Why does muscles work in pairs

Find out more about page archiving. Prehistoric Life. The mind The body. Nervous system. Brain Sex Sleep. If you can see the Flash movie then please ignore this message. Muscle pairs: Muscles are grouped together in pairs on your skeleton Relaxed or contracted: When one muscle of a pair contracts, the other relaxes.

Human body homepage The body homepage Interactive body Muscles game Facts and features Muscle anatomy diagram - front view Muscle anatomy diagram - back view Muscles and Exercise Facial Muscles Fast and slow twitch muscles Structure and contraction Muscle tone Skeletal, smooth and cardiac muscle Psychology tests Disgust Spot the fake smiles Memory test. Anderson Shelters. Back of the House. Child's Bedroom. Creative Writing- Alternate Story Endings.

Creative Writing-Strap-lines. Dancing Skeleton. Endo, Exo, Hydro Skeletons. Fast Facts- Skeletal System. Four "4" Functions of your Bones. Front of House. History Units. Howard Carter. Human Skeleton. Lesson 1- Why the War Began. Maths Topics. Muscles work in pairs to move a bone.

Do all muscles work in pairs? Skeletal muscles only PULL in one direction. For this reason they always come in pairs. When one muscle in a pair contracts, to bend a joint for example, its counterpart then contracts and pulls in the opposite direction to straighten the joint out again. Why can't muscles push? Well, the muscles are designed to only contract, and not to push. This is why muscles cannot push. The muscles would not be able to pull if the two protein molecules are not present: the actin and myosin.

These two are arranged from the end to end of muscle cells, and so they provide the muscles striated appearance. Which muscles are prime movers? Only three of the nine muscles act as prime movers for arm movements — pectoralis major, latissimus dorsi and the deltoid muscles.

The other six are used as synergists or fixators. What muscle causes a joint to straighten when it contracts? The muscle that contracts to cause a joint to bend is called the flexor. The muscle that contracts to cause the joint to straighten is called the extensor. What muscle is a flexor? Contracting your biceps exhibits flexion, i. So, your biceps is described as a "flexor" muscle. Why are 2 muscles needed to move bones? Generally, two skeletal muscles are joined to one bone, so that when one muscle contracts in one direction for enabling the bone to move in that specific direction; the other muscle becomes relaxed to facilitate the movement of the bone.

How do muscles control the movement of your arm?