PARALYSIS OF SUPRASCAPULAR NERVE. 
513 
shoulder-joint. He especially mentions abrasion in the bursa of the 
postea-spinatus muscle, and rupture of its tendon. It can be proved that 
rupture of this tendon, which sometimes occurs after inflammation of its 
sheath, produces the same disturbance in movement as paralysis. Section 
of the tendon of the postea-spinatus results in precisely similar lameness. 
Professor Dewar has pointed out that the foregoing description of 
paralysis of the suprascapular nerve is exactly applicable to the con¬ 
dition known to horsemen in Scotland as “ slipped or prised shoulder,” 
the most common form of which is atrophy of the subspinatus muscle in 
thiee year old horses being trained to agricultural work. The muscles of 
both sides are often affected. As these animals work in traces, and have 
not to back, the cause in their case can scarcely be a backward movement 
of the shoulder. 
The disease may, of course, be accidentally complicated with other 
injuries. Thus, in a riding-horse which had run away and struck its 
shoulder against a tree, the levator humeri and pectoralis transversus 
were ruptured and there was paralysis of the suprascapular nerve. 
Rupture had probably occurred in other of the breast muscles. Soon 
after the injury the hair fell away from a particular point on the skin, 
and severe eczema developed. The longish oval spot, which began 
about a hand s-breadth below the shoulder-joint, extended perpendicularly 
upwards almost to the middle of the neck. At the centre, and just over 
the shoulder-joint, it was about 8 inches broad, and became smaller both 
in an upward and downward direction. The hair which afterwards 
grew on the spot was of a lighter colour, and if the animal was excited 
or slightly pushed active secretion of sweat occurred here whilst all 
the rest of the body remained dry. The spot was also insensitive to 
the prick of a needle. Without doubt this was a case of simultaneous 
paralysis of the superficial scapular nerve, a twig of the sixth cervical. 
The condition improved, but very slowly. 
VII.—PARALYSIS OF THE RADIAL NERVE (PARALYSIS 
NERVI RADIALIS. 
The radial (or musculo-spiral) nerve derives its fibres from the seventh and 
eighth cervical, and from the dorsal roots of the plexus, and passes downwards 
and backwards on the subscapularis and teres major muscles, and some little 
distance behind the axillary vessels, from which it is separated by the ulnar 
nerve. On reaching the deep humeral artery, it disappears in front of the 
large head of the triceps, and is continued round the humerus in the musculo- 
spiral groove, where it rests on the brackialis anticus, and afterwards, on the 
posterior or outer border of that muscle. Before the nerve disappears behind 
the humerus, it gives _ branches to the great and small heads of the triceps, 
and a long branch which passes backward to divide under the scapulo-ulnaris 
for the supply of that muscle. Behind the limb it supplies the medium head 
v.s. 
L L 
