The original presentation of auricular correspondence or the "inverted fetus" presentation came to be recognized as a somatotype which corresponds to normal physiology or to acute pain or dysfunction. In this model, the musculoskeletal (mesodermal) structures present in the upper aspect of the ear, covering the helix, antihelix, scaphoid fossa, and triangular fossa. 1,3,7,9,10(See figure 3) Visceral organs (endoderm) are identified in the concha, and the cephalic structures (ectoderm) present in the lobule. 11,13
In time, Nogier recognized that chronic and degenerative conditions presented in alternate auricular presentations, depending on the stage of illness. The respective embryologic tissue layers will shift in their auricular representation based on their Phase status. 3 According to this model, degenerative conditions are identified in Phase 2 presentation, wherein the fetus presentation "morphs" to an upright position. 3,5 (See figure 4) In Phase 2, the mesoderm presents in the concha, the endoderm in the lobule, and the ectoderm in the upper ear.(See figure 3) Degenerative conditions are more dense in their pathological presentation and represent the most serious progression of a pain or functional problem. Generally, though with exceptions, progression to Phase 2 will take weeks to months from the onset of the injury or illness.

Chronic conditions are identified as Phase 3 auricular correspondences. Phase 3 presents with the mesoderm in the lobule, the endoderm in upper ear, and the ectoderm in the concha.(See figure 2) The homonculus is now seen in a transverse presentation.(See figure 4) Chronic presentations will generally emerge within several days or weeks of the initial insult or injury. Depending on the stage of a patient's illness, the pathology may be identified in one or more locations within the ear. 3,5

As disease progresses, it is now known that the auricular reflection will shift from Phase 1 to Phase 3 to Phase 2. Phase 2 was recognized second, and it is thus labeled"2", in spite of the fact that Phase 2 represents a condition more chronic and degenerative than those seen in Phase 3. Recovery of illness follows the reverse pattern, from Phase 2 to Phase 3 to Phase 1. 1,5 (See figure 4)
Through extensive clinical observation, Nogier and his colleagues also identified 7 zones of the auricle which demonstrate favorable response to specific frequencies of electrical stimulation.(See figure 5) These zones are further influenced by specific Master Points within the respective zones, which exert generalized influence over their zone. In this model, the concha is identified as Zone "B" and includes the location of Zero Point. 1,5 (See figure 6) Specifically, Zero Point corresponds to the Master Point of Zone B and therefore has influence over the entire concha.

Often a physician's confusion regarding the significance of an auricular point will become clear when the anatomy and embryology is considered within these Phase dynamics. Further, a study of the auricular neurology and an appreciation of the influence of the zonal Master Points may lead to greater understanding of the clinical efficacy of various auricular points.

Zero Point:
Functionally, the Zero Point was used early as a reference point for auricular point electrodetection, as noted above. Zero Point has also been referred to as the "umbilicus", "vitelline duct", or "solar plexus" of the ear1,11, indicating its central physiologic importance for many body functions.

Anatomically, Zero Point lies in an area of innervation by the Vagus Nerve. Stimulation of the point may yield a significant parasympathetic effect which may be important for all endodermal structures found in the concha. Included in the superior concha are the Phase 1 representations of the abdominal viscera, including the small and large bowels, gall bladder, pancreas, et cetera; within the inferior concha are the lungs.(See figure 7) This parasympathetic effect has also been recognized to effect the auricular energetics, in general. Clinically, the parasympathetic tone may be enhanced or diminished depending on the specific direction of auricular massage. A centrifugal massage will diminish the parasympathetic tone as a probe or rod is used to massage outward from the Zero Point. Conversely, a centripital massage toward the Zero Point will enhance the parasympathetic tone of the ear. 1 The point has also been used to treat panic attacks by needling the non-dominant ear (generally ipsilateral to the dominant hand). 1

The location of Zero Point also corresponds to the Phase 2 cerebullum zone (See figure 8). Cerebellar functions include coordination of somatic motor activity, regulation of muscle tone, and mechanisms of equilibrium2,12. Its positive effects on emotional status and drug detoxification have been recognized among auricular therapists. 11 With such significant impact on the body's fundamental coordinating functions, it is not surprising that this point may be identified as an active point through electrostimulator detection in patients with pain or functional problems.

The Zero Point location is also shared by the Phase 3 corpus callosum (See figure 9). The role of the corpus callosum as neural relay is imperative for proper neurophysiological function. Abundant fibers connect to the cortex from the lower brainstem and spinal cord, and integration of information between the hemispheres is vital to to carry information which is essential to proper brain function. Disturbances of this neural integration may manifest as ADD/ADHD, stuttering, dyslexia, confusion with directions, and visual and auditory processing disturbances. 2 Chronic pain or functional illness may thus be represented at the Zero Point location because of the disturbance of corpus callosum.

Practicing advanced Auricular Therapy, with consideration of Phase dynamics rather than just the simple "inverted fetus", will thus give further clarification to the nature of the presenting pain or illness. Specific and definitive identification to the Phase of presentation is only made through the energetic techniques of Auricular Medicine, using the Vascular Autonomic Signal (VAS) of the radial pulse, and the electromagnetic field (EMF) signal of the auricle. 5 While further detail of Auricular Medicine is beyond the scope of this article, it is important to note that these are the techniques used to specifically identify the exact nature of the disturbance. With advanced Auricular Therapy techniques, clinicians have much greater information to be able to recognize an active auricular zone as a disturbance in one of 3 Phase presentations, rather than as a single point on the basic auricular somatotopic model.

Conclusions:
The significance of Zero Point may be more specifically recognized when the physician understands the neurological, anatomical and embryological implications, rather than simply the functional importance of this zone.3,7 Additionally, this advanced auricular acupuncture approach will lead to clearer diagnostic interpretation of a presenting illness as it is represented in one or more areas on the auricle. Ultimately, more enduring clinical effects may be realized with treatment of properly identified points. Proper identification and treatment of auricular points is encouraged for the physician to treat the patients' auricle in a true medical model rather than in a cursory technical approach.