Yoga Anatomy

Muscular joint actions

Spine

Concentric contraction or passively lengthening

Erector spinae

Lower limbs

Front leg Back leg

Concentric

contraction

Eccentric

contraction

Concentric

contraction

Eccentric

contraction

Passively

lengthening

To extend knee:

Articularis genu,

vastii

To allow hip

flexion:

Hamstrings at hip

joint, gluteus

maximus

To level and

center pelvis

over feet and

to maintain

balance side to

side:

Gluteus medius

and minimus,

piriformis,

superior and

inferior gemel-

lus, intrinsic

and extrinsic

muscles of foot

To extend knee:

Articularis genu,

vastii

To maintain

arches of

foot without

inhibiting

dorsiflexion

of ankle:

Intrinsic muscles

of foot

To allow hip flex-

ion without

dropping back

leg forward:

Hamstrings at hip

joint, gluteus

medius (pos-

terior fibers),

adductor

magnus, glu-

teus maximus

To allow outer

ankle to

lengthen with-

out collapsing

inner knee or

inner foot:

Peroneals

Soleus, gas-

trocnemius

Parsvottanasana (continued)

Notes

The action of the legs in parsvottanasana is almost the same as in utthita trikonasana (page
111), and this asana can be a challenge to balance in for the same reason—the narrowness
of the base and the need for the outer hip muscles to be both long and active. Additionally,
if you are accustomed to using your eyes to help you balance, this position with the head
rolled forward might be interesting.
This forward-bending action is more intense in the hamstrings of the front leg than utta-
nasana because of the asymmetry of the pose: The back leg’s position directs the flexion
more specifically into the front leg hip joint, and mobility in the spine can compensate less
for lack of mobility in the leg. (This is seen in an even more extreme form in hanumanasana
[page 156].)