Which nerve root lesion characterizes Klumpke's palsy?

Klumpke's palsy is characterized by lesions affecting the lower trunk of the brachial plexus, specifically involving the C8 and T1 nerve roots. This condition typically occurs due to extreme abduction of the arm, such as in childbirth when excessive pulling during delivery can stretch or tear the lower trunk of the brachial plexus.

When there is damage to the C8 and T1 roots, it results in weakness or paralysis of the intrinsic muscles of the hand, leading to issues such as a "claw hand" deformity. Patients may also have reduced sensation in the ulnar aspect of the hand and the forearm. This clinical presentation is distinctly associated with Klumpke’s palsy, making the identification of the specific nerve roots involved critical for diagnosis and subsequent management.

In contrast, other options include nerve roots that do not directly correlate with the typical presentation of Klumpke's palsy, which is why they do not correctly represent the condition's nerve root lesion.