The spinal arachnoid mater becomes continuous with the cerebral arachnoid mater as it traverses the foramen magnum and terminates at the S2 vertebral level 2. It is in direct contact but does not adhere to the inner aspect of the dura mater, from which it is separated by a thin film of lymph. The arachnoid mater sends many wispy web-like processes or trabeculae across the cerebrospinal fluid-filled subarachnoid space to the underlying pia mater 3. These form an incomplete posterior median septum in the posterior midline of the spinal cord 1.
The blood supply to the spinal arachnoid mater mirrors the other layers of the spinal meninges and comes from the one anterior and two posterior spinal arteries running the length of the spinal cord. Supply to these comes from the basilar portion of the circle of willis and is reinforced by the segmental arteries at each level which themselves originate from a variety of sources (see spinal cord blood supply)4.
The largest of these segmental arteries and the dominant supplying artery to the thoracolumbar spinal cord is the artery of Adamkiewicz which has a variable origin5.
The venous drainage principally follows the arterial supply. The anterior and posterior spinal veins drain into the segmental veins4.
The spinal arachnoid mater is innervated by sensory fibres of the meningeal branches of each spinal nerve. These fibres branch off from each spinal nerve near the bifurcation of the ventral and dorsal rami4.
- 1. McMinn. Last's Anatomy. Elsevier Australia. (2003) ISBN:0729537528. Read it at Google Books - Find it at Amazon
- 2. Hansen JT. Netter's Clinical Anatomy. Elsevier Health Sciences. (2014) ISBN:1455770639. Read it at Google Books - Find it at Amazon
- 3. Vandenabeele F, Creemers J, Lambrichts I. Ultrastructure of the human spinal arachnoid mater and dura mater. J. Anat. 1997;189 ( Pt 2): 417-30. Free text at pubmed - Pubmed citation
- 4. Susan Standring. Gray's Anatomy. (2015) ISBN: 9780702052309
- 5. Moore, Keith (2010). Clinically Oriented Anatomy. Philadelphia: Lippincott Williams and Wilkins. pp. 472–3
- spinal canal
- cervical spine
- thoracic spine
- lumbar spine
- vertebral body
- neural arch
- transitional vertebrae
- ossification centres
- intervertebral disc
- anterior longitudinal ligament
- posterior longitudinal ligament
- posterior ligamentous complex
- cervical spine ligaments
- iliolumbar ligament
- musculature of the vertebral column
- muscles of the neck
- muscles of the back
- gross anatomy
white matter tracts
- anterolateral columns
- lateral columns
- dorsal columns
- gray matter
- nerve root
- spinal meninges and spaces
- functional anatomy
- spinal cord blood supply