2.1 Osteological Appearance of Skull Flashcards
How do the vault bones form?
Intramembranous ossification of membranes
How do the floor/base bones form?
Endochondrial ossification from cartilage
What is the role of the neurocranium?
Encase and protect brain
What do most structures of the viscerocranium form from?
Pharyngeal arches (1 and 2)
Name the three depressions of the cranial floor
Anterior, middle and posterior cranial fossa
What causes the grooves in the bones of the skull?
Dural venous sinuses
Explain the arrangement of the bones of the calvaria
Trilaminar arrangement
Protective strength without adding significant weight
Outer table -> Diploic cavity -> Inner table
What are sutures?
Fibrous joints between bones
Why are the edges of bones forming sutures serrated?
Prevents slippage and movement
What covers the surface of outer table of bone and is continuous with inner table?
Periosteum
What are fontanelles?
Large areas of unossified membranous gaps between flat bones of calvaria
What is the role of fontanelles?
Allow alteration of skull size and shape during childbirth
Permit growth of infant brain
When do the fontanelles fuse?
Anterior 18mnth-2yr
Posterior 1-3mnth
What condition causes early fusion of fontanelles?
Craniosyntosis
What is the anterior fontanelle clinically useful for?
Assessing ICP and hydration status
What is the main concern following skull fracture?
Intracranial injury
What scan should always be done following known or suspected skull fracture?
CT
Name the two types of skull fracture
Linear
Depressed
What is the pterion?
Thinnest area of skull so relatively easy to fracture
What vessel is associated with pterion?
Middle meningeal artery
What can injury of middle meningeal artery lead to?
Extra dural haemorrhage
What are some signs of a basilar skull fracture?
Racoon eyes
Battles sign
Haemotympinum
CSF leak e.g. through nose
Fractures to which facial bones are common?
Nasal bones
Zygomatic bone and arch
Mandible
