1) cranium meninges and brain Flashcards
How many bones are in the skull?
22 bones (excluding ear ossicules) Mainly seperated in Mandible, Cranium (Vault and base)
Facial skeleton is part in the front
What are the bones of the cranium?
Frontal, parietal x2 bonesm occipital bones, temporal x2, Sphenoid and ethmoid
What are the bones of the facial?
Maxilla x2, Zygoma x2, nasal x2, lacrimal x2, Vomer, Inferior Conchae x2, palatine x2, Mandible
What can you see from a superior view of skull? Why are they there
See T shaped sutures (T anterior). Frontal bone joins Partietal bone via coronal suture (joining at Bregma)
Both partital joins at Sagittal suture, and join occipital at lamdadoid suture. Junction is Lambda
Fusion of 4 bones in children
Frontal bones and parietal bones fuse around the anterior fontanelle
Occipital and Parietal fuse at posterior Fontanelle
What bones do you find in an eye orbit?
Fusion of Zygomatic, sphenoid, lacrimal and maxilla
LABEL A PICTURE OF A SKULL (FRONTAL VIEW)
DO EIT
LABEL A PICTURE OF A SKULL (LATERAL VIEW)
DO IT
Just to add-can see external acoustic meatus and zygomatic eye, and temporal-mandible joiny
LABEL A PICTURE OF A SKULL (POSTERIOR VIEW)
do it
What are the main “holes” in the skull?
Foramen magnum, in occipital bone (where medulla exits). Sourrounded by occipital condyl (nearly like vertebrae-sit on C1 to join up)
Right lateral to that-Jugular foramen
Skull foramina-where arteries and nerves run
WHat can we see in a superior view of the inside of a skull
Regions based on which part os the bone fits in (Anterior cranial fossa-frontal), Middle cranial fossa (Temporal lobes), posterior medial fossa (NOT OCCIPITAL BUT CEREBELLUM -occipital sits above that)
Foramen magnum medial to that
Describe the anterior cranial fossa
Two depressions found in frontal lobe due to eyes being underneath-same in bone
middle top-frontal crest giving to frontal cecum-crista galli in the center. (part of ethnoid)
Under, batman shaped body of the sphenoid (lateral lesser wing, middle is body)
Describe the middle cranial fossa
Temporal bone, then tegmen typani, and frontal is tuberculum sellae
3 holes on each side-most mediale foramen lacerum-internal carotid artery, 2nd foramen ovale, 3rd foramen spinosum
Also holes not down but towards eye (frontal to other holes)-Foramen rotundum
Not all holes entry in skull are entry in brain
Describe the posterior cranial fossa
Occipital bone, temporal bone
Holes for acoustic meatus, jugular foramen
and foramen magnum
List the cranial nerves in order and show them on a diagram. List their names and function (and diagnostic tests)
Oh Oh Oh to touch and feel very good velvet, Ah heaven
Olfactory-cribiform plate, Optic nerve-optic canal, Occulomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Acessory, Hypoglossal
List what exits from the following structures. Cribiform plate, Optic canal, Superior orbital fissure, Foramen rotundum, Foramen ovale, Foramen lacerum, Foramen spinosum, Carotid cana, Internal acoustic meatus, Jugular foramen, Hypoglossal canal, foramen magnum
Olfactory-cribiform plate, Optic nerve-optic canal, Superior orbutal fissure-Occulormotor, Trochlear, Oph div of V (V1), abducent, subopthalmic vein
Foramen rotundum (Maxillary div of V (V2)
Foramen ovale-Mandibular div of V (V3)
Foramen lacerum (Internal carotid)
Foramen spinosum (middle meningeal artery/vein)
Carotid canal (internal carotid as well)
Internal acoustic meatus-facial, vestibulocochlear
Jugular foramen: Glossopharyngeal, Vagus, acesspry, sigmoid sinus
Hypoglossal canal-hypoglossal
Foramen magnum-vertebral artery, medulla, spinal roots of acessory nerve
What are the 3 layers of the meninges?
3 layers- dura-2 layersm periosteal (follows the skull)+meningeal (this ones follows the brain), arachnoid-continous over brain, pia
What are the 2 layers of the dura?
Periosteal and meningeal-mostly fused
Only seperate to create sinuses at points
After foramen magnum, lose the periosteal and becomes spinal dura matter
Where does the dura layers sperate?
Around the longitudinal fissure-create superior sagittal sinus. fold called falx cerebelli-crosses tentorium cerebelli at back and continues a bit after
(where arachnoid exits a bit to let CSF out
Also peels around the cerebellum and forms a shelf betweeen cerebullum and occipital lobe-Tentorium cerebelli
Where are the 3 places you can get brain herniation?
Because of the dura sheets, in cases of hypertensions and stuff, brain can be pushed around/between it
Around falx cerebelli (top), tentorium cerebelli and falx cerebelli (bottom)
Where does the middle meningeal artery run
Run around most meninges (frontal, parietal and part of occipital)-but majorly over the terrium-a weak point on side of skull-fracturs can cause bad hemmorghage
Where are the main venous drainage of the skill. Why is it infection prone
Superior sagittal sinus at top of falx cerebelli, Inferior sagittal sinus at bottom (into straight sinus, into bottom of superior sagittal sinus)-splits into left/right transverse sinuses, into sigmoid sinuses and to internal jugular vein
Remember cavernous sinus connecting to transverse sinus vua superior petrosal sinus
The skull uses the same supply-some veins comes from outside of the cavity and drain into the sinus-can get infection
Where is the cavernous sinus?
Around eyes and front of face-lots of bleed can occur here-connect to transferse sinus via superior petrosal sinus
