Thecal sac

Thecal Sac

The thecal sac, also known as the dural sac or dural thecal sac, is a protective membrane that surrounds the spinal cord and the cerebrospinal fluid (CSF) within the spinal canal. It is a long, tubular structure that extends from the base of the skull to the sacrum.

Etymology

The term "thecal" is derived from the Greek word "thēkē", which means "a case" or "a sheath". The term "sac" is derived from the Latin word "saccus", which means "a bag" or "a pouch". Therefore, the term "thecal sac" can be interpreted as "a sheath-like bag".

Anatomy

The thecal sac is made up of two layers: the dura mater and the arachnoid mater. The dura mater is the outermost layer and the arachnoid mater is the inner layer. The space between these two layers is filled with cerebrospinal fluid, which provides cushioning and protection to the spinal cord.

The thecal sac is located within the vertebral canal, which is formed by the alignment of the vertebral foramina of the individual vertebrae. The sacrum, at the lower end of the vertebral canal, is where the thecal sac terminates.

Clinical Significance

The thecal sac plays a crucial role in various medical procedures and conditions. For instance, during a lumbar puncture (also known as a spinal tap), a needle is inserted into the thecal sac to collect a sample of cerebrospinal fluid for diagnostic purposes.

In certain pathological conditions, such as spinal stenosis, herniated disc, or spinal tumor, the thecal sac can be compressed, leading to a range of symptoms including pain, numbness, and weakness in the limbs.

See Also

• Spinal cord
• Cerebrospinal fluid
• Dura mater
• Arachnoid mater
• Vertebral canal
• Lumbar puncture
• Spinal stenosis
• Herniated disc
• Spinal tumor

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