Skull (15-28)

Question 1

What are the main sutures of the cranial vault and what skull bones do they separate;

Answer 1

Sagittal suture (longitudinal - separates parietal bones), Coronal suture (transverse - separates frontal bones from parieteal bones), Lambdoid suture (transverse - separates occipital bone from parietal bones), Squamous suture (longitudinal - separates parietal from temporal), Metopic suture (longitudinal - separates frontal bones)

Question 2

At what ages do the fontanelles fuse (close)?;

Answer 2

1st Posterior fontanelle (2-3 months olds), 2nd Sphenoid fontanelle (6 months), 3rd Mastoid fontanelle (6-18 months), 4th [last] Anterior fontanelle (16-18 months)

Question 3

What pathology is associated with improper fusion of the suture lines?;

Answer 3

Cranial synotosis - needs to be treated early on to avoid speech & breathing difficulities. Hydrocephalus

Question 4

Name three syndromes associated craniosynostosis pathology;

Answer 4

Apert’s syndrome (deformities of skull, face, hand and feet bones), pfeiffer syndrome (premature fusion of skull bones - craniosynostosis), Crouzon syndrome (dental abnormalities)

Question 5

What bones make the ‘pterion’?;

Answer 5

Temporal, frontal, parietal and greater wing of sphenoid

Question 6

What is the significance of the pterion?;

Answer 6

Middle menigeal artery runs over it - if damaged = extral dural haematome

Question 7

What are the main parts of the sphenoid bone?;

Answer 7

4 parts - lesser wing, greater wing, body, pterygoid process (V.I.N. for anatomy exam)

Question 8

What are the main compnents (parts) of the sella turcica?;

Answer 8

Chiasmatic sulcus, Tuberculum sellae, Hypophyseal fossa, Dorsum Sellae

Question 9

Name the bony boundaries of the anterior cranial fossa;

Answer 9

Anterior - Orbital plate of frontol bone, cribriform plate of ethmoid bone. Posterior - Lesser wings and limbus of sphenoid bone. Floor - ethmoid bone

Question 10

Name the bony boundaries of the middle cranial fossa;

Answer 10

Anteriormedially - limbus of sphenoid bone. Anteriorlaterally - lesser wings of sphenoid bone. Posteriormedially - dorsum sellae of sphenoid bone. Posteriolaterally - petrous part of temporal bone

Question 11

Name the bony boundaries of the posterior cranial fossa;

Answer 11

Anterior - the clivus & petrous temporal bone. Posterior - occipital bone. Lateral - squamous and mastoid parts of temporal bone.

Question 12

What three key structures are in relation to the clivus;

Answer 12

Abducens nerve, basillar artery, pons

Question 13

What is the clinical significance of the course of the abducens nureve?;

Answer 13

Largest anatomical intracranial course of cranial nerves. Nucleus in Pons. Fracture of peterous temporal bone can compress abducens nerve at Dorello’s canal. In increased ICP then abducens nerve is first of CNs to be affected.

Question 14

What is the key finding in a patient with abducens nerve palsy?;

Answer 14

Lateral rectus palsy. Eye turns inwards.
Unable to abduct eye.