Anatomy HNS 1 - Cranium, Meninges and Brain Flashcards
What are the bones of the cranium?
- Occipital
- Sphenoid
- Parietal (2)
- Ethmoid
- Temporal (2)
- Frontal
What are the bones of the facial skeleton
- Maxilla (2)
- Zygoma (2)
- Nasal (2)
- Vomer
- Lacrimal (2)
- Palatine (2)
- Inferior nasal conchae (2)
- Mandible
What 3 structures are present in the ethmoid bone
- Orbital plate
- Middle nasal conchae
- Perpendicular plate
What foramen is present on the mandible
Mental foramen
What 2 structures are present on the maxilla
- Anterior nasal spine
2. Infraorbital foramen
The sphenoid bone consists of 2 wings which are
Greater wing and lesser wing
Which bone contains the sagittal suture
Parietal bone
Which suture runs horizontally, and what bone is it part of?
Coronal suture, runs along frontal bone
Which suture runs posteriorly on the occipital bone
Lambdoid suture
What is the point where the sagittal suture and lambdoid suture meet?
Lambda
What is the point where the coronal suture and the sagittal suture meet?
Bregma
The temporal bone is posterior to the frontal bone and the ….
Sphenoid bone
On what bone is the mastoid process?
Temporal
On which bone is the styloid process
Temporal
What is the name of the region where 4 bones meet?
What are the 4 bones that meet
The pterion
- Greater wing of sphenoid
- Frontal
- Temporal
- Parietal
The pterion is the weakest part of the skull. Trauma to this structure may rupture what to cause an epidural haematoma?
Middle meningeal artery
From what artery does the middle meningeal artery arise?
Maxillary artery - a branch of the external carotid artery
How many fossa are there in the cranial base?
3
What does the anterior cranial fossa contain?
Frontal lobes
What bone is the cribriform plate part of?
Ethmoid
What forms the lower/posterior border of the anterior cranial fossa?
Lesser wing of sphenoid and body of sphenoid
What is the foramina between the frontal crest and cribriform plate?
Foramen cecum
What does the middle cranial fossa contain?
Temporal lobes
Which 3 foramina are part of the greater wing of the sphenoid?
Foramen lacerum Foramen vale (largest) Foramen spinosa (lateral)
Which is the deepest and largest fossa?
Posterior cranial fossa
What does the posterior cranial fossa contain?
Brainstem and cerebellum
Where is the foramen magnum located?
Posterior cranial fossa
Name the 11 structures in the cranial fossa that allow nerves/vasculature to pass through
(anterior to posterior)
- Cribriform plate
- Optic canal
- Superior orbital fissure
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
- Carotid canal
- Internal acoustic meatus
- Jugular foramen
- Hypoglossal canal
- Foramen magnum
What passes through the cribriform plate?
Olfactory nerve
What passes through the optic canal
- Optic nerve (& central artery of retina)
2. Ophthalmic artery
What passes through the superior orbital fissure
- Oculomotor nerve
- Trochlear
- Ophthalmic division of trigeminal
- Abducens
- Superior ophthalmic vein
What passes through the foramen rotundum
Maxillary division of trigeminal nerve
What passes through the foramen ovale
Mandibular division of trigeminal nerve
What passes through the foramen spinosum
Middle meningeal artery and vein
Nothing significant passes through foramen lacerum
Y
What passes through carotid canal
Internal carotid artery
What passes through internal acoustic meatus
- Facial nerve
- Vestibulocochlear nerve
- Labyrinthine artery
What passes through the jugular foramen
- Glossopharyngeal nerve
- Vagus nerve
- Accessory nerve
- Sigmoid sinus - internal jugular vein
What passes through the hypoglossal canal
Hypoglossal nerve
What passes through the foramen magnum
- Vertebral arteries
- Medulla of brain
- Spinal roots of accessory nerve
LEARN MRI - USE JAS SLIDES, MUBARAK HAS EMAILED THEM
Y
Superficial to deep - what are the tissue components of the scalp
S - Skin C - Connective tissue A - Aponeurosis L - Loose areolar tissue P - Periosteum
What are the 3 meningeal layers of the brain
- Outer dura mater
- Middle layer - arachnoid mater
- Inner layer - Pia mater
What are the 2 dura mater layers in the brain
- Outer periosteal layer
2. Inner meningeal layer
What do the 2 dura mater layers separate from each other to form?
- Dural partitions
2. Intradural venous sinuses
Within what fissure does the falx cerebri dural fold exist?
Longitudinal cerebral fissure - separates left and right hemisphere
Where does the tentorium cerebelli dural fold exist?
Between the occipital lobes
Also between cerebellum and brainstem
What are the 3 types of herniation?
- Subfalcine herniation
- Uncal herniation
- Tonsillar herniation
What happens in a subfalcine herniation
Frontal lobe herniates below falx cerebra
- Not clinically significant
Describe uncal herniation
Uncus of temporal lobe herniates below tentorium cerebelli - compresses midbrain
Can lead to loss of consciousness
Describe tonsillar herniation
Cerebellar tonsils move downwards through the foramen magnum - may cause compression of the medulla
This can lead to cardiorespiratory arrest
Where is CSF present?
In the ventricles
CSF is not ECF. How does ECF drain back into the capillaries?
Via BBB
2 functions of CSF
- Shock impact - protects the brain
2. Nutrition for the brain
Explain how CSF is formed and drained
- Choroid plexi create CSF in each ventricle
- Lateral ventricles drain into 3rd ventricle via inter ventricular foramina
- 3rd into 4th via cerebral aqueduct
- From the 4th ventricle into subarachnoid space via foramina of luschka and magendie
- CSF drains from subarachnoid space into dural venous sinuses via arachnoid villi
What is the source of anterior blood supply to the brain
Internal carotids
What is the source of posterior blood supply to the brain?
Vertebro-basilar
At what vertebral level does the common carotid split into the internal and external carotids?
C4
The internal carotid artery enters the cranium through which foramen?
Carotid canal
In the cranial cavity, what 3 branches does the internal carotid divide into?
- Ophthalmic branch
- Anterior cerebral artery - supplies medial surface and small superior strip on the lateral surface
- Middle cerebral artery - main branch of ICA - goes through transverse fissure of the brain and supplies most of lateral surface
Where do the vertebral arteries come from?
1st part of subclavian arteries
Through which foramina of C1-C6 vertebrae does the vertebral artery ascend?
Transverse foramina
What are the 3 branches of the vertebral artery
- Anterior spinal artery - anterior 2/3rds of SC
- Posterior spinal - posterior 1/3rd of SC
- Posterior inferior cerebellar artery - supplies posterior inferior aspect of cerebellum
What do the vertebral arteries unite to form?
Basilar artery on the anterior aspect of the pons
What are the branches of the basilar artery
- Anterior inferior cerebellar artery
- Pontine arteries
- Labyrinthine arteries
- Superior cerebellar arteries
- Posterior cerebral arteries
Which artery joins the 2 anterior cerebral arteries?
Anterior communicating artery
What connects the posterior cerebral artery to the middle cerebral artery?
Posterior communicating artery
How is blood from the cerebral veins drained?
Drained into dural venous sinuses - then drained into the internal jugular vein
Superior and inferior sagittal sinuses run along the margin of what?
Falx cerebri
Transverse sinuses run along what margin?
Tentorium cerebelli
Between which 2 structures does the cavernous sinus exist?
Sella turcica and temporal lobe
The inferior sagittal sinus drains into what before draining into the confluence of sinuses (before draining into the TV sinus)
Straight sinus
Superior sagittal sinus drains straight into confluence of sinuses
What does the confluence of sinuses drain into before draining into the internal jugular vein?
TV sinus - Sigmoid sinus - Internal jugular vein
Where does the cavernous sinus sit?
Lateral side of the body of sphenoid bone
Where does the cavernous sinus receive blood from?
Cerebral veins
Ophthalmic veins
Emissary veins (outside cranium)
Due to the location of the cavernous sinuses, what are they susceptible to?
Inflammation
What is the medial border of the cavernous sinus?
- Internal carotid artery
2. Abducens nerve - lies alongside artery so is susceptible to damage
What lies on the lateral border of the cavernous sinus
CrN 3, 4, Vi, Vii