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The interossei are intrinsic hand muscles situated between the metacarpals. These muscles are categorized into 2 groups: palmar and dorsal interossei, each comprising 4 muscles. The palmar interossei facilitate finger adduction, while the dorsal interossei enable abduction. Both muscle groups contribute to metacarpophalangeal (MCP) joint flexion and interphalangeal joint extension. All interossei receive innervation from the deep branch of the ulnar nerve.[1] Consequently, ulnar nerve injury may significantly impair intrinsic hand functions, particularly finger abduction and adduction. Understanding the anatomy and function of the interossei is essential in assessing ulnar nerve injuries, which often present with impaired finger abduction and adduction. In hand surgery, precise knowledge of interosseous muscle location and innervation guides safe dissection and reconstructive procedures, particularly in cases of trauma or deformity. Electrophysiological evaluation of interossei activity also aids in diagnosing neuromuscular disorders and monitoring nerve recovery.