Embryologically the tongue develops from the foregut. The primitive pharynx develops from the foregut. The pharyngeal apparatus consists of arches, grooves, membranes, and pouches. Each pharyngeal arch consists of a core of mesenchyme covered externally by ectoderm and containing an aortic arch artery, a bar of cartilage, a nerve, and muscle tissue.
The first pharyngeal arch produces two distal tongue buds (lateral lingual swellings) that form the anterior two-thirds of the tongue, and a median tongue bud (tuberculum impar) that has no identifiable adult derivatives.. The hypobranchial eminence overgrows the copula, forming the posterior third of the tongue. Some of the tongue muscles probably develop in situ from mesenchyme, but most develop from myoblasts that migrate from the occipital myotomes. The connective tissue, lymphatic vessels, and blood vessels of the tongue arise from pharyngeal arch mesenchyme.
The hypoglossal nerve innervates all intrinsic and extrinsic tongue muscles, except M. palatoglossus innervated by the vagus nerve. The general sensory innervation of the tongue depends upon pharyngeal arch contribution.
In a healthy individual, the tongue should have a solid, fleshy pink colour, with a thin whitish coating over the whole area. There should be an absence of other distinguishing features. As an acupuncturist and naturopathic physician I continue to remain fascinated by the diagnostics of the tongue.
The tongue can give valuable information on organ function. Many meridian lines run through the tongue and thus it is an important location of bodily function. During sickness the tongue will appear duller and even a different colour and texture than when it is healthy. Similarly the tongue may appear bloated when the body is experiencing edema or disorders that cause water retention. Marking on the tongue can relate to the lungs, gastro-intestinal, spleen, gall bladder and liver, kidney, urinary bladder and sex hormones.
Patients with pulmonary and or respiratory problem, the area just behind the tip of the tongue will be red or spotted like a strawberry. Tip of the tongue red refers to heart problems as well as worrying too much, nervousness. It also extends to hyperthyroid activity, acute appendicitis or the symptoms of PMS. (herbals like hawthorn will be useful)
Liver/ gall bladder problem – Sides of tongue reddest (Liver herbals like Milk Thistle or Dandelion, no alcohol).
If whole tongue is red and patient experiences dry mouth, then stomach problem.(Herbals like licorice, lotus root).May also be due to bacteria infecting the blood. (herbals like Echinacea)
Red spot on the tip of the tongue- person overworking, may experience insomnia and stress. Also deficiency of vitamins and nutrition.( Rest, relaxation , a spa holiday, multivitamins, valerian to help in sleep).If both sides of tongue are red, person may suffer from high blood pressure and a hyperactive thyroid.
Cracks in the tongue refer to B complex deficiency, chronic digestive problems, kidney, spleen and stomach problems (TCM style).
Cracking down the centre of the tongue towards the back is due to poor kidney function. Cracking closer to the centre is due to stomach or gastrointestinal problems and is also known as fissured tongue. If there are cracks running horizontally across the tongue in the middle area, it may also be a kidney problem and if there is a crack along the edges it’s a spleen problem. Any crack over 2 mm should be considered a serious condition and be given attention immediately. Asparagus extracts, Digestive enzymes and B Complex may be useful.
Tongue coating refers to the influential levels of heat and cold in the body. If you don’t feel well, obviously the sense of self esteem will take a beating. Generally the thicker the coating, the worse the problem. If the root of the tongue has a coating but no coating elsewhere, the condition is acute.
Respiratory – A thick coating all over the tongue. Thicker the coating and more mucosy, the worse the problem. Use herbal formulas for the lungs like mullein. Adopt a diet that is bland, warm food (cold hurts the lungs).
Stomach problems – yellowish white coating signals digestive problems. A diet like the above. Herbs like licorice or lotus root can be useful.