Norma Basalis OBJECTIVES At the end of this lecture, students will ...

– Divided into 2 parts by petrotympanic fissure
– Anterior portion - concave, smooth, & bounded in front by
articular tubercle - articulates with condyle of mandible.
– Posterior portion is rough & bounded behind by tympanic part
of temporal bone.
Middle Part
• Foramen lacerum
– At base of medial pterygoid plate in dried skull
– Irregular in shape & variable in size
– Not complete foramen in intact body, because its inferior part is
covered over by fibrocartilaginous plate, across superior (inner
or cerebral) surface of which passes internal carotid artery.
– Boundary
- In front by great wing of sphenoid
- Behind by apex of petrous portion of temporal bone
- Medially by body of sphenoid & basilar portion of occipital bone
• Carotid canal
– Inferior surface of petrous temporal bone is pierced by round
opening.
– Internal carotid artery, coursing within canal, immediately takes
right angle turn to reach side of foramen lacerum.
• Quadrilateral surface
– Rough surface near apex of petrous portion of temporal bone,
lateral to which is orifice or entrance of carotid canal.
– Attachment to levator veli palatini
•
• Sulcus tubae auditivae
– Lateral to foramen lacerum, between petrous part of temporal &
great wing of sphenoid
– Lodges cartilaginous part of auditory tube which is continuous
with bony part within temporal bone
– Petrosphenoidal fissure at bottom of this sulcus