Pacific Wellness Institute Clinic: Bloor-Yorkville Toronto

Tongue Examination of Sublingual Veins



Tim H. Tanaka, Ph.D.

ICMART 2011 World Congress on Medical Acupuncture,

The Hague, Netherlands, May, 2011


Observation of sublingual vein (SLV) appearance is considered as a vital component of traditional tongue diagnosis. Tongue appearance can vary due to both internal and external factors, including the fact that tongue shape and the appearance of SLVs can change depending on the way a patient sticks out his/her tongue. However, most TCM texts fail to mention it or offer ambiguous information when it comes to SLV inspection. In order to clarify the matter, a series of digital images of the tongue at different tongue elevation angles have been taken. Those images were inspected based on four different diagnostic parameters and evaluated morphological and color alterations of SLVs within the subject.


142 subjects (mean age: 39.1±9.6) were asked to stick out their tongues in three specific ways, using anatomical landmarks and palate diagrams. The variations were designed to create approximately three different tongue angles (approximately 30, 45, and 80 degrees).  Subjects held each tongue position approximately for 1 second in relaxed manner while photo being taken. There were about 5 second intervals between the three tongue positions.

Subjects’ tongue images were captured using a digital SLR camera with a macro lens and twin flash system. Focal length (70mm), aperture (F19), color temperature (5500 K), and other settings remained consistent throughout the examinations.

Acquired images were transferred to PC, and then morphological and color characteristics of SLVs were evaluated on 4 commonly used parameters, which are length, thickness, tortuousness (including varicosis and nodule) and color of the SLV. Alterations on each parameter were classified as “no change”, “moderate change” and “marked change”


A total of 426 images from 142 subjects were carefully examined on PC monitor. There were marked changes on length (24.6%, n=35), thickness (20.4%, n=29), tortuousness (14.8%, n=21) and color (16.9%, n=24,) of the SLV. Abnormal characteristics of SLVs were pronounced on both occasions when subjects tongue elevation was larger and smaller.

Discussion and Conclusion:

It has been stated that abnormal SLV appearance may be suggestive of conditions including hepatitis, coronary heart disease, and hypertension. In Traditional East Asian Medicine, it is generally considered to reflect a disease pattern of blood stasis.

In the present study, notable alterations of SLV appearance were observed in multiple cases, depending on the tongue angle. It suggests the vital importance of developing standardized SLV inspection procedures to minimize intrasubject variability and enhance reproducibility of this widely used traditional diagnostic method.