What Makes Skeletal Flexors and Extensors Skeletal Muscles? Flexors and extensors are crucial to this. They work together to bend and straighten the body's joints to produce motion and stimulate other muscle groups, resulting in muscular activity—a fancy way of describing working out. The word "flexor" is used for muscles that move or stretch something toward your chest (as opposed to extensors, which lift things away from your chest). The muscles that control movement of the shoulder girdle are the main flexors of the arm; the main extensors are the ones that pull things back toward the trunk. Other important flexors and extensors include the biceps and triceps at the elbow, and the wrist and hand muscles when moving the finger joints.
How Do Flexors and Extensors Work? Flexors and extensors work by pulling on tendons, which are thick bundles of collagen and elastic fibers that connect muscles to bones. When you contract a flexor or extensor muscle, it pulls its corresponding tendon, which in turn pulls on the bone that it is attached to. This causes the joint above the muscle to move, which can be useful for bending objects with your arms or lifting things with your legs.
Flexors and extensors are very important muscles to have strong, healthy versions of. If you don't use them often enough, they will become weak and possibly damaged.
Table of Contents
- What is the function of a flexor muscle and an extensor muscle?
- What is the action of a flexor muscle?
- What are muscle flexors?
- How does skeletal muscle work?
- What is an example of a flexor?
- What do extensor muscles do to a joint?
- How do skeletal muscles function in the movement of a limb?
What is the action of a flexor muscle?
A flexor muscle is a type of skeletal muscle that bends a joint, reducing the angle between limb components such as the wrist. This is referred to as flexion. Flexor muscles act mainly to extend or bend back the arm, hand, or finger; for example, to open a closed fist or squeeze a fruit in order to eat it.
Flexor muscles are often named for their role in the movement they produce. For example, the flexor carpi radialis (FCR) muscle acts to flex or bend back the wrist and palm of your hand. It does this by attaching to the radius of the forearm bone and the first row of wrist bones (the carpals).
The FCR is one of four flexor muscles in the forearm, and it plays an important role in using the hand for grasping and lifting objects. Damage to the FCR can lead to limited ability to use the hand due to pain or weakness. However, with proper treatment this can be improved upon through physical therapy.
Other flexor muscles include the palmar interossei (PI) of the hand and the dorsal interosseous (DO) of the hand. The PI's role is to flex the hand while the DO's role is to extend the hand.
What are muscle flexors?
Flexor muscles are any muscles that reduce the angle between bones on opposite sides of a joint, such as when bending the elbow or knee. This function is called after many muscles in the hands and feet. The term "flexor" is derived from the Latin word meaning "to bend". Flexors are so named because they allow the bone to bend without causing pain by covering the articular surface of the joint with smooth muscle tissue.
Flexor muscles originate mainly from tendons but also sometimes from ligaments and capsules. They insert into bones, tendons, or other flexors.
The two main groups of flexors are the intrinsic (or primary) muscles-those belonging to the skeletal system-and the extrinsic (or secondary) muscles-those belonging to the muscular system. The intrinsic flexors include:
Biceps brachii - the main flexor of the upper arm
Brachialis - another muscle of the upper arm involved in pronation (turning over) of the forearm
Capsule of the shoulder - this thick band of tough connective tissue covers and protects the shoulder joint
Deltoid - the main flexor of the shoulder blade
How does skeletal muscle work?
Skeletal muscles and bones work together to provide your body with power and strength. A skeletal muscle is usually linked to one end of a bone. It spreads across a joint (the point at which two bones come together) and then joins to another bone. The combination of bone and muscle forms a strong structure that can produce powerful forces. There are several different types of skeletal muscles, each responsible for moving a particular part of the body. The muscles control how these parts are positioned relative to other parts of the body during movement. They also help prevent the body from being pulled too far when it's standing up or sitting down.
The skeleton is made up of many different kinds of bones that protect the body's inside and support its various parts. The skin covers both the internal and external portions of the body. Under the skin you will find some fat cells and connective tissue including muscles and nerves. The main types of bones include: skull bones, vertebral bones, ribs, clavicle/collarbone, long bones, sacrum/tailbone, hipbones, leg bones, and flat bones such as pelvis and skull. Each bone has a hollow center called a marrow cavity where blood cells are produced. The cortex is the tough outer layer of a bone, which provides most of the weight-bearing support for the body. Motor neurons spread out from the spinal cord to link with the muscles they control.
What is an example of a flexor?
A flexor muscle is one that flexes a joint. When one extends their hand closer to their shoulder, their elbow joint flexes. Flexion is often initiated by flexor muscle contraction. The term "flex" comes from the Latin for "to bend," and "torque" comes from the Greek for "turning." Thus, a flexor muscle bends its target tissue (in this case, the elbow) while simultaneously twisting it.
The flexors are divided into two groups: intrinsic and extrinsic. Intrinsic flexors include those muscles that run along the inside of the arm directly beneath the skin. They include the deep head of the triceps, the main body of the triceps, and the anconeus muscle. The deep head of the triceps is also known as the lateral triceps muscle because it lies lateral (outside) to the main trunk of the triceps. The anconeus is a small flat muscle that lies at the bottom of the forearm, opposite the extensor carpi radialis longus. It can be seen by bending the wrist upward toward the eye. Extrinsic flexors include those muscles that cross the arm to reach the surface of the body. They include the superficial head of the triceps and the brachialis muscle.
What do extensor muscles do to a joint?
Extensor muscles are those that increase the angle between limb members, such as straightening the elbow or knee or bending the wrist or spine backward. With the noteworthy exception of the knee joint, the movement is normally rearward. Extensor muscle activity is necessary to maintain the position of a rigid-bone limb member in extension (straight). Without this activity, the bone would flex (bend forward), causing pain and possibly injury.
The four extensor muscles responsible for moving the forearm away from the body are the biceps, the brachialis, the supinator, and the pronator. The two main extensors of the leg are the quadriceps femoris group, which includes the rectus femoris, the vastus lateralis, and the vastus medialis, and the hamstring group, which includes the semimembranosus, the semitendinosus, and the biceps femoris. The three major extensors of the spine are the erector spinae group, which includes the spinalis and the multifidus muscles; the intercostal muscles group, which includes the internal and external intercostals; and the suboccipital muscles group, which includes the obliquus internus and externus muscles.
How do skeletal muscles function in the movement of a limb?
The activities of muscles on bones propel vertebrates forward. Tendons connect multiple skeletal muscles across joints, allowing muscle contraction to move the bones. Muscles often move in pairs: as one flexes (or contracts), the other relaxes, a process called as antagonism. Antagonistic muscles act against each other to prevent unwanted movements.
In animals that breathe air instead of water, skeletal muscles are used to expand and constrict the lungs. The diaphragm is a flat muscle that separates the chest from the abdomen and plays an important role in breathing. The major muscles of the chest wall include the pectoralis major, the latissimus dorsi, and the intercostal muscles between the ribs. These muscles help us lift our arms above our head or pull ourselves up using ropes or wires. They also help us shrug our shoulders for good posture. The abdominal muscles include the rectus abdominis, the internal and external obliques, and the transverse abdominus. These muscles are responsible for lifting our legs off the ground when we walk or run, and also play a part in maintaining our posture.
When muscles contract, they shorten and produce force. This shortening causes the bone which the muscle attaches to, to lengthen. For example, when you clench your fist, your hand and forearm become shorter while your arm remains completely still.
FAQs
What is the function of a flexor muscle? ›
flexor muscle, any of the muscles that decrease the angle between bones on two sides of a joint, as in bending the elbow or knee. Several of the muscles of the hands and feet are named for this function.
What is the function of extensor muscle? ›extensor muscle, any of the muscles that increase the angle between members of a limb, as by straightening the elbow or knee or bending the wrist or spine backward. The movement is usually directed backward, with the notable exception of the knee joint.
What are the flexor and extensor muscles of hand? ›Extensors: carpi radialis longus and brevis, digitorum, digiti minimi, carpi ulnaris, pollicis longus and brevis, and indicis. Other: abductor pollicis longus. Flexors: carpi radialis, pollicis longus, digitorum profundus (half), superficialis, and pollicis brevis (superficial head). Other: palmaris longus.
What is the difference between flexor and extensor tendons? ›There are two types of tendons present in the hand- extensor tendons and flexor tendons. Extensor tendons present on top of the hand help with straightening the fingers. Whereas, flexor tendons that lie on the palm side of the hand help in bending the fingers.
What is flexor and extensor examples? ›So, your biceps is described as a "flexor" muscle. In the illustration below, the image on the right shows the biceps flexing. The opposing muscle of a flexor is called the "extensor" muscle. Your triceps is an extensor.
What is an extensor muscle example? ›Examples of extensor muscles include the latissimus dorsi, teres major, and triceps brachii of the upper limb and the biceps femoris, gluteus maximus, and quadriceps of the lower limb.
Do extensors contract or relax? ›Muscles and Joints
The extensor muscle relaxes and stretches as the flexor muscle contracts to bend the joint. The flexor relaxes and the extensor contracts to straighten (or extend) the limb at the same joint.
The knee extensor muscle strength was significantly greater than for the knee flexor muscles, both on the dominant and non-dominant side (p<0.05). There was no difference between the dominant and non-dominant side in a given muscle group (Table 3).
Where are the extensor muscles? ›Anatomy. The extrinsic extensor muscles located in the forearm and inserting into the phalanges include the extensor pollicis longus (EPL), extensor pollicis brevis (EPB), extensor indicis proprius (EIP), and extensor digiti minimi (EDM).
What is diff between flexion and extension? ›The difference between flexion and extension comes down to joint angle. Flexion makes it smaller, bringing two body parts closer together (e.g., biceps curl), while extension makes it larger, moving two body parts farther away from each other (e.g., triceps extension).
What is flexion vs extension? ›
Flexion of the shoulder or hip is movement of the arm or leg forward. Extension is the opposite of flexion, a straightening movement that increases the angle between body parts. For example, when standing up, the knees are extended.
What is flexor and extensor muscles of the wrist? ›Flexor – this means the muscle 'flexes' the wrist or thumb. Extensor – means it extends the wrist or thumb. Pollicis – means thumb. So if a muscle or injury has this word then the thumb is likely to be involved.
What is the main function of the common extensor tendon? ›Function. The common extensor tendon is the major attachment point for extensor muscles of the forearm. This enables finger extension and aids in forearm supination.
What are examples of flexor muscles? ›Examples of flexor muscles include the brachialis, biceps brachii, pectoralis major (upper limb flexors) and the psoas major and iliacus muscle, also collectively referred to as the iliopsoas (lower limb flexors).
Is elbow a flexor or extensor? ›The biceps brachii, brachialis, and brachioradialis are the primary elbow flexors. The tricpes brachii is the primary elbow extensor. While the anconeus is thought to also contribute to elbow extension, it is also likely to provide dynamic constraint to varus and posterolateral instability of the elbow [4].
Is the knee a flexor or extensor? ›The knee extensors play an essential role in human movement. The one agonist muscle that extends the knee is the massive quadriceps. Knee extension ROM is from full flexion to 5-10° hyperextension. The iliotibial tract (ITB) and tensor fascia latae (TFL) also play a role in knee extension.
Where are the flexors and extensors found in the arm? ›These muscles are divided into two compartments: the anterior and posterior compartments of the forearm. The muscles associated with flexion are specifically located in the anterior compartment, while the muscles of extension are found in the posterior compartment.
What are the three extensor muscles? ›The extrinsic extensor muscles located in the forearm and inserting into the phalanges include the extensor pollicis longus (EPL), extensor pollicis brevis (EPB), extensor indicis proprius (EIP), and extensor digiti minimi (EDM). The tendons arising from these muscle bellies have an independent origin and action.
What are common extensors? ›The common extensor tendon is a tough band of fibrous connective tissue that attaches to the lateral epicondyle of the humerus (long bone in the upper arm) at the elbow. Rupture or tear of the common extensor tendon is the most common acute tendon injury of the elbow.
What is the meaning of flexion muscle? ›Flexion: decreasing the angle between two bones (bending). Extension: increasing the angle between two bones (straightening a bend). The triceps brachii and anconeus are muscles that extend the elbow. The biceps brachii, brachialis, and brachioradialis flex the elbow.
What are the flexors and extensors of the lower limb? ›
The knee extensors are the four muscles forming the quadriceps femoris, while the flexors include the biceps femoris, semitendinosus, semimembranosus, sartorius, popliteus, and gastrocnemius.
Are extensors on the front or back? ›Extensor muscles. Attached to the back of the spine, these muscles allow us to stand and lift objects. They include the large muscles in the lower back (erector spinae), which help hold up the spine, and gluteal muscles.
What muscle contracts to straighten legs? ›The quadriceps and hamstrings work together to move your leg. When you bend your leg, the hamstring muscles contract and the quads relax. Conversely, when you straighten your leg, the quads contract and the hamstring muscles relax.
What is a muscle that helps the prime mover called? ›The prime mover is helped by other muscles called synergists. These contract at the same time as the prime mover. They hold the body in position so that the prime mover can work smoothly.
Where are your flexor muscles? ›Flexor Muscles Acting on the Wrist Joint and the Joints of the Forepaw. The flexor muscles of the wrist joint arise from the medial epicondyle of the humerus, radius and ulna; and are inserted into the metacarpal bones.
Is flexion stronger than extension? ›Flexion/extension ratio was calculated for all measures. Results: Elbow extensor muscles were significantly stronger than the elbow flexors in both groups (p<0.001), with a flexor/extensor total work ratio ranging from 0.76-0.86.
Which muscle gives the most strength? ›The strongest muscle based on its weight is the masseter. With all muscles of the jaw working together it can close the teeth with a force as great as 55 pounds (25 kilograms) on the incisors or 200 pounds (90.7 kilograms) on the molars.
Where does the extensor muscle come from? ›The extensor carpi ulnaris muscle originates from the lateral epicondyle of humerus, via the common extensor tendon, and adjacent fascia. The lateral epicondyle is a common origin for extensor carpi ulnaris, extensor digitorum, extensor carpi radialis brevis and extensor digiti minimi muscles.
What are the muscles extensors of the hand? ›| Muscle | Origin | Action |
|---|---|---|
| Extensor carpi radialis longus | lateral supracondylar ridge | extends, abducts wrist |
| Extensor carpi radialis brevis | common extensor tendon | |
| Extensor digitorum | extends fingers, wrist | |
| Extensor digiti minimi | extends little finger at all joints |
Flexor vs Extensor Muscles
The muscles that decrease the angle between bones are called flexor muscles. The muscles that increase the angles between bones are called extensor muscles. These muscles decrease the angles between two body parts. These muscles increase the angle between two body parts.
What happens during flexion and extension? ›
In the limbs, flexion decreases the angle between the bones (bending of the joints) while extension increases the angle and straightens the joint. All anterior motions or bending at the joint is considered flexion and all posterior motions are extension.
Why is flexion and extension important? ›Improving the range of motion
Foot Flexion and Extension help to improve the range of motion. It does so by helping to stretch the muscles and tendons in the foot.
Just remember: flexion = forward. This action occurs at many joints and always brings the bones that make up a joint closer together, or closes the joint. Extension is the opposite of flexion, which means it lessens the angle between the two bones or opens the joint.
What is an example of flexion movement? ›Flexion – bending a joint. This occurs when the angle of a joint decreases. For example, the elbow flexes when performing a biceps curl. The knee flexes in preparation for kicking a ball.
What joints function in flexion and extension? ›Hinge joints function by allowing flexion and extension in one plane with small degrees of motion in other planes. [4] The hinge joint is an essential component of the complex biomechanics of the human body. [1] The knee, elbow, and ankle can support large amounts of force and aid in the performance of work.
What is the function of the wrist flexor and extensor Retinaculum? ›Its principal function is to serve as a pulley for the carpal flexor muscles and stabilize the carpal system's morphology.
What are the flexors and extensors of the upper limb? ›They are divided into two distinct compartments of the arm. The anterior (flexor) compartment contains the biceps brachii, coracobrachialis and brachialis muscles. The posterior (extensor) compartment contains only the triceps brachii muscle.
What is the flexor tendon used for? ›Flexor tendons run from the forearm to the ends of the fingers across the palm side of the hand. They control the ability to bend fingers down to the palm (for example to make a fist, grip, or pinch objects). When these tendons are cut or injured, it can be impossible to bend the fingers or thumb.
What are the muscles of the common flexor and extensor tendons of the elbow? ›The common extensor tendon that originates from the lateral epicondyle of the elbow is directly involved. The extensor carpi radialis brevis (ECRB) and longus, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris come together to form the common extensor tendon.
What is the action of extensor digitorum muscle? ›Function. The extensor digitorum muscle extends the phalanges, then the wrist, and finally the elbow. It tends to separate the fingers as it extends them. In the fingers, the extensor digitorum acts principally on the proximal phalanges, acting to extend the metacarpophalangeal joint.
What is flexor movement? ›
A flexor is a muscle that flexes a joint. In anatomy, flexion (from the Latin verb flectere, to bend) is a joint movement that decreases the angle between the bones that converge at the joint. For example, one's elbow joint flexes when one brings their hand closer to the shoulder.
Is the quadriceps a flexor or extensor? ›The quadriceps femoris is a hip flexor and a knee extensor. It consists of four individual muscles; three vastus muscles and the rectus femoris. They form the main bulk of the thigh, and collectively are one of the most powerful muscles in the body.
Is triceps a flexor or extensor? ›The triceps brachii muscle is the primary extensor of the elbow joint and the anconeus muscle assists for extension of the elbow joint (Fig. 12.16).
What is the role of elbow flexors? ›The brachialis is an elbow flexor that originates from the distal anterior humerus and inserts onto the ulnar tuberosity. The brachialis is one of the largest elbow flexors and provides pure flexion of the forearm at the elbow. [2] It does not provide any supination or pronation of the forearm.
What are the flexor muscles of the body? ›Flexor muscles. The flexor muscles are the brachialis, the brachioradialis and the brachial biceps (Table 1). Their action is maximal when the elbow is flexed at 90°.
What is the primary function of the hip flexor muscles? ›Hip flexors are a group of muscles responsible for flexing the hip and raising the legs. These muscles are essential in movement as you use this muscle group every time you stand or take a step; they also help maintain your stability and posture.
Where is your flexor muscle? ›What are the hip flexors? Your hip flexors are a group of muscles along the front of your upper thigh. They include the iliacus, psoas major, rectus femoris and sartorius.
Where are flexors and extensors located? ›Like the wrist muscles, the flexors and extensors of the hand originate in the forearm and insert onto the phalanges or finger bones.
Are flexors stronger than extensors? ›The traditional notion about the distribution of weakness in upper motor neuron lesions may be explained by a combination of two factors: an intrinsic difference in strength (flexors being stronger in the arms and extensors in the legs), and the occurrence of hypertonia in the stronger muscle groups.
Where are extensor muscles located? ›Anatomy. The extrinsic extensor muscles located in the forearm and inserting into the phalanges include the extensor pollicis longus (EPL), extensor pollicis brevis (EPB), extensor indicis proprius (EIP), and extensor digiti minimi (EDM).
What is difference between flexion and extension? ›
The difference between flexion and extension comes down to joint angle. Flexion makes it smaller, bringing two body parts closer together (e.g., biceps curl), while extension makes it larger, moving two body parts farther away from each other (e.g., triceps extension).
What is muscle flexion and extension? ›Flexion and extension are usually movements forward and backward from the body, such as nodding the head. Flexion: decreasing the angle between two bones (bending). Extension: increasing the angle between two bones (straightening a bend). The triceps brachii and anconeus are muscles that extend the elbow.
What do hip extensors do? ›This powerful group of hip extensors is used for functional activities involving upward and forward propulsion of the body, such as for jumping, running, stair climbing, and transitioning from sitting to standing. With the femur well stabilized, activation of the hip extensors can also posteriorly tilt the pelvis.
What is hip flexion and extension? ›The structure of the hip allows a wide range of motion to (and between) the extreme ranges of anterior, posterior, medial, and lateral movement. Raising the leg toward the front is termed flexion; pushing the leg toward the back is termed extension (Figure 2).
What movement uses hip flexors? ›A hip flexor muscle is a muscle that functions in flexing the hip, ie bringing the knee closer to the chest. Hip flexion is maximal with a high, forward kick that brings the leg above the level of the waist. Every time you take a step, you are using your hip flexor muscles.
Does the flexor muscle contract? ›The muscle that contracts to bend a joint is called the flexor. The muscle that contracts to straighten a joint is called the extensor.
Is flexor muscle voluntary or involuntary? ›They are all voluntary muscles because we can make them work by our conscious thinking. We can either lift our arm by moving our muscles or allow them to relax, which means that our arm will fall to our side.