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Anatomy Atlases: Illustrated Encyclopedia of Human Anatomic Variation: Opus III: Nervous System: Spinal Nerves and Ganglia

Illustrated Encyclopedia of Human Anatomic Variation: Opus III: Nervous System

Spinal Nerves and Ganglia

Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD

Peer Review Status: Internally Peer Reviewed

There are a number of variations in the posterior (dorsal or sensory) and anterior (ventral or motor) roots and spinal ganglia. The first cervical nerve may either have no dorsal root or share a dorsal root with, or derived a dorsal root from the spinal accessory (CN XI) nerve. The dorsal root and ganglion of the first cervical nerve may be rudimentary or entirely absent. With this singular exception, the sensory or dorsal root of spinal nerves is always larger than the motor or ventral root. The anterior or posterior root (or both) are sometimes absent in one or more thoracic spinal nerves. The dorsal root ganglia associated with any one of the lumbar or upper sacral spinal nerves may be doubled. Ganglia aberrantia (small detached portions of spinal ganglia) may be found along the posterior roots of the upper cervical, lumbar, and sacral spinal nerves.

In the coccygeal region, anterior roots may be completely absent or increased in number (one, two or more). This is usually associated with an unusual number or arrangement of vertebrae. The spinal ganglion and sensory root of the coccygeal nerves may be absent; the same may occur to a lesser degree in other spinal nerves. Occasionally, rudimentary anterior roots are found in the filum terminale. One or two additional coccygeal nerves may be present bilaterally or only on one side.

Communicating branches between roots (dorsal or ventral) of adjacent spinal nerves may occur.

The majority of spinal ganglia are located in the intervertebral foramina, closely ensheathed but entirely outside the cavity or sac of the dura mater.

The ganglia of the fifth lumbar and first four sacral lie within the vertebral canal, but these are also extradural. The fifth sacral and the coccygeal nerves (when present) are located within the dural cavity. This may also be true of the first cervical ganglion when it is present.

Blood Supply of Nerves, 1 - 22

Blood Supply of Nerves, 23 - 29

Blood Supply of Nerves, 30 - 41

Blood Supply of Nerves, 42 - 60

Blood Supply of Nerves, 61 - 74

Blood Supply of Nerves, 75 - 90

Blood Supply of Nerves, 91 - 105

Blood Supply of Nerves, 106 - 117

Blood Supply of Nerves, 118 - 122

Blood Supply of Nerves, 123 - 127


Bartholdy, K. (1897) Die Arterien der Nerven. Morphologische Arbeiten 7:393-456.

Henle, J. (1868) Handbuch der Systematischen Anatomie des Menschen. von Friedrich Vieweg und Sohn., Braunschweig.

Huber, G.C., Ed. (1930) Piersol's Human Anatomy, 9th ed., L.B. Lippincott Co., Philadelphia.

Kopsch, F. (1908) Rauber's Lehrbuch der Anatomie des Menschen. Georg Thieme, Leipzig.

Latarjet, A. (1948) Testut's Traité d'Anatomie Humaine, 9th ed., G. Doin & Cie., Paris.

Schaefer, E.A., Symington, J. and T.H. Bryce., Eds. (1915) Quain's Anatomy, 11th ed., Longmans, Green, and Co., London.

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