Vasculature Of The Head Flashcards
What is the main arterial blood supply to the meninges?
Middle meningeal artery (arising from foramen spinosum)
Which nerve innervates the meninges?
CN V1-3
What is cerebrospinal fluid?
A clear colorless liquid that circulates in the ventricles and subarachnoid space
Bathes the exposed surfaces of the CNs and completely surrounds it
What are the functions of CSF?
Buoyancy, protection and environmental stability
What is CSF formed by?
The choroid plexus in each ventricle of the brain and is produced by secretion of fluid from the ependymal cells that originate from blood plasma
What is the concentration of ions in CSF?
Similar to blood plasma but has greater amounts of Na, H and Ca, but less K
Describe the drainage of CSF to DV sinuses
Located within the subarachnoid space -> through arachnoid granulations/villi —> to dura venous sinuses
What are emissary and diploic veins?
Drainage of CSF from the scalp (emissary) and bone (diploic)
What is hydrocephallus?
“Water on the brain”
Typically from an obstruction in CSF flow that restricts its reabsorption in the venous bloodstream
Causes downward rotation of the eyes and a large swollen head
How is hydrocephallus treated?
By inserting a ventriculoperitoneal shunt that drains to the abdominal cavity
Or a ventriculostomy (ETV) that creates a hole in the floor of the 3rd ventricle that drains into the subarachnoid space
Describe the venous drainage of the superficial face and scalp
Superficial temporal vein -> posterior branch of retromandibular vein -> external jugular vein
Facial vein -> anterior branch of retromandibular vein -> internal jugular vein
Which two veins form the external jugular vein?
Posterior auricular and retromandibular veins
The internal jugular vein receives blood from which veins?
Facial, lingual, occipital, superior and middle thyroid veins
Describe venous drainage of the orbit and eyeball
Supra-orbital vein -> superior ophthalmic and angular vein (to cavernous sinus)
Facial vein -> inferior ophthalmic and angular vein (to pterygoid venous plexus)
What are the branches of the common carotid?
Internal and external carotid
Forms a carotid sinus superior to the bifurcation of branches
What are the baroreceptors of the carotid sinus innervated by and what is its function?
Glossopharyngeal nerve (CN IX) Indirectly modulates activity of sympathetic and parasympathetic response to blood pressure
What is the mnemonic for external carotid branches?
Some - superior thyroid A Anatomists - ascending pharyngeal A Like - lingual A Freaking - facial A Out - occipital A Poor - posterior auricular A Med - maxillary A Students - superficial temporal A
Which arteries does the superior thyroid A give rise to?
Infrahyoid, superior laryngeal and sternocleidomastoid branch
The superior laryngeal A runs with what structure?
Superior laryngeal N
What does the ascending pharyngeal A supply?
Pharynx musculature
What is the arterial course of the lingual artery?
Obliquely upwards and medially to the greater horns of the hyoid bone
Curves down and forward passing beneath the digastric and stylohyoid M (crossed by the hypoglossal N)
Runs deep to hyoglossus M
What are the terminal branches of the lingual artery?
Sublingual and deep lingual arteries
What does the sublingual A supply?
Sublingual gland and oral floor
What does the deep lingual A supply?
Base of the tongue
What structure does the deep lingual A run with?
Lingual N (superficial to hyoglossus M)
What is the arterial course of the facial A?
Arises in carotid triangle
Runs beneath digastric and stylohyoid M (superficial to hypoglossal N)
Enters groove on posterior submandibular gland
Curves upward over the body of the mandible running anteroinferior to masseter M
Runs obliquely past the nose
What are the cervical branches of the facial A?
Ascending palatine (pharyngeal wall, soft palate, pharyngotympanic tube) Tonsillar branch (palatine tonsils) Submental and glandular branches (submandibular and oral floor)
What are the facial branches of the facial A?
Inferior labial A, superior labial A, lateral nasal branch and angular A
What is the terminal branch of the facial A?
Angular A
What is the arterial course of the occipital A?
Arises in carotid triangle from posterior aspect of the external carotid A
Runs posterior and upwards
Terminal portion runs with greater occipital N
What is the arterial course of the posterior auricular A?
Arises above the digastric and stylohyoid M
Ascends posteriorly beneath the parotid gland between the ear and mastoid process along the lateral side of the head behind the ear
What structure does the posterior auricular A run with?
Posterior auricular N
What are the branches of the posterior auricular A?
Stylomastoid, posterior tympanic, auricular, occipital and parotid branches
What are the three parts to the maxillary A?
Mandibular, pterygoid and pterygopalatine parts
What are the branches of the mandibular part of the maxillary A?
Deep auricular, anterior tympanic, inferior alveolar, middle meningeal and accessory meningeal arteries
What does the deep auricular A supply?
External acoustic meatus, external tympanic membrane and TMJ
What does the anterior tympanic A supply?
Internal TM
What structures does the inferior alveolar A supply?
Enters mandibular foramen and supples mandible, mandibular teeth, chin and mylohyoid M
Branches into mylohyoid and mental A
What does the middle meningeal A supply?
Enters cranium via foramen spinosum and supplies dura mater of the lateral, trigeminal ganglion, facial nerve and geniculate ganglion, tympanic cavity and tensor tympani N
What does the accessory meningeal A supply?
Enters cranium via foramen ovale and supplies extracranial muscles of infratemporal fossa, otic ganglion and sphenoid bone
What is an epidural hematoma?
When bleeding occurs between the dura mater and the skull
What is an subdural hematoma?
A type of bleeding in which a collection of blood gathers between the dura and arachnoid
What is a subarachnoid hematoma?
Caused by bleeding into the brain and the space surrounding it (subarachnoid space)
What are the branches of the pterygoid part of the maxillary A?
Deep temporal (temporalis M), pterygoid branches (supplies pterygoid M), masseteric (supplies TMJ and masseter) and buccal A (buccal fatpad, buccinator, buccal oral mucosa)
What structure does the buccal A run with?
Buccal N
What are the branches of the pterygopalatine part of the maxillary A?
Posterior superior alveolar, Infraorbital, artery of pterygoid canal, pharyngeal branch, descending palatine and sphenopalatine
What does the posterior superior alveolar A supply?
Maxillary molar and premolar teeth, adjacent gingiva and mucous membrane of maxillary sinus
What does the Infraorbital A supply?
Traverses inferior orbital fissure, Infraorbital groove and foramen
Supplies inferior oblique M, inferior rectus , lacrimal sac, maxillary canines, incisors teeth and skin of infra-orbital region of the face
What does the artery of the pterygoid canal supply?
Runs posterior through pterygoid canal and supplies mucosa of upper pharynx, pharyngotympanic tube and tympanic cavity
What does the pharyngeal branch of the pterygopalatine part of maxillary A?
Runs through palatovaginal canal to supply mucosa of nasal roof, nasopharynx, sphenoidal air sinus and pharyngotympanic tube
What does the descending palatine A supply?
Descends through palatine canal
Branches into greater palatine A supplying hard palate and lesser palatine A supplying the soft palate, palatine tonsil and pharyngeal wall
What does the sphenopalatine A of the pterygopalatine part of the maxillary A supply?
Walls and septum of nasal cavity, frontal/ethmoidal/sphenoid/maxillary sinuses and anterior most palate
What is the terminal branch of the maxillary A?
Sphenopalatine A
What is the arterial course of the superficial temporal A?
Begins b/w the TMJ and the ear
Enters the temporal fossa
Terminates by dividing into frontal and parietal branches
Branches of the superficial temporal artery runs close to what structure?
Auriculotemporal N
What are the branches of the superficial temporal A?
Transverse facial, middle temporal, anterior auricular and terminal branches including frontal and parietal A
Does the internal carotid A have branches in the neck?
No
Describe the course of the internal carotid A
Enters the cranial cavity through the petrous part of the temporal bone via carotid canal
Goes over foramen lacerum
Courses anteriorly through the cavernous sinuses
Runs in the carotid groove
What are the branches of the internal carotid A?
Opthalamic, anterior cerebral and middle cerebral A
What does the vertebral A run through?
C6-1 making a sharp turn between C1 and skull
What can cause the stretching of the vertebral A?
Rotation and extension of the head
What does the vertebral A continue as?
Basilar A
What is the main blood supply to the brain?
Vertebral and internal carotid A
What is vertebrobasilar insufficiency?
Decreased posterior circulation due to intermittent vertebral A occlusion either from atherosclerosis or during head rotation/extension
What are the sx of vertebrobasilar insufficiency?
Syncope, vertigo, dizziness Double vision or loss of vision Numbness or weakness in hands or feet Slurred speech Nausea and vomiting Loss of coordination or weakness
What are the risk factors for vertebrobasilar insufficiency?
Smoking, HTN or HLD, DM, obesity, over 50 years old and family history
How is vertebrobasilar insufficiency diagnosed?
History and physical
Cardiovascular and neurologic exams
CT angiogram/MRA looking at blood vessels
What is the treatment of vertebrobasilar insufficiency?
Change diet, quit smoking, lose weight/become more active, medications to control BP, DM or cholesterol, blood thinners, bypass surgery or endarterectomy (removal of blood vessel lining)
Which arteries form the circle of Willis?
Anterior cerebal arteries, internal carotid arteries and posterior cerebal arteries
Anterior and posterior communicating A
What is subclavian steal syndrome?
Proximal stenosis or occlusion of the subclavian artery
Blockage causes reverse flow through the vertebral A of the affected side to supply blood to UE which decreases blood flow to the brain
What are the sx of subclavian steal syndrome?
Presyncope or syncope
Different blood pressures in the upper extremities
Neurologic deficits or memory problems
What are the causes subclavian steal syndrome?
Atherosclerosis or a cervical rib
How is subclavian steal syndrome diagnosed?
Doppler ultrasound and CT angiography
How is subclavian steal syndrome treated?
Stent and balloon angioplasty
Endarterectomy
What is the function of the circle of Willis?
Provides a route of blood to the brain in case of a blockage
