Arachnoid mater

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Brain: Arachnoid mater
The medulla spinalis and its membranes.
Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc.
Gray's	subject #193 876
Part of	Meninges
NeuroNames	ancil-561
MeSH	Arachnoid
Dorlands/Elsevier	a_56/12149123

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Overview

The arachnoid mater is one of the three meninges, the membranes that cover the brain and spinal cord. It is interposed between the two other meninges, the more superficial dura mater and the deeper pia mater, and is separated from the pia mater by the subarachnoid space.

The delicate, spiderweb-like (therefore the name) arachnoid layer, attached to the inside of the dura, surrounds the brain and spinal cord but does not line the brain down into its sulci (folds). Cerebrospinal fluid flows under this membrane in the subarachnoid space, which is full of the delicate fibres of the arachnoid extending down to attach to the pia mater.

The portions covering the brain and spinal cord are called arachnoidea encephali and arachnoidea spinalis, respectively.

The arachnoid and pia mater are sometimes considered as a single structure, the leptomeninx, or the plural version, leptomeninges. (Lepto- from the root meaning thin in Greek). Similarly, the dura in this situation is called the pachymeninx.

Etymology

Arachnoid is from a Greek root, and means cob web like. The mater designation (meaning mother in Latin) is borrowed from the dura mater and pia mater, which were Latin translations of Arabic terms. While mater does not technically belong with the arachnoid layer, it has nevertheless been adopted by it for uniformity with the other meninges, and arachnoid mater is currently the Terminologia Anatomica international standard.

Additional images

Meninges of the CNS

Diagrammatic section of scalp.

References

• Orlando Regional Healthcare, Education and Development. 2004. "Overview of Adult Traumatic Brain Injuries." Retrieved on 2008-01-16.

External links

• SUNY Figs 02:05-09
• Slide

See also

• Arachnoid cyst

v • d • e Anatomy: meninges of the brain and medulla spinalis
Layers	Dura mater (Falx cerebri, Tentorium cerebelli, Falx cerebelli, Diaphragma sellae) Arachnoid mater (Arachnoid granulation) Pia mater
Spaces	Epidural space - Subdural space - Subarachnoid space (Cerebrospinal fluid)
Subarachnoid cisterns	Cisterna magna - Pontine cistern - Interpeduncular cistern - Chiasmatic - Lateral cerebral fossa - Of great cerebral vein

v • d • e Anatomy of torso (primarily): the spinal cord
Spinal nerve	Dorsal (Root, Ganglion, Ramus) • Ventral (Root, Ramus) • Sympathetic trunk • rami communicantes (Gray, White)
Gray matter/Rexed laminae	Posterior horn (Posteromarginal nucleus, Column of Clarke, Substantia gelatinosa of Rolando, Nucleus proprius) Lateral horn/Anterior horn (Intermediolateral nucleus) Central canal/Substantia gelatinosa centralis - Gray commissure
White matter	somatic/ascending (blue) Posterior/PCML: touch: Gracilis • Cuneatus Lateral: proprioception: Spinocerebellar (Dorsal, Ventral) • pain/temp: Spinothalamic (Lateral, Anterior) • Posterolateral (Lissauer) • Spinotectal motor/descending (red) Lateral: Corticospinal (Lateral) • Ep (Rubrospinal, Olivospinal) Anterior: Corticospinal (Anterior) • Ep (Vestibulospinal, Reticulospinal, Tectospinal)
Layers	Epidural space • Dura mater • Subdural space • Arachnoid mater • Subarachnoid space • Pia mater
Other structures	Denticulate ligaments • Conus medullaris • Cauda equina • Filum terminale • Cervical enlargement • Lumbar enlargement Anterior median fissure • Posterior median sulcus Anterior white commissure

fr:Arachnoïde

it:Aracnoide (anatomia) nl:Spinnenwebvlies ja:クモ膜 no:Spindelvevshinnesv:Arachnoidea th:เยื่ออะแร็กนอยด์

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Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .