medial branch of posterior rami of cervical/thoracic/lumbar/sacral/coccygeal spinal nerves
terminal branch (with the lateral branch) of the posterior ramus of spinal nerves. In the thoracic region, the medial branches of the upper thoracic spinal nerves are musculocutaneous, supplying and continuing through the muscles of the back to reach the overlying skin; the medial branches of the lower thoracic spinal nerves are muscular only, terminating before reaching the skin.
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