Skull, face, meninges Flashcards
Describe the layers of the cranial bones
Covered with periosteum
external and internal compact bone with spongey bone in between
Describe the 8 cranial bones
2x temporal 2x parietal frontal orbital ethmoid sphenoid
Describe the facial bones
All paired except vomer and mandible zygomatic 2x maxillary 2x nasal 2x palatine 2x inferior conchae 2x
Do an anatomy flashcard of the skull and face
Okay
Which two bones are separated by the coronal, squamous and lambdoid suture?
Coronal:Frontal and parietal
Squamous: Parietal and temporal
Lambdoid: Parietal and occipital
Which four bones make up the pterion?
Frontal, sphenoid, temporal, parietal
Lies over middle meningeal artery and vein
Within which bone are the pterygopalatine fossa and sphenopalatine foramen?
Sphenoid
Within which bone is the sella turcica and sulcus chiasmaticus/prechiasmatic groove?
Sphenoid
Where pituitary gland sits
Which bones does the palaptine bone articulate with?
Sphenoid Nasal concha Maxillary Vomer Ethmoid
Which bones make up the anterior cranial fossa?
Frontal bone, ethmoid and lesser wing of sphenoid
Contains frontal lobe
Contains crista gali
Which bones make up the middle cranial fossa?
Greater wing and body of sphenoid
Temporal bone
Parietal bone (laterally)
Houses temporal lobe
Which bones make up the posterior cranial fossa?
Mainly occipital
also parietal
Houses cerebellum, pons and medulla
What travels through the incisive fossa?
Nasopalatine nerve
Branches of sphenopalatine and greater palatine artery
What travels through the jugular fossa?
CN IX
CNX
CN XI
Internal jugular vein
What travels through the foramen lacerum?
Greater petrosal nerve
What travels through the foramen ovale?
Lesser petrosal nerve
CN V3
Accessory meningeal artery
What travels through the foramen spinosum?
Middle meningeal vessels
meningeal branch of mandibular nerve
What travels through the carotid canal?
Internal carotid artery and internal carotid plexus
What travels through stylomastoid foramen?
Facial nerve
What travels through mastoid foramen?
Mastoid emissary vein
Posterior meningeal artery
What travels through the foramen magnum?
Medulla oblongata
Vertebral arteries and venous plexus
What lies in the superior orbital fissure?
Between lesser and greater wings of sphenoid bones
CN III
CNIV
Lacrimal, frontal and nasociliary branches of V1
CNVI
Superior ophthalmic vein
What travels through the foramen rotundum?
V2 maxillary nerve
What is the attachment for the free border of the tentorium cerebelli?
Anterior clinoid process of sphenoid bone
Where is the optic canal and what travels within it?
Lesser wing of sphenoid
Optic nerve and ophthalmic artery and meninges
What travels in the internal acoustic meatus?
Facial nerve
Vestibulocochlear nerve CN VIII
Labyrinthine artery
Where does the trigeminal ganglion sit?
Trigeminal impression of temporal bone
What travels within the hypoglossal canal?
Hypoglossal nerve
What are the two layers of dura mater?
Periosteal and meningeal
Separates to form sinus
What is the blood supply of the dura?
Middle meningeal artery
Middle meningeal vein
What lies between the two cerebral hemispheres?
Falx cerebri
Attaches to crista gali (ethmoid) anteriorly
Attaches to tenetorium cerebelli posteriorly
Contains inferior sagittal sinus, superior sagittal sinus and straight sinus
Where is the tentorium cerebelli?
Between the cerebellum and occipital lobe
Fixed at posterior clinoid process anteriorly and occipital protuberance posteriorly
medial edge is free
Roofs over cavernous sinus
Where free and fixed borders cross is cavernous sinus
Describe the nerves and vessels in the cavernous sinus from superior to inferior
Optic chiasm Internal carotid artery (above) Run between endothelial lining and dura mater CN III CN IV Internal carotid artery (within) CN VI CN V1 CNV2
What is special about the venous sinuses?
Nil muscles in walls
Nil valves
Which way do the inferior and superior sagittal sinuses turn as they join the transverse sinus?
Superior: right
Inferior: left
Which sinus surrounds the pituitary gland?
Anterior and posterior intercavernous sinuses
Which is it significant that the superior ophthalmic vein joins the cavernous sinus?
Orbital cellulitis can spread to the meninges
Where is the arachnoid mater?
Between dura and pia mater
Potential subdural space
Actual subarachnoid space filled with nerves, arteries and CSF
Where is CSF produced?
Choroid plexuses of lateral, 3rd, 4th ventricles
CSF enters blood stream via arachnoid villi projecting into venous sinuses
What is significant about pia mater?
Adherent to brain
Fuses with cranial nerves and arteries
Forms tela choroidea on the roof of 3rd and 4th ventricles
Fuses with ependyma to form choroid plexus of lateral, 3rd and 4th ventricle
What is the embryological development of the skull?
Neurocraniam in 2 parts
Cartilaginous anteriorly
3rd month base of skull formed and ossifies
Membranous part forms flat bones of sides and roof of skull
Bones are reabsorbed internally and deposited externally to allow for growth of growing brain
Neonatal skull not fused with anterior posterior fontanelles
Fused by 18 months
Describe what is special about the skin of the face
Thinnest skin in body over eyelids
Highly vascular
Many sebaceous glands
Sweat glands regulate body temperature
What are the four fat pads in proximity to the orbit?
Sub brow
Malar (central, medial and lateral)
Orbital
Pre-aponeurotic
What is the embryonic origin of the facial muscles?
Mesoderm of 2nd branchial arch
What are the muscles of the upper face?
Frontalis (elevates brow)
Corrugator supercilli (depresses brow)
Procerus (depresses brow)
Orbicularis oculi (depresses brow)
What are the muscles of the mid face?
Nasalis Levator labii superioris alaequae nasi Levator labii superioris Zygomaticus minor Zygomaticus major Levator anguli oris Buccinator Orbicularis oris
What are the muscles of the lower face?
Depressor labii inferioris
Depressor anguli oris
Mentalis
Platysma
Insertion and origin of corrugator supercilli
Attaches to orbital ring medially
Inserts with frontalis on skin more laterally
Produces frown lines
Insertion and origin of procerus
Origin facial aponeurosis overlying nasal bones
Inserts on skin of the eyebrow and lower forehead
Glabellar lines
What is the course of the facial nerve?
Through internal auditory canal into inner and middle ear and mastoid bone, emerges from skull at stylomastoid foramen
After exiting bone gives off 3 small branches, supplying postauricular muscles, posterior belly of digastric and stylohyoid
Main trunk then enters parotid and divides into 5 at pes anserinus 1.5cm distal to foramen
What is the course of the VII temporal?
Superficial to zygomatic arch
Motor innervation to OO, frontalis and corrugator
What is the course of the VII zygomatic?
Courses towards lateral canthus to innervate OO above and below the canthus
What is the course of the VII buccal?
Supplies muscles of midface, including zygomaticus major and minor, levator labii superioris, levator anguli oris and the buccinator
What is the course of the VII mandibular?
Dips below angle of mandible and back again to supply OO, depressor anguli oris and mentalis
What is the course of the VII cervical?
Courses through neck to innervate platysma
Follows a superficial course
Describe the course and innervation of the ophthalmic nerve?
Trigeminal ganglion-> cavernous sinus -> orbital fissure
Divides into lacrimal branch to the upper lateral lid, nasociliary to glabella and larger frontal branch.
Frontal branch becomes supraorbital and supratrochlear
Supplies skin over forehead, glabella and upper nose
Describe the course and innervation of the maxillary nerve?
Skin of midface
Exits skull via foramen rotundum
Gives off zygomaticotemporal and zygomaticofacial branches
Infraorbital foramen to supply cheek, lower lid, upper lip and lower nose
Describe the course and innervation of the mandibular nerve?
Supplies lower lip,chin, lower mandible, gingiva and around the ear and temple
Exits skull via foramen ovale
Divides into buccal, auricotemporal and inferior alveolar nerve and exits the mental foramen as the mental nerve
Which arteries of the face come from the internal carotid artery?
Ophthalmic artery (supraorbital and supratrochlear arteries)
List the branches of the external carotid artery
Superior thyroid Ascending pharyngeal Lingual Facial Occipital Posterior auricular Maxillary Superficial temporal
Where are the sites of anastomoses in the face between the ICA and ECA?
Supratrochlear, supraorbital, superficial temporal, infraorbital and angular arteries
Allows reverse flow in occlusive disease
What are the two major complications of superficial temporal artery biopsy?
Stroke due to compromise of collateral circulation with ICA occlusion
Facial nerve trauma
What is the anatomical danger zone for superficial temporal artery biopsy?
Temporal region where facial nerve runs close to STA
The temporal branch of the facial nerve runs beneath the superficial temporal fascia and superficial temporal artery
Do not go into fascia when doing STA biopsy
What is the danger triangle of the face?
Triangle around eyes and nose
Ophthalmic veins drain into cavernous sinus and meninges potentially spreading infection
What is the lymph drainage of the face?
Variable Periparotid lymph nodes Submandibular lymph nodes Submental nodes Jugular chain Eyelids: Submandibular and preauricular lymph nodes
What are the 5 layers of the scalp?
Skin (thick)
Connective tissue (nerves and blood vessels)
Aponeurosis epicranium (insertion of frontalis)
Loose areolar tissue (relatively avascular)
Pericranium
What are the attachments of the epicranial aponeurosis?
Posterior: superior nuchal line
Lateral: superior temporal line
Anterior: subaponeurotic space extends to upper eyelids
Blood can pass from scalp to upper eyelids and orbit
Origin, insertion, nerve and action of occipitofrontalis
Origin: occipital bellies- superior nuchal lines
frontal bellies- skin and superficial fascia of upper eyelids
Insert: Epicranial aponeurosis
Nerve: occipital belly=posterior auricular branch of facial nerve
frontal belly=frontal branch of facial nerve
Action: raises eyebrows
Which surgery is frontalis used in?
Ptosis correction
Frontalis sling operation
What are the six sensory nerves of the scalp?
Supratrochlear V1 Supraorbital V1 Zygomaticotemporal V2 Auricotemporal V3 Lesser occipital C2 Greater occipital C2
What is the blood supply of the scalp?
ICA and ECA
Freely anastomose
Venous drainage accompanies arteries
No valves so can transmit infection
Lymph drainage of scalp
Parotid, submandibular and deep cervical =anterior to auricles
Posterior auricular, occipital = posterior to auricles
Why do scalp wounds bleed profusely?
Fibrous fascia prevents vasoconstriction
What anastomoses occurs at the medial canthus?
Facial artery (ECA) and dorsal nasal branch of ophthalmic artery (ICA) In ICA occlusion, intracranial arterial supply may be obtained via retrograde flow from ECA
Which layer of the dura acts as the blood brain barrier?
Arachnoid
No vessels pass between arachnoid and dura mater
Which vessels are contained within the tentorium cerebelli?
Right and left transverse sinuses, sigmoid sinus, superior petrosal sinus
What is the main blood supply of the meninges?
Middle meningeal
Ophthalmic and anteriorly ethmoidal
Internal carotid
Where is an extradural haemorrhage?
Between dura mater and cranium
Looks like a lemon
Arterial injury
What is a subdural haemorrhage?
Between dura and arachnoid mater
Bridging vein bleeding
Looks like a banana
What is a subarchnoid haemorrhage?
Bleeding between arachnoid mater and pia mater
Usually rupture of circle of willis
Memorise circle of Willis grays anatomy cue card
Okay
Which two vessels form the basilar artery?
Left subclavian-> left vertebral
Right subclavian -> right vertebral
Both vertebral combine-> basilar
Which vessels form the circle of Willis?
Right and left internal carotid arteries Basilar artery Posterior communicating arteries Posterior cerebral Middle cerebral Anterior cerebral Anterior communicating arteries
What does the basilar supply?
Cerebellum and pons
Which two structures are encircled by the optic chiasm?
Pituitary and optic chiasm
What does the MCA supply?
Most commonly embolises
Biggest
Travels up lateral sulcus between temporal and parietal lobes
Supply motor and sensory areas contralateral half (but not leg or perineum)
Supplies auditory and speech areas
What does the ACA supply?
Lies superior to optic nerve
Supplies orbital surface of frontal lobe
Medial surface of hemisphere
Above corpus collusum
Reaches pareitoccipital sulcus
Supply motor and sensory areas for contralateral leg and perineum
Supplies micturation and defecation centres
What does the PCA supply?
Passes posteriorly over cerebral peduncle
Superior to tentorium supplies inferomedial temporal lobes and occipital lobe
Supplies contralateral visual area
Sometimes MCA can extend posteriorly enough to supply macula
What do the striate branches supply?
Internal capsule
Thalamus
Basal nuclei
What is the venous drainage of the cerebrum?
Superior sagittal->Straight sinus-> transverse sinus-> cavernous sinus->sigmoid sinus-> internal jugular vein
What is the basilar plexus?
Lies on the clivus
Drains lower pons and medulla
Thrombosis can be fatal due to backward pressure on the brain stem
