Introduction: Obstetrical brachial plexus injuries present a dramatic insult not only to the peripheral nervous system but also to its central components. Thus far only the peripheral pathology has been given adequate attention both in regards to diagnosis/prognosis and treatment. In the current work we have investigated the hypothesis that obstetric brachial plexus injuries will lead to permanent changes in spinal cord architecture, that not only represent an important part of the pathology but also mechanisms of recovery. Materials & Methods: A total of forty SD-rats were used and divided in to 3 groups. Control group A and B consist of 10 adult animals each, the experimental group C of 20 neonate animals. In control group A the size of the normal musculocutaneous (MC) motoneuron pool was determined through retrograde tracing using Fast Blue and Fluorogold. In control group B the relative contribution of spinal root C7 to the normal adult MC motoneuron pool was determined. Further, total force generation of the biceps muscle, as well as C7 individual contribution of force generation were measured. In the experimental group C the upper trunc of the brachial plexus was crushed at the time of birth. After 8 weeks force measurement of the biceps with individual C7 and MC stimulation were performed and quantification of corresponding motoneuron pool done. Results: In normal animals the motoneuronpool of the MC nerve extends from segments C4 to C7. The contribution of C7 however is minimal (28±24) and not present in all animals. In the experimental animals, where the upper trunc was crushed at birth, a major portion (132±56) of the motoneuron pool of the MC nerve was found in the C7 segment, that also contributed significantly to biceps function 12 weeks after the injury. Summary: Injury to the brachial plexus at birth leads to irreversible changes in spinal cord architecture. Above experiments indicate that these changes are not only an important part of the primary pathology of obstetrical brachial plexus injuries but also of the subsequent recovery process. This more complete understanding of OBPL pathology lays a better groundwork for understanding the natural course of recovery that may also lead to new therapeutic concepts.