The musculoskeletal system

THE THE MUSCULOSKELETALMUSCULOSKELETAL SYSTEMSYSTEM

THE THE MUSCULOSKELETALMUSCULOSKELETAL SYSTEMSYSTEM

Bones, joints and musclesBones, joints and musclesTendons, ligaments and Tendons, ligaments and

cartilagecartilage

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-200125.htm

Structure of bones

Compact bone

• Outside part of the bone• Extremely strong and hard• Periosteum

Spongy bone

• Mesh-like network (trabeculae)• Red marrow (blood cells)• Yellow marrow (fat)

http://youtu.be/yFJ4iswRiu4

Micrographs

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

• Meeting of two bones

• Make the skeleton flexible

• Types:

- Immovable or fibrous

- Partially movable, or cartilaginous - Freely movable, or synovial

Joints

Joints

• Types of synovial joints:

- Hinge: knees and elbows

- Gliding: wrists and ankles

- Ball and socket: hips and

shoulders

- Pivot: Head

•Cartilage: the bones are covered with cartilage (a connective tissue), 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 it into a joint capsule. The synovial membrane secretes synovial fluid (a clear, sticky fluid) around the joint to lubricate it.

•Ligaments: strong ligaments (tough, elastic bands of connective tissue) surround the joint to give support and limit the joint's movement.

Joints consist of the following:

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.

Synovial joints

The Muscles

• Pull on the joints, allowing us to move.

• Help the body perform other functions.

• More than 650 muscles ( half of a person's 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