The Tendino-Muscular Meridians (TMM) or Sinew Meridians, are secondary meridians named in Chinese Medicine JING JIN:

  • JING means: Texture of a fabric. Road drawn from north to south. Meridian, longitude.
  • JIN means: Tendons; muscles. Muscle strength. Physical force.

They represent, therefore, the muscular strength of a body oriented according to precise and immutable directions and rules. They are widely described in the Ling Shu at chap.13. They take their name from the Primary Meridian to which they are linked (see Main/Principal/Primary Meridians). 
The TMMs have an anatomical localization and an energy path that is the most superficial among all the Meridians (Primary and Secondary); in all their pathways they never penetrate at the level of the organs and viscera (Zang Fu).
The anatomical localization of the TMM usually similar to the pathway of the Primary Meridian that are connected to, but more superficial. In some of them the pathway is very different from their primary primary Meridian. In fact, points belonging to other Primary Meridians can also be part of a TMMs.
The TMM are related to a specific type of Energy called WEI QI, or Defense Energy. This is a much more dynamic and less nutritive energy, than the one that flows in the Primary Meridians. Wei Qi warms, protects, activates upright posture, and activates movement. But the more important function is to protect the body from External Pathogenic Factors (Cold, Humidity, Heat, Fire, Dryness, Wind).
For more information, see Tendino-Muscular Meridians (TMM) (Tendino-Muscular Meridians (TMM)).