Originating from ulnar border of little finger and absorbs qi of heart meridian of hand-shaoyin. Going along ulnar end of little finger, ulnar end of the fifth metacarpal bone, passing between ulna styloid process of wrist and triquetral bone and ascending along posterior lateral side of ulna it reaches between olecranon process of ulna and epicondylus of humerus. Passing between caput and lateral head of triceps brachii and running along dorsal side of triangular muscle to spine of scapula below, it runs obliquely along superior angle of shoulder-blade upward to shoulder. Going forward from shoulder to supraclavicular fossa, and then running downward to chest, it is distributed in heart along lower branch of esophagus. The trunk descends along esophagus, penetrates disphragmatic muscle and passes through stomach, then is distributed in small intestine. It goes up along neck from supraclavicular fossa branch, passes through angle of mandible, runs obliquely toward to external canthus, and turns backward along upper border of ansa capitis to the anterior aspect of ear then penetrates into ear. Forking from lower mandible, it runs obliquely below cheek bone and goes around nasal side, ascends to inner canthus and is associated with bladder meridian of foot-taiyang which associates qi of bladder meridian. There is a small branch which runs obliquely upward and is distributed in zygomatic region.

Another branch which arises from small intestine, runs downward, then comes out of abdomen and runs obliquely between stomach meridian and spleen meridian of foot-taiyin, it connects with stomach meridian at Xiajuxu (ST39) acupoint.

Collateral of Small intestine meridian of hand-taiyang:
Originating from Zhizheng acupoint of small intestine meridian of hand-taiyang at lateral side which is 5 cun behind wrist, forking two branches from here, the first branch comes across and connects with meridians in internal and external relation- heart meridian of hand-shaoyin which is at medial side of ulna, forming intercommunication gangway of qi of meridians in internal and external relation. The second branch which is the only great collateral distributed in shoulder joint floats along small intestine meridian, passes lateral side of ulna, ulnar end of olecranon process of ulna and triceps brachii, then reaches posterior aspect of shoulder joint and is distributed above shoulder joint.

Divergent collateral of Small intestine meridian of hand-taiyang:
Forking from small intestine meridian of hand-taiyang at dorsal side of triangular muscle which is at posterior lower aspect of shoulder joint, and then running downward to oxter, ascending from rib to costal bone, crossing to sternum from collarbone and descending to chest from esophagus, it is distributed in heart. Lower branch passes through disphragmatic muscle, goes along stomach downward and is distributed in small intestine, forming the connection in parallel which enforces the relationship between small intestine meridian of hand-taiyang and two viscera.