The kidney governing the bones means that the development and functions of the bones depend on the kidney-essence. The kidney stores essence and the essence can transform into bone marrow to nourish the bones, promote the growth and repair of the skeleton and strengthen the skeleton. If kidney-essence is deficient, it will affect the production of bone marrow, leading to flaccidity of the skeleton and hypoevolutism in infants as well as brittleness of bones and susceptibility to fracture in the aged.

The teeth are the extensions of the bones. Both the bones and teeth need kidney-essence to nourish. If kidney-essence is abundant, the teeth are firm and not easy to lose. If kidney-essence is deficient, the teeth will grow slowly in infants and tend to become loose or even lose in adults.

Kidney-essence produces marrow and the ears are connected with the cerebral marrow. Thus the functional states of the ears are closely related with kidney-essence. When the kidney-essence is sufficient, the cerebral marrow will be sufficient and the ears will be keen in hearing. If kidney-essence is insufficient, the cerebral marrow will be deficient and the ears will become weak in hearing, leading to tinnitus and deafness. The reason that old people tend to be poor in hearing lies in the fact that kidney-essence declines naturally when people are growing old.

The relationship between the kidney and the external genitals can be understood from the functions of the kidney to govern water and reproduction. For example, the excretion of urine must depend on the function of the kidney to transform qi. So the symptoms of frequent urination, enuresis, incontinence of urine and anuria are usually caused by failure of the kidney to govern water. Besides, the function of the kidney to govern reproduction also covers the function of the external genitals. Thus failure of the kidney to govern reproduction may lead to impotence, premature ejaculation and seminal emission, or leukorrhea.

     

The relationship between the kidney and the anus refers to the fact that the kidney influences the functions of the spleen, the large intestine and the anus to control defecation through kidney-yin and kidney-yang. The function of kidney-yang is to absorb water by warming to promote the formation of feces. The function of kidney-yin is to moisten the intestines and the anus to smooth defecation. 

So insufficiency of kidney-yin and kidney-yang all lead to disorder of defecation. For example, insufficiency of kidney-yin leads to constipation due to intestinal dryness; deficiency of kidney-yang brings on insufficiency of spleen-yang, consequently causing diarrhea due to disorder in transportation and transformation.

     

The hair depends on blood to nourish. That is why it is said that "the hair is the extension of blood." Since the kidney stores essence which can transform into blood, exuberance of essence and blood will make the hair appear thick and lustrous. If the kidney-essence is insufficient and blood is deficient, the hair will appear thin, dry, white and easy to lose. So the state of the hair is closely related to the kidney-essence. That is why it is said that "the kidney focally manifests itself on the hair".