Oral physical function, a core component of human physiological health, comprises three interdependent pillars: mastication, swallowing, and speech. Impairments in these functions caused by neural factors (e.g., stroke, Parkinson’s disease), structural abnormalities (e.g., tooth loss, head and neck cancer), or systemic disorders severely compromise nutritional intake, social communication, and quality of life. This review comprehensively summarizes and integrates current knowledge of oral function physiology, etiological mechanisms of related disorders, and the latest advances in assessment and rehabilitation. We first elaborate on the physiological basis of each oral function, emphasizing the intricate neuromuscular coordination and central nervous system regulation underlying normal operation. Subsequently, we classify etiologies of functional impairments into central and peripheral factors, highlighting distinct clinical manifestations for clinical identification. For assessment, we cover traditional clinical scales (e.g., Mandibular Function Restriction Scale, Gugging Swallowing Screen) and advanced instrumental techniques (e.g., video fluoroscopic swallowing study, surface electromyography). In rehabilitation, we review evidence-based interventions: behavioral approaches (e.g., oral muscle training, articulation therapy), physical therapies (e.g., neuromuscular electrical stimulation), neural modulation techniques (e.g., repetitive transcranial magnetic stimulation), and complementary methods (e.g., acupuncture). Finally, we discuss key challenges and future directions, including personalized treatment paradigms, artificial intelligence integration in assessment, and optimization of neural modulation parameters. This review provides a comprehensive theoretical framework and clinical reference for researchers and clinicians, aiming to advance effective, targeted therapeutic strategies.