
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)
© 2012 Pearson Education, Inc. Figure 5.28
Tarsals:
Medial cuneiform
Intermediatecuneiform
Navicular
Talus
Calcaneus
Cuboid
Lateral cuneiform
Tarsals:
Metatarsals
Proximal
MiddleDistal
Phalanges:
© 2012 Pearson Education, Inc.
Joints
•Articulations of bones•Functions of joints
•Hold bones together•Allow for mobility
•Two ways joints are classified•Functionally•Structurally
© 2012 Pearson Education, Inc. Figure 5.31
Acromion of scapula
Ligament
Bursa
Ligament
Tendon sheath
Tendon of biceps muscle
Humerus
Fibrous layer of the articular capsule
Synovial membrane
Articular (hyaline) cartilage
Joint cavity containing synovial fluid
© 2012 Pearson Education, Inc. Figure 5.32a
NonaxialUniaxialBiaxialMultiaxial
(a) Plane joint
(a)
© 2012 Pearson Education, Inc. Figure 5.32b
NonaxialUniaxialBiaxialMultiaxial
(b)
HumerusUlna
(b) Hinge joint
© 2012 Pearson Education, Inc. Figure 5.32c
NonaxialUniaxialBiaxialMultiaxial
(c)
(c) Pivot joint
UlnaRadius
© 2012 Pearson Education, Inc. Figure 5.32e
NonaxialUniaxialBiaxialMultiaxial
(e)
Carpal
(e) Saddle joint
Metacarpal #1
© 2012 Pearson Education, Inc. Figure 5.32f
NonaxialUniaxialBiaxialMultiaxial
(f)
Head of humerus
Scapula
(f) Ball-and-socket joint
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc. Figure 5.34
Frontal bone of skull
Mandible
RadiusUlna
Humerus
Femur
Tibia
Hip bone
Vertebra
Ribs
Scapula
Clavicle
Occipital bone
Parietal bone
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc. Figure 5.36
© 2012 Pearson Education, Inc. Figure 5.37