Mulabhanda

Mulabhandasana
Pose of the Root Lock
From Personal MD.com
Explanation:
"Bhandha" in Sanskrit means to lock and "Moola" means the perineum/ bottom, or to quote David Swensen, "Between the fruit and the vegetables.

Mulabhanda - a lock, or tightening, of the rectal muscles
Muladhara - chakra (energy center in the subtle body) located at the base of the spine
Muni - saint; sage ...

Krishnamacharya mulabhandasana.jpg
Tirumalai Krishnamacharya in Mulabhandasana.
Tirumalai Krishnamacharya in Svastikasana.

Mulabhanda is strictly about energetic vs placidness. All successive bhanda benefit whether activated or not.

See also: Breath, Prana, Pranayama, Yoga, Sanskrit