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MUSCULAR SYSTEM. Our muscular system is formed by muscles, and tendons (held to muscles to move our body). Muscles are organs that move the skeleton. They are formed by muscle fibers, that can contract and relax under the orders from nerves cells.

Muscles move our body and different organs. They use a lot of energy supplied by blood (oxygen, glucose and other nutrients, and blood also remove waste products from them). 1.- TYPES OF MUSCLES: A.- Smooth muscles: we can’t control them, (their movements are involuntary). They are in our digestive system, blood vessels‌ B.- Cardiac muscles: they form our heart. Their movement are very strong. C.- Skeletal Muscles: they form our muscular system, are joint to our bones and their movements are voluntary (we can control them). Their fibers are very long, and our brain can give orders to them. 2.- HOW OUR MUSCLES WORK: If a muscle contracts, move a tendon held to a bone and produce a movement. There are always two opposite muscles (or antagonist muscles) for example one to bend and another to stretch the arm.

Joints usually have a pair of muscles to do the movement. These are called opposing muscle groups. If one muscle pulls (contract) to move the joint in one direction, the second muscle will pull (contract) to move the joint back in the opposite direction. Most of muscles are thicker in the centre than at the ends. 3.- THE HUMAN MUSCULAR SYSTEM: A.- Face muscles: There are lots of muscles in our face under our skin, that control facial expression and other movements. We can express different feelings, smile, laugh, open and close the eyes‌

B.- Muscles of Trunk: There are several muscles in the trunk. .- Pectoralis and deltoid to move the arm.

.- Trapezius to move the shoulder. .- Diaphragm to breath. .- Abdominus to bend the body, and protect our intestines.

C.- Muscles of arm: .- Biceps and triceps to move the arm.

D.- Muscles of leg: .- Gluteus, Biceps femoris and Quadriceps to move the leg. .- Calf that stretch the foot.



Trapezius Triceps



Quadriceps Gluteus Biceps Femoris




Muscle: músculo

tendon: tendón

to hold (held): sujetar

Fiber: fibra

to contract: contraer

to relax: relajar,

To stretch: estirar

to supply: suministrrar

glucose: glucose (tipo de azúcar)

Smooth muscle: músculo liso

cardiac: cardiaco (del corazón) skeleton: esqueleto

To bend: doblar

to stretch: estirar

to pull: tirar (de algo)

joint: articulación

thicker: más grueso

end: final, punta

to express different feelings: expresar distintos sentimientos

smile: sonrisa

laugh: risa

several: varios

trunk: tronco