Transcript Chapter 5 The Skeletal System

Chapter 5
The Skeletal System
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ACOS 6
• You will be able to:
– identify bones that compose the skeletal system
– identify the functions of the skeletal system
– identify subdivisions of the skeleton as axial and
appendicular skeletons
– classify types of joints according to their movement
– identify the four bone types
– identify various types of skeletal system disorders
• Examples: fractures, arthritis
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What would happen if humans didn't have bones?
You'd be floppy like a beanbag. Could you stand up?
Forget it. Could you walk? No way. Without bones you'd
be just a puddle of skin and guts on the floor.
Halloween skeletons and the skull and
crossbones symbol for poison and pirates
may make bones seem like lifeless
objects, but in actuality, bones are not
only very much ALIVE but are also
multifunctional.
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Bone Function
•
Besides contributing to body shape and form, our bones perform
several important body functions.
1.
SUPPORT: forms the internal framework that supports and
anchors all soft organs; the bones of the legs acts as pillars to
support the body trunk when we stand
2.
PROTECTION: protect soft body organs
3.
MOVEMENT: skeletal muscles, attached by tendons, use the
bones as levers to move the body and its parts
4.
STORAGE: serves as a storehouse for minerals (Ca and P);
fat is stored in the internal cavities of the bone
5.
HEMATOPOIESIS: blood cell formation
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Skeletal System—an Overview
•
The skeleton is subdivided into two divisions:
1.
axial skeleton: bones that form the longitudinal axis of the
body
2.
appendicular skeleton: bones of the limbs and girdle
•
The skeletal system also includes joints, cartilage, and
ligaments
•
The adult skeleton is composed of 206 bones.
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Classification of Bones
•
There are two basic types of osseous, or
bone, tissue:
1. compact bone—dense and looks smooth
and homogeneous
2. spongy bone—composed of small
needlelike pieces of bone and lots of open
space
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Classification of Bone—cont.
• Bones come in many sizes and shapes. For
example, the tiny pisiform bone of the wrist is the
size and shape of a pea, whereas the femur, or
thigh bone, is nearly 2 feet long and has a large,
ball-shaped head. The unique shape of each
bone fulfills a particular need.
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Classification of Bones—cont.
•
Bones are classified according to shape into
four groups:
1. long bones
– typically longer than they are wide
– generally have a shaft with heads at both ends
– mostly compact bone
– includes all bones of the limbs, except the wrist
and ankle bones
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Structure of a Long Bone
• diaphysis—shaft; makes up
most of the bone’s length;
composed of mostly compact
bone
• periosteum—fibrous
connective tissue membrane;
protective covering; attached
by Sharpey’s fibers
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Structure of a Long Bone—cont.
• epiphyses—ends of the
long bone; consists of a
thin layer of compact
bone enclosing an area
filled with spongy bone
• articular cartilage—
covers the epiphyses
• medullary cavity—hollow
chamber of the shaft that
is a storage area for fat
(yellow marrow)
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Classification of Bones—cont.
• Bones are classified according to shape into four
groups:
2. short bones
– generally cube-shaped
– mostly spongy bone
– includes bones of the wrist and ankle
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Classification of Bones—cont.
• Bones are classified according to shape into four
groups:
3. flat bones
– thin, flattened, and usually curved
– have two thin layers of compact bone sandwiching
a layer of spongy bone between them
– includes bones of the skull, ribs, and sternum
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Classification of Bones—cont.
• Bones are classified according to shape into four
groups:
4. irregular bones
– bones that do not fit one of preceding categories
– includes vertebrae and hip bones
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Skeletal Organization
• What bones are
found in the axial
skeleton?
• What bones are
found in the
appendicular
skeleton?
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Axial Skeleton
• Consists of the bony and cartilaginous parts that
support and protect the organs of the head,
neck, and trunk.
– SKULL: composed of the cranium and the facial
bones
– HYOID BONE: located in the neck between the lower
jaw and the larynx
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Axial Skeleton—cont.
– VERTEBRAL COLUMN: backbone that consists of
many vertebrae separated by intervertebral discs
• SACRUM: found near the distal end of the
vertebral column; fusion of several vertebrae
• COCCYX: small, rudimentary tailbone composed
of several fused vertebrae; attached at the end of
the sacrum
– THORACIC CAGE: protects the organs of the
thoracic cavity and the upper abdominal cavity
• RIBS: 12 pairs
• STERNUM: where ribs are attached anteriorly
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Appendicular Skeleton
• Consists of the bones of the upper and lower
limbs and the bones that anchor the limbs to the
axial skeleton
– PECTORAL GIRDLE: connects bones of the upper
limbs to the axial skeleton and aids in upper limb
movement
• SCAPULA: shoulder blade
• CLAVICLE: collarbone
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Appendicular Skeleton—cont.
– UPPER LIMBS
• HUMERUS: arm bone
• RADIUS: forearm bone
• ULNA: forearm bone that runs into small finger
• The humerus, ulna and radius come together at he
elbow joint. At the distal end of the radius and ulna
is the hand.
• CARPALS: 8 wrist bones
• METACARPALS: 5 bones of the wrist
• PHALANGES: 14 bones of the fingers
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Appendicular Skeleton—cont.
– PELVIC GIRDLE
• COXAE: hipbones that form the pelvic girdle and
are attached to each other anteriorly and to the
sacrum posteriorly; connect the bones of the lower
limbs to the axial skeleton
• PELVIS: includes the coxae, sacrum and coccyx
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Appendicular Skeleton—cont.
• LOWER LIMBS
– FEMUR: thighbone
– TIBIA: thick lower legbone
– FIBULA: slender lower legbone
– PATELLA: kneebone—where the femur and tibia
come together at the knee joint
– TARSALS: 7 ankle bones
– METATARSAL: 5 bones of the instep of the foot
– PHALANGES: 14 bones of the toes
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Joints
• also called articulations
• functional junctions between bones
• hold bones together securely but also give the
skeleton mobility
• With the exception of the hyoid bone, every
bone in the body forms a joint with at least one
other bone.
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Joints—classified structurally
• Fibrous Joints
– bones are united by fibrous tissue
– example: sutures of the skull
– syndesmoses: connecting fibers longer than
those of sutures (giving the joint more “give”);
found connecting the distal ends of the tibia
and fibula
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Joints—classified structurally—cont.
• Cartilaginous Joints
– bones are united by hyaline cartilage
– example: separate the vertebrae of the
vertebral column
– allow only limited movement
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Joints—classified structurally—cont.
• Synovial Joints
– most common joint of the skeletal system
– allow free movement
– all have 4 distinguishing features
• Articular cartilage
• Fibrous articular capsule
• Joint cavity
• Reinforcing ligaments
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Features of Synovial Joints
1.
2.
3.
4.
Articular cartilage: covers
the ends of the bones
forming the joint
Fibrous articular capsule:
encloses joint surfaces;
lined with a smooth
synovial membrane
Joint cavity: cavity
enclosed by the articular
capsule; contains
lubricating synovial fluid
Reinforcing ligaments:
reinforce the fibrous
capsule
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Disorders of the Joints
• dislocation: when a bone is forced out of its
normal position in the joint cavity
– reduction: returning a dislocated bone to its
proper location
• bursitis: “water on the knee”; due to
inflammation of bursae or synovial membrane
• sprain: ligaments or tendons reinforcing a joint
are damaged by excessive stretching; or are
torn away from the bone
– heal slowly and are very painful
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Disorders of the Joint—cont.
• Arthritis describes over 100 different
inflammatory or degenerative diseases
that damage the joints.
– most widespread, crippling disease in the
United States
– affects 1 out of 7 Americans
• What are the initial symptoms of all forms
of arthritis?
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•
Describe the three types of arthritis
including the following information.
1. Definition
2. Who is affected?
3. What joints are affected?
4. Can you control symptoms? If so, how?
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