Theme 8c

Question 1

What is the skull composed of?

Answer 1

Cranium & Mandible

Neurocranium: Bones forming the protective cranial vault around the Brain & Brianstem

Cranial base: Bones making up the floor of the

Question 2

What are the divisions of the interior of the skull?

What are their boundries?

Answer 2

Anterior cranial fossa:

• frontal bone
• lesser wing of sphenoid

Middle cranial fossa:

• Lesser wings of spenoid
• petroud temporal bone

Posterior cranial fossa:

1. Petrous temporal bone
2. Dorsum sellae

Question 3

How do the Cranial nerves leave the skull?

Answer 3

V:

• V1 - Superior orbital fissue
• V2 - Fo. Rotundum
• V3 - Ovale

III, IV, VI: Cavernous sinus & superior orbital fissue

VII: Internal auditory meatus, facial canal, stylomastoid foramen

VIII: Internal auditory meatus

IX, X, XI: Jugular foramen

XII: Hypoglossal canal

Question 4

Venous drainage of the Brain

What are the different Sinus’s involved?

Answer 4

Superior sagittal:

• Runs backwards attached to Falx cerebri
• Ends at metting of tentorium & cerebri in confluence of sinus’s

Inferior Saggital:

• Runs backwards in faux cerebri to drain into straight sinus

Straight:

Junction between falx cerebri & tentorium

Ends at confluence of sinuses

Transverse:

• Drains from Sup.Sagittal & Straight
• Turns & continues as sigmoid sinus into jugular foramen as Jugular Vein

Sigmoid:

• Greater & lesser petrosal sinus drain into here

Cavernous & petrosal:

• Cavernous sinus drains into superior & inferior petrosal sinus’s

Question 5

What are the protective functions of the Meninges & Dura?

Answer 5

CSF: supports brain as a shock absorber & absorbs engery from impact - between arachnoid & pia layrs

Dural reflections: supports brain by transmitting its weight to the skull = shock absorber

Question 6

What are the protective functions of the Venous sinus’s?

Answer 6

Drains 70% of venous blood

Temperature regulation: cools rterial blood

Protects against changes in venous pressure