Filum terminale

Filum terminale
Cauda equina and filum terminale seen from behind. The dura mater has been opened and spread out, and the arachnoid has been removed. (Filum terminale labeled at center right.)
Sagittal section of vertebral canal to show the lower end of the medulla spinalis and the filum terminale. Li, Lv. First and fifth lumbar vertebra. SII Second sacral vertebra. 1. Dura mater. 2. Lower part of subarachnoid cavity. 3. Lower extremity of medulla spinalis. 4. Filum terminale internum. 5. Filum terminale externum. 6. Attachment of filum terminale to first segment of coccyx.
Gray's	subject #185 750

The filum terminale (a.k.a. Terminal Filament) is a delicate filament, about 20 cm. in length, prolonged downward from the apex of the conus medullaris.

It consists of two parts, an upper and a lower.

• The upper part, or filum terminale internum, measures about 15 cm. in length and reaches as far as the lower border of the second sacral vertebra. It is contained within the tubular sheath of dura mater, and is surrounded by the nerves forming the cauda equina, from which it can be readily recognized by its bluish-white color.

• The lower part, or filum terminale externum, is closely invested by, and is adherent to, the dura mater; it extends downward from the apex of the tubular sheath and is attached to the back of the first segment of the coccyx.

The filum terminale consists mainly of fibrous tissue, continuous above with that of the pia mater.

Adhering to its outer surface, however, are a few strands of nerve fibers which probably represent rudimentary second and third coccygeal nerves; further, the central canal of the medulla spinalis extends downward into it for 5 or 6 cm.

See also

• Spinal cord

External links

• terminal+filum at eMedicine Dictionary
• MedEd at Loyola grossanatomy/dissector/practical/back/back2.html
• lesson6spinalcord&coverings at The Anatomy Lesson by Wesley Norman (Georgetown University)
• SUNY Labs 02:08-0104 - "Vertebral Canal and Spinal Cord: Regions of the Spinal Cord"
• Roche Lexicon - illustrated navigator, at Elsevier 03281.000-1

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated.

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