Skeletal System
- 206 bones
- long/shot/flat bones
- Long/shot are used as levers/to transfer forces
- Flat bones are used to protect vital organs
- Anatomical position - person standing erect, facing front on and has the palms facing forwards.
- • Superior — towards the head; for example, the chest is superior to the hips
• Inferior — towards the feet; for example, the foot is inferior to the leg
• Anterior — towards the front; for example, the breast is on the anterior chest wall
• Posterior — towards the back; for example, the backbone is posterior to the heart
• Medial — towards the midline of the body; for example, the big toe is on the medial side of the foot
• Lateral — towards the side of the body; for example, the little toe is on the lateral side of the foot
• Proximal — towards the body's mass; for example, the shoulder is proximal to the elbow
• Distal — away from the body's mass; for example, the elbow is distal to the shoulder
- A joint is a junction of two or more bones and is commonly referred to as an articulation.
- There are three types of joint — immovable/fibrous, slightly movable/cartilaginous, and freely movable/synovial.
Ligaments
- Inelastic fibrous bands connecting bones
- Assist maintaining stability in joint and control degree/direction movement occurs.
- Can lengthen when stretched excessively causing injury and instability
Tendons
- Tough, inelastic cords of tissue attaching muscle to bone.
- Joints are further strengthened by muscle tendons that extend across the joint and assist ligaments to hold the joint closed.
Synovial Fluid
- Acts as a lubricant
- Keeps moving surfaces apart.
- No joints fit together perfectly so synovial fluid forms a cushion in between.
- Provides nutrition for the cartilage/carries away waste products.
- Aamount depends on the amount/type of physical activity of the joint.
- When under pressure fluid is pumped into the joint space.
- Viscosity changes (during cold weather it becomes more sticky possibly causing joint stiffness in cold weather.
Cartilage
- Surfaces of the bonesare covered with it
- allow the bones to move freely over each other
- has a limited blood supply but gets nourishment via the synovial fluid
- Thicker in leg joints where there is more weight bearing
Joint movements
Muscular System
Muscles are unable to push to enable movement. Instead they shorten, causing joint movement, then relax as opposing muscles pull the joint back into position
To locate muscles, it is important to establish the origin and insertion of the muscle. The origin of the muscle is usually attached directly or indirectly to the bone via a tendon.
pOINTS OF ORIGIN AND INSERTION
DELTOID
Origin: scapula, clavicle
Insertion: humerus
Action: abduction of arm
Origin: scapula, clavicle
Insertion: humerus
Action: abduction of arm