- Ossification of skull sutures- Cranial sutures normally ossify by the age of 18-24 months after birth. Before that all fontanelles are open & a raise in intracranial pressure causes them to bulge.
- Cranial sutures- Metopic , Sagital, Coronal, Lamdoid & Squamosal sutures; in the case of suspected non-accidental injury in children, the persistence of sutures should not be mistaken as fractures on X-ray or CT scan of skull.
- Craniosynostosis– a condition where all the cranial sutures are fused at birth, Sagittal synostosis, the most common form leading to “boat shaped skull”
- Pterion- the junction where these 4 bones meet together- the Frontal, the Parietal, the Temporal & the Sphenoid (Fig.)
- Importance of Pterion– the Middle meningeal artery runs behind the Pterion & trauma at this area causes injury the artery leading to an Extradural haemorrhage.
- Middle meningeal artery- a branch of the Maxillary artery ( one of the terminal branch of External carotid artery), enters the skull through the Foramen spinosum.
- Basal skull fractures: when a skull fracture involves one/more of the following bones: Temporal (the most common bone involved), occipital, sphenoid or ethmoid.
- C/F of basal skull fracture- Symptoms: CSF rhinorrhea, anosmia, bleeding from nose &/or ears, haematympanum, deafness, facial nerve palsy; Signs: Battle’s sign (mastoid ecchymosis- bruising over the mastoid process), Racoon eyes/Panda eyes (periorbital ecchymosis- bruising of the periorbital region).
- Foramen lacerum- is present lateral to the Clivus (basilar artery lies behind the Clivus); part of the foramen is occluded by cartilage & part of it is traversed by internal carotid artery; artery & nerve of the pterygoid canal pass through the foramen lacerum.
- Cavernous sinus: two in number, one on each side of sella turcica laterally; filled with venous blood from tributeries-— Superficial middle cerebral vein, Superior & Inferior Ophthalmic veins & Sphenoparietal sinuses; cavernous sinuses of each side are joined by inter-cavernous sinuses; & drain into the Superior & Inferior Petrosal sinuses. Contents- Internal Carotid artery with Sympathetic plexus, & VI CN;Lateral wall contains- III, IV, Va & Vb CN.