THE MUSCULOSKELETAL SYSTEM Bones, joints and muscles Tendons, ligaments and cartilage
The human skeleton • Contains 206 bones •Initially: flexible cartilage •Ossification
Process of ossification• Approximately 20 years• Growth plates• Bone building: - Osteoblasts - Osteocytes - Osteoclasts• Video http://health.howstuffworks.com/adam-2001 25.htm
Structure of bonesCompact bone• Outside part of the bone• Extremely strong and hard• PeriosteumSpongy bone• Mesh-like network (trabeculae)• Red marrow (blood cells)• Yellow marrow (fat)http://youtu.be/yFJ4iswRiu4
Anatomical classification of bones• Bones are characterized anatomically as: – long bones (e.g. humerus, femur) – flat bones (membrane bones) – irregular bones (such as the vertebrae)• All these bone types, regardless of their anatomical form, are composed of both spongy and compact bone.
Functions of the skeleton • Bone provides the internal support of the body and provides sites of attachment of tendons and muscles, essential for locomotion. • Bone provides protection for the vital organs of the body: the skull protects the brain; the ribs protect the heart and lungs. • The hematopoietic bone marrow is protected by the surrounding bony tissue. • The main store of calcium and phosphate is in bone. Bone has several metabolic functions especially in calcium homeostasis. • http://youtu.be/8d-RBe8JBVs
Joints• Meeting of two bones• Make the skeleton flexible• Types: - Immovable or fibrous - Partially movable, or cartilaginous - Freely movable, or synovial
Joints• Types of synovial joints: - Hinge: knees and elbows - Gliding: wrists and ankles - Ball and socket: hips and shoulders - Pivot: Head
Joints consist of the following:•Cartilage: the bones are covered with cartilage (a connectivetissue), which is made up of cells and fibers and is wear-resistant. Cartilage helps reduce the friction of movement.•Synovial membrane: a tissue that lines the joint and seals itinto a joint capsule. The synovial membrane secretes synovialfluid (a clear, sticky fluid) around the joint to lubricate it.•Ligaments: strong ligaments (tough, elastic bands ofconnective tissue) surround the joint to give support and limitthe joints movement.
Joints consist of the following (II)• Tendons: tendons (another type of tough connective tissue) on each side of a joint attach to muscles that control movement of the joint.• Bursas: fluid-filled sacs, between bones, ligaments, or other adjacent structures help cushion the friction in a joint.• Synovial fluid: a clear, sticky fluid secreted by the synovial membrane.• Meniscus: a curved part of cartilage in the knees and other joints.
The Muscles• Pull on the joints, allowing us to move.• Help the body perform other functions.• More than 650 muscles ( half of a persons body weight)• Tendons: tough, cord-like tissues• 3 different kinds of muscle
How do muscles move?• Contracting and relaxing.• Work in pairs of flexors and extensors.• The flexor contracts to bend a limb at a joint.• The extensor contracts to extend or straighten the limb at the same joint.
How do skeletal muscles work? http://youtu.be/XoP1diaXVCI