Skull Anatomy Flashcards
how many bones are in the skull
22
how are the bones in the skull joined together
- 21 are linked by fibrous joints – the mandible articulates via the synovial temporomandibular joint
what is the role of the neurocranium
- this is the cranial vault
Role - Protect the fragile brain
- Attachment site for head and neck muscles
what is the role of the viscerocranium
this is the facial skeleton Role • Form framework of the face • Contain cavities for special sense organs (sight, taste and smell) • Opening for air and food passage • Secure teeth • Anchor facial muscles of expression
How many cranial bones are there
There are 8 cranial bones
what are the 8 cranial bones
- Parietal (x2)
- Temporal (x2)
- Sphenoid
- Frontal
- Ethmoid – CSF leaks in if it is damaged
- Occipital
what are the sutures in the cranium
- Sagittal suture – between two parietal bones
- Coronal suture – between frontal and parietal bones
- Lambdoid suture
- Squamous suture
what is the pterion
it is where the frontal, parietal, temporal and sphenoid all join
- it is the weak part of the skull
what part of the ear does the temporal bone have in it
- The temporal bone has both the middle and internal ear in it,
describe the structure of the temporal bone
- Superior part is called the squamous part
- The internal aspect of the temporal bone (bony shelf) is called the petrous part of the temporally bone
- Externally projecting anteriorly is the zygomatic process
- And inferior is the mastoid process
- Styloid process is just anterior
- And anterior to the styloid process is the external acoustic meatus
where is all of the inner ear housed
all of the inner ear is housed between the petrous part of the temporal bone
what is the sphenoid bone
- This is the bone that links the facial skeleton to the cranial skeleton
what can fractures of the sphenoid bone do
- separate the cranial and facial skeleton
what is the part of the sphenoid bone where the muscles attach
- Pterygoid plate – this is where the muscles of mastication attach to
describe the structure of the sphenoid bone
- The greater wing makes the external edge of the skull whereas the lesser wing makes up the internal aspect of the skull
- Pterygoid plate – this is where the muscles of mastication attach to
- There is a sella turnica – this is the depression, it is a bony cradle that protects the pituitary gland
- Either side of the sella turica there is the anterior clinoid process and posterior clinoid process
what are the 3 meninges in the brain
- Dura mater, arachnoid mater, and pia mater
how many layers of the dura mater are there in the skull
2
what are the two layers of the dura mater in the skull
periosteal and meningeal layer
what does the periosteal layer of the dura mater do
it attaches to the skull itself
what does the meningeal layer of the dura mater do
at certan points pulls always from the inside of the skull it forms inwards folds
what separates the cerebellum form the brain
- Flax cerebri and tentorium cerebellum separates the cerebellum from the brain above
- Compartmentalises the brain and gives support to the brain
what structure allows the brainstem to pass up into the brain
- Compartmentalises the brain and gives support to the brain
- The tentorial notch allows the brainstem to pass up the brain
what is between the periosteal and meningeal layers of the dura mater
- Between the periosteal and meningeal layers of the dura mater is a network of endothelial lined spaces, which are filled with venous blood; the dural venous sinuses.
what are the different types of dural venous sinuses
- Superior sagittal sinus and inferior sagittal sinus
- Transverse and straight and sigmoid and periosteal and cavernous sinuses
How does the dural venous sinuses drain
- The sigmoid sinus is continuous with the jugular vein which goes through the jugular foramen
- Also have a cavernous sinus this is clinically important, this is because the internal carotid artery runs straight through it, there is also a petrosal sinus
what does the facial skeleton surround
- it surrounds the orbit, mouth and nasal cavities
what is the orbit
- This is a bilateral pyramidal shaped cavity on the anterior aspect of the skull
what does the orbit contain
- Has the eyeball, extraocular muscles and associated neurovascualture
what bones contribute to the orbit
- Frontal
- Maxilla
- Lacrimal
- Ethmoid
- Sphenoid
- Zygomatic
where is there most likely to be fractures in the nasal part
Medial part of the nasal part is thin bone and laterally there is thick bone
If there is fractures it will be medial or inferior as these areas are thinner
what is the oral cavity made up of
- The bony skeleton of the oral cavity is made up of the maxilla and mandible which has the upper and lower teeth
what is the hard plate made up of
the hard plate is made out of 2/3 maxillary and 1/3 palatine
what types of tissue makes up the nasal septum
- both bony and cartiligoaneous contributions
describe the structure of the nasal cavity
- Anterior part of the nasal cavity is made up of cartilage
- the emthmoid bone
- Have the cristal gali either side of this is the ciriboform plate of the ethmoid bone,
- Nasal septum is made up of the perpendicular plate
what are the different types of paranasal sinuses
- These are hollow spaces with the frontal, sphenoid and ethmoid and maxillary bones,
describe the structure of the paranasal sinuses
- Lined by the mucous membrane and drains into the nose
describe the skull of a newborn
- The calvarium of newborn has large membranous regions between the bones
what is the largest fontanelles
anterior fontanelle
what is the role of the fontanelle
Also important for giving birth when it is being pushed down the birthing canal it means that the bones of the skull can slide over each other and prevent the skull from fracturing
what are the fontanelle bones in the skull
posterior fontanelle – closes at 12 months
Sphenoid fontanelle
Mastoid fontanelle
Anterior fontanelle – closes at 18 months
what are the internal features of the skull divided into
- Anterior cranial fossa
- Middle cranial fossa
- Posterior cranial fossa
- Lesser wing of sphenoid separates the anterior cranial fossa from the middle cranial fossa
- Petrous temporal – separates the middle cranial fossa from the posterior cranial fossa
what goes through the foramen spinous and what happens if there is damage to it
middle meningeal artery runs underneath the pternoin, therefore if there is a fracture here and the middle meningeal artery will be damaged, therefore you get an extradural haematoma
what kind of haemotoma do you get if the middle meningeal artery is damaged
extradural haematoma
what drains into the jugular foramen
dural venous sinuses drain into here
what goes through the carotid canal
- internal carotid artery travels through it
- the carotid canal travels through bone for a bit, and thought he temporal bone
what passes through the foramen lacrum
nothing passes through this as it is covered with cartilage
what does the olfactory nerve do and where does it run
- Involved in smelling
- There are tiny little olfactory nerves that go through the cribiform plate into the cranial cavity
- The olfactory nerves run inferiorly from the olfactory bulb, though the perforated cribiform plate of the ethmoid bone to enter the nasal cavity.
where does the optic nerve enter
- The optic nerve traverses the optic canal to enter the orbit.
what nerves control eye movement
Oculomotor (III), Trochlear (IV) and Abducens (VI)
what do Oculomotor (III), Trochlear (IV) and Abducens (VI) do
control eye movement
where does the oculomotor nerve emerge from
midbrain
where does the trochlear nerve emerge from
posterior surface of the midbrain
where does the abducnt nerve emerge from
the pons
where do the Oculomotor (III), Trochlear (IV) and Abducens (VI) enter
- All 3 cranial nerves traverse the superior oribtial fissure to enter the orbit
where does the bigeminal nerve emerge form
The trigeminal nerve emerges from the lateral surface of the pons
what are the 3 branches of the trigeminal nerve
- Opthalmic (V1)
- Maxillary (V2)
- Mandibular (V3)
how do the 3 branches of the trigeminal nerve run through
The ophthalmic branch traverses the superior orbital fissure to enter the orbit
The maxillary branch leaves the cranium by passing through foramen rotundum
The mandibular branch runs through foramen ovale
how do the 3 branches of the trigeminal nerve reach the face
The ophthalmic branch reaches the face by exiting through the supraorbital foramen
The maxillary branch reaches the face by passing through the infraorbital foramen
The mandibular branch reaches the face via the mental foramen
where does the facial nerve run
- The facial nerve emerges from the pons, and passes through the internal acoustic meatus.
- The facial nerve runs through the petrous temporal bone and exits the skull via the stylomastoid foramen
where does the vetribulocohlera run
- This emerges from the pons and enters the internal acoustic meatus
where does the glossophargeal and vagus nerve run
- The glossopharyngeal nerve emerges from the lateral surface of the medulla oblongata with the vagus nerve, they both exit the skull via the jugular foramen
where does the spinal accessory run
- The spinal accessory emerges from the first 5-6 cervical segments and then runs superiorly through the foramen magnum then leaves the skull via the jugular foramen
where does the hypoglossal nerve run
- The hypoglossal nerve emerges from the anterior aspect of the medulla oblongata and runs through the hypoglossal canal
