Human Anatomy, Part 2 - K. A. Diubenko, A. K. Kolomiitsev, Yu. B. Chaikovskyi 2008

Special Part
Nervous system, systema nervosum - Special Part
Spinal cord - Meninges of the spinal cord

The Spinal Cord is enclosed by three Connective Tissue Meninges (Fig. 130). On the outside is the dura mater, dura mater spinalis (pachymeninx), which is formed of dense Fibrous connective tissue. Deeper lies the arachnoid mater, arachnoidea mater spinalis, an avascular layer of fibrous connective tissue. Directly adjacent to the spinal cord tissue is the pia mater, pia mater spinalis (leptomeninx), which is also composed of fibrous connective tissue but, unlike the arachnoid, contains a network of Blood Vessels of the spinal cord.

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Fig. 130. Meninges of the spinal cord, meninges medullae spinalis (superior view) after R. D. Sinelnikov

Upon exiting the foramen magnum, the spinal dura mater, dura mater spinalis, divides into two layers: outer and inner (H. Corning). The outer layer lines the walls of the vertebral canal and fuses tightly with the periosteum. The inner layer forms the dural sac, which expands caudally and reaches the II—III sacral vertebrae. Below the conus medullaris, the membrane continues as the external terminal filum of the spinal dura mater, filum terminale externum (durale), which attaches to the periosteum of the coccyx. Between the two layers of the dura mater lies the epidural space, cavitas epidurale, which contains the vertebral venous plexus, plexus venosus vertebralis, and loose adipose tissue. At the level of the intervertebral foramina, the dura mater forms funnel-shaped sheaths for the spinal nerve roots, spinal ganglia, and spinal nerve trunks. As a result, the dural sac is firmly anchored to the vertebral canal. The spinal arachnoid mater, like the dura mater, is a sac-like membrane surrounding the spinal cord. Between the dura and the arachnoid lies a slit-like subdural space, spatium subdurale. The subarachnoid space, spatium subarachnoideum, is the cavity between the arachnoid and pia mater. It is wider than the spatium subdurale, especially in the anterior and posterior regions, reaching 1-2 cm; it is filled with CEREBROSPINAL FLUID, liquor cerebrospinalis, and communicates with the cranial subarachnoid space (cavum subarachnoidale). The arachnoid mater is connected to the dura mater in the area where the nerve roots exit through the dura. It is connected to the pia mater by numerous connective tissue trabeculae that form the posterior subarachnoid septum. In addition, the arachnoid mater is connected to the dura mater, as well as to the underlying pia mater, by the denticulate ligament, lig. denticulatum. The spinal pia mater, pia mater spinalis, is somewhat thicker and stronger than that of the Brain. It closely adheres to the external surface of the spinal cord and penetrates into its anterior median fissure. The denticulate ligaments, numbering 20-30, originate from the pia mater between the anterior and posterior roots and attach to the spinal dura mater.