ioo THE SUPERIOR EXTREMITY 



As the arm is fully pronated, the extensor digitorum com- 

 munis and carpi ulnaris (C. 6, 7, and 8) may subsequently be 

 able to produce a small degree of flexion at the elbow. 



When the lesion is confined to the anterior ramus (primary 

 division) of C. 5, no sensory changes can be discovered; as it is 

 not responsible for the exclusive supply of any definite area of 

 skin. If C. 6 also is involved, there is usually some loss of 

 epicritic sensibility on the lateral aspects of the arm and forearm. 



In the treatment of this and other similar conditions, it must 

 be remembered that unless the paralysed muscles are relaxed 

 they will become overstretched by the unopposed action of the 

 unparalysed antagonistic muscles. 



Surgical approach to the plexus is described on p. 127. 



Klumpke's Paralysis : Lower Arm Type. This condition 

 results from upward traction on the shoulder, e.g. when a man 

 falling from a height seizes something to save himself, or in a 

 breech presentation when the arms are carried up above the 

 head. The lesion usually affects the first thoracic nerve, but it 

 may involve the whole of the lower trunk (C. 8 and T. i). The 

 intrinsic muscles of the hand are paralysed and a characteristic 

 claw-hand develops. (The fingers are hyper-extended at the 

 metacarpo-phalangeal joints and flexed at the inter-phalangeal 

 joints.) If the whole of the lower trunk is affected the flexors 

 and extensors of the fingers are paralysed in addition (Sherren). 



Diminution of sensibility occurs over the medial side of the 

 arm, forearm, and hand, the area of protopathic loss being 

 greater than the area of epicritic loss. When the first thoracic 

 nerve is injured proximal to the point at which it sends off the 

 white ramus communicans to the first thoracic ganglion of the 

 sympathetic, the cilio-spinal reflex (p. 125) is abolished. 



A Cervical Rib (p. 128) may produce a supra-clavicular 

 lesion of the brachial plexus. In these cases the symptoms 

 appear usually on the right side and indicate involvement of 

 the lower trunk. No pupillary changes are present, as T. i 

 is affected beyond the origin of its white ramus communicans. 

 Neuralgic pain radiates down the ulnar side of the upper limb 

 in the areas supplied by the nerves involved (Fig. 14), and 

 there may be some epicritic loss in the same situation. Wasting 

 and progressive paresis occur in the intrinsic muscles of the 

 hand. Recent observations have shown that the same symptoms 

 may be produced by the pressure of the first rib. 



Injuries to the Cords of the Plexus. The Medial 



