Basic
Human
Motion
Flexion & Extension of the
Lower Extremity
![](https://static.wixstatic.com/media/312842_5b91e94a3ead4faf81bc91f13144da56.jpg/v1/fill/w_173,h_225,al_c,q_80,usm_0.66_1.00_0.01,enc_avif,quality_auto/312842_5b91e94a3ead4faf81bc91f13144da56.jpg)
Hip Flexion
Flexion=The bending of a joint.
A movement of the hip resultant of the action of the hip flexors (anterior hip & thigh muscles).
It moves the whole leg into an anterior orientation (toward the ventral surface) in the sagittal plane.
![](https://static.wixstatic.com/media/312842_75ed8d542a384d54b3269366444af09d.png/v1/fill/w_163,h_236,al_c,lg_1,q_85,enc_avif,quality_auto/312842_75ed8d542a384d54b3269366444af09d.png)
Hip Extension
Extension=The straightening of a joint.
A movement of the hip resultant of the action of the hip extensors (posterior hip & thigh muscles.
It moves the whole leg into a posterior orientation (toward the dorsal surface) in the sagittal plane.
![](https://static.wixstatic.com/media/312842_f4cda8b5c1b74cda84110e45b3448f44.png/v1/fill/w_214,h_219,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/312842_f4cda8b5c1b74cda84110e45b3448f44.png)
Knee Flexion
Flexion = The bending of a joint.
A movement of the knee resultant of the action of the knee flexors (posterior thigh & calf muscles).
It bends the knee moving the lower leg into a posterior orientation (toward the dorsal surface) in the sagittal plane.
![](https://static.wixstatic.com/media/312842_d0261f1eedda412fa815e8fb82be67ef.png/v1/fill/w_206,h_217,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/312842_d0261f1eedda412fa815e8fb82be67ef.png)
Knee Extension
Extension = The straightening of a joint.
A movement of the knee resultant of the action of the knee extensors (anterior thigh & calf muscles).
It straightens the knee moving the lower leg into an anterior orientation (toward the ventral surface) in the sagittal plane.
![](https://static.wixstatic.com/media/312842_227d763071ea40cbbedfaf28aa7cfb25.png/v1/fill/w_199,h_194,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/312842_227d763071ea40cbbedfaf28aa7cfb25.png)
Dorsiflexion
A bending of the foot at the talocrural articulation.
A movement of the foot/ankle resultant of the action of the dorsiflexors (anterior calf muscles).
It moves the foot into a superior orientation (toward the head) in the sagittal plane.
![](https://static.wixstatic.com/media/312842_662799eb53434674aeba2153b050fad6.png/v1/fill/w_187,h_211,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/312842_662799eb53434674aeba2153b050fad6.png)
Plantarflexion
A bending of the foot at the talocrural articulation.
A movement of the foot/ankle resultant of the action of the plantarflexors (posterior calf muscles).
It moves the foot into an inferior orientation (toward the floor) in the sagittal plane.