 Lecture 2
The skeleton
 FDSc FISM year 2
 Janis Leach

 Understand the main functions of bone
 Define the four classifications of bones and features of a long bone.
 Identify the microscopic structures of compact bone.
 Describe the process of bone growth.
 Define the different types of fractures and describe the healing process.
 Define osteoporosis and identify risk factors.
 Research arthritis and bone disease

 Group presentation lasting 15 minutes in Week 20.
The content of the presentation will link factors involved in physiology, disease and drugs. The module title lends itself to opportunities for an even distribution of group work and allows students to experience the coordination of group work and individual research that contributes to the group presentation. The nature of the course makes communication of information to an audience a vital element in the practitioner’s skills. The ability to work as part of a team in a professional context is also implied. ICA 30% Group Presentation.

 A written examination in Week 30. This paper will consist of 6 essays covering key aspects of the module, specifically function of the body systems, common drugs in sport and exercise and relevant common diseases.
END 70% Written exam.


Bone despite its appearance is a dynamic living tissue. Without bone and associated soft tissue such as cartilage, ligaments and tendons we would be immobile lumps of tissue.

 Think about the functions of the skeleton
 Discuss them with a partner
 Write them down to explain to the rest of the group.

Function
 Support

Bones provide a rigid internal framework for support and anchorage of soft tissues
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Protection

Bones protect soft organs of the body e.g. the bones of the skull protect the brain, the vertebrae protect the spinal cord, and the ribs and sternum protect the vital organs of the thorax

Movement

Attached to the bones by tendons, skeletal muscles use the bones as levers to move the body and its parts.
Without this contribution to movement we would be immobile lumps of tissue.

Function
 Storage

Bone serves as a storehouse for minerals (calcium and phosphorous, potassium, sulphur, sodium, magnesium and copper) which can be mobilised to other parts of the body as required. Fat is also stored in bone in the marrow cavity.
 Red blood cell formation

Formation of red blood cells occurs in the bone marrow of certain bones

Classification
 The adult skeleton is comprised of 206 bones, with many shapes and sizes. Classification reflects the shape not the size of bones. The unique shape of each bone has evolved so it fulfils a particular function.
Bones are classified by shape into five groups:

Long - longer than they are wide

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Short - more-or-less cube shaped
Flat - thin, flattened and usually curved


Irregular - bones that do not fit into the above categories
Sesamoid - bones embedded in tendon (floating)

Structure of a typical long bone epiphysis
 With a few general exceptions, all long bones have the same general structure:


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The diaphysis or shaft
The epiphyses (bone ends) with articular cartilage
Medullary cavity or marrow cavity containing fat in adults diaphysis epiphysis articular cartilage

lamellae osteon blood vessel spongy bone
Compact bone
 Structural unit is called an osteon.
Functionally osteons are similar to tiny weight bearing pillars.

An osteon consists of hollow tubes of bone matrix called lamellae.

Central canals run through each osteon.
The canals contain small blood vessels and nerves.

Compact bone osteocyte
Central canal canaliculi lacuna


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Spider shaped osteocytes (mature bone cells) occupy small cavities called lacunae.
Although the bone matrix is hard, small canals called canaliculi allow bone cells to be well nourished.
The canaliculi connect all osteocytes in an osteon together.

Cancellous bone (spongy)


Cancellous bone consists of trabeculae (meshwork) that are aligned along lines of stress.
Although the arrangement of trabeculae appears haphazard, the structure of the bone enables it absorb considerable stress.
spongy bone compact bone

 In early foetal life the skeleton is primarily made of hyaline cartilage.
 By birth or shortly after, most cartilage has ossified except for two regions - the articular cartilage and the epiphyseal
(growth) plates.

The growth plate between the diaphysis (shaft) and epiphysis (ends of the bones) are sites of growth in the length of long bones - this allows growth to proceed without interfering with the shape of joints.

At the end of the growth period, the cartilaginous plates ossify (end of teenage years). Some growth continues into the early twenties - widening of the shoulder and pelvic girdles.

 There are many different types of fractures. Below, identify the three types of fractures in the diagram
A. What type of fracture is this?
B. What type of fracture is this?
C. What type of fracture is this?

 The figures below illustrates the four major events of the repair of bones:
Blood vessels are ruptured when the bone breaks. As a result, a mass of forms. Bones cells deprived of nutrition die.
Within 2-3 days new capillaries grow into the hematoma and phagocytes clean up the debris. Over time connective tissue cells form a mass of repair tissue which splints the broken ends of the bone

Osteoblasts invade the area and the fibrocartilage is transformed into a
__________ within 3-4 weeks.
Healed fracture
This process continues until the bone is united completely a few months later. The bone is gradually remodelled to resemble the original shape and alignment.

 Osteoporosis is a deficiency of bone resulting from an imbalance in the rate of remodelling, where osteoclast activity is higher than osteoblast activity.

Consequently, compact bone and spongy bone becomes thinner and more porous - the density of the bone reduces.

The bone becomes fragile and can increase the risk of fractures occurring, especially in weight bearing structures such as the fractured heads and the vertebrae.
Groups
Woman of all ages?
at high
Osteoporosis risk
Exercise/biomechanical stress
Risk factors Nutrition
Steroid use

 Osteoarthritis

 Most common type in UK
 Estimated 8.5 million people affected
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
Any joint can be affected
Causes cartilage damage – therefore affects smooth joint movement
 Research risk factors

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Rheumatoid Arthritis (RA) is a chronic, progressive and disabling auto-immune disease which affects approximately 8% of the UK adult population (NRAS, 2008)
Systemic disease – can affect the whole body
 Unknown causes
 Genetic?
 Environmental

 TASK
 In groups of 3, you will research a given topic on bone disorders. Include the following in your research


Genetic aspects
Steroid use and bone disease

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Environment
Repetitive strain.