Skeletal System
Animal Science I
Unit 5: Anatomy, Physiology and Absorption
of Nutrients
Objectives
• Name, locate and describe the functions
of the parts of the skeletal systems of
animals.
Components of the Skeleton
Bones
Cartilage
Teeth
Joints
Fig 5-1, 5-2
See p. 105 Major Differences Between
Mammal and Avian Skeletal Systems
• Quiz over beef skeleton on January 14
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Cartilage
• Tough connective tissue that is flexible and
elastic
• Forms the early skeletal structure of the
embryo in vertebrate animals
• As development occurs it is replaced by bone
• Also found in
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Joints
Trachea
Nose
Larynx
External ear
In the form of disc in the vertebral column
Bone Composition
• Calcium compounds
• Ossein
• Small amounts of other minerals
Bone Growth & Development
• Start out as cartilage
• Transformation is carried out by
specialized cells that break down the
cartilage and replace it with bone cells
called osteocytes
• Flat bones of the skull develop from
membranes
• By birth most of the cartilage has been
replaced by bone
• Secondary bone development and growth
occur as the animal matures
Bone Structure
• Contain blood, lymph vessels and nerve
fibers
• Grow and repair themselves if damaged
• Some have hollow centers that are
filled with marrow
• Type of marrow found is a function of
age
Bone Marrow
• Red Marrow
– Forms blood cells
– May only be found in animals with short life
spans
• Yellow, White, Gelatinous
– Tend only to form in animals with life spans
greater than 10 years
Bone Marrow
Red Bone Marrow
Functions of the Skeletal System
Form
Protection
Support
Strength
With muscles attached act as the levers
to allow movement
• Store minerals
• Bone marrow produces blood cells
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Types of Skeletal Systems
Rigid
• Able to move because
muscles are attached
• Two types
– Endoskeleton-Vertebrate
animals
– Exoskeleton-insects,
crustaceans
Hydraulic
• Able to move by the
application of force to a
fluid confined in a small
space and surrounded by
muscle tissue
• Worms, Octopus and
Starfish
Kinds of Bones
Cancellous
• Spongy
• Generally found in the
ends of long bones
Compact
• Composed of Haversian
systems and usually found on
the outside of bones and
surrounding marrow
• Composed of cylindrical or
tubular structures of hard,
inorganic material arranged
in concentric layers. In the
center there is the
Haversian canal through
which blood vessels and
nerves pass
• Not found in small mammals
or birds
• Fig 5-3
Bone Shape X
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Long
Short
Flat
Irregular
Table 5-1
Parts of the Skeletal System
• Axial
– Skull
– Vertebral column
– Rib cage
• Pectoral limb
– Front legs
• Pelvic limb
– Hind legs
Joints
• Classifications are based on the
structure of the joint and the
movement it is capable of
Synarthroses (fibrous) Joints
• Joined by fibrous and in some cases
cartilage tissue
• Generally do not permit movement
• Example:
joints of the skull
Amphiarthroses (Cartiligionous)
Joints
• Consists of discs of fibrous cartilage
• Separate and cushion the vertebrae
• Allow limited movement
Diarthroses (Synovial) Joints
• Allow free movement
• Have a fluid filled cavity
• Surrounded by ligaments that hold the joint
together
• Synovial fluid membrane found inside the
ligaments lubricates the joint
• Classifications
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Ball and socket
Gliding
Pivot
Hinge
Summary
• Mammal skeletal system is composed of bone,
cartilage, teeth and joints
• Cartilage forms the early skeletal structure of the
embryo
• Bones are made up calcium compounds, ossein and
small amounts of other minerals
• As bones grow the cartilage that makes up the
early skeletal structure is replaced with bone cells
called osteocytes
• Bones contain blood, lymph vessels and nerve fibers
• Some bones have hollow centers that contain
marrow
Summary
• Marrow may be red, yellow, white or gelatinous
• The skeletal system provides form, protection,
support and strength
• Two types of skeletal structures-rigid and
hydraulic
• Two types of bones-cancellous and compact
• 4 shapes of bones-long, short, flat and irregular
• Skeleton is broken down into 3 parts-axial,
pectoral limb, pelvic limb
• Joints are classified based on their structure
and type of movement
Assignment
• Discussion Questions 1-5 p.128