Arachnoid granulations or Pacchionian granulations; Structure & Location, Function скачать в хорошем качестве

Arachnoid granulations or Pacchionian granulations; Structure & Location, Function

Arachnoid granulations, also known as Pacchionian granulations, are small, specialized structures that play a vital role in the drainage of cerebrospinal fluid (CSF) from the brain into the venous system. 🧠 What Are They? They are outpouchings of the arachnoid mater (the middle layer of the meninges) that protrude into the dural venous sinuses, especially the superior sagittal sinus and transverse sinuses2. These granulations act as one-way valves, allowing CSF to flow from the subarachnoid space into the venous blood, but preventing backflow3. 📍 Location Most commonly found along the superior sagittal sinus, particularly in the lateral lacunae. Also present in the transverse, straight, and superior petrosal sinuses. Can be lodged within granular foveae, small pits on the inner surface of cranial bones. 🔬 Structure Each granulation has: A thin stalk penetrating the sinus wall A bulbous head within the sinus lumen A collagenous core covered by arachnoid cells and endothelial lining3 🧪 Imaging & Clinical Relevance On CT or MRI, they appear as CSF-density filling defects in the dural sinuses and can mimic dural venous thrombosis, though they are typically well-defined and benign. Giant arachnoid granulations (greater than 10 mm) may cause venous sinus obstruction in rare cases. 🧬 Historical Note Named after Antonio Pacchioni, an Italian physician who described them in the early 18th century. #Arachnoid