Skull & Cranial Cavity Flashcards
How many bones in the skull?
22
“skull cap”
Calvaria
Upper part of the skull is called
Neurocranium
Lower part of the skull is called
Viscerocranium
This part of the skull consist of the cranial cavity and calvaria
Neurocranium
“facial skeleton”
Viscerocranium
Lateral separation point between neurocranium and viscerocranium
External auditory meatus
The nasal bones are within the ______cranium
viscerocranium
The calvaria consists of what 4 bones? (2 paired & 2 unpaired)
Frontal bone
2 parietal bones
2 temporal bones
Occipital bone
Where does the upper trapezius connect to the occipital bone?
Superior nuchal line
*Nuchal means “neck”
What’s the name of the little bump that you can feel medially near the bottom of the occipital bone?
External occipital protuberance
The cranial bones are separated by _________ sutures
fibrous sutures
What is it called when your fibrous sutures of the cranium become ossified w/ advancing age?
Synostosis
*kinda sounds like “stasis”
What does squamous mean (regarding the bones)
“flat”
The suture that divides the frontal and parietal bones
Coronal suture
The suture that divides the 2 parietal bones
Sagittal suture
The suture that divides the parietal bones from the occipital bone
Lambdoid suture
The suture that divides the parietal bone from the squamous portion of the temporal bone
Squamous suture
The name of the suture that divides the frontal bone sagittally in infants. (fuses together at 3-9 months of age)
Metopic suture
Unossified gaps between bones
Fontanelles
Name the 4 fontanelles in infants
Anterior
Posterior
Anterolateral
Posterolateral
Which is significantly smaller in infants vs adults? (neurocranium or viscerocranium)
Viscerocranium
Why do infants have a higher prevalence of otitis media?
Their eustachian tubes are positioned more horizontally
________ bones lie within sutures
Wormian
Wormian bones are typically found in the _______ suture
Lambdoid suture
Wormian bones may occur normally or in some diseases, such as ___________ __________, ________ _________, and _________
Osteogenesis imperfecta (brittle bone disease)
Genu varus (bow legs)
Rickets (Vitamin D deficiency)
AKA “brittle bone disease”
Osteogenesis imperfecta
Present w/ robin’s egg blue sclera
Osteogenesis imperfecta
Disease causing bow legs
Genu varus
Disease caused by Vitamin D deficiency
Rickets
Wormian bone disease resulting in a small or absent clavicle
Cleidocranial dysostosis
Wormian bones also occur in pts w/ _________ syndrome
Down syndrome
Name the 3 layers/zones of the neurocranium
Superficial (outer table)
Intermediate (cancellous bone)
Deep (inner table)
Which layer of the neurocranium is compact and dense?
Superficial (outer table)
Which layer of the neurocranium houses and protects red bone marrow and venous pathways?
Intermediate (cancellous bone)
AKA diploe
Which layer of the neurocranium is compact, dense, but brittle?
Deep (inner table)
This layer of the neurocranium is also called the diploe
Intermediate layer
Which layer of bone is closest to the dura matter?
Deep (inner table)
What veins run with the diploic bone?
Diploic veins
Name the 4 diploic veins
Frontal diploic vein
Anterior temporal diploic vein
Posterior temporal diploic vein
Occipital diploic vein
AKA venous network of “anastomotic channels”
Diploic veins
What 2 things do the diploic veins drain?
Scalp
Neurocranium
Where do the diploic veins terminate?
Dural Venous Sinuses
*these are the structures alex was emphasizing
Venous channels formed from dura matter
Dural Venous Sinuses
What veins “pierce the skull” and carry scalp & diploic venous drainage into the dural venous sinuses?
Emissary veins
What makes the emissary veins dangerous?
They are valveless and can lead to spread of infection from scalp to the meninges and/or brain
Meninges (dura/arachnoid/pia matter)
Encephalitis is inflammation of the ______
brain
What bone makes the roof of the orbit?
Frontal bone
What 2 bones make up the medial wall of the orbit (be specific)
Lacrimal bone
Orbital plate of ethmoid bone
What bone makes up the lateral wall of the orbit?
Zygomatic bone
What bone makes up the floor of the orbit?
Maxilla
What bone makes up the apex of the orbit? (be specific)
*the apex of the orbit is the posterior wall
Greater wing of sphenoid bone
What 3 openings does the apex of the orbit contain?
Optic canal
Superior orbital fissure
Inferior orbital fissure
What runs through the optic canal?
Optic nerve (CN II)
Ophthalmic artery
*this is pretty explanatory. The nerve and artery that feeds the eye. Obvious those are gonna run through the optic canal
The tip of what bone can be found on the medial wall of the orbit? (be specific)
perpendicular plate of palatine bone
What runs through the inferior orbital fissure?
Infraorbital v.
Infraorbital n.
What does the infraorbital n. run along after it passes through the inferior orbital fissure?
Infraorbital groove
What opening is on the medial wall of the orbit?
(think about this, we know this)
Nasolacrimal canal
What runs through the nasolacrimal canal and where does it terminate?
Nasolacrimal duct
Inferior nasal meatus
Point at where the parietal, temporal and sphenoid bones meet?
Pterion
Why does it suck that the pterion is a weak spot?
The anterior branch of the middle meningeal artery runs just deep to the pterion
What runs just deep to the pterion?
Anterior branch of the middle meningeal a.
What artery does the middle meningeal a. branch from?
Maxillary a.
What does a skull fracture at the pterion cause?
Epidural hematoma
What most commonly causes an epidural hematoma from trauma?
Skull fracture at the pterion, causing tear in the anterior branch of the middle meningeal a.
What 2 structures does the middle meningeal a. run between?
Inner table bone layer & dura matter
With a skull fracture, you should be worried about what?
Epidural hematoma
*tear in the middle meningeal a.
AKA the floor of the cranial cavity
Cranial vault
What bone forms the orbital plates that cover the orbit and also contains the cerebral cortex?
Frontal bone
What bone of the cranial vault contains the brainstem, cerebellum, and foramen magnum?
Occipital bone
What bone helps form the mid-floor of the cranial vault?
Sphenoid bone
The 2 lesser wings of the sphenoid bone make the 2 _______ ________ _________
Anterior clinoid processes
What structure houses the pituitary gland?
Hypophyseal fossa of the sphenoid body
What structure makes the 2 posterior clinoid processes?
Dorsum sellae
The dorsum sellae makes the 2 ________ ________ __________
Posterior clinoid processes
What 4 structures make turk’s saddle?
Hypophyseal fossa
posterior clinoid processes
dorsum sellae
tuberculum sellae
Where do the muscles that move the mandible attach to the sphenoid?
The pterygoid plates
What structure does the tensor veli palantini hook around?
The Hamulus of the medial pterygoid plate (of the sphenoid bone)
Big hole in the floor of the occipital bone
Foramen magnum
What part of the occipital bone is directly posterior to the sphenoid bone?
Basilar part
*think how the basilar a. runs on the circle of willis
The dip in the basilar part of the occipital bone
Clivus
What is the inferior surface of the occipital bone called
Cranium
Round bilateral impressions protruding externally from the bottom of the occipital bone that are positioned just laterally from the foramen magnum
Occipital condyles
What are the 2 “portions” of the temporal bone?
Squamous portion (flat part)
Zygomatic portion (connects to the zygomatic bone)
What are the 2 processes off of the temporal bone?
Styloid process
Mastoid process
What is the fossa medial to the ramus of the mandible?
Infratemporal fossa
Which part of the temporal bone houses the inner ear?
Petrous part
What’s the technical name for “inner ear”
Labyrinth
What part of the inner ear controls hearing?
cochlea
What part of the inner ear controls static positioning?
vestibule
What parts of the inner ear control balance and equilibrium?
3 semicircular canals
What 2 nerves run through the internal acoustic meatus?
Facial n. (CN VII)
Vestibulocochlear n. (CN VIII)
Which cranial fossa houses the frontal lobes of the cerebral cortex?
Anterior cranial fossa
Which cranial fossa houses the temporal lobes of the cerebral cortex?
Middle cranial fossa
Which cranial fossa houses the cerebellum and brain stem?
Posterior cranial fossa
What 3 bones make up the posterior cranial fossa?
Occipital bone
parietal bone
petrous part of temporal bone
What bones make up the middle cranial fossa?
Greater wing & body of sphenoid
Petrous & squamous part of temporal
What bone structures make up the anterior cranial fossa (be specific, there’s a lot)
2 lesser wings & anterior clinoid processes of sphenoid bone
Frontal bone & 2 orbital plates
2 cribriform plates & crista galli of ethmoid bone
Where does the mandible articulate w/ the cranium?
Temporomandibular joint (TMJ)
*mandible articulates w/ the temporal bone
What muscles causes protrusion of the mandible?
lateral & medial pterygoid muscles
What muscles cause retraction of the mandible?
temporalis m.
masseter m.
geniohyoid m.
digastric m.
What muscles cause elevation of the mandible?
temporalis m.
masseter m.
medial pterygoid m.
What muscles cause depression of the mandible?
digastric m.
geniohyoid m.
mylohyoid m.
*gravity
What part of the mandible connects to the TMJ
Mandibular condyle process
What’s the vertical portion of the mandible called?
ramus
What’s the name of the bilateral holes on the mandible?
Mental foramen
What nerve exits through the mental foramen?
Mental nerve
Inferior alveolar n. terminates as what nerve?
Mental n.
The inferior alveolar n. is a branch of what CN?
CN V (trigeminal n.)
Name the 5 layers of the scalp
S - skin
C - connective tissue
A - aponeurosis
L - loose connective tissue
P - pericranium
To which layer of the scalp does the frontalis m. & occipitalis m. attach?
Aponeurosis layer
