Congenital and developmental cervical spine variants, as well as acquired or sport-adapted cervical morphologies, may alter canal reserve, segmental stability, foraminal dimensions, and the cervicothoracic outlet in athletes. This narrative review aimed to integrate the anatomically and methodologically heterogeneous literature linking these findings with sports-related injury and return-to-play decisions. PubMed/MEDLINE was searched from database inception through 6 July 2026 using controlled vocabulary and free-text terms for cervical anatomy, specific variants, athletic exposure, neurological syndromes, injury mechanisms, and return to sport; reference lists of relevant publications were also examined. English-language human studies were selected for direct anatomical, biomechanical, clinical, or athlete relevance and synthesized by evidence type, mechanism, vertebral level, and sport. The strongest athlete-specific evidence concerned developmental or functional cervical stenosis, space available for the cord, cervical cord neurapraxia, transient quadriparesis, and stingers in collision sports. Evidence for atlas arch defects, os odontoideum, Klippel-Feil syndrome, cervical spondylolysis, and cervical rib-related thoracic outlet syndrome was predominantly case-based or derived from expert guidance. These findings support cautious, individualized interpretation rather than universal clearance rules. Clinical assessment should integrate symptoms, neurological findings, imaging, dynamic stability, recurrence, and sport-specific exposure while recognizing that prospective athlete-specific evidence remains limited.