e patient's first complaint is of pain and stiffness in the
muscles of mastication, notably the masseter, so that he has difficulty
in opening the mouth--hence the popular name "lock-jaw." The muscles of
expression soon share in the rigidity, and the face assumes a taut,
mask-like aspect. The angles of the mouth may be retracted, producing a
grinning expression known as the _risus sardonicus_.

The next muscles to become stiff and painful are those of the neck,
especially the sterno-mastoid and trapezius. The patient is inclined to
attribute the pain and stiffness to exposure to cold or rheumatism. At
an early stage the diaphragm and the muscles of the anterior abdominal
wall become contracted; later the muscles of the back and thorax are
involved; and lastly those of the limbs. Although this is the typical
order of involvement of the different groups of muscles, it is not
always adhered to.

To this permanent tonic contraction of the muscles there are soon added
clonic spasms. These spasms are at first slight and transient, with
prolonged intervals between the attacks, but rapidly tend to become more
frequent, more severe, and of longer duration, until eventually the
patient simply passes out of one seizure into another.

The distribution of the spasms varies in different cases: in some it is
confined to particular groups of muscles, such as those of the neck,
back, abdominal walls, or limbs; in others all these groups are
simultaneously involved.

When the muscles of the back become spasmodically contracted, the body
is raised from the bed, sometimes to such an extent that the patient
rests only on his heels and occiput--the position of _opisthotonos_.
Lateral arching of the body from excessive action of the muscles on one
side--_pleurosthotonos_--is not uncommon, the arching usually taking
place towards the side on which the wound of infection exists. Less
frequently the body is bent forward so that the knees and chin almost
meet (_emprosthotonos_). Sometimes all the muscles simultaneously become
rigid, so that the body assumes a statuesque attitude (_orthotonos_).
When the thoracic muscles, including the diaphragm, are thrown into
spasm, the patient experiences a distressing sensation as if he were
gripped in a vice, and has extreme difficulty in getting breath. Between
the attacks the limbs are kept rigidly extended. The clonic spasms may
be so severe as to rupture muscles or even to fracture one of the long
bo