🧠 Accessory Sphenoidal Septum (ASS) [Neurosurgery Wiki]

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===== 🧠 Accessory Sphenoidal Septum (ASS) =====

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==== 📌 Definition ====
The **accessory sphenoidal septum (ASS)** is an additional bony partition within the **[[sphenoid sinus]]**, separate from the central sphenoidal septum. It may appear as a ridge or complete wall and varies significantly between individuals.

==== 🦴 Anatomical Context ====
  * Located inside the **sphenoid sinus**, below the **sella turcica**.
  * Unlike the **main sphenoidal septum**, the ASS:
    * Can be multiple or incomplete.
    * May arise from various sinus walls.
    * Often attaches asymmetrically.
  * **Important attachments**:
    * **Optic canal**
    * **Internal carotid artery (ICA)**
    * **Lateral opticocarotid recess (LOCR)**

==== 🔍 Clinical Relevance ====
  * During **endoscopic transsphenoidal surgery**, the ASS:
    * Can obscure visualization of the **LOCR**.
    * Serves as a **reliable landmark** for locating LOCR when it's not directly visible.
  * Recognizing the **ASS ridge** helps avoid injury to:
    * **Optic nerve**
    * **Carotid artery**
  * The recent anatomical study (Guo et al., 2025) showed that:
    * In cases where LOCR is indistinct, its position can be inferred using the **ASS ridge** and its prolongation.