Glossary

The Eighteen Pathologies are diseases that can affect any system, mentioned by Zhang Zhongjing in the introduction to the Jin Gui Yao Lue, lines 16-18.

The student asks "Yang diseases are 18, what does this mean (陽病十八，何謂也)?" to which the Master replies that these are:

頭痛 Tou Tong:		Headache,
項 Xiang:		Neck,
腰 Yao:		Waist,
脊 Ji:		Spine,
臂 Bi:		Arm and
腳 Jiao:		Foot
掣痛 Che Tong:		Pulling pain

Next, the Student asks: "Yin diseases are 18, what does this mean (陰病十八，何謂也)?" to which the Master replies:

欬 Kai:		Cough
上氣 Shang Qi:		Rising Qi
喘 Chuan:		Wheezing
噦 Hui:		Vomiting
咽 Yan:		Sore throat
腸鳴 Chang Ming:		Bowel sounds
脹滿 Zhang Man:		Distention
心痛 Xin Tong:		Heart pain
拘急 Ju Ji:		Sudden arrest

In the next line it ennumerates that the Five Zang (臟) have 18 diseases each, totalling 90 (五藏病各有十八，合為九十病), and that man has 6 "minor" systems (微), which also have 18 diseases each, totalling 108 diseases (人又有六微，微有十八病，合為一百八病). The Five Taxations (五勞), Seven Injuries (七傷), Six Extremes (六極) and 36 Women's Disorders (婦人三十六病) are not among them (不在其中).

Analysis

It is notable that these do not add up to 18. All that is certain is that the Yang diseases are Exterior, muskuloskeletal disorders while the Yin diseases refer to Internal dysfunctions of the Zangfu (臟腑). While only the Zang are mentioned specifically, the symptoms given appear to include various Fu, especially "vomiting" that comes from the Stomach and "bowel sounds" from the Intestines, and seem to be included as subordinates of the Zang.

The Yang diseases could be extrapolated to 18 if "arm" and "foot" counts all 6 joints on the limbs (shoulders, elbows & wrists on the upper; hips, knees, ankles on the lower) on both sides to make 12 plus fingers and toes counted as two grouped entities to make 14, plus head, neck, waist and spine (+4 = 18). These are probably what is referred to as the Six Minors (六微) since their diseases are less severe and the Channel system is divided into Six Divisions (六經) which all cross those areas making 108 possible disease patterns for muskuloskeletal pain patterns and headaches.

The Yin Diseases only list 9 and many of these are referring to one specific system. However, if the pathomechanism behind each symptom is identified, then they may be referring to a set of universal pathomechanisms that can affect any Zang or Fu, using the most exemplary manifestation as an example. This would then make 18 disorders for each pair (9 each).

What remains is to decipher the pathomechanism implied by each symptom given. My interpretation is as follows:

欬 Kai:		Cough		滯 Shi:		Excess / Stagnation
上氣 Shang Qi:		Rising Qi		逆: Ni:		Rebellion / Counterflow
喘 Chuan:		Wheezing		虛 Xu:		Deficiency / Emptiness
噦 Hui:		Vomiting		滑脱 Hua Tuo:		Leakage / Loss
咽 Yan:		Sore throat		熱 Re:		Heat
腸鳴 Chang Ming:		Bowel sounds		風 Feng:		Wind
脹滿 Zhang Man:		Distention		濕 Shi:		Dampness
心痛 Xin Tong:		Heart pain		失神 Shi Shen:		Loss of Shen aspect
拘急 Ju Ji:		Sudden arrest		厥 Jue:		Reversal / Sense Obstruction

The reason Cold and Dryness are not included in this list is because the body is fundamentally a hot, wet and transformative environment so Heat, Dampness and Wind are Pathologies that can be generated internally, while Cold and Dryness are a result of External invasion or Deficiency that lead to the inner environment becoming Cold or Dry.