The Skeletal System

The Skeletal System

Role of the skeletal system• Protects• Supports• Movement• Produces blood cells• Stores minerals

The Skeletal System

• The human skeletal system normally– has 206 bones– has over 200 articulations

The Muscular System

• Muscles – maintain posture, generate heat, provide driving force for movement

• Muscles are the actuators of the musculoskeletal system.

The Muscular System

• The human muscular system normally– has approximately 640 skeletal muscles– accounts for 36 to 45% of total body weight.

Muscles and Tendons

• Tendons connect muscles to bone– Tendons are strong elastic

bands, like very stiff rubber bands.

Finger Flexor Pulleys

Biomechanics

Levers

Levers

Levers

Levers

• What type of levers are these?

Draw diagrams showing the pivot (fulcrum), the load and the effort

• Seesaw, nut cracker, scissors, stapler, wrench pliers, crowbar, tweezers.

Overview of the skeletal system

Synovial Joints

Synovial Joints

Synovial joints contain synovial fluid which is secreted by the synovial membrane. This fluid helps lubricate and protect the bones.

Cartilage

• Cartilage is a tough and fibrous substance that is between bone ends in some joints.

• The cartilage allows the bones to move freely over each other, reducing friction and protecting the bone ends.

• Cartilage is thicker in the leg joints where the load is greater.

Types of Synovial Joints

Give a brief description of the different types of synovial joints and identify their location

• ball and socket hinge• saddle• sliding• pivot

https://sites.google.com/site/annesleymedical/

How is the robotic hand different from a human hand?

Ligaments

Ligaments

• connect bone to bone.

• ligaments are composed of strands of collagen fibres.

• are slightly stretchy, but are arranged in crossing patterns which prevents the joint itself to become loose.

Bone

• A bone is generally made up of two types of tissue: spongy bone and compact bone.

Compact bone

• provides protection and support, and forms a hard, thin layer over the inner spongy bone.

• much denser than spongy bone

Spongy Bone

• very porous and contains the bone marrow.

• soft and spongy• it distributes and dissipates the energy

transferred to it by compact bone.

Homework

Check the website, cut and paste

Problems with bones/joints

Fractures and breaks

Osteoarthritis

A degradation of joints including cartilage and bone

Osteoporosis

A decrease in bone mineral density – increases the risk of fractures.

Prevent Osteoporosis

• Get regular exercise• Eat calcium rich food• Get enough vitamin D• Don’t eat too much meat

Pins, screws and plates

Pins, screws and plates

Pins, screws and plates

Materials

• very strong - they must not break or even bend  permanently under heavy load

• not too stiff – must have some give

• biocompatible

Materials

• Cobalt-Chrome alloys • Titanium alloys  • Stainless Steel  alloys

Materials

Characteristics S-Steel Cobalt-Chrome Titanium Stiffness High Medium LowStrength Medium Medium HighCorrosion Resistance

Low Medium High

Biocompatibility Low Medium High

Joint replacement

Total knee prostheses have polyethylene joint surfaces.

Polyethylene

• similar density to living tissue• it is relatively elastic• it has a low coefficient of friction• will not deform under stress.

Artificial Hip components

1. titanium femoral component,

2. polyethylene cup

3. ceramic head

3. acrylic bone cement, and/or screws.

Treatment of finger arthritis.

Joint replacement surgery is called joint arthroplasty.

Silicone joints would be suitable substitutes for small joints in the fingers and toes because they can be made as strong and as flexible as natural joints. They are biocompatible, as they allow the flow of oxygen and do not react with living tissue.

When good hips go bad...

within the first two years following implantation, 14 out of 165 patients of his who received the Durom hip replacement system had to undergo revision surgery to correct a failed device.