Called in Chinese the "Jade Pillow" (Yu Chen), and referred to by Mantak Chia as the Small Brain (Cerebellum) Centre, this chakra lies at the opening of the base of the skull, above the first cervical (neck) vertebra.  It is part of a pump that draws spinal fluid and chi energy upwards, as well as promoting yin energy and helping to balance the yang energy of the Large Brain (Cerebrum).[Chia, p.214].

This very important centre connects with the Crown Chakra at the top of the head [Paulson, p.70]. Ann Ree Colton calls this the "Mouth of God" or "Bindu" Center, and identifies it with the Medulla oblongata at the base of of the skull, in the proximity of the brain stem. This is the centre where one connects with the cosmic mantra or "logos" [Colton, Colton, The Third Music , p.272]. It also controls the in-and out-breath, hence the association of breathing, sound, and mantra [Colton, Kundalini West, p.38]. Ann Ree Colton adds that this centre can be damaged through excessive drug-use, leading to mental unbalance [Colton, The Third Music , pp.58-9].  Due to the association with the breath, one could suppose that asthma, laryngitis, and other respiratory problems could arise from an imbalance here [Tansley, Radionics and the Subtle Anatomy of Man, p.42]

Correspondences:

None given.

Associated Psychological states:

Open and Balanced: You receive spiritual inspiration [Chia, p.216], and are able to acknowledge yourself as one with the Godhead, and can harmonise lower insights with an understanding of the higher purpose in your life [Paulson, p.77].

Overactive: You are too preoccupied with higher levels of existence at the expence of the everyday human level [Paulson, p.78]

Malfunctioning: You may suffer from illusions [Chia, p.216] and fantasies, and perhaps mental unbalance [Colton, The Third Music] and schizophrenia.

Blocked: You are too preoccupied with the ordinary human mundane level of existence [Paulson, p.78]; you may feel your life to be suffocatingly limited, one may suffer from headaches (due to too much pressure in the upper brain) [Chia, p.216].

Chakra balancing

This centre is not mentioned in the Tantric system.  Some Kabbalists associate this position, the base of the skull, with the sefirah Daat or Daath, "Knowledge", which bridges the "abyss" between the seven lower and the three higher sefirot.  This sefirah is usually associated with Pluto.  However, if the Lower Vishuddha centre corresponds to Mars, then this centre would represent the Asteroid zone between Mars and Jupiter, which in a sense is also an "abyss" (since there is no major planet where one would expect to find one there) that is between the inner "rocky" planets and the outer "gas giants".  Frater Albertus locates the largest asteroid, Ceres, in this position [The seven Rays of Qbl ].

major and minor Chakras | Notes on Psychological terms

rear chakras ascending		front chakras descending
Crown
Back of Head		upper forehead
		forehead
Mouth of God		Talu/Lalana
Back of Neck		Throat
Base of Neck		Thymic
Shoulder Blades		Heart
Diaphragmatic		Solar Plexus
Door of Life		Navel / Sea of Ch'i
Sacral		Pubic
Coccygeal
Perineum