Human spinal arachnoid septa, trabeculae, and “rogue strands”

Abstract

This study was undertaken because of confusion arising from a diversity of names, descriptions, and drawings of the human spinal subarachnoid septa and trabeculae in the standard texts and dictionaries. Sixty-two complete human cords were examined under the dissecting scope. The finely "woven" adult arachnoid membrane was two-layered, and there were essentially no connecting septa or trabeculae between the cord and the arachnoid membrane anteriorly. Posteriorly, in the upper cervical region there is a scanty series of connecting fibers and fenestrated sheets 1 or 2 mm on either side of the midline; these become progressively more extensive in the lower cervical region, remain extensive to the lumbar enlargement, beyond which they progressively dwindle to end abruptly at the filum terminale origin. Throughout the cauda equina, strands are haphazardly arranged connecting the roots and supporting blood vessels. These occasionally become tangentially adherent to the arachnoid membrane. Throughout the length there are many unexplained, redundant, nonbranching, beaded, thicker "rogue strands". All of the above are of a different character from the right-angle fiber arrangement of the denticulate ligament, the two leaves of which are often separated form segmental longitudinal tunnels. The nerve rootlets (fila radicularia) for each dermatome are joined by strands and webs to each other. There was no evidence of change in number or type of connection with age.

Architecture of arachnoid trabeculae, pillars, and septa in the subarachnoid space of the human optic nerve: anatomy and clinical considerations

“…[1][2][3][4][5][6][7][8] In order to find appropriate terminology for the structures transversing the spinal subarachnoid space, Parkinson used the terms arachnoid septa, trabeculae, and "rough strands." 9 A classification of cranial arachnoid trabeculae in stout, columnar or sheet-like types was suggested by Delmas. 10 The same paper describes a close association of the trabeculae with blood vessels, a finding that also was confirmed by Alcolado. 11 Detailed information on anchorage of the fibroblasts that form the arachnoid trabeculae in the arachnoid and the pia layer is provided by Haines.…”

Complete failure of spinal anaesthesia in obstetrics

“…[26][27][28] Such anatomical barriers might limit or even prevent the flow of correctly injected local anaesthetic agent to the nerve roots, but their presence has not, to the authors' knowledge, been demonstrated clinically in association with complete failure of spinal anaesthesia.…”

Nerve fibers innervating the cranial and spinal meninges: Morphology of nerve fiber terminals and their structural integration

“…The trabecular leptomeninx is mainly restricted to the dorsal part with few trabecles in the upper cervical region. It becomes most prominent in the dorsal lumbar region and diminishes more caudally at the filum terminale (Parkinson, 1991). On each side of the spinal cord, the denticulate ligaments connect the lateral circumference of the pial leptomeninx and the dura mater.…”