The "little orbit" is a smaller version of the microcosmic orbit: it encompasses just the lower tan tien, not the entire torso.  This vertical loop passes through the following four major acupoints (as well as through the major physical landmarks along the way):

            1) Ren-6: qi hai, the acupoint below the navel by about the distance of the width of your index and middle finger together.

            2) Ren-4: guan yuan, four fingers below the navel.

            3) Ren-1: hui yin, the middle of the perineum (a 'well' between the genitals and anus).

            4) Sacrum: loaded w/ acupoints.

            5) Du-4: ming men, literally "life gate", which is the acupoint between the kidneys and classically one of the critical transformation points along the back channel.

(NOTE:  All of these acupoints are somewhat interior, I find.  Their potency is not centered on the surface of the skin.)

After ming men, the little orbit leaves the governing vessel and loops towards the front of the body, joins the conception vessel and passes through qi hai.  A little loop.

The more obvious way and as it turns out the much more profound and powerful way to view the little orbit is in terms of major anatomical landmarks:

           1) Belly button: deep, deep, and too often ignored.

           2) Genitals:  obvious (sometimes not so obvious: unaroused practices are predominant)

           3) Sacrum: pulsing of the sacral muscles is critical to draw jing to the spine.

           4) MingMen Du-4: included as a major anatomical landmark because it is where the kidneys interact and that interaction is a pump that is naturally integral with the umbilicus and the spine. 

All four of the above are major players in the internal arts scene and there are various pertinent methods; look for them in your travels.  "Embryonic Breathing" is relevant.  (post #20)

In practice, at some times you might formally focus to activate and include all of these acupoints (and/or landmarks), perhaps resulting in a sort of bucket-shaped loop shown below.  Other times, certain points will be emphasized more over others, in your alchemy, which may vary the shape.  Or, you may be focusing mainly on some other practice, with which the little orbit works in conjunction, and it might be more convenient for you to circulate the little orbit as a simple circle.  All of that is ok.

... and while you focus on these points, you'll find that focus only intermediately produces isolation and then transitions to connection to all sorts of other things and that's the way it's supposed to be.  This is about focus and integration.  Smooth.

LITTLE ORBIT ACUPRESSURE:

twiddle-your-tan-tien

twiddle thumbs on 

not so fast!: lazy pace.

front and back of little orbit

(any hand-position adjustments per your comfort)

Why use the little orbit?

            - To build up jing.

            - To circulate & refine the energies of the lower tan tien.

            - To stabilize jing within the lower tan tien.

            - One of the tricks to relieving sexual pressure 

                  and one of the first steps of refining sexual energy 

                      is to activate acupoints adjacent to the sex organs.

A danger of relying excessively on the microcosmic orbit is that the real work of actually producing a genuine lower "medicine field" (tan tien) gets avoided, in favor of "up & around" for refinement.  In the long term this can have devastating consequences.  Jing's dense nature includes the dangers of becoming stagnant, turbid (in the physical tissues, in the channels, energetically, and psychologically, behaviorally) and the intense sensations of sexuality facilitate dualistic entanglement (loss of Wholeness, Tao).  It is these issues that make the production of a true lower "medicine field" considerably more laborious than within the higher centers.  I'm not saying that the higher centers should avoided, their energies help balance the lower tan tien, but the lower tan tien does need steady dedicated work in order to transform its dense nature.

Some approaches to Taoist cultivation go something like

            1. Fill and stabilize the lower tan tien.

            2. Once the lower is abundant, circulate in the microcosmic orbit.

            3. Repeat.

Note that it's important to maintain a sense of gentle, open space, and radiant Light, within the loop.  This allows the space / substances in the center of the loop to be filled / refined, which is a large part of the purpose of this practice.  A tan tien ("medicine field") is a functional interplay of substance, space, and Light.

Also, adding testicle / ovarian breathing to the little orbit offers a simple and helpful variation.

Working with the little orbit is often beneficial, both for beginners and for people who've been on a path for a long while.

RELATED ESSAYS

The Sacrum - critical physical landmark that's part of the little orbit.

Dealing with the Force - muscular strength exercises for the lower tan tien.

Exploring the Exhale - breathing method to activate the major points of the little orbit.

The "Zen Pakua" - meditation with no visualizations.

TAN TIEN (DANTIAN): 

A FEW NOTES FROM AN ENGLISH-LANGUAGE CHINESE MEDICAL TEXT

(not pretending to define any whole version of "dantian")