236 TETANUS 
sive tonic spasms. The tetanic spasms usually begin in the muscles of 
the head and neck, extending from these to the muscles of the throat, 
trunk and extremities. It often happens that the spasms first appear 
in the hind quarters and extend forward. There is stiffness of the 
parts affected. If in the head, the muscles of mastication are first 
attacked with spasms, while if the hind quarters are first attacked, 
there are usually spasms of the muscles of the tail. The muscles at 
the site of inoculation are frequently the first to show spasms and, 
if the disease is of a mild type, they may be the only ones to exhibit 
symptoms. Friedberger and Fréhner have grouped the muscles 
which are attacked with the more obvious effects upon the appearance 
of the animal. They are as follows: 
The muscles of mastication. The contraction of these muscles is 
called trismus or “lockjaw.’’ According to the degree of contraction, 
the jaws remain in more or less close contact, rendering prehension or 
mastication difficult or impossible. 
The other muscles of the head. These are spasmodically contracted 
in different degrees. Spasms of the muscles of the ears cause the ears 
to be “pricked” and their tips to be drawn together; of the recti 
muscles of the eyes, cause the eyes to be retracted in the orbit with 
protrusion of the nictitating membrane; of the nose, produce dilata- 
tion of the nostrils; of the dilator of the upper lip, give an abnormal 
shape to the opening of the mouth. The muscles of the tongue, of 
deglutition and of the larynx are also usually attacked by spasms. 
The extensor muscles of the neck. Contraction of these muscles 
causes a stiff, outstretched carriage of the head and “‘ewe neck.” The 
muscles of the neck become hard and tense to the touch. 
The extensor muscles of the back. Spasms of these muscles are 
manifested by an extremely hard condition of the muscles of the 
back, loins and croup. Several conditions may arise: orthotonous 
in which the neck is stretched out and the back and croup are 
carried horizontally, or opisthotonous in which the head is raised or 
drawn back and the vertebral column slightly depressed. This is 
the most common occurrence. There may be a lateral curvature of 
the cervical vertebrae which is uncommon and also a convex curva- 
ture of the vertebree which is very rarely observed. The tail, espec- 
ially in horses, is often raised and occasionally said to be straight 
with the back. ; 
The muscles of the limbs. The spasms in these muscles make the 
limbs stiff and cause the animal to assume an attitude in which the 
