The energy of a hexagram.

The Yin    The Yang
A lower line Yang indicates the period of the ascending celestial yang, from the winter solstice to the summer solstice. A lower line Yin indicates the period of increasing yin terrestrial, from summer solstice to winter solstice.

The energy of the 3 fields and 3 Sections.

The lesser (young or little) yang   The Greater yang   The lesser (or little) yin   The greater (Complet or Old) yin   
A hexagram comprise 3 superimposed bigrams. There are 4 possible bigrams: Shao yang , Tai yang, Shao yin, Taï yin,
These 3 superimposed bigrams represent the state of energy in the 3 energy fields of the human environment: the Terrestrial, Human and Celestial Fields.
These 3 Fields are the ground (surface and subsoil) for the Terrestrial Field, the middle space for the Human Field, and the Near Sky (the one above our heads, which also includes the sun, moon and planets but not the stars) for the Celestial Field.
In the human organism these 3 Fields have their correspondences in the 3 Sections of the body. These sections are in resonance with energy of the 3 Fields. The lower part of the body, or Terrestrial Section, from the pelvis to the feet, is in resonance with the Terrestrial Field; the middle part, or Human Section, from waist to the top of the trunk, is in resonance with the Human Field; the upper part, or Celestial Section, from the top of the trunk to the top of the skull, resonates with the Celestial Field.

Energy of Heaven (yang) and Earth (yin).

Zhen       Li      Dui    Qian   
Xun      Kan    Gen     Kun

A hexagram is also composed of 2 superimposed trigrams. The lower trigram represents the Earth energy, the upper one the Celestial energy. In the human body the Earth energy is the physical, the Celestial energy is the dynamic energy.
There are 8 trigrams, also called the 8 energizers or 8 Winds in the Su Wen, which are related to the 8 directions, paired with the 5 elements and the meridians.

Table of relations between trigrams, 5 elements, meridians and pathologies according to Fu Xi's Anterior Heaven logical order.

Trigramme	Name	Nomber	Orient	Element	Organ/Channel	Pathologies
	Kan Water	1	N	Water	Kidneys urinary bladder	Kidneys Ears Sang
	Kun Earth	2	S W	Earth	Ren Mai	Spleen Abdomen Digestion
	Zhen Thunder	3	E	Wood	Master of the heart Three Heaters	Feet Lungs Gorge
	Xun Wind	4	S E	Wood	Liver Gall Blader	Diaper Thighs
		5	Center	Earth		Spleen Stomach Fascias
	Dui Lake	7	W	Metal	Lungs Large intestine	Breath Headache
	Qian Sky	6	N W	Metal	Du Mai	Head Lunngs Mouth
	Gen Mountain	8	N E	Earth	Spleen Stomach	Hands Fingers Back
	Li Fire	9	S	Fier	Heart Small intestine	Heart Eyes

There is also in the Chinese medical tradition a relationship between the trigrams and the 8 meridians wonderful. The trigrams are arranged according to King Wen Posterior Heaven manifested order

Trigramme	Name	Orient	Channel
	Kan Water	N	Yang jiao mai
	Kun Earth	S W	Yin jiao mai
	Zhen Thunder	E	Yang wei mai
	Xun Wind	S E	Dai mai
	Dui Lake	W	Du mai
	Qian Sky	N W	Chong mai
	Gen Mountain	N E	Yin wei mai
	Li Fire	S	Ren mai

Pulses and hexagrams.
A hexagram includes 6 vectors, each being yin or yang. The general energy also includes 6 vectors including 3 yin: jue yin, shao yin, tai yin and 3 yang: shao yang, yang ming, tai yang. These 6 vectors can be found on the pulse, which includes 6 superficial pulse, related to 6 yang (Fu) entrails and 6 energies, and 6 deep pulses related to 6 yin organs (Zhang) and 5 Movements.

Here is Su Wen's definition of pulse (there are some differences with contemporary definition):
To left, elbow: The superficial, external pulse responds to the left kidney (yang) and to the deep organs of the abdomen; the deep, internal pulse responds to the last ribs on the left.
to left, barrier: External to liver, internal to diaphragm.
To left, thumb: External to heart, internal to mediastinum
To right, elbow: External to right kidney (yin) and deep organs of the abdomen, internal to last ribs to the right.
To right, barrier: External to spleen and pancreas, internal to stomach.
To right, thumb: External to lungs, internal to thorax interior.

Study hypothesis:
A yang trait in a hexagram is defined as an energy in fullness (fullness rather than excess) of a yang meridian, a yin trait as a full energy of a yin meridian. The cycle of the maximum energy amplitude in the meridians is the same as that of the hours.