What are Flexor Muscles?
The muscles that decrease the angle between bones on two sides of a joint are called flexor muscles. The bending of the elbow and knee are examples of flexion. A flexor muscle initiates flexion which is the phenomenon of decreasing angle between bones. The muscles of the hand and legs perform this function.
Example: In hand, flexor carpi radialis and flexor carpi ulnaris stretch from the upper arm (humerus) along the insides of the forearm and reaches the metacarpal to flex the wrist; flexor digitorum profundus originates from the ulna (forearm bone) and contracts to bend the fingers at tips; the flexor digitorum superficialis originates from the ulna and the radius, and contracts to act upon the midsection of fingers.
In the foot are flexor digitorum brevis flexor and digitorum longus, that originate from the calcaneus (heel bone) and tibia (shinbone) and flex the smaller four toes; flexor hallucis brevis and the flexor hallucis longus originate from the calves and flex the big toe of the foot.
Refer: Bones of Legs
What are Extensor Muscles?
The muscles that initiate extension in our body are known as extensor muscles. Extension is a straightening movement that increases the angle between two body parts. Straightening of the elbow, knee or bending the wrist and spine backwards are examples of extension.
Example: In the hand, extensor carpi ulnaris, extensor carpi radialis longus and extensor carpi radialis brevis run from the humerus along the backside of the forearm to the metacarpal bones and extend the wrist; the extensor digitorum runs from the humerus to a common tendon that is attached to all the fingers and extends them; the extensor indicis extends the index finger; extensor pollicis longus and extensor pollicis brevis that arise from ulna and radius respectively, extend the thumb.
In the foot, extensor digitorum brevis and extensor digitorum longus originate at the lower leg and extend the toes through tendons; extensor hallucis longus and extensor hallucis brevis extend the toe.
Flexor vs Extensor Muscles
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The muscles that decrease the angle between bones are called flexor muscles. |
The muscles that increase the angles between bones are called extensor muscles. |
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These muscles decrease the angles between two body parts. |
These muscles increase the angle between two body parts. |
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The body parts are pulled closer by flexor muscles. |
The body parts are pushed away from each other in extensor muscles. |
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It causes bending of bones. |
It causes straightening of bones. |
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Bending of the knee and elbow. |
Standing up and straightening of the elbow. |
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Also see:
- Difference between Cardiac Muscle and Skeletal Muscle
- Facts about Muscles
- Muscle Contraction Proteins
