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PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College
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PART A 5
The Skeletal System
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The Skeletal System § Parts of the skeletal system
§ Bones (skeleton)
§ Joints
§ Cartilages
§ Ligaments
§ Two subdivisions of the skeleton
§ Axial skeleton – bones that form the longitudinal axis of the body
§ Appendicular skeleton – bones of the limbs and girdles.
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Functions of Bones 1. Support the body
2. Protect soft organs
3. Allow movement due to attached skeletal muscles
4. Store minerals and fats (most important of which are calcium and phosphorous)
5. 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
§ Dense and looks smooth
§ Homogeneous
§ Spongy bone
§ Small needle-like pieces of bone
§ Many open spaces
Figure 5.2b
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Classification of Bones on the Basis of Shape
Figure 5.1
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Classification of Bones § Long bones
§ Typically longer than they are wide
§ Have a shaft with heads at both ends
§ Contain mostly compact bone
§ Example:
§ Femur
§ Humerus
** All the bones of the limbs, except the patella, carpals, and tarsals are long bones
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Classification of Bones
Figure 5.1a
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Classification of Bones § Short bones
§ Generally cube-shape
§ Contain mostly spongy bone
§ Example:
§ Carpals
§ Tarsals
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Classification of Bones
Figure 5.1b
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Classification of Bones § Sesamoid Bones (round bones)
§ Special type of short bone
§ Form within tendons
§ Best known example
§ Patella
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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
Figure 5.1c
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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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Classification of Bones
Figure 5.1d
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Anatomy of a Long Bone Gross/Macroscopic Anatomy
§ Diaphysis
§ Shaft
§ Composed of compact bone
§ Epiphysis
§ Ends of the bone
§ Composed mostly of spongy bone
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Anatomy of a Long Bone
Figure 5.2a
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Anatomy of a Long Bone § Periosteum
§ Outside covering of the diaphysis
§ Fibrous connective tissue membrane
§ Sharpey’s fibers/Perforating fibers
§ Secure periosteum to underlying bone
§ Arteries
§ Supply bone cells with nutrients
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Anatomy of a Long Bone
Figure 5.2c
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Anatomy of a Long Bone § Articular cartilage (articulate – join w/another bone)
§ Covers the external surface of the epiphyses
§ Made of hyaline cartilage
§ Decreases friction at joint surfaces
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Anatomy of a Long Bone § Epiphyseal plate/Growth 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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Anatomy of a Long Bone
Figure 5.2a
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Anatomy of a Long Bone § Medullary cavity
§ Cavity inside of the shaft
§ Contains yellow marrow (mostly fat) in adults
§ In infants this area forms blood cells and red marrow is found there
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Anatomy of a Long Bone
Figure 5.2a
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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
§ Depressions or cavities—indentations
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Bone Markings
Table 5.1 (1 of 2)
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Bone Markings
Table 5.1 (2 of 2)
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Microscopic Anatomy of 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 (Volkman’s) canal
§ Canal perpendicular to the central canal
§ Carries blood vessels and nerves from osteon to osteon
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Microscopic Anatomy of Bone
Figure 5.3a
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Microscopic Anatomy of Bone § Lacunae
§ Cavities containing bone cells (osteocytes)
§ Arranged in concentric rings
§ Lamellae
§ Rings around the central canal
§ Sites of lacunae
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Microscopic Anatomy of Bone
Figure 5.3b–c
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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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Microscopic Anatomy of Bone
Figure 5.3b
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Macro/Micro Labeling Diaphysis
Periosteum Central (Haversian) canal
Epiphyseal plate/line Canaliculus
Epiphysis Lacuna
Compact bone Osteocyte
Spongy bone Perforating (Volkman’s) canal
Medullary cavity Lamella
Yellow/Red bone marrow Osteon (Haversian system)
Articular cartilage
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
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 oppositional growth)
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Long Bone Formation and Growth
Figure 5.4a
Bone starting to replace cartilage
Epiphyseal plate cartilage
Articular cartilage
Spongy bone
In a child In a fetus In an embryo
New bone forming
Growth in bone width
Growth in bone length
Epiphyseal plate cartilage
New bone forming
Blood vessels
Hyaline cartilage
New center of bone growth
Medullary cavity
Bone collar Hyaline cartilage model
(a)
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Long Bone Formation and Growth
Figure 5.4a, step 1
Bone starting to replace cartilage
In an embryo
Bone collar Hyaline cartilage model
(a)
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Long Bone Formation and Growth
Figure 5.4a, step 2
Bone starting to replace cartilage
In a fetus In an embryo
Growth in bone length
Blood vessels
Hyaline cartilage
New center of bone growth
Medullary cavity
Bone collar Hyaline cartilage model
(a)
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Long Bone Formation and Growth
Figure 5.4a, step 3
Bone starting to replace cartilage
Epiphyseal plate cartilage
Articular cartilage
Spongy bone
In a child In a fetus In an embryo
New bone forming
Growth in bone width
Growth in bone length
Epiphyseal plate cartilage
New bone forming
Blood vessels
Hyaline cartilage
New center of bone growth
Medullary cavity
Bone collar Hyaline cartilage model
(a)
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Long Bone Formation and Growth
Figure 5.4b
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Types of Bone Cells § Osteocytes—mature bone cells
§ Osteoblasts—bone-forming cells
§ Osteoclasts—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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**HOMEOSTATIC IMBALANCE**
- Rickets - a disease in children in which bones fail to calcify
- bones soften and show bowing
- due to a lack of calcium or vitamin D
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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 – realignment of bone ends, and § immobilization – by cast or traction
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common types of fractures: 1. Comminuted - bone breaks into many fragments
2. Compression - bone is crushed
3. Depressed - broken bone portion is pushed inward
4. Impacted - broken bone ends are forced into each other
5. Spiral - ragged break occurs when excessive twisting forces are applied to a bone
6. Greenstick - bone breaks incompletely, like a green twig breaks
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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 (bone remodeling)
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Stages in the Healing of a Bone Fracture
Figure 5.5
Hematoma External callus
Bony callus of spongy bone
Healed fracture
New blood vessels
Internal callus (fibrous tissue and cartilage)
Spongy bone trabecula
Hematoma formation
Fibrocartilage callus formation
Bony callus formation
Bone remodeling
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Stages in the Healing of a Bone Fracture
Figure 5.5, step 1
Hematoma
Hematoma formation
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Stages in the Healing of a Bone Fracture
Figure 5.5, step 2
Hematoma External callus
New blood vessels
Internal callus (fibrous tissue and cartilage)
Spongy bone trabecula
Hematoma formation
Fibrocartilage callus formation
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Stages in the Healing of a Bone Fracture
Figure 5.5, step 3
Hematoma External callus
Bony callus of spongy bone
New blood vessels
Internal callus (fibrous tissue and cartilage)
Spongy bone trabecula
Hematoma formation
Fibrocartilage callus formation
Bony callus formation
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Stages in the Healing of a Bone Fracture
Figure 5.5, step 4
Hematoma External callus
Bony callus of spongy bone
Healed fracture
New blood vessels
Internal callus (fibrous tissue and cartilage)
Spongy bone trabecula
Hematoma formation
Fibrocartilage callus formation
Bony callus formation
Bone remodeling
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II. Joints - joints are also called articulations
- 2 functions are to join bones together securely but also give the rigid skeleton mobility
A. Functional Classification of Joints:
1. Synarthroses - immovable joints
2. Amphiarthroses - slightly movable joints
3. Diarthroses - freely movable joints
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B. Structural Classification of Joints:
1. Fibrous joints - bones are united by fibrous/dense connective tissue
- examples – sutures of the skull
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2. Cartilaginous joints- bone ends are connected by cartilage
- examples: pubic symphysis of the pelvis (amphiarthrotic)
- intervertebral joints of the spinal column
- joints between the first ribs and the sternum (synarthrotic)
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3. Synovial joints
- articulating bone ends are separated by a joint cavity containing synovial fluid
- synovial joints account for all joints in the limbs
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C. Types of Synovial Joints Based on Shape 1. Plane joint
- articular surfaces are flat
- only short slipping & gliding movements are allowed
- examples: intercarpal and intertarsal joints
2. Hinge joint
- cylindrical end fits into trough-shaped end of another bone
- examples: elbow joint, knee joint, and joints between the phalanges of the fingers
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3. Pivot joint
- rounded end of one bone fits into sleeve or ring of bone
- examples: proximal radioulnar joint and the first two vertebrae – atlas and axis
4. Condyloid joint
- egg-shaped articular surface of one bone fits into oval concavity of another bone
- examples: metacarpophalangeal joints/knuckles
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5. Saddle joint
- each articular surface has both concave & convex surfaces
- examples: carpometacarpal joints in the thumb
6. Ball-and-Socket joint
- spherical head of one bone fits into a round socket in another
- examples: shoulders and hips
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**HOMEOSTATIC IMBALANCES** 1. Bursitis - inflammation of the bursae or synovial
membranes
2. Sprain- when the ligaments or tendons reinforcing a joint are damaged by excessive stretching or are torn away from the bone – poorly vascular
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**HOMEOSTATIC IMBALANCES** 3. Arthritis - inflammation of the joints/pain, stiffness, and
swelling of the joint
- most widespread progressive disease in the US
4. Osteoarthritis - chronic degenerative condition typically affecting the aged
- over the years, the cartilage softens, frays, and eventually breaks down
- most common in the fingers, cervical & lumber joints of the spine, and the large weight-bearing joints of the lower limbs (knees & hips)
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**HOMEOSTATIC IMBALANCES** 5. Rheumatoid Arthritis - chronic inflammatory disorder
- affected joints are in the fingers, wrists, ankles, and feet in a symmetrical manner
- RA is an autoimmune disorder - a disorder in which the body's immune system attempts to destroy its own tissues