Floor of the Skull

Question 1

When is the floor of the skull viewed?

Answer 1

part of the skull that you view when you remove the skull cap and look into the calvarium.

It is divided into three fossae.

Question 2

Which bone forms the posterior boundary of the anterior cranial fossa?

Answer 2

Lesser wing of sphenoid

Question 3

Identify the following features in the anterior cranial fossa:

Answer 3

Cribiform plate of the ethmod bone

Crista galli in the midline

Question 4

Which bone forms the anterior boundary of the middle cranial fossa?

Answer 4

Greater Wing of Sphenoid

Question 5

Which bones form the floor of the middle cranial fossa?

Answer 5

Sphenoid bone (Body & Greater Wings) & temporal bone (squamous and petrous parts)

Question 6

Which bone forms the posterior border of the middle cranial fossa?

Answer 6

Superior Borders of the petrous part of the temporal bone

Question 7

Identify the Pterion in the image on the left. Which four bones come together at this H-shaped suture?

Answer 7

• Frontal Bone*
• Parietal Bone*
• Sphenoid Bone*
• Temporal Bone*

Question 8

Which bone forms the anterior and which the posterior border of the posterior cranial fossa?

Answer 8

• Anterior Dorsum sellae of Sphenoid Bone*
• Posterior Squamous part of Occipital Bone*

Question 9

What structures pass through the small foramina of the skull?

Answer 9

Emissary veins

Question 10

What is in the anterior cranial fossa?

Answer 10

Formaina of the cribiform plate

Question 11

What is in the middle cranial fossa?

Answer 11

Optic foramen

Superior orbital fissure

Foramen rotundum

Foramen ovale

Foramen spinosum

Foramen laecrum

Carotid canal

Question 12

What is the posterior cranial fossa?

Answer 12

Internal acoustic foramn

Jugular foramen

Hypoglossal foramen

Foramen magnum

Question 13

What passes through the foramina of the cribifrom plate?

Answer 13

CN1- Olfactory nerve

Question 14

What passes through the foramina of the optic foramen?

Answer 14

CN II Optic Nerve, Ophthalmic Artery, Sympathetic N fibres

Question 15

What passes throgh the superior orbital fissure?

Answer 15

CN III Oculomotor Nerve

CN IV Trochlear Nerve

CN V1 Ophthalmic Nerve

CN VI Abducens Nerve

Question 16

What passes through the foramen rotundum?

Answer 16

CN V2 Maxillary Nerve

Question 17

What passes throguh the foramen ovale?

Answer 17

CN V3 Mandibular Nerve

Question 18

What passes throgh the foramen spinosum?

Answer 18

Middle Meningeal Artery & Vein

Meningeal branch of CN V3

Question 19

What passes throguh the foramen laecrum?

Answer 19

Closed Cartilage in life

Question 20

What passes through the carotid canal?

Answer 20

Internal Carotid Artery & Carotid Plexus

Question 21

What passes throguh the internal acoustic meatus?

Answer 21

CN VIII Vestibulocochlear Nerve

CNVII facial nerve

Question 22

What passes throguh the jugular foramen?

Answer 22

CN IX Glossopharyngeal Nerve

CN X Vagus Nerve

CN XI Accessory Nerve

Question 23

What passes throguh the hypoglossal foramen?

Answer 23

CN XII Hypoglossal Nerve

Question 24

What pases throguh the foramen magnum?

Answer 24

Medulla Oblongata, Meninges

Question 25

What are the grooves in the skull formed as?

Answer 25

As the bone of the skull develops (and is maintained) around pre-existing blood vessels or nerves. In the main, the grooves that are easily identified are those formed by arteries or by the intra-cranial venous blood sinuses.

Question 26

The intra-cranial venous blood sinuses are found between what?

Answer 26

The inner and outer layers of dura – the inner layer is the dura proper and the outer layer the periosteum of the inside face of the skull bone

Question 27

Identify a groove that begins just lateral to the foramen spinosum. What artery and its branches makes this groove?

Answer 27

Middle meningeal artery

Question 28

Identify this artery in the image below- what part of the skull does it cross?

Answer 28

Pterion This is very thin

Question 29

The pterion artery is commoly damaged in injuries. What can this result in?

Answer 29

A bleed collecting between the periosteum of the skull and the dura mater (an extradural haemorrhage) as shown in the image to the right.

Question 30

What anatomical factor prevents the collected blood from spreading over a wider area, restricting it to this lens-shaped area in the skull when the pteron artery is damaged?

Answer 30

Parietal (periosteal) part of the Dura Mater limits its spread

Question 31

What are the grooves for the intracranial venous sinus called?

Answer 31

The transverse sinus ## Footnote *If you trace these laterally until they continue as the S-shaped groove for **the sigmoid sinus**.*

Question 32

Into which foramen does the groove for the sigmoid sinus lead?

Answer 32

Jugular foramen

Question 33

Which major vein emerges into the neck from this foramen?

Answer 33

Jugular vein

Question 34

What is the sella turcicia?

Answer 34

A deep depression in the midline in the middle cranial fossa which houses the pituitary gland.

Question 35

In the body of which cranial bone is the sella turcica found?

Answer 35

Sphenoid bone

Question 36

Answer 36

Question 37

Which foramen lies immediately anterior to the groove for the cavernous sinus?

Answer 37

Carotid sinus

Question 38

What is on either side of the sella turcica?

Answer 38

A groove for the cavernous venous

Question 39

What is the groove in the midline of the skull cap made by?

Answer 39

Superior saggital sinus

Question 40

What are the pits on either side of the superior saggital sinus?

Answer 40

These are for little finger like projections from the arachnoid mater into the superior sagittal sinus which help CSF to be reabsorbed into the systemic circulation.

Question 41

Answer 41

Question 42

Which bone are they a part of?

Answer 42

Sphenoid

Question 43

* Name the muscle(s) that attach to:* * Medial pterygoid plate* * Lateral pterygoid plate*

Answer 43

* Medial pterygoid plate- Superior pharyngeal constrictor* * Lateral pterygoid plate- Lateral and medial pterygoid muscles*