2.1 (b) - Role Of Muscles, Ligaments & Tendons In

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• To label the bones, the skeletal muscle and tendons in a diagram of the arm; • To explain how movement is brought about in a limb; • To state the function of cartilage & synovial fluid at joints.

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• Movement is caused by the contraction of skeletal muscles which interact with the bones. • Muscle cells contract in response to stimulation which carried by nerve impulses. • Muscles are attached to bones by tendons near a joint.

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• Tendons consist of very strong inelastic, non-stretchable collagen fibres & appear as glistening silver-grey strands between the muscles & bones • Function : to ensure that the force produced by the contraction of muscles is transmitted to the part of the body to be move. 5

• A joint is formed where 2 or more bones come together  held together at a joint by ligaments. • Ligaments are tough & strong connective tissues, elastic & allow the movement of bones at a joint. Also important in preventing dislocation. 6

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TYPE OF JOINT

CHARACTERISTIC

EXAMPLE

•Skull Immovable/ Bones held fixed together by •Pelvic fibrous (suture) girdle connective tissue. No movement between bones.

Partially movable

•Vertebral Cartilage bridges the column. joints. Movement is restricted.

FUNCTION •Protects delicate tissues of brain & sense organs •Protect urogenital organs; support body •Some degree of flexibility •Cartilage is a shock absorber, cushions joint & reduces friction 8

TYPE OF JOINT

CHARACTERISTIC

•Ends of Movable/ articulating sinovial (iii)Hinge bones are covered with cartilage. Joint enclosed by joint capsule. It is lined with a thin synovial membrane which secretes synovial fluid. (ii) Ballandsocket

EXAMPLE

FUNCTION

•Knee, elbow, finger joints

•Movement in one plane

•Shoulder, hip joint

•Movement in all planes and some rotational movement 9

COMPARISON BETWEEN TENDON & LIGAMENT TENDON

LIGAMENT

similarities made up of collagen fibres hold two types of tissues together differences Bone & muscle

Bone & bone

No elastin tissues

Elastin tissues present Elastic

Inelastic

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MUSCL ES

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• Action on muscles in bringing about movement • Some muscles work together to bring about movement while other muscles work in opposition to one another 12

Antagonistic Muscles • Muscles which work in opposition. Eg : biceps and triceps • Muscles can contract and relax • Muscles can pull on the bones but cannot push • Muscles which straighten limbs are called extensors • Muscles which bend limbs are called flexors • Extensor work antagonistically with flexor.

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ANTAGONISTIC MUSCLES

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• All muscles have 2 primary proteins – Actin – MyosiN

• Actin and myosin are found in sarcomeres, the functional units of muscle contradiction • Sacromeres consist of thick filaments (actin) which interact to bring about muscle contraction.

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• The source of energy for contradiction of muscles is ATP, which is produced in adjacent mitochondria in the muscles • Movement of the body involves the coordination of opposing muscles which are attached to the bones across the joints 16

• At the joint, the bones are allowed to move, in relation to each other, y the elastic ligaments. • The Synovial membrane secretes synovial fluid which serves as a lubricant to minimize the friction between two bones 17

• The articulating surfaces of the bones are covered by flexible cartilage. • Cartilage protects the joint and allows smooth movements. • It also absorb shock when pressure is placed on the joint, for example when walking. • W/out synovial fluid and cartilage, the bones will rub together. • It can lead pain and swelling of joints 18

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