File:Spinal cord anatomy.jpg

Summary

General anatomy of the human spinal cord. (a) Sagittal view of the spinal cord and vertebral column. The spinal column consists of 31 paired segments (8 cervical, 12 thoracic, 5 lumbar, and 1 coccygeal). The spinal cord is encased by the vertebral column (commonly known as the backbone or spine), which consists of 33 individual vertebrae [7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused), and 4 coccygeal (fused)]. (b) A close-up ventrolateral view over two spinal segments (C6–C7 is depicted as an example). The spinal cord itself is encased by the pia mater; together with the arachnoid mater it forms the leptomeninges. The leptomeninges envelops the spinal roots and blends with the perineum of the spinal nerves. The lateral extensions of the pia mater are known as the denticulate ligaments, which anchors the spinal cord to the dura via the arachnoid mater. The sub-arachnoid space is the gap in between the pia and arachnoid mater, and is filled with cerebrospinal fluid. Finally, the dura mater is the outermost layer; a tough, fibrous layer which serves to protect the spinal cord. The subdural space is a virtual space between the dura and arachnoid mater. Comprised of fat and small blood vessels, the epidural space is found in between the dura mater and vertebral column; it is a site of administration for some local anesthetics and analgesics. (c) Conus medullaris and spinal meninges. The conus medullaris is considered the end of the spinal cord. The filum terminale (internum, upper 3/4; externum, lower 1/4) is a fibrous band of connective tissue that serves to stabilize the distal end of the cord

Source:Tan S, Faull RLM, Curtis MA. The tracts, cytoarchitecture, and neurochemistry of the spinal cord. Anat Rec (Hoboken). 2023 Apr;306(4):777-819. doi: 10.1002/ar.25079. Epub 2022 Sep 29. PMID: 36099279.

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