Floor of the Skull Flashcards
When is the floor of the skull viewed?
part of the skull that you view when you remove the skull cap and look into the calvarium.
It is divided into three fossae.
Which bone forms the posterior boundary of the anterior cranial fossa?
Lesser wing of sphenoid
Identify the following features in the anterior cranial fossa:
Cribiform plate of the ethmod bone
Crista galli in the midline
Which bone forms the anterior boundary of the middle cranial fossa?
Greater Wing of Sphenoid
Which bones form the floor of the middle cranial fossa?
Sphenoid bone (Body & Greater Wings) & temporal bone (squamous and petrous parts)
Which bone forms the posterior border of the middle cranial fossa?
Superior Borders of the petrous part of the temporal bone
Identify the Pterion in the image on the left. Which four bones come together at this H-shaped suture?
- Frontal Bone*
- Parietal Bone*
- Sphenoid Bone*
- Temporal Bone*
Which bone forms the anterior and which the posterior border of the posterior cranial fossa?
- Anterior Dorsum sellae of Sphenoid Bone*
- Posterior Squamous part of Occipital Bone*
What structures pass through the small foramina of the skull?
Emissary veins
What is in the anterior cranial fossa?
Formaina of the cribiform plate
What is in the middle cranial fossa?
Optic foramen
Superior orbital fissure
Foramen rotundum
Foramen ovale
Foramen spinosum
Foramen laecrum
Carotid canal
What is the posterior cranial fossa?
Internal acoustic foramn
Jugular foramen
Hypoglossal foramen
Foramen magnum
What passes through the foramina of the cribifrom plate?
CN1- Olfactory nerve
What passes through the foramina of the optic foramen?
CN II Optic Nerve, Ophthalmic Artery, Sympathetic N fibres
What passes throgh the superior orbital fissure?
CN III Oculomotor Nerve
CN IV Trochlear Nerve
CN V1 Ophthalmic Nerve
CN VI Abducens Nerve
What passes through the foramen rotundum?
CN V2 Maxillary Nerve
What passes throguh the foramen ovale?
CN V3 Mandibular Nerve
What passes throgh the foramen spinosum?
Middle Meningeal Artery & Vein
Meningeal branch of CN V3
What passes throguh the foramen laecrum?
Closed Cartilage in life
What passes through the carotid canal?
Internal Carotid Artery & Carotid Plexus
What passes throguh the internal acoustic meatus?
CN VIII Vestibulocochlear Nerve
CNVII facial nerve
What passes throguh the jugular foramen?
CN IX Glossopharyngeal Nerve
CN X Vagus Nerve
CN XI Accessory Nerve
What passes throguh the hypoglossal foramen?
CN XII Hypoglossal Nerve
What pases throguh the foramen magnum?
Medulla Oblongata, Meninges
What are the grooves in the skull formed as?
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.
The intra-cranial venous blood sinuses are found between what?
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
Identify a groove that begins just lateral to the foramen spinosum. What artery and its branches makes this groove?
Middle meningeal artery
Identify this artery in the image below- what part of the skull does it cross?
Pterion
This is very thin
The pterion artery is commoly damaged in injuries. What can this result in?
A bleed collecting between the periosteum of the skull and the dura mater (an extradural haemorrhage) as shown in the image to the right.
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?
Parietal (periosteal) part of the Dura Mater limits its spread
What are the grooves for the intracranial venous sinus called?
The transverse sinus
If you trace these laterally until they continue as the S-shaped groove for the sigmoid sinus.
Into which foramen does the groove for the sigmoid sinus lead?
Jugular foramen
Which major vein emerges into the neck from this foramen?
Jugular vein
What is the sella turcicia?
A deep depression in the midline in the middle cranial fossa which houses the pituitary gland.
In the body of which cranial bone is the sella turcica found?
Sphenoid bone
Which foramen lies immediately anterior to the groove for the cavernous sinus?
Carotid sinus
What is on either side of the sella turcica?
A groove for the cavernous venous
What is the groove in the midline of the skull cap made by?
Superior saggital sinus
What are the pits on either side of the superior saggital sinus?
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.
Which bone are they a part of?
Sphenoid
- Name the muscle(s) that attach to:*
- Medial pterygoid plate*
- Lateral pterygoid plate*
- Medial pterygoid plate- Superior pharyngeal constrictor*
- Lateral pterygoid plate- Lateral and medial pterygoid muscles*
