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Courtesy of 3dneuroanatomy.com

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AC: anterior clinoid process; ICA: internal carotid artery; LT: lamina terminalis; ON: optic nerve; OlN; olfactory nerve; SW: sphenoid wing; TS: tuberculum sellae; A1: A1 segment of the Anterior Cerebral Artery; A2: A2 segment of the Anterior Cerebral Artery; M1: M1 segment of the Middle Cerebral Artery.


The anterior clinoid, which represents the terminal portion of the lesser wing of sphenoid bone, forms the anterior aspect of the lateral wall of the optic canal.

see Anterior clinoidectomy


The olfactory nerve (Latin: Nervus olfactorius), known as the first cranial nerve, or simply CN I, carries the sensory information for the sense of smell. Derived from the embryonic nasal placode, the olfactory nerve is capable of regeneration. The olfactory nerve is sensory in nature and originates on the olfactory mucosa in the anterosuperior nasal cavity.

From the olfactory mucosa, the nerve travels down the olfactory tract until it reaches the olfactory bulb, where the fascicles of the olfactory nerve pass through foramina on the cribriform plate, which resides on the roof of the nasal cavity. These fascicles are not visible on a cadaver brain because they are severed upon removal.

Sacrifice of the olfactory nerves is often required during a transbasal approach or subfrontal approach.


In the sphenoid bone, behind the chiasmatic groove is an elevation, the tuberculum sellae (or the tubercle of sella turcica). A variable slight to prominent median elevation forming the posterior boundary of the prechiasmatic sulcus and the anterior boundary of the hypophysial fossa.

A challenging area in skull base surgery is microsurgery of the tuberculum sellae and sphene-orbital lesions.

see Tuberculum sellae meningioma

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