## Structural Differences Between Medial and Lateral Menisci ### Key Anatomical Distinctions **Key Point:** The medial meniscus is C-shaped, firmly attached to the joint capsule (especially the posterior capsule), and relatively immobile. The lateral meniscus is O-shaped (nearly circular), loosely attached to the capsule, and highly mobile. ### Comparative Table | Feature | Medial Meniscus | Lateral Meniscus | | --- | --- | --- | | Shape | C-shaped (crescent) | O-shaped (nearly circular) | | Capsular attachment | Firm (especially posteriorly) | Loose and minimal | | Mobility | Relatively fixed | Highly mobile | | Posterior horn attachment | Firm to posterior capsule | Loose; popliteus muscle origin | | Injury pattern | Longitudinal tears (bucket-handle) | Peripheral tears; less prone to entrapment | | Relation to ACL | Firm posterior attachment | Loose; can move with femoral rotation | ### Clinical Correlations **Clinical Pearl:** The firm capsular attachment of the medial meniscus makes it prone to being trapped and torn during knee flexion-extension movements, whereas the lateral meniscus's loose attachments allow it to escape entrapment and thus sustain fewer tears overall. **High-Yield:** The medial meniscus's firm posterior capsular attachment is why it is more commonly injured in degenerative joint disease and why posterior horn tears are more clinically significant on the medial side. ### Mnemonic **MEDIAL = More Attached, Firm, Less mobile** **LATERAL = Loose, Agile, Moves freely** [cite:Gray's Anatomy 42e Ch 8] 
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