The Intracranial Region Flashcards
Which part of cranium is formed by endochondral ossification?
Chondrocranium
What is another word for skull cap?
Calvarium
What is another word for skull cap?
Calvarium
Name the collagen type that makes up the fibrous joints of the skull
Type 1 collagen
What are fontanelles?
Membranous filled gaps that allows deformation of the skull during development of the brain - so that skull and brain can both grow
When does the neurocranium and viscerocranium reach their adult morphology?
At around 21 years of age
Name the 6 bony parts of the skull
Frontal
Parietal
Occipital
Temporal
Sphenoid
Ethmoid
What are the 3 layers of the bone in the calvarium in an adult?
Compact bone -> Spongy bone -> Compact bone
What is another name for the spongy bone found in the calvarium?
Diploe
Between which 2 bones does the coronal suture lie?
Frontal bone and parietal bone
Name the suture that occurs between the 2 frontal bones
Metopic suture
Name the suture that occurs between the 2 parietal bones
Sagittal suture
Between which 2 bones does the lambdoid suture lie?
Between the parietal and occipital bones
What is the asterion?
Point where the temporal, occipital and parietal bones meet
What is the pterion?
Point where the frontal, parietal, sphenoid and temporal bones meet
What is the pterion?
Point where the frontal, parietal, sphenoid and temporal bones meet
Name the 2 main fontanelle of the skull
Anterior fontanelle
Occipital fontanelle
Name the 2 main fontanelle of the skull
Anterior fontanelle
Occipital fontanelle
What is otorrhea?
CSF leaks into the ear (due to blunt trauma)
What is rhinorrhea?
CSF leaks into the nose (due to blunt trauma)
Which artery is at risk of being lacerated if the pterion is fractured?
Middle meningeal artery
What can occur in the skull if the middle meningeal artery is lacerated?
Extradural haemoatoma
How many layers of the scalp are there?
5
What is the innermost layer of the scalp called?
Periosteum
What is the outermost layer of the scalp called?
Skin
Name the 5 layers of the scalp
Skin
Dense connective tissue
Epicranial aponeurosis
Loose areolar connective tissue
Periosteum
Which layer of the scalp does not contain any blood vessels?
Epicranial aponeurosis
In which layer of the scalp would you find emissary veins?
Loose areolar connective tissue
What are diploic veins?
Veins that are found in the spongy bone of the skull cap
Name the structure of the arachnoid mater that regulates cerebrospinal drainage
Arachnoid villi
Name the structure of the arachnoid mater that regulates cerebrospinal drainage
Arachnoid villi
What veins have to pass across the subarachnoid space?
Cerebral veins
How does CSF enter the venous sinuses of the cranium?
Diffusion
What is the falx cerebri?
Extensions of the dura mater that invaginate downwards to separate the cerebral hemispheres
What is the falx cerebri?
Extensions of the dura mater that invaginate downwards to separate the cerebral hemispheres
What are the inferior boundaries of the falx cerebri?
The inferior sagittal sinus and straight sinus
What is tentorium cerebelli?
Extensions of the dura mater that invaginate transversely to separate the cerebrum from the cerebellum and brain stem
Name 3 superficial arteries of the external carotid that supply the scalp
Superficial temporal artery
Occipital artery
Posterior auricular artery
Does the posterior and middle meningeal artery rise from the internal or external carotid?
External carotid
Does the anterior meningeal artery rise from the internal or external carotid?
Internal carotid
Through which foramen does the middle meningeal artery enter the intracranial region?
Foramen spinosum
Through which foramen does the middle meningeal artery enter the intracranial region?
Foramen spinosum
Name the 2 routes by which arterial blood can reach the brain
Through the vertebral arteries
Through the internal carotid
Which supplies more blood to the brain, the vertebral arteries or the internal carotid?
Internal carotid
What artery its formed by the joining of the 2 vertebral arteries?
Basilar arteries
Through which foramen do the vertebral arteries travel in up to the intracranial region?
Transverse foramen
What structures of the brain are supplied by the basilar artery?
Pons and cerebellum
Name the branches of the basilar artery that supply the pons
Pontine arteries
Name the branches of the basilar artery that supply the cerebellum
Anterior inferior cerebellar arteries
Superior cerebellar arteries
Posterior cerebral arteries
Name the branches of the basilar artery that supply the cerebellum
Anterior inferior cerebellar arteries
Superior cerebellar arteries
Posterior cerebral arteries
Name the arteries that join the internal carotid artery to the basilar artery
Posterior communicating artery
What other 3 branches come off the internal carotid artery?
Anterior choroidal artery
Opthalmic artery
Anterior cerebral artery
Name the artery that joins the anterior cerebral arteries together
Anterior communicating artery
Why is it important that the vertebral arteries are joined to the internal carotid arteries?
To equalise the pressure in the brain and give collateral supply to all parts of the brain
Does the course of the internal carotid artery cross through the cavernous sinus?
Yes it does - then enters then intracranial region just after
Name 2 arterial branches that arise form the ophthalmic artery
Supraorbital arteries
Supratrochlear arteries
Name 2 arterial branches that arise form the ophthalmic artery
Supraorbital arteries
Supratrochlear arteries
List 5 superficial veins of the scalp and face
Superficial temporal veins
Occipital veins
Posterior auricular veins
Supraorbital veins
Supratrochlear veins
What is the pterygoid plexus?
Large complex of veins located in the infratemporal fossa, between the temporalis and lateral pterygoid muscles
Which vein does the pterygoid plexus drain into?
Maxillary vein
Which vein does the pterygoid plexus drain into?
Maxillary vein
What are emissary veins?
Veins that connect the diploic veins to the veins of the scalp
What are emissary veins?
Veins that connect the diploic veins to the veins of the scalp
What does the inferior sagittal sinus become when it reaches the tentorium cerebelli?
Straight sinus
What does the inferior sagittal sinus become when it reaches the tentorium cerebelli?
Straight sinus
Which left and right venous sinus does the superior, straight and occipital sinus drain into?
The transverse sinus
What does the left transverse sinus drain into?
Left sigmoid sinus
What does the right transverse sinus drain into?
Right sigmoid sinus
What does the left sigmoid sinus drain into?
Left jugular vein
What does the right sigmoid sinus drain into?
Right jugular vein
Where is the cavernous sinus located?
Around the sphenoid bone
From where does the pterygoid plexus drain blood from?
Palate
Nasal cavity
Paranasal sinuses
Auditory tube
Nasopharynx
From where does the cavernous sinus drain blood from?
Ophthalmic veins
Anterior part of the brain
Middle cerebral veins
Sphenoparietal sinuses
Name 5 structures that pass through the walls of the cavernous sinus
Internal carotid artery
Oculomotor nerve CNIII
Trochlear nerve CNIV
Trigeminal nerve CNVi + Vii
Abducens nerve CNVI
From where do the petrosal sinuses drain blood from?
Cavernous sinus
Midbrain
Cerebellum
Inner ear
What does the petrosal sinuses drain into?
Transverse sinuses
List 2 reasons why scalp lacerations lead to profuse bleeding
1 - Scalp blood vessels are closely adhered to connective tissue, so vasoconstriction cannot occur as easily
2 - Blood vessels in the scalp have many anastomoses
What shape do extradural haemorrhages appear on CT?
Lens shaped
Does the dura mater remain attached to the scalp during an extradural haemorrhage?
No, it detaches from the scalp
Are extradural haemorrhages usually caused by arteries or veins?
They are usually caused by arteries
What shape do subdural haemorrhages appear on CT?
Crescent shaped
Does the dura mater remained attached to the scalp during a subdural haemorrhage?
Yes
Are subdural haemorrhages usually caused by arteries or veins?
They are usually caused by veins
Which is more extensive, extradural or subdural haemorrhages?
Subdural haemorrhages are more extensive
What is the main symptom of a subarachnoid haemorrhage?
Sudden severe onset headache
What is the main symptom of a subarachnoid haemorrhage?
Sudden severe onset headache
What is the main cause of a subarachnoid haemorrhage?
Ruptured cerebral blood vessels
Between which layers does the extradural haemorrhage occur?
Between the dura mater and bone of the scalp
Between which layers does the subdural haemorrhage occur?
Between the dura mater and arachnoid mater
Which is cranial nerve 1?
Olfactory nerve
Which cranial nerve enters the intracranial region through the cribriform plates?
Olfactory nerve
Through which canal does the optic nerve travel?
Optic canal
Name the 4 structures that pass through the superior orbital fissure
Ophthalmic division of trigeminal nerve
Oculomotor nerve
Trochlear nerve
Abducens nerve
What structure passes through the foramen rotundum?
Maxillary division of the trigeminal nerve
What outlet does the mandibular division of the trigeminal travel in?
Foramen ovale
Name the 2 structures that travel in the internal acoustic meatus
Facial nerve
Vestibulocochlear nerve
Name 3 structures that travel through the jugular foramen
Glossopharyngeal nerve
Vagus nerve
Accessory nerve
Which cranial nerve passes through the hypoglossal canal?
Hypoglossal nerve
Does the olfactory nerve have only motor or sensory innervation?
Motor
What does the olfactory nerve give motor innervation to?
The nose
Where does olfactory nerve rise from in the brain?
Olfactory bulb connected to the cerebrum
What is the only motor control of the optic nerve to?
The eye
Where does the optic nerve rise from in the brain?
Diencephalon region
What is the only motor control of the trochlear nerve to?
Superior oblique muscle of eye
What is the only motor control of the abducens nerve?
Lateral rectus muscle of the eye
What is the only motor control of the oculomotor nerve?
Superior rectus
Medial rectus
Inferior rectus
Inferior oblique
Where does the trochlear nerve rise from in the brain?
Midbrain
Where does the abducens nerve rise from in the brain?
Pons
Where does the oculomotor nerve rise form in the brain?
Midbrain
What is the sensory control of the trigeminal nerve to?
Forehead
Sinuses
Face
Jaw
Teeth
What is the motor control of the trigeminal nerve?
Masseter
Temporalis
Medial pterygoid
Lateral pterygoid
What is the only motor control of the facial nerve?
Muscles of the face
What is the only sensory control of the vestibulocochlear nerve?
Vestibular
Cochlear
Where does the facial nerve rise form in the brain?
Junction of pons and medulla
Where does the vestibulocochlear nerve rise form in the brain?
Junction of pons and medulla
What is the sensory control of the glossopharyngeal nerve?
Posterior part of tongue
Tonsils
Pharynx
What is the motor control of the glossopharyngeal nerve?
Superior
Middle
Inferior pharyngeal constrictor
What is the sensory control of the vagus nerve?
Heart
Lungs
Bronchi
Trachea
Larynx
Pharynx
Gastrointestinal tract
External ear
What is the motor control of the vagus nerve?
Heart
Lungs
Bronchi
Gastrointestinal tract
Where does the glossopharyngeal nerve rise form in the brain?
Medulla oblongata
Where does there vagus nerve rise from in the brain?
Medulla oblongata
What is the motor control of the accessory nerve?
Sternocleidomastoid
Trapezius
Where does the accessory nerve rise from in the brain?
Medulla oblongata
What is the motor control of the tongue?
Hypoglossal nerve
Where does the hypoglossal nerve rise from in the brain?
Medulla oblongata
What is the crista galli?
Triangular projection from the ethmoid bone
Name 2 other nerves that also pass through the cribriform plates
Nasociliary nerve
Nasopalatine nerve
Where is the sella turcica located?
Central part of the sphenoid bone
Name the 3 parts of the sella turcica
Tuberculum sella
Hypophysial fossa
Dorsae sellae
What is the function of the anterior and posterior crinoid processes?
Surrounds sella turcica
Attachment points for the tentorium cerebelli
What is the function of the anterior and posterior crinoid processes?
Surrounds sella turcica
Attachment points for the tentorium cerebelli
Which important gland lies in the sella turcica?
Pituitary gland
Which important gland lies in the sella turcica?
Pituitary gland
Where is the internal acoustic meatus in relation to the jugular foramen?
Located above and to the right/left
What is cerebellar tonsillar herniation?
Cerebellar tonsils displace downwards through the foramen magnum
What are causes of cerebellar tonsillar herniation?
Increased intracranial pressure
Hydrocephalus
Lesions
What is hydrocephalus?
Abnormal build up of CSF in the ventricles of the brain
What can cerebellar tonsillar herniation lead to?
Compression of the pons and medulla, leading to cardiorespiratory arrest
Where is cerebrospinal fluid formed?
Choroid plexuses of the brain
Through which structure does the CSF enter the venous sinuses?
Arachnoid villi
In which pressure situation will CSF flow into the venous sinuses?
If the CSF pressure is larger than the venous sinus pressure
In which situation will CSF NOT flow into the venous sinuses?
If the CSF pressure is less than the venous sinus pressure
How can a blockage of the arachnoid villi cause hydrocephalus?
CSF cannot be taken into the venous system, but CSF is still produced in the choroid plexuses, resulting in increased pressure of the brain
What arteries does the internal common carotid artery terminate as?
Middle cerebral arteries
Anterior cerebral arteries
Why is it important that the vertebral arteries and internal carotid are connected?
Ensures that blood pressure is equalised
Why are subdural haematomas more likely to occur in the elderly?
Brian shrinks in the elderly, so the cerebral veins that are attached to the dura and venous sinuses are stretched, so more easily ruptured
