Clivus

Where is the clivus located and what are its borders?

• Clivus (clivus) is located on the intracranial (upper) surface of the basilar part (pars basilaris).
• The basilar part is located anterior to the foramen magnum (foramen magnum).
• The clivus faces the ventral surface of the brainstem.
• Laterally, it is bounded by the sulcus of the inferior petrosal sinus (sulcus sinus petrosi inferioris). This sulcus continues onto the petrous parts of the temporal bones.
• On the opposite, external (lower) surface of the basilar part in the midline lies the pharyngeal tubercle (tuberculum pharyngeum), which serves as the site of pharyngeal attachment.

What vessels are associated with the clivus region?

• After emerging from the carotid canal, the internal carotid artery courses rostrally along the clivus and approaches the cavernous sinus deep to the dura mater.
• Within the cavernous sinus, the artery curves posteriorly and superiorly, forming the internal carotid siphon — a loop opening posteriorly.
• The dura mater in the region of the clivus is supplied by fine extradural branches of the internal carotid artery. These same branches supply the floor of the tympanic cavity, the trigeminal (Gasserian) ganglion, and the pituitary gland.

What nerves are associated with the clivus region?

• The clivus is a topographic-anatomical landmark along the pathway of extraocular motor nerves — the III, IV, and VI cranial nerve pairs.
• These nerves pass through the cavernous sinus or its wall in close relation to the internal carotid artery, and then enter the orbital cavity via the superior orbital fissure (fissura orbitalis superior).

Do not confuse: other "clivi" in anatomy

In medical literature, the term "clivus" is also used to describe sloped surfaces of other anatomical structures of the face and jaws:

• Slopes of the articular tubercle — structures of the temporomandibular joint (TMJ). During the second phase of mouth opening, the articular disc along with the head of the mandible glides anteriorly and inferiorly down the posterior slope of the articular tubercle, and the condylar process moves forward by approximately 12 mm. In TMJ dislocation, the head of the condylar process displaces far forward past the slope of the articular tubercle. At the base of the anterior slope of the articular tubercle, an anesthetic depot is established during Egorov's block.
• Slope of the pterygomandibular fold (plica pterygomandibularis) — the lateral slope of this fold forms a groove with the cheek, which serves as a landmark for needle insertion during torusal anesthesia. In the apodactylic method of anesthesia, the needle is inserted into the outer slope of the fold to a depth of 1.5–2 cm.
• Lateral slopes of the nose — referred to in traumatology and reconstructive surgery: upon a lateral impact, the lateral slope of the nose on the side of the impact depresses while the contralateral slope is displaced; upon completion of nasal plastic surgery, firm gauze rolls are placed over the lateral slopes.
• Oral slope of the alveolar process — a term from prosthetic dentistry: the wire for reinforcing the wax denture base is bent to match the shape of the oral slope of the alveolar process.

Class and exam questions

What else to study on this topic

• Basilar part
• Internal carotid artery
• Cavernous sinus
• Extraocular motor nerves (III, IV, VI pairs)

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.