Cranium, meninges and brain Flashcards
How many bones make up the skull?
22
Recall the 9 main bones of the skull
Frontal Parietal Temporal Parietal Zygoma Ethmoid Mandible Maxilla Occipital
What bone forms the roof of the mouth?
Palatine
What bone is seen to split the 2 halves of the nose?
Vomer
What foramina are found in the maxilla?
Intraorbital
Recall the 3 main sutures of the skull
Coronal
Saggital
Lamboid
What name is given to the protrusion at the most dorsal point of the occipital bone?
Inion (external occipital protuberance)
What name is given to the “soft spots” in the infant skull?
Fontanelles
What is the internal capsule?
Fibrous tract where fibres from the cortex come together
Recall the layers of the scalp, from superficial to deep
Skin Connective tissue Aponeurosis Loose areolar tissue Periosteum
Within which layer of the scalp are arteries, veins and nerves found?
Connective tissue
Which muscle’s aponeurosis forms the aponeurotic layer of the scalp?
Occipital and frontal bellies of the occipitofrontalis muscle
Which layer of the scalp facilitates movement?
Loose areolar tissue
Recall the fossae of the skull
Anterior, middle and posterior cranial; cerebellar
Recall the structures that pass through the foramen magnum
Medulla
Meninges (these surround medulla)
Vertebral and spinal arteries (brain needs blood supply)
Dural veins (brain needs draining)
Which cranial fossa is the most shallow?
Anterior
Recall the borders of each cranial fossa
Anterior = frontal bone to body and lesser wings of sphenoid Middle = to dorsum sellae of sphenoid Posterior = to internal occipital proturberance
Recall the relative positioning of the wings of the sphenoid bone
Lesser wing = anterior
2 lateral greater wings of sphenoid
What lies posteriorly to the hypophysial fossa?
Dorsum sellae
Recall the foramina of the sphenoid bone, from anterior to posterior
Optic canals Orbital fissures Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum
Recall the positioning of the sphenoid sinuses
There are 2: one anterior to and one posterior to the sphenoid body
Recall the layers of the meninges from superficial to deep
Dura mater, arachnoid mater, pia mater
Where do emissory veins run?
Originate in superficial fascia, drain into diploic vein within bone of skull
Where does the cerebral vein run in relation to the meninges?
Deep to all of them
Where is the subarachnoid space?
Between arachnoid mater and pia mater
Describe the structure and structural properties of the dura mater
Thich and inelastic
Periosteal and meningeal layer
Describe the structure and structural properties of the arachnoid mater
Elastic
Spider-like projections
Describe the structural properties of the pia mater
Thin and delicate
Which meningeal space is very large in the spine?
Extradural space
What is the falx cerebri?
Fold of meningeal layer of dura mater that runs into the longitudinal fissure
What is located at the base of the falx cerebri?
Inferior saggital sinus
Where is CSF produced and where is this located?
Choroid plexus = superior part of inferior horn of lateral ventricle
Recall the flow of CF from its production to its drainage
Lateral ventricle (choroid plexus) interventricular foramen 3rd ventricle cerebral aqueduct 4th ventricle *various foramina* subarachnoid space arachnoid granulation villi = drainage --> superior saggital sinus
Why is an epidural bleed more dangerous in the skull than the spine?
Very small epidural space in brain so bleed is dangerous whereas in spine epidural space is large - ammeanable to CSF removal
What is the tenorium cerebelli and what is its function?
Extension of the dura mater that separates the cerebellum from the inferior part of the occipital lobes
Recall the foramina through which each of the cranial nerves enter
CNI = cribiform plate of ethmoid CNII = optic canal CNIII = superior orbital fissure CNIV = superior orbital fissure CNV1 = superior orbital fissure CNV2 = foramen rotundum CNV3 = foramen ovale CNVI = superior orbital fissure CNVII = internal acoustic meatus CNVIII = internal acoustic meatus CNIX = jugular foramen CNX = jugular foramen CNXI = jugular foramen CNXI spinal roots = foramen magnum CNXII = hypoglossal canal
Recall the vascular components that enter the skull via the optic canal
Ophthalmic artery
Central artery of retina
Recall the vascular components that enter the skull via the superior orbital fissure
Superior ophthalmic vein
Recall the path of the internal carotid artery entering the skull
Enters via the carotid canal, turns a right angle and runs just posterior to foramen lacerum
Recall the vascular components that enter the skull via the foramen spinosum
Middle meningeal artery and vein
Recall the vascular components that enter the skull via the internal acoustic meatus
Labyrinthine artery
Through which foramen of the skull does the sigmoid sinus drain into the internal jugular vein?
Jugular foramen
Recall the components of the Circle of Willis, from anterior to posterior
2 x Anterior cerebral
(connected by 2 x anterior communicating)
Joins: Bilateral internal carotids (medial) and middle cerebrals (lateral)
Posterior communicating arteries join them to the posterior cerebral
Superior cerebellar
Basilar
Anterior inferior cerebellar
Posterior inferior cerebellar
Vertebral
Anterior spinal
What is the main danger of a cavernous sinus thrombosis?
Disruption of cranial nerve travelling through
From which sinus does the great cerebral vein form?
Straight
Name the sinus branches that travel around the sides of the brain
Transverse sinuses
Which sinus encircles the IJV?
Sigmoid sinus
What do the transverse sinuses converge to form?
Cavernous sinuses
Why do scalp lacerations threaten the brain
Emissory veins provide a route of transmission of infection since they drain into deeper veins
Where is the pterion and why is it clinically significant?
Where temporal, frontal, occipital and parietal bones meet
Thin part of skull
MMA runs just below = very vulnerable to extradural bleed
Recall the names of the cranial nerves
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Accessory
- Hypoglossal
Describe the course of the facial nerve as it exits the skull
Exits skull via internal acoustic meatus and then stylomastoid foramen
Runs over parotid gland
Branches into 5 nerves supplying the face
Where is the primary motor cortex located?
Pre-central gyrus
Where is the primary somatosensory cortex located?
Post-central gyrus
Recall the function of Wernicke’s area
Sensory - speech
Recall the function of Broca’s area
Motor - speech
Where are the colliculi seen on the brainstem?
Posteriorly, either side of pineal gland, on top of tectum
Posteriorly, what is seen in the centre of the pons?
4th ventricle
Recall some key distinguishing structures seen ANTERIORLY on the brainstem
Optic chiasm
Pituitary stalk
Mamillary bodies
Cerebral peduncles
