Wei Collection, Lower Volume
Radical: Meat (ròu)
肋
Kangxi strokes: 8
Page 973, Entry 05
Pronounced le (rising tone). According to the Tang Rhyme (Tangyun), Collection of Rhymes (Jiyun), Rhyme Compilation (Yunhui), and Orthodox Rhyme (Zhengyun), the pronunciation is the same as the character pronounced le.
Explanation of Writing (Shuowen): Refers to the bones of the chest.
Broad Rhyme (Guangyun): Refers to the area on the side of the chest.
Orthodox Rhyme (Zhengyun): Refers to the trunk of the chest and abdomen.
Explanation of Names (Shiming): The word for rib implies restraint. It is used to constrain the five internal organs.
Also, according to the Collection of Rhymes (Jiyun), it is pronounced jin (level tone), with the same pronunciation as the character pronounced jin. This refers to the strength of the muscles. It is the same as the character for tendon. See the detailed annotation under the Bamboo (zhú) radical for the character for tendon.