This sphincter opens automatically only in connection with the act of swallowing.
The sphincter is kept in a state of tonic contraction by a nervous centre situated in the lumbar portion of the spinal cord.
Thus, Jules Aron reports from the epidemic at Joigny a case of recovery after complete paralysis of the sphincter ani.
These are usually fibrous when situated below, or vascular when situated above, the sphincter ani muscle.
The sphincter ani is constantly in a state of tonic contraction, but the force of its contraction may be voluntarily increased.
After the operation return the parts within the sphincter and cut off any tabs of redundant integument with scissors.
If the nates present, the state of the sphincter ani will be a sure guide in ascertaining whether the child be alive or not.
The entrance into these compartments can be closed by a sphincter muscle after they are filled with water (Fig. 84).
On what principle could a piece of chocolate inhibit the call to stool or contract the sphincter muscle?
It thrusts the Meat down by locking up the Pharynx as a sphincter.
1570s, from Middle French sphincter, from Late Latin sphincter "contractile muscle," from Greek sphinkter "band, anything that binds tight," from sphingein "to squeeze, bind," of unknown origin. First used in anatomical sense by Galen.
sphincter sphinc·ter (sfĭngk'tər)
n.
A ringlike muscle that normally maintains constriction of a body passage or orifice and that relaxes as required by normal physiological functioning. Also called anatomical sphincter.
