F- CLINICAL ASPECTS OF SPINAL CORD INJURIES
241
complication greatly aggravating the disability of the tetraplegic (Fig. 8). It must be
remembered that the degree of segmental innervation of the triceps by the 6th, yth and
8th cervical segments shows individual variations. In certain cases, the segmental inner
vation of C6 may be strong enough to compensate to some degree the loss of Cy and C8.
Therefore, the degree of functional recovery of the triceps due to this remaining inner
vation of C6 depends largely on the efficiency of the early management of the upper
limbs in tetraplegics. If the triceps during the stage of denervation is allowed to become
overstretched by faulty positioning of the forearms in permanent flexion, its functional
recovery, if it occurs at all, will be very poor. Therefore, in transverse lesions of C6
attention must be paid to keeping the forearm in extension and the arms in adduction.
The deltoid and biceps reflexes are often exaggerated but the triceps reflex is absent.
Tapping of the triceps produces contraction of the biceps (inversion of the triceps
reflex). The degree of spasticity of all muscles below the level of the lesion varies and the
paralysis of the lower limbs may be one in flexion or extension. With regard to the extent
of the reflex responses to extrinsic and intrinsic stimuli see page 228.
The sensory loss in the upper limbs involves the forearms, hands and fingers includ
ing the thumbs. The sensibility over the lateral aspect of the arms including the dorso-
lateral aspect of half of the forearm is intact as this is supplied by
05.
CJ
SEGMENT
As a rule, the function of the diaphragm and auxiliary respiratory muscles is strong
enough to compensate for the paralysis of the intercostal and abdominal muscles, and
tracheostomy is indicated in selected cases only when complications develop. The
posture of the arms is still one of abduction and external rotation although sometimes
less pronounced than in C6 lesions since the adductors and internal rotators (subscapu-
laris, pectoralis major, teres major and latissimus dorsi) are only partly paralysed. The
forearm is kept in flexion due to overaction of the biceps. However, as already pointed
out, in a considerable number of complete lesions at Cy, especially when confined to its
more distal part, the C6 innervation of the triceps is strong enough to compensate for the
loss of the Cy-C8 innervation of this muscle and, in due course, may ensure its function
against resistance and sometimes even against gravity, provided faulty positioning of the
forearm in permanent flexion has been prevented from the start. This experience is not
in accordance with Foerster's (1936) view, who found the triceps always totally paralysed
in complete lesions at Cy. The more the transverse lesion is confined to the distal part
of Cy the stronger the function of the triceps.
In contrast to complete lesions at C6, the extensor carpi radialis longus is functioning
and the hand shows radial deviation. However, if the lesion involves the more distal
part of the nuclear part of Cy, the extensor carpi radialis brevis is also functioning and
the hand shows less radial deviation. Moreover, in such an instance, there is also some,
though reduced, function of the extensor digitorum communis, especially of the extensor
indicis proprius. The function of the pronator teres and flexor carpi radialis is reduced
and so is the function of the flexors digitorum sublimis and profundus and also flexor
pollicis longus.
