Moore Notes Flashcards
Orbitomeatal plane
Connects the inferior margin of the orbit and the superior margin of the external acustic meatus.
Horizontal plane that determines anatomical position of the skull.
Also Frankfort horizontal plane
Calvaria
skullcap
dome-like roof of neurocranium
Basicranium
Floor of skull
cranial base
Bones of neurocranium
Frontal Ethmoid Sphenoid Occipital Temporal x2 Parietal x2
Synchondroses
Hyaline cartilage uniting some skull bones during childhoods (e.g. sphenoid & occipital)
Viscerocranium
Mandible Ethmoid Vomer Maxilla x2 Inferior nasal concha (turbinate) x2 Zygomatic x2 Palatine x2 Nasal x2 Lacrimal bones x2
Nasion
Intersection of frontal and nasal bones
Frontal bone - supra-orbital margin
Angular boundary between the squamous (flat) and orbital parts of frontal bone
Supercilliary arch
Ridge just superior to the supra-orbital margin
Metopic suture
Suture in the midline of the glabella
Remnant of the developmental frontal suture
Glabella
Smooth area between the superciliary arches
Metopic suture is visible in the midline of this area
Zygomatico-facial foramen
Pierces lateral aspect of zygomatic bones
Piriform aperture
Means “pear-shaped”
Anterior nasal opening of the cranium (without cartilage)
Intermaxillary suture
Union of the maxillary bones in the median plane
Superior and posterior bounds of the temporal fossa
Superior and inferior temporal lines
Infratemporal fossa
Irregular space inferior and deep to the zygomatic arch and mandible and posterior to the maxilla.
Pterion word
Greek: pteron “wing”
Pterion bones
Frontal
Parietal
Sphenoid (greater wing)
Temporal
Superior nuchal line
Marks the superior limit of the neck
Extends laterally from each side of the posterior occipital protuberance
Most common type of skull fracture
Linear calvarial fracture
Linear calvarial fracture
Occur at point of impact
Fracture lines often radiate away from it in two or more directions
Countercoup (counterblow) fracture
Fracture occurs on opposite side of cranium rather than at the point of impact
Basilar fracture
Fracture of bones forming the cranial base (includes roof of orbit)
CSF may leak into nose (CSF rhinorrhea) and ear (CSF otorrhea)
Parietal eminence
Widest part of skull when looking from superior (dorsal) aspect
Coronal suture
Unites frontal and parietal bones
Sagittal suture
Unites the R & L parietal bones
Lambdoid suture
Unites occipital bone w/R&L parietal and temporal bones
Bregma
Landmark formed by intersection of sagittal and coronal sutures
Vertex
Superiormost point of the cranium
Near midpoint of the saggittal suture
Hard palate bones
Palatine process of maxillae
Horizontal plates of the palatine bones
Three processes of the sphenoid bone
Greater wing
Lesser wing
Pterygoid process (consists of medial & lateral pterygoid plates)
Medial & lateral pterygoid plates location
Part of sphenoid bone
Extend inferiorly on each side of the sphenoid from the junction of the body and greater wings
Sphenoid spine
Edge of greater wing by foramen spinosa
Contacts temporal bone
Opening of the bony part of the pharyngotympanic (auditory) tube & sulcus (groove) for cartilaginous part of tube lie medial to spine
Petrous word origin
Latin
“rock-like”
Squamous word origin
Latin
“flat”
Jugular foramen location
- Large fissure between occipital lobe and the petrous part of the temporal bone
- At the base of the petrous ridges of the temporal bones
Foramen lacrum location
- Between the temporal, sphenoid & occipital bones
- Lies posterolateral to the hypophyseal fossa
- Enclosed by a cartilage plate
Foramen cecum contents
At the base of the frontal crest
Nasal emissary vein (1% of population; danger during surgery)
Cribiform foramina in cribriform plate
Axons of olfactory cells in olfactory epithelium that form olfactory nerves (CNI)
Anterior and posterior ethmoidal foramina contents
Vessels and nerves with same names as foramina
Optic canals contents
Optic nerves (II) and ophthalmic arteries
Superior orbital fissure contents
Ophthalmic veins; ophthalmic nerve (CN V1); CN III, IV, and VI; and sympathetic fibers
Foramen rotundum contents
Maxillary nerve (V2)
Foramen ovale contents
Mandibular nerve (V3)
Foramen spinosum
Middle meningeal artery and vein and meningeal branch of V3
Foramen lacerum - contents
Internal carotid artery and accompanying sympathetic and venous plexuses cross horizontally
Groove or hiatus of greater petrosal nerve
Greater petrosal nerve and petrosal branch of middle meningeal artery
Foramen magnum
Medulla & meninges, vertebral arteries, CN XI, dural veins, anterior and posterior spinal arteries
Jugular foramen
IX, X, XI, superior bulb of internal jugular vein; inferior petrosal and sigmoid sinuses; and meningeal branches of ascending pharyngeal and occipital arteries
Hypoglossal canal
Hypoglossal nerve (CN XII)
Condylar canal
Emissary vein that passes from sigmoid sinus to vertebral veins in neck
Mastoid foramen
Mastoid emissary vein from sigmoid sinus and meningeal branch of occipital artery
Vertex - origin
“vertere”
latin to turn
Bregma
Greek “bregma”
Top of head
Anterior cranial fossa
Frontal bone - anterior
Ethmoid bone - central
Body and lesser wings of sphenoid - posterior
Orbital plates of the frontal bone
Frontal crest
Median bony extension of the frontal bone
Foramen cecum is at the base of this
Crista galli - word origin
Latin
Cock’s comb
Crista galli
- Median ridge of bone that projects superiorly from the ethmoid
- Sieve-like cribriform plate of the ethmoid is present on each side
Clinoid word meaning
Greek
Bedpost
3 parts of sella turcica
Tuberculum sellae - horn of saddle
Hypophysial fossa
Dorsum sellae - back of saddle
Tuberculum sellae
Slight elevation anteriorly on the body of the sphenoid
Hypophysial fossa
saddle-like depression for the pituitary gland
Middle cranial fossa
- Sella turcica (body of sphenoid)
- Greater wings of the sphenoid
- Squamous (flat) parts of the temporal bones laterally
- Petrous (rock-like) parts of the temporal bones posteriorly
Boundary between middle and posterior cranial fossa
- Petrous ridge - superior border of the petrous part of the temporal bones
- dorsum sellae of the sphenoid
Sphenoidal crests
- Sharp posterior margins of the lesser wings of the sphenoid bones
- Overhang the lateral parts of the fossa anteriorly
Prechiasmatic sulcus
Extends between the right and left optic canals
Four foramina perforating the roots of the greater wings of the sphenoid
- Superior orbital fissure
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
Superior orbital fissure - location
Teardrop-shaped opening between the greater and lesser wings
Foramen rotundum - location
Circular foramen located posterior to the larger medial end of the superior orbital fissure
Foramen ovale - location
Oval foramen located posterolateral to the foramen rotundum
Foramen spinosum
Located posterolateral to the foramen oval, opening anterior to the spine of the sphenoid on the external surface
Posterior fossa bones
- Mostly occipital and temporal bones
- Parts of sphenoid and parietal bone make smaller contributions
Clivus
Marked incline that leads from the dorm sella to the foramen magnum
Internal occipital crest
- Landmark dividing the posterior part of the fossa into two cerebellar fossae
- Crest ends superiorly in the internal occipital protuberance
Layers of the scalp
Skin Connective tissue Aponeurosis (epicranial aponeurosis) Loose connective tissue Pericranium/periosteum
Loose connective tissue layer of the scalp
- Has potential spaces that may distend with fluid as a result of injury or infection
- Allows free movement of the scalp proper over the underlying calvaria
- Danger area of the scalp because pus or blood spreads easily
Leptomeninx
Arachnoid mater - avascular
Pia mater - highly vascularized
Cells that make CSF
Choroid plexus within the four ventricles of the brain
Dura mater layers
Periosteal layer
Meningeal layer
Meningeal layer of the dura
Reflects from the external periosteal layer of the duration form dural infoldings that divide the cranial cavity into compartments and support parts of the brain
Dural infoldings
From the meningeal layer of the dura
Falx cerebri
Tentorium cerebelli
Falx cerebelli
Diaphragma sellae
Falx cerebri attachments
Frontal crest of the frontal bone
Crista Galli of the ethmoid bone
Internal occipital protuberance
Becomes continuous with the tentorium cerebelli
Tentorium cerebelli attachments
Clinoid processes
Petrous part of the temporal bone
Internal surface of the occipital bone
Part of the parietal bone
Tentorium word origin
Latin
tent
Diaphragma sellae
Smallest dural infolding
Circular extension of dura
Suspended between the clinoid process
Forms a partial roof over the hypophyseal fossa
Contains an aperture for passage of the infundibulum (pituitary stalk) and hypophyseal veins
Dural venous sinuses
Endothelial-lined spaces between the periosteal and meningeal layers of the dura
Diplöe
Soft spongy material between the inside table and outside table of the skull
Superior sagittal sinus
- Lies in the convex attached (superior) border of the falx cerebrum
- Begins at the crista galli
- Ends near the internal occipital protuberance at the confluence of sinuses
Arachnoid granulations
- Collections of arachnoid villi
- Tufted prolongations of the arachnoid that protrude through the meningeal layer of the dura mater into the dural venous sinuses and lateral venous lacunae
- Transfer CSF to the venous system
Inferior sagittal sinus
- Smaller than the superior sagittal sinus
- Runs in the inferior, free concave border of the falx cerebri
- Ends in the straight sinus
Straight sinus
- Formed by the union of the inferior sagittal sinus with the great cerebral vein
- Runs inferoposteriorly along the line of attachment of the falx cerebri to the tentorium cerebella to join the confluence of sinuses
Transverse sinuses
- Pass laterally from the confluence of sinuses
- Groove the occipital bones
- Leave the tentorium cerebelli at the posterior aspect of the petrous temporal bone and become sigmoid sinuses
Sigmoid sinus
- Follows an S-shaped course in the posterior cranial fossa
- Forms deep grooves in the temporal and occipital bones
- Continues as the IJV after traversing the jugular foramen
Occipital sinus
- Lies in the attached border of the falx cerebelli
- Ends superiorly in the confluence of sinuses
- Communicates inferiorly with the internal vertebral venous plexus
Cavernous sinus
- Located bilaterally on each side of the sella turcica on the body of the sphenoid bone
- Extend from the superior orbital fissure anteriorly to the apex of the petrous part of the temporal bone posteriorly
- Receives blood from the superior and inferior ophthalmic veins, superficial middle cerebral vein, sphenoparietal sinus
- Communicate via inter cavernous sinuses
Cavernous sinus drainage
- Postero-Inferiorly through the superior and inferior petrosal sinuses
- Emissary veins to the pterygoid venous plexuses
What CN crosses the internal carotid artery as it courses through the cavernous sinus
CN VI - Abducens nerve
CN’s on the lateral wall of each cavernous sinus - superior to inferior
- Oculomotor - CN III
- Trochlear - CN IV
- Ophthalmic div. of Trigeminal - CNV1
- Maxillary division of Trigeminal - CNV2
Note - abducens is in cavernous sinus as well, but more medial - right by ICA
Superior petrosal sinus
- Runs from the posterior end of the cavernous sinuses to join the transverse sinuses where they become the sigmoid sinuses
- Lies in the anterolateral attached margin of the tentorium cerebelli
Inferior petrosal sinus
- Commences at the posterior end of the cavernous sinus
- Drain the cavernous sinuses directly into the origins of the IJVs
Basilar plexus
Connects the inferior petrosal sinuses and communicates inferiorly with the internal vertebral venous plexus
Middle meningeal artery
- branch of the maxillary artery
- enters middle cranial fossa through the foramen spinosum
- runs lateral in the middle cranial fossa
- turns super-anteriorly on the greater wing of the sphenoid –> divides into anterior (frontal) and posterior (parietal) branches
Innervation of the dura
- Largely CN V
- Some from CNX and CN XII
- Sensory endings are more numerous in the dura along each side of the superior sagittal sinus & where arteries and veins course in the dura
Arachnoid trabeculae
web-like network passing between the arachnoid and pia
