Lecture 1: Skull

Question 1

Answer 1

…

Question 2

Answer 2

Question 3

Pathalogical condition?

Answer 3

Combined with absence of clavicle, falure of the bregma to form (closure of frontal fontanelle) it is called Cleidocranial dysplasia

Question 4

Pathological condition?

Answer 4

Craniosynostosis - when posterior fontanelle closes quickly in first month of life and so when head grows it grows from anterior point. very common.

Question 5

What is the pterion?

Answer 5

Clinically important as it is the weakest part of the skull due to many bones coming together. The anterior part of the middle meningeal artery runs right behond this part. (main artery supplying the meninges)

Question 6

intracranial foramina?

Answer 6

21 - foramen magnum

11 - foramen ovale

26 - jugular foramen

foramen rotundum not seen on this image

Question 7

Anterior intracranial fossae

Answer 7

Anterior

• parts of the frontal (anterior and lateral directions), eithmoid (midline) and sphenoid bone (body and lesser wings)
• Is above the nasal cavity and is filled by the frontal lobes
• frontal crest forms attachment of falx cerebri
• the ethmoid bone, specifically the cristae galli is another attachment for the falx
• the cribriform plate is a sieve-like structure allowing small olfactory nerves to pass through

Question 8

Middle intracranial fossa

Answer 8

Middle

• seperated from anterior by the anterior edge of the chiasmatic sulcus against the body of the sphenoid. Laterally by the greater wings and the lesser wings of the spheniod bone (SOF forms gap between).
• The floor is formed from the elevated sphenoid bone. Laterally there are large depressions formed from the greater wings of the sphenoid bone and the squamous part of the temporal bone.
• Depressions contain the temporal lobes and the hypophyseal fossa contains the pituitary gland
• The greater wigs contains the foramen rotundum (V2), ovale (V3), spinosum (middle men. a and v), SOF as well as Foramen lacerum (fibrous closing) and the opening of the carotid canal.

Question 9

posterior intracranial fossa

Answer 9

Consists mostly of the temporal and occipital bones with small contributions from the sphenoid and parietal bones

Largest and deepest fossa containing the brainstem and the cerebellum

contains the foramen magnum, hypoglossal canal, jugular foramen and internal acoustic meatus are contained within

Boundaries:

• anteriorally the join of the clivus (sloped bone anterior to foramen magnum formed from the body of sphenoid and basilar part of occipital bone) and the dorsum sallae
• Laterally the superior part of the petrous bone (petromastral part of temoral bone).

Question 10

Aire filled spaces in the skull?

Answer 10

Sinuses

Has nothing to do with making the skull lighter (little kids don’t have fully formed sinuses esp. fontal sinus and they seem to do fine)

Question 11

Label : 20, 19, 18, 16, 14, 13, 12

Answer 11

Question 12

Surface anatomy of the pterior?

Answer 12

Where the MMA and the Sylvian point are (where lateral fissure splits into ascending and posterior rami)

Point for potetial epidural haemorrhage

1cm diameter around pterior found 2.6cm behind and 1.3cm above the posterolateral margin of the frontozygomatic suture overlapping anterior branch of MMA in 68%.

70% aMMA is in a bony canal of parietal bone vs a groove that is seen more often in males