Week 1: Lecture 2 - The Skull Flashcards
How many bones are there in the skull?
22
What are the bones in the skull connected by?
fibrous sutures
-a suture is a joint that is non moveable
which is the only joint in the skull that is moveable?
The temporomandibular joint in the cranial cavity of the brain
Which bones form the surroundings of the orbital cavity?
Roof - frontal bone Lateral walls - Zygomatic bones Medial - lacrimal bone and ethmoid bone Floor - maxilla bones Posterior wall - sphenoid bone
Which suture connects the parietal bones?
sagittal suture
Which suture joints the frontal bone to both parietal bones?
coronal suture
Which bone is the ‘cheek’ bone?
zygomatic bones
Which bones are in the nasal cavity?
- ethmoid bone
- vomer bone
- inferior nasal concha
Which part of the ethmoid bone connects to the vomer?
middle process of ethmoid
How is the shape of the sphenoid bone usually described?
butterfly shape
Which 5 bones in the skull are not paired?
- frontal bone
- ethmoid bone
- vomer
- mandible
- sphenoid
Which 7 bones in the skull are paired?
- parietal
- nasal
- temporal
- zygomatic
- lacrimal
- maxillary
- inferior nasal concha
Which 4 paranasal sinuses do we have?
- frontal sinuses
- ethmoidal sinuses
- maxillary sinuses
- sphenoid sinuses
all found where the corresponding bones are
What are the functions of the paranasal sinuses?
- lighten the weight of the skull
- filter and humidify air
- resonate voice
- drain fluid into specific channels in the nasal cavity called meatuses
Which concha are found in the ethmoid bone?
superior and middle concha
What are meatuses?
channels underneath the concha
paranasal sinuses drain fluid into these spaces
Which gland sits on the sphenoid bone?
pituitary gland
Which sinuses drain into the superior meatus? (SES)
SES -
Sphenoid sinus and ethmoidal air cells drain into superior meatus
Which sinuses drain into the middle meatus? (MFM)
MFM-
Maxillary and frontal sinus drain into middle meatus
What drains into the inferior meatus?
nasal lacrimal duct - bringing tears to our nasal cavity when we cry
Where is the mastoid process?
Protrusion in the posterior temporal lobe
-so called because its breast shaped
Which sharp and pointy projection is found anterior to the mastoid process?
styloid process
-so called because it resembles a pen
What does the external auditory canal/ tube do? What membrane is it covered with?
- connects external ear to middle ear
- covered by tympanic membrane
What connects the temporal bone to zygomatic bone?
zygomatic process
So what are the 3 processes found in the temporal bone?
- mastoid process
- styloid process
- zygomatic rocess
What is the temporal-mandibular joint formed from?
- temporal bone articulates with the mandible
- formed between the mandibular fossa and condyle of the mandible
What are two landmarks of the mandible?
- coronoid process of the mandible
- ramus of mandible - quadrilateral shape with angle of mandible at bottom
What is the Pterion and what is its clinical significance?
- region where frontal, parietal, temporal and sphenoid bones join together
- very thin and dangerous if fractured as the middle meningeal artery and its branches are just underneath
- rupture of MMA can cause blood accumulation between skull and dura mater causing an extradural haematoma
What does the middle meningeal artery supply?
The dura mater and the calvaria
What connects the parietal bones to the occipital bone?
lambdoid suture
What are the occipital condyles?
two protrusions that sit on top of our first cervical vertebrae
What are fontanelles?
Large membranous areas between bones that are not yet fused in skulls of new borns
Why are bones in the skull of new borns not yet fused?
to accommodate for post-natal brain growth and allow birth through the birth canal
How is the cranial cavity divided?
into 3 regions:
- anterior cranial fossa
- middle cranial fossa
- posterior cranial fossa
What separates the anterior and middle cranial fossa?
Sphenoid ridges
What divides the middle and posterior cranial fossa?
petrous temporal bone (roughened area of temporal bone)
In what cranial fossa is the brainstem and cerebellum found?
posterior cranial fossa
What is the name of the process arising from the superior surface of the ethmoid bone, projecting into the anterior cranial fossa
crista Galli of the ethmoid bone
Where is the cribriform plate of the ethmoid bone found?
between anterior cranial fossa and nasal cavity
In which bone is the optic canal?
two foramina in the spehnoid bone
Which 3 foramen are found on the floor of the skull?
ROS
- rotundum foramen
- ovale foramen
- spinosum foramen
Which foramen is covered by a layer of cartilage in living humans?
foramen lacerum
Name all the foramina in the floor of the skull
- rotundum foramen
- ovale foramen
- spinosum foramen
- foramen lacerum
- jugular foramen
- foramen magnum - big
- hypoglossal canal
- pituitary fossa
- internal auditory meatus
- superior orbital fissure
- optic canal
Where is the jugular foramen?
large foramen between the petrous temporal bone and occipital bone
where is the hypoglossal canal?
tucked under the occipital condyles
what travels through cribriform plate of ethmoid bone?
Cranial nerve I - olfactory nerve
what travels through the optic canal?
CN II - Optic nerve
what travels through the superior orbital fissure?
- CN III - Oculomotor nerve
- CN IV - Trochlear nerve
- 1st division of CN V (trigeminal nerve) - ophthalmic branch
- CN VI - Abducens nerve
what travels through the foramen rotundum
maxillary branch - 2nd branch of the trigeminal nerve
What travels through the foramen ovale?
3rd branch of the trigeminal nerve (mandibular branch)
What travels through the foramen spinosum?
middle meningeal artery
What travels through the internal auditory meatus?
- CN VII (facial nerve)
- CN VIII (vestibulocochlear nerve)
What travels through the jugular foramen?
- internal jugular vein
- CN IX (glossopharyngeal)
- CN X (vagus)
- CN XI (accessory)
What travels through the hypoglossal canal?
CN XII (hypoglossal nerve)
What travels through the foramen magnum?
spinal cord
What is the hard palate formed from?
- horizontal process of the maxilla
- palatine bones
What travels through the carotid canal?
internal carotid artery
