I agree with Lisa Marasco's view that jaw clamp is frequently the result of
a compensation the baby has adopted due to weakness in some other aspect of
the mechanisms used during breastfeeding.  What could that be:
 Weakness of the lips can result in inability to form an adequate seal
(creating problems with generating sufficient negative pressure to hold
breast in mouth and to facilitate milk transfer).  You could test this by
gently pushing on lips.  There should be some "resist" to your push.  The
lips should shape easily into a flange, and the seal should be tight.

Weakness of the tongue (caused by tongue-tie, trauma to nerves controlling
tongue due to birth injury -- e.g. forceps, short tongue, or bunched or
elevated tongue).  The tongue plays a role with the lips in creating a seal
to hold breast in mouth.  Tongue must also express free range of motion to
lift, extend, groove and lateralize in order to facilitate pressure
extraction of milk and to channel milk to back of mouth for safe swallow.

If tongue or lips are weak, baby will often clench with jaws to hold breast
in mouth, to apply possitive pressure on breast to strip milk from ducts,
and to compensate for reduced ability to form negative pressure by applying
excess positive pressure.

Weaknesses in the neck muscles, or injury there may also be causing baby to
posture the head in hyper-extension.  This will also tighten the jaw and
create clenching or clamping. Tip your own head back and see the kind of
pull this exerts on your jaw.

Solutions include:  Feed baby in postures that emphasize hip flexion with
firm control at the base of the head (on neck and shoulders) to maintain
head position in very slight extension with chin slightly tipped forward.
The lips can be massaged with firm (rather than tickle touch) motions rather
like applying lipstick.  Tongue mobility should be evaluated.  I find that
doing "push-ups" with a soft gel-filled pacifier or someone's clean finger
provides non-nutritive sucking opportunities to exercise the weak or injured
tongue.

Barbara Wilson-Clay, BSEd, IBCLC
Austin Lactation Associates, Austin, Texas
http://www.lactnews.com

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