Figure 216.1.— Typical posture of a neonate with Duchenne-Erb palsy [A and B]. The posture consists of arm adduction and internal rotation, extended elbow, forearm pronation, palmar flexion of the wrist, and good finger movements. The presence of wrist flexion indicates minimal or no involvement of C7.
Duchenne-Erb palsy indicates involvement of C5 and C6 spinal segment fibers. The most frequent site of involvement of these fibers is at the upper trunk prior to the origin of the suprascapular nerve (Figure 216.2 B), but more proximal damage can also occur (Figures 216.2 A). The clinical manifestations of Duchenne-Erb palsy are so typical that it can not be confused with a lesion at any other location.
Figure 216.2.— Schematic representation of the brachial plexus and its nerves and muscles. Site of injury. A: C5 root and C6 spinal nerve; B: upper trunk; (PS): paraspinal muscles; (R): rhomboid muscle; DS: dorsoscapular nerve; LT: long thoracic nerve; (SA): serratus anterior muscle; (SS): supraspinal muscle; (IS): infraspinal muscle; SPS: suprascapular nerve; PL: pectoral lateralis nerve; (P): pectoralis muscle; PM: pectoralis medialis nerve; SF: sympathetic fibers to the eyes; (M of M): muscle of Müller; (DP): dilator pupillary muscle; (TM): teres major muscle; (SBS): subscapularis muscle; SBS: subscapularis nerves; TD: thoracodorsal nerve; (LD): latissimus dorsi muscle; MC: musculocutaneous nerve; (Bi): biceps muscle; (Br): brachialis muscle; M: median nerve; U: ulnar nerve; A: axillary nerve; (TMi): teres minor muscle; (D): deltoid muscle; R: radial nerve.