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

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 (hence 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.

Contents 1 Etymology 2 Additional images 3 References 4 External links 5 See also

[edit] 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.

[edit] Additional images

Meninges of the CNS

Diagrammatic section of scalp.

[edit] References

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

[edit] External links

• SUNY Figs 02:05-09
• Slide

[edit] See also

• Arachnoid cyst
• Leptomeningeal collateral circulation

v • d • e Anatomy: meninges of the brain and medulla spinalis (TA A14.1.01, GA 9.749/9.872) Layers Dura mater Falx cerebri · Tentorium cerebelli · Falx cerebelli · Diaphragma sellae · Trigeminal cave Arachnoid mater Arachnoid granulation Subarachnoid cisterns: Cisterna magna · Pontine cistern · Interpeduncular cistern · Chiasmatic · Lateral cerebral fossa · Of great cerebral vein Pia mater Denticulate ligaments Tela chorioidea (Tela chorioidea of third ventricle, Tela chorioidea of fourth ventricle) · Choroid plexus Combined Filum terminale · Leptomeninges Spaces Epidural space · Subdural space · Subarachnoid space (Cerebrospinal fluid)

v • d • e Anatomy of torso (primarily): the spinal cord (TA 14.1.02, GA 9.749) External, dorsal Posterior median sulcus · Posterolateral sulcus Grey matter/ Rexed laminae I-VI: Posterior horn I: Marginal nucleus · II: Substantia gelatinosa of Rolando · III+IV: Nucleus proprius · Spinal lamina V · Spinal lamina VI VII: Lateral horn Intermediolateral nucleus · Posterior thoracic nucleus VIII-IX: Anterior horn Interneuron · Alpha motor neuron (Onuf's nucleus) X: Other Central gelatinous substance · Gray commissure Central canal White matter somatic/ ascending (blue) Posterior/PCML: touch: Gracile · Cuneate Lateral: proprioception: Spinocerebellar (Dorsal, Ventral) · pain/temp: Spinothalamic (Lateral, Anterior) · Posterolateral (Lissauer) · Spinotectal Spinoreticular tract · Spino-olivary tract motor/ descending (red) Lateral: Corticospinal (Lateral) · Ep (Rubrospinal, Olivospinal) Anterior: Corticospinal (Anterior) · Ep (Vestibulospinal, Reticulospinal, Tectospinal) both Anterior white commissure External, ventral Anterior median fissure External, general Cervical enlargement · Lumbar enlargement · Conus medullaris · Filum terminale · Cauda equina

This neuroscience article is a stub. You can help Wikipedia by expanding it. v • d • e