3.4 The Floor of the Skull Flashcards
What is the Floor of the Skull?
The Part of the Skull which is Visible when you remove the Skull Cap and look into the Calvarium
What are the 3 Fossae the Floor of the Skull is divided into?
- The Anterior Cranial Fossa
- The Middle Cranial Fossa
- The Posterior Cranial Fossa
What is present on the Floor of the Skull?
- Many Foramina which Nerves / Blood Vessels can Enter / Leave the Cranium
- Grooves / Depressions which indicate the position of blood vessels and other structures
Which bone forms the border of the Anterior to Middle Cranial Fossa?
The Sphenoid Bone:
a) The Lesser Wings of the Sphenoid Bone
b) The Limbus of the Sphenoid Bone
Which Bones form the floor of the Anterior Fossa contain?
- The Frontal Bone
- The Ethmoid Bone (Cribriform Plate and Crista Galli)
- The Sphenoid Bone (Lesser Wing and Limbus)
Which Bones form the floor of the Anterior Fossa contain?
- The Greater Wing of the Sphenoid
- The Petrous Part of the Temporal Bone
- The Squamous Part of the Temporal Bone
Which bone forms the border of the Middle to Posterior Cranial Fossa?
Laterally - The Petrous Part of the Temporal Bone
Medially - The Dorsum Sallae of the Sphenoid Bone
What is the Pterion?
A āHā Shaped suture of 4 Bones:
- Frontal Bone
- Parietal Bone
- Temporal Bone
- Sphenoid Bone
What structures pass through the small Foramina of the Skull?
Cranial Nerves
What is the name of the Foramen in the Anterior Cranial Fossa?
The Foramina of the Cribriform Plate (of the Ethmoid Bone)
What structure(s) pass through the Foramina of the Cribriform Plate?
Olfactory Nerves (Cranial Nerve I)
What are the names of the Foramen in the Middle Cranial Fossa?
- The Optic Foramen
- The Superior Orbital Fissure
- The Foramen Rotundum
- The Foramen Ovale
- The Foramen Spinosum
- The Foramen Lacerum
- The Carotid Canal
What structure(s) pass through the Optic Foramen?
The Optic Nerve (Cranial Nerve II)
What structure(s) pass through the Superior Orbital Fissure?
- The Occulomotor Nerve (Cranial Nerve III)
- The Trochlear Nerve (Cranial Nerve IV)
- The Ophthalmic Division of the Trigeminal Nerve (Cranial Nerve V1)
- The Abducens Nerve (Cranial Nerve VI)
- The Ophthalmic Artery
What structure(s) pass through the Foramen Rotundum?
The Maxillary Division of the Trigeminal Nerve (Cranial Nerve V2)
What structure(s) pass through the Foramen Ovale?
The Mandibular Division of the Trigeminal Nerve (Cranial Nerve V3)
What structure(s) pass through the Foramen Spinosum?
- The Middle Meningeal Artery
- The Middle Meningeal Vein
- The Meningeal Branch of the Mandibular (Branch of the Trigeminal) Nerve
What structure(s) pass through the Foramen Lacerum?
Nothing
What structure(s) pass through the Carotid Canal?
The Carotid Arteries
What are the names of the Foramen in the Posterior Cranial Fossa?
- The Internal Acoustic Foramen
- The Jugular Foramen
- The Hypoglossal Foramen
- The Foramen Magnum
What structure(s) pass through the Internal Acoustic Foramen?
- The Facial Nerve (Cranial Nerve VII)
2. The Vestibulocochlear Nerve (Cranial Nerve VIII)
What structure(s) pass through the Jugular Foramen?
- The Glossopharyngeal Nerve (Cranial Nerve IX)
- The Vagus Nerve (Cranial Nerve X)
- The Accessory Nerve (Cranial Nerve XI)
- The Internal Jugular Vein
What structure(s) pass through the Hypoglossal Foramen?
The Hypoglossal Nerve (Cranial Nerve XII)
What structure(s) pass through the Foramen Magnum?
- The Spinal Cord
- The Left Veretebral Artery
- The Right Veretbral Artery
How are the Grooves on the floor of the Skull formed?
As the Bone of the Skull Develops (and is Maintained) around pre-existing blood vessels (Arteries or Intra-Cranial Venous Sinuses) or Nerves
Where are the Intra-Cranial Venous Blood Sinuses found?
Between the:
- Inner Layer of Dura (Proper Dura)
- Outer Layer of the Periosteum of the Inside face of the Skull Bone
What forms the Groove found lateral to the Foramen Spinosum?
The Middle Meningeal Artery
What is the Clinical Significance of the Middle Meningeal Artery being Thin and crosses the Pterion on the Inner Surface?
Common place for Extradural Haemorrhages to occur after trauma
What is the Groove which runs laterally on both sides of the Internal Occipital Proturbance for?
The Transverse Sinus
The Transverse Sinus Grooves run laterally and lead into an āSā Shaped Groove, what is this Groove for?
The Sigmoid Sinus
Into which Foramen does the Groove for the Sigmoid Sinus lead?
The Jugular Foramen
Which major Vein emerges into the Neck from the Jugular Foramen?
The Internal Jugular Vein
What is the Sella Turcica?
A deep depression in the Midline in the Sphenoid Bone (Middle Cranial Fossa) which houses the Pituitary Gland
What, on either side of the Sella Turcica, gives attachments to the Tentorum Cerebelli?
An Anterior and a Posterior Clinoid Processes are on both sides (so there are 2 of each)
What is the Groove for on either side of the Sella Turcica?
The Cavernous Sinus
Which Foramina lies immediately anterior to the Groove for the Cavernous Sinus?
The Superior Orbital Fissure
On the Internal Surface of the Skull Cap, what is the Groove in the Midline formed by?
The Superior Saggital Sinus
What is the Base of the Skull?
The part of the Skull which can be viewed from the bottom
What Bones make up the Base of the Skull?
- The Palatine Process of the Maxilla
- The Palatine Bone
- The Pterygoid Process of the Sphenoid Bone
- The Greater Wing of the Sphenoid Bone
- The Temporal Bone
- The Occipital Bone
What bones are the Pterygoid Plate and the Pterygoid Hamulus a part of?
The Sphenoid Bone
What muscles attach to the Medial Pterygoid Plate?
- The Tensor Veli Palatini glides over this
2. The Pterygomandibular Raphe Muscle
What muscles attach to the Lateral Pterygoid Plate?
- The Medial Pterygoid Muscle
2. The Lateral Pterygoid Muscle
