• Lynton GF
• Giles DC

• Back Pain / etiology
• Dissection
• Lumbar Vertebrae / innervation
• Spinal Nerves / anatomy and histology

Gross dissection anatomical studies have investigated the course of the human lumbar posterior primary ramus and its branches. This nerve has frequently been associated with low back pain; however, the cross-sectional area of the space beneath the mamillo-accessory ligament, which is occupied by the medial branch of the posterior primary ramus, has not been clearly defined. The purpose of this study is to use a histological procedure to identify the cross-sectional area of the space beneath the mamillo-accessory ligament which is occupied by the medial branch of the posterior primary ramus as it passes en route to the zygapophyseal joint capsules. The main findings are that the medial branch of the posterior primary ramus occupies only a small percentage (approximately 3%) of the space enclosed by the mamillo-accessory ligament, and that it is surrounded by adipose tissue which provides an adequate protective "cushion" around it. Therefore, it is unlikely that the medial branch of the posterior primary ramus could be trapped beneath the mamillo-accessory ligament and cause pain.

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