| Debye sheath | <radiobiology> The region of strong electric field in front of a material surface in contact with a plasma. Its characteristic thickness is the Debye length, and it is caused by Debye shielding of the negative surface charge resulting from electrons flowing to the surface much faster (initially) than the ions. The lost electrons leave behind a region of net positive charge which gradually diminishes the strength of the electric field over the Debye length. (13 Nov 1997) |
|---|---|
| dentinal sheath | A layer of tissue relatively resistant to the action of acids, which forms the walls of the dentinal tubules. Synonym: Neumann's sheath. (05 Mar 2000) |
| dural sheath | An extension of the dura mater that ensheathes the roots of spinal nerves or, more particularly, the vagina externa nervi optici. (05 Mar 2000) |
| dural sheath of optic nerve | <anatomy, nerve> The outer sheath around the optic nerve, continuous with the dura mater. Synonym: vagina externa nervi optici, dural sheath of optic nerve. (05 Mar 2000) |
| infundibuliform sheath | The fascia enclosing the femoral vessels, formed by the transversalis fascia anteriorly and the iliac fascia posteriorly; two septa divide the sheath into three compartments, the lateral of which contains the femoral artery and the femoral branch of the genitofemoral nerve, the middle the femoral vein, and the medial is the femoral canal. Synonym: crural sheath, infundibuliform sheath. (05 Mar 2000) |
| inner sheath | The material that encases the two central microtubules of the ciliary axoneme. (18 Nov 1997) |
| internal sheath of optic nerve | <anatomy, nerve> The innermost sheath around the optic nerve, continuous with the leptomeninges (pia-arachnoid) and including a cerebrospinal fluid-filled intervaginal space, continuous with the subarachnoid space. Synonym: vagina interna nervi optici. (05 Mar 2000) |
| optic nerve sheath decompression | A venting of the optic nerve sheath into the retrobulbar space, by slitting or by fenestrating the sheath. See: optic nerve sheath fenestration. (05 Mar 2000) |
| optic nerve sheath fenestration | The cutting of a window in the dura of the optic nerve sheath to relieve papilledema and prevent further loss of optic nerve fibres. (05 Mar 2000) |
| tail sheath | The protoplasmic envelope in the tail of a spermatozoon. (05 Mar 2000) |
| tendon sheath | <anatomy> A membranous sleeve which envelops the tendon and creates a lubricated low-friction environment for easy movement. (13 Jan 1998) |
| tendon sheath of abductor pollicis longus and extensor pollicis brevis muscles | The synovial sheath lining the compartment of the extensor retinaculum that contains the abductor pollicis longus and extensor pollicis brevis tendons. Synonym: vagina tendinum musculorum abductoris longi et extensoris brevis pollicis. (05 Mar 2000) |
| tendon sheath of extensor carpi radialis muscles | The synovial sheath lining the compartment of the extensor retinaculum containing the tendons of the extensor carpi radialis longus and brevis muscles. Synonym: vagina tendinum musculorum extensorum carpi radialium. (05 Mar 2000) |
| tendon sheath of extensor carpi ulnaris muscle | The synovial sheath surrounding the tendon of the extensor carpi ulnaris in its course deep to the extensor retinaculum. Synonym: vagina tendinis musculi extensoris carpi ulnaris, peritenon. (05 Mar 2000) |
| tendon sheath of extensor digiti minimi muscle | <anatomy> The synovial sheath surrounding the tendon of the extensor digiti minimi in its passage deep to the extensor retinaculum. Synonym: vagina tendinis musculi extensoris digiti minimi. (05 Mar 2000) |