| Meninges | the 3 layers of covering that surround the brain and spinal cord. Consists of the pia mater, the arachnoid, and the dura mater. |
| Meningitis | inflammation of the meninges. May be due to bacterial or viral infection. |
| Myelogram | special radiology study that involves injecting contrast dye into the spinal canal and taking x-rays of where the dye travels. The test is often followed by a CAT scan of the area. The test is often done to determine if there is blockage of flow or a nerve root that is being compressed. This test is less commonly used than MRI. |
| Myelomeningocele | herniation or protrusion of the spinal cord through a defect in development of the neural tube- seen in infants. Often associated with Chiari type II. |