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Flexion

In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal (bones, cartilage, and ligaments) and muscular (muscles and tendons) systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder. The trunk may be flexed toward the legs or the neck to the chest.

The opposite term is extension, or straightening. Flexion decreases the angle between the bones of the limb at a joint, and extension increases it.

Note that specific flexion activities may occur only along the sagittal plane, i.e. from the forward to backward direction, and not side-to-side direction, which is further discussed in abduction.

Additional recommended knowledge

Daily Visual Balance Check

Essential Laboratory Skills Guide

Exercises

Active range of motion exercises include movements such as flexion and extension. These exercises are used after an injury or surgery. They are done by a physical therapist or nurse initially, and may be continued by the patient.

In the healing process, active range of motion exercises, should avoid forcing the appendage into the extension or flexion position. The stress induced may re-injure the affected appendage (limb).

Muscles of flexion

Upper limb

of arm, at shoulder^[1]
- Anterior compartment of the arm
  - Coracobrachialis
  - Biceps brachii

of forearm, at elbow^[2]
- Anterior compartment of the arm
- Anterior compartment of the forearm
  - Pronator teres
  - Flexor carpi radialis
  - Palmaris longus
  - Flexor carpi ulnaris
  - Flexor digitorum superficialis

of hand, at wrist^[3]
- Anterior compartment of the forearm
  - Flexor carpi radialis
  - Palmaris longus
  - Flexor carpi ulnaris
  - Flexor digitorum superficialis
  - Flexor digitorum profundus

of proximal phalanges, at metacarpophalangeal joint ^[4]
- Lumbricals of the hand
- Dorsal interossei of the hand
- Palmar interossei
- Flexor digiti minimi brevis (little finger only)

of intermediate phalanges, at proximal interphalangeal joints ^[5]
- Flexor digitorum superficialis

of distal phalanges, at distal interphalangeal joints
- Flexor digitorum profundus

of thumb^[6]^[7]
- Flexor pollicis longus
- Flexor pollicis brevis

Lower limb

of femur/thigh at hip (L1-L2)^[8]
- Iliopsoas
- Tensor fasciae latae
- Rectus femoris
- (additional minor contributions from other hip flexors)

of leg at knee (L5-S2)^[9]
- Posterior compartment of thigh/Hamstrings
  - Biceps femoris
  - Semitendinosus
  - Semimembranosus
- Gracilis
- Sartorius
- Tensor fasciae latae
- Gastrocnemius
- Popliteus
- Plantaris (negligible)

of toes
- Posterior compartment of leg
  - Flexor hallucis longus
  - Flexor digitorum longus
- Flexor digitorum brevis
- Quadratus plantae
- Flexor hallucis brevis
- Flexor digiti minimi brevis

of proximal phalanges at metatarsophalangeal joint^[10]
- Lumbrical muscle (foot)
- Plantar interossei
- Dorsal interossei

Other

torso/lumbar vertebrae
- Rectus abdominis muscle

neck at atlanto-occipital joint
- Longus capitis muscle

Additional images

References

^ http://www.exrx.net/Articulations/Shoulder.html#anchor102874
^ http://www.exrx.net/Articulations/Elbow.html#anchor764071
^ http://www.exrx.net/Articulations/Wrist.html#anchor260949
^ http://www.exrx.net/Articulations/Fingers.html#anchor801484
^ http://www.exrx.net/Articulations/Fingers.html#anchor783387
^ http://www.exrx.net/Articulations/Thumb.html#anchor206196
^ http://www.exrx.net/Articulations/Thumb.html#anchor212077
^ http://www.exrx.net/Articulations/Hip.html#anchor845056
^ http://www.exrx.net/Articulations/Knee.html#anchor22052
^ http://www.exrx.net/Articulations/Toes.html#anchor229680

v • d • e Joints
Types of joints	Amphiarthrosis - Symphysis - Gomphosis - Synovial joint (Hinge joint, Pivot joint, Condyloid joint, Saddle joint, Ball and socket joint, Gliding joint)
Terminology	Kinesiology - Anatomical terms of motion - Agonist/Antagonist
Motions	Flexion/Extension - Adduction/Abduction - Internal rotation/External rotation - Supination/Pronation - Plantarflexion/Dorsiflexion - Eversion/Inversion - Elevation/Depression - Protraction/Retraction

Category: Musculoskeletal system

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Flexion". A list of authors is available in Wikipedia.