CORPSE  POSE
This involves lying on one's back with one's legs straight along the floor. The legs are a little apart and relaxed so that they are rolled outwards slightly. The arms rest on the floor a short distance from one's side and are rolled outwards so that the palms face mostly upwards.  This is a very open position and is considered to be the "classical" pose for practising relaxation in yoga. However, it is not comfortable for everyone. Those who find this pose too open may wish to try slightly modifying the arm position by placing their hands on their abdomen.


SUPINE WITH SUPPORT UNDER KNEES.
This is very like the corpse pose, but here some padding (e.g. a rolled-up towel or cushion) is placed under the knees so that the legs are supported in a slightly bent position and the knees point upwards.      Placing a support under the knees takes potential tension out of the ilio-psoas muscles. Since the ilio-psoas muscles tend to pull the lower back up into a backbend, bending the knees like this tends to allow the lower back to sink down more. This tends to be good for many with lower back problems and those with a tendency to have excessive lumbar lordosis.

SEMI-SUPINE
This involves lying on one's back with one's legs in the crooked position - soles of feet resting on floor and knees pointing upwards. It can be helpful to angle knees inwards slightly so that they are touching and supporting each other. Arms either rest on the floor on either side as in corpse pose, or one places hands on the abdomen.
This is good when it is not convenient to place support under the knees. This tends to be good for many with lower back problems and those with a tendency to have excessive lumbar lordosis.


SEMI-SUPINE WITH CHAIR SUPPORT
This is like semi-supine relaxation but with legs resting on a chair or a stool. Care is needed to ensure that there is enough soft padding to ensure that no hard surface presses into the legs reducing local circulation. Legs could also be rested on a wall. Some teachers suggest that the angle at the hips (between the front of the trunk and the front of the thighs) should be greater than 90 degrees to ensure that circulation is not impeded in the hip region.
With the legs elevated like this, excess tissue fluid and blood - which has a tendency to accumulate in the legs - is encouraged to drain out of the legs. It is thus good for those with varicose veins and oedema in the legs.  It also tends to be good for many with lower back problems and those with a tendency to have excessive lumbar lordosis. However, with the legs elevated, there tends to be a higher blood pressure in the trunk and head and so may not feel comfortable (or be good) for those with some forms cardiovascular problems (especially high blood pressure).

FOETUS POSITION

This involves lying on one's sides in a curled up position such as a foetus adopts in the womb. For the neck to feel truly comfortable, some padding (e.g. yoga block, towel, or cushion) should be placed under the head.
This is a very closed position that tends to feel very safe and comforting - this is a very natural position to adopt when one is feeling emotionally vulnerable. It is also a good position in the later stages of pregnancy when it is undesirable to lie on one's back for long periods because of the weight of the foetus pressing down on the major blood vessels in the abdomen.


THE RECOVERY POSITION.
This is the position into which a first-aider would put an unconscious, but breathing, person. One lies on one's side with the hand of the top arm under one's head. The bottom leg is straight (or nearly straight). The top leg is bent with the knees resting on the floor in front of one's hips so that the pelvis is slightly tilted towards the floor.
This is an excellent position in the later stages of pregnancy when it is undesirable to lie on one's back for long periods because of the weight of the foetus pressing down on the major blood vessels in the abdomen.

LYING PRONE.
This involves lying on one's front. The arms can be placed by one's side or under one's cheek or forehead. The head can be turned to one side (this is what is most comfortable for most people), but in this case care should be taken that one practises relaxation with the head turned alternately to each side. The head can be placed in a more neutral position with the forehead resting on one's fingers, a couple of folds of towel or on one's mat - if one does this, then consciously making the effort to draw the chin in towards the neck will help to ensure that the back of the neck is long and that there is enough space for one's nose.
This is a good position for experiencing the movement of the spine with the breath. It can be good for lower back problems especially those where strain has occurred while leaning forwards and for those with little or no inwards curving of the lumbar back when standing. However, it is a mild back bend for the lower back and so is not an ideal relaxation position for those with excessive lumbar lordosis.