Anatomy Flashcards
How many layers compose the cranial dura? What are there names?
External Periosteal Layer and Inner Meningeal layer
How many layers compose the spinal dura? What composes the spinal dura? Where does the spinal dura end?
One layer
The inner meningeal layer of the cranial dura
Ends at S2
What two layers compose the leptomeninges? Which one is characterized by the presence of tight junctions?
Arachnoid (tight junctions) and Pia
What are the two layers of the pia?
Initmal and Epipial Layers
The outer layer of the pia is covered by _____
simple squamous epithelium
What is the dentate ligament?
thickening of the pia that stretches from the midpoint between the dorsal and ventral roots on the lateral spinal cord to attach to the surface of the arachnoid and dura
What is the filum terminale? Where is it and what derives from it?
extension of epipia which condenses and continues from S2 down; ends as the coccygeal ligament
What are Virchow Robin Spaces?
a perivascular potential space existing between the blood vessels and the leptominges as the vessels enter the CNS tissue
Name the midbrain cisterns.
Interpeduncular
Crural
Ambient
Quadrigeminal
What vessels are contained within the ambient cistern?
vein of Galen
Posterior Cerebreal Artery (PCAs)
Superior Cerebellar Arteries (SCAs)
What are the three meningeal arteries and what vessels are they branches of?
Anterior Meningeal Artery branch of the Ophthalmic Artery
Mindle Meningeal Artery branch of the Maxillary Artery
Posterior Meningeal Artery branch fo the Occipital and Vertebral Arteries
Which nerves innervate the supratentorial dura?
V1 - Anterior Fossa
V2 - Middle Fossa
V3 - Posterior Fossa and mastoid air cells
What is the embryologic origin of the dura, subarachnoid, and pia?
Dura - Mesoderm
Leptomeninges - Neuroectoderm
What innervates the infratentorial dura?
CN X, C2-C3
What is Froin’s Syndrome? What triad characterizes is?
Characterized by the triad of: 1. Xanthrochromia 2. CSF coagulation 3. CSF protein increased (up to 1000)
Generally occurs whenever there is obstruction to flow causing stasis or if the CSF becomes loculated
What RBC to WBC ratio defines a traumatic tap?
at least 700 RBCs per 1 WBC
What cellular mechanism is fundamental to CSF production?
Na/K ATP pump
What nucleus and molecule control CSF production?
Raphe Nucleus sends serotonin to periependymal vessels
What two factors can increase production of CSF?
Volatile Anesthetics and CO2
What two factors decrease production of CSF?
Carbonic anhydrase inhibitors (acetazolamide) and Norepinephrine
How much CSF is produced per hour? Per day? What is the total volume of CSF?
20 mL/h
450 mL/day
150 mL total
What comprises the choroid plexus?
single layer of cuboidal epithelial cells surrounding blood vessels
Where are the primary locations of choroid plexus?
- Roof of the 4th ventricle
- Inferior Medullary Vellum
- Lateral Recess to the foramen of Luschka
- Posterior roof of the 3rd Ventricle
- Floor of the body of the Lateral Ventricle
- Roof of the temporal horn of the lateral ventricle
What three components make up the Blood Brain Barrier?
- Capillary endothelial tight junctions (primary)2. Pinocytic Activity in endothelial cells3. Astrocytic foot processes
Which glucose configuration can travel across the BBB? Through what mechanism?
D-Glucose through Carrier Mediated Transport. BBB is impermeable to L-Glucose.
The Blood-CSF Barrier is formed by _______ .
tight junctions of choroid cuboidal epithelium
What are circumventricular organs?
Midline ventricular structures of specialized tissues with absent BBB due to fenestrated capillaries
How many circumventricular Organs are there? What are there names?
- Organum vasculosum (lamina terminalis)2. Neurohypophysis3. Median eminence of the Hypothalamus4. Subfornical Organ5. Subcommissural Organ6. Pineal Gland7. Area Postrema
Which is the only circumventricular organ with an intact BBB?
Subcommissural organ
What is the only paired circumventricular organ? Where is it located?
Area Postrema on the floor of the 4th Ventricle
What stimulates the area postrema to induce emesis?
Digitalis or apomorphine
What three major head and neck arteries are branched of the subclavian artery?
Vertebral Artery
Thyrocervical Trunk
Costocervical Trunk
Which vertebral artery is usually dominate? What percent of time? What percent is usually the other side dominant?
Left 50%Right 25%Nondominant 25%
What percentage of the population has a hypoplastic vertebral artery?
40%
What are the branches of the external carotid artery from proximal to distal?
Superior thyroid arteryAscending pharyngeal arteryLingual arteryFacial arteryOccipital arteryPosterior auricular artery Superficial temporal arteryInternal MAXillary artery
Which branch of the external carotid supplies CN IX, X, and XI?
Ascending pharyngeal artery
What gives off the middle meningeal artery? Accessory meningeal arteries?
Internal maxillary artery for both
At what level is the carotid bifurcation?
C3-C4 or C4-C5
Name the segments of the ICA, proximal to distal.
- Cervical2. Petrosal3. Lacerum4. Cavernous5. Clinoidal6. Ophthalmic7. Communicating.
How many segments are there to the Petrous portion of the ICA?
- Vertical 2. Genu3. Horizontal
What are the branches at each ICA segment?
C1 - noneC2 - Caroticotympanic artery, Vidian artery (sometimes, usually ECA)C3 - noneC4 - Meningohypophyseal trunk, Inferolateral trunk, Medial Trunk (McConnell’s Capsular arteries)C5 - noneC6 - Ophthalmic artery, Superior hypophyseal artery,C7 - Anterior choroidal, ACA, MCA, PCom
What does the caroticotympanic artery supply? What does it anastamose with? What does an aberrant artery symptomatically present as?
Supplies the middle and inner ear
Anastamoses with the inferior tympanic artery, which is a branch of the ascending pharyngeal
Retrotympanic pulsatile mass
What is the most common origin of the Vidian artery? Second most common?
External Carotid Artery
Internal Carotid artery at the petrous portion
Serves as an anastamosis between the two.
The inferolateral trunk anastamosis with the ECA by ________.
maxillary artery (through foramen rotundum) and the MMA
What are the branches of the meningohypophyseal trunk? What do they supply?
Tentorial Artery (Bernasconi and Cassinari) - tentorium
Inferior Hypophyseal Artery - Neurohypophysis
Dorsal Meningeal Artery - CN VI and part of the clivus
Pt goes in for MMA embolization. Develops unilateral blindness. Why?
in 0.5% of the population, the ophthalmic artery comes off the MMA
What is the origin of the Anterior Choroidal Artery?
Communicating segment of the ICA just distal to the PcommA origin
Recurrent Artery of Heubner arises from where?
A1 or A2 segment (medial distal striate artery)
Usually off of the A2
What does the Recurrent Artery of Heubner supply?
Head of the caudate
Anterior limb of the internal capsule
Anterior Putamen and Globus Pallidus
Septal Nuclei
Inferior Frontal Lobe
What defines the M2 segment of the MCA?
from the bifurcation to the genu; insular segment
Lateral Lenticulostriate arteries emerge from what origin?
perforated arteries that emerge from M1 (supply much of the basal ganglia)
Which segment of the PCA lies within the ambient cistern?
P2
Which segment of the PCA lies within the quadrigeminal cistern?
P3
The medial and lateral posterior choroidal arteries arise from what origin?
P1 and P2 segments respectively
The vertebral arteries arise from what origin?
Subclavian arteries typically (many variants)
The verts enter the foramina transversarium at what level?
C6
Occlusion of what vessel causes lateral medullary syndrome? What are the classic symptoms?
PICAClassic signs:- loss of pain and temperature on ipsilateral face but contralateral body- CN IX and X dysfunction- horner’s syndrome
What are the branches of the basilar artery?
AICALabyrinthine Artery Paramedian ArteryPontine ArteriesSCAPCA(of note PICA comes off the Verts)
What’s the vascular supply to the striatum?
Mainly: MCA (lenticulostriates)Rostrally: Recurrent Artery of HuebnerCuadally: anterior choroidal artery
What’s the vascular supply to the internal capsule?
Anterior Limb: mostly ACA, RAH (also lateral MCA lenticulostriates)
Genu: ICA perforaters and MCA lenticulostriates)
Posterior Limb: Anterior Choroidal, PcommA
What’s the vascular supply to the Thalamus?
Primarily through the PCA and its branches (including posterior choroidal)Rostrally: PcommA and Basilar Bifurcation perforators (thalamoperforating arteries)
What’s the vascular supply to the Medulla?
Anterior and Posterior Spinal ArteriesPICA and Verts
What’s the vascular supply to the Pons?
Basilar Paramedian arteries and branches Circumferential branches from the basilar
What’s the vascular supply to the midbrain?
Basilar artery, PCA, SCA, PcommA, Anteior Chroidal
What’s the vascular supply to Cerebellum?
PICA: Inferior cerebellar peduncle, vermis, tonsils, choroid of the 4th
AICA: Middle cerebellar peduncle, choroid of the 4th, anterior cerebellum
SCA: superior cerebellar peduncle, choroid of the 4th, and the DEEP nuclei
The SSS drains predominantly to which transverse sinus?
Right Transverse Sinus (60%)
Where does the SSS end and the transverse sinus begin?
internal occipital proturberance
The medial internal cerebral venous drainage pathway is as follows:
cortical medical hemisphere veins -> ISS ISS joins great cerebral vein of Galen to form Straight SInusStraight sinus - > Torcula -> transverse sinus (predominantly left)
What joins with the sigmoid sinus to become the superior jugular bulb?
inferior petrosal sinus
The vein of Trolard and Labbe drain into the which sinuses respectively?
SSS and Transverse Sinuse respectively (both originate at sylvian fissure)
What forms the internal cerebral veins?
union of the thalamostriate, choroidal, septal, and epithalamic, and lateral ventricular veins
What’s the course of the internal cerebral veins?
located in the tela choroidea of the roof of the third ventricle (velum interpositum)
travels through quadrigeminal cistern to contribute to the vein of Galen
What is the course of the Basal Vein of Rosenthal?
passes through the ambient cistern and joins the internal cerebral vein to form the vein of Galen
What is the course of the vein of Galen?
travels under the splenium and merges with the inferior sagittal sinus to form the straight sinus
Left vertebral artery arises from the aorta what percent of times?
5%
The ____ branch of the facial artery anastamoses with the ____ branch of the ophthalmic artery.
angular
orbital
The internal maxillary artery anastomoses with inferior lateral cavernous sinus trunk and ophthalmic artery through ____.
ethmoidal branches
What are the segments of the intracavernous ICA?
- Ascending portion2. posterior genu3. horizontal portion4. anterior genu5. remainder of ICA
The intracranial portion of the ICA begins at the ____.
distal dural ring
What are the branches of the medial trunk? What do they supply?
anterior and inferior capsular arteriesanterior and inferior pituitary
Aneurysms of the ICA arise from which four vessels? What is the orientation?
Ophthalmic - superiorly and anteriorly
Superior hypophyseal - inferiorly and medially
PComm - posterior
Anterior choroidal - superior lateral
Medial lenticulostriates branch from _____.
A1
The Acomm lies in what cistern?
cistern of the lamina terminalis
The recurrent artery of Heubner passes through what anatomical structure?
anterior perforating substance
The genu of the MCA courses around what structure?
island of Reil
The M3 is also known as the ______ segment.
opercular
The largest cortical branch of the MCA is the _____.
angular artery
Occlusion of what branch of the MCA causes Wernicke’s Aphasia and hemianopsia?
posterotemporal branch (M2 inferior trunk branch)
P1 lies within what cistern?
interpeduncular
What cistern does the Anterior choroidal artery go through?
ambient
The anterior choroidal artery enters the choroidal fissure at the _____.
plexal point (temporal horn of lateral ventricle)
What artery was historically sacrificed to treat parkinson’s disease? Why?
anterior choroidal probably due to decreased supply to VL thalamus
What percent of people have a complete circle of willis?
25%
What are the segments of the PICA?
- Anterior medullary segment
- Lateral medullary segment: supply CNs IX, X, and XI
- Tonsillomedullary segment: forms a large loop
- Telovelotonsillar segment: between tela choroidea and inferior medullary velum rostrally superior pole of the tonsils caudally
- Hemispheric branches
What are three midbrain stroke syndromes?
Weber’s (CN III palsy w/ contralateral hemiplegia)
Benedikt (same plus red nucleus lesion aka tremors)
Claude (CN III, contralateral hemiparesis and ataxia)
What percent of patients with persistent trigeminal arteries have vascular malformations or aneurysms?
25%
What is the second most common persistent fetal artery?
hypoglassal (after trigeminal)
What is the Artery of Adamkiewicz?
Major anterior radicular artery Originates usually at lower thoracic or upper lumbar levels (most commonly T7 but 75% arise between T9 - T12)Most frequently on the left side (70 - 80%)Joins the anterior spinal artery
Where do radicular arteries arise from?
originate from segmented branches off of the aorta (i.e. intercostals, ascending cervical, etc.)
What is the entrance of the radicular artery into the spinal canal?
intervertebral foramina
What is the vascular supple to the dorsal root ganglion?
Posterior Radicular Arteries
What regions of the spinal cord are especially vulnerable to ischemia?
border/transition areas especially T1-T4 and L1
Intracranial-Extracranial Anastamoses:Occipital artery
Vertebral (C1 and C2)
Intracranial-Extracranial Anastamoses:Ascending Pharyngeal Artery
Vertebral
ICA via petrous and cavernous branches
Intracranial-Extracranial Anastamoses:Angular Branch of Facial Artery
ICA vis angular branch of the facial artery to the orbital branch of the ophthalmic artery
Intracranial-Extracranial Anastamoses:Posterior Auricular Artery
ICA via stylomastoid artery
Intracranial-Extracranial Anastamoses:Middle Meningeal Artery (Maxillary)
ethmoidal branch of the ophthalmic
Intracranial-Extracranial Anastamoses:Artery of foramen rotundum (Maxillary)
inferior lateral trunk
Intracranial-Extracranial Anastamoses:Accessory meningeal artery (Maxillary)
inferior lateral trunk
Intracranial-Extracranial Anastamoses:Vidian Artery (Maxillary)
Petrous ICA
Intracranial-Extracranial Anastamoses:Pharyngeal Artery
Cavernous ICA
Intracranial-Extracranial Anastamoses:Temporal branches (Maxillary)
Ophthalmic Artery