Meaning & use
thecal sac
Last updated
Meaning
nouncountable
The tube-like membrane inside the spinal canal that holds the spinal cord, nerve roots and the fluid around them.
Grammar: Countable but usually singular: the thecal sac.
Patterns
- compression of the thecal sac
- indent the thecal sac
The MRI showed a disc pressing on the thecal sac.
Cerebrospinal fluid surrounds the nerves inside the thecal sac.
The surgeon explained how the thecal sac is protected by the bones of the spine.
Word forms
| plural | thecal sacs |
|---|
Common combinations
- compress the thecal sac
- A bulging disc may compress the thecal sac.
- indentation of the thecal sac
- The report noted mild indentation of the thecal sac.
- thecal sac narrowing
- Thecal sac narrowing can cause leg pain.
- normal thecal sac
- The scan showed a normal thecal sac.
Synonyms and how they differ
- dural sac
- Dural sac is the same structure and is often used interchangeably in medical reports.
- spinal sheath
- Spinal sheath is a looser, non-technical description of the covering.
- spinal membrane
- Spinal membrane is a vaguer phrase that could mean any covering.
Word family
- theca noun
- a sheath or case in anatomy
- intrathecal adjective
- inside the membrane around the spinal cord
- dura noun
- the tough outer membrane around the spinal cord
Commonly confused: thecal sac or spinal canal?
thecal sac vs spinal canal
The spinal canal is the bony channel; the thecal sac is the membrane tube inside it.
Practice
A report says a disc is pressing on the thecal sac. Which structure is affected?
Choose one answer.
The thecal sac is the membrane tube within the spinal canal containing the cord and fluid. The other structures are in different parts of the body.
Make it your own
Write a sentence using “thecal sac”, then check it and compare it with the examples above.