Neuroanatomy 1 Flashcards
Layers of the SCALP (5)
Skin
Connective tissue
Aponeurosis
Loose connective tissue
Periosteum
*superficial to deep
“Scalp Proper”
-First 3 layers of the scalp, they are all connected and move together
Skin
Connective tissue
Aponeurosis
Deep Scalp
-Deepest 2 layers
Loose connective tissue
Periosteum
*emissary veins in the LCT provide a potential infection pathway into the cranial vault
Aponeurosis function
Helps prevent stretching of the scalp
What are the Meninges
3 layers of tissue, provide protection and support to the spinal cord (CNS)
Superficial to deep:
-Dura mater
-Arachnoid mater
-Pia mater
Dura Mater
-Thick layer of meninges deep to the calvarium (skull cap)
-Encloses dural venous sinuses, major structures that drain the cranial vault
Forms 3 invaginations (folds) within cranial vault
1. Falx cerebri
2. Tentorium cerebelli
3. Falx cerebelli
*falx cerebri attaches anteriorly to the crista galli of ethmoid bone
2 Layers of Dura Mater
- Periosteal layer
- Meningeal layer
-At the edge of the skull, at the foramen magnum, this menix splits and continues around the edge of the skull (periosteal layer) AND around the spinal cord (meningeal layer)
*layers split to help form the dural venous sinuses
2 Spaces of Dura Mater
- Epidural space
- Subdural space
*these spaces are potential spaces (not found unless trauma/disease cause separation if them)
Arachnoid Mater
-Sits deep to the dura, on the dura
-Subarachnoid space sits between arachnoid and pia, contains CSF
*Arachnoid granulations drain CSF through the dura
*Arachnoid trabeculae support the arachnoid mater
Cerebrospinal Fluid (CSF) Functions
Help to metabolically and physically support the brain
Metabolically- exchange medium
Physically- buoyancy and cushion
Pia Mater
-Closely covers cortical sulci and gyri
-Subpial space exists b/t pia and cortex
(another potential space not normally present)
Spinal Meninges
-Dura and arachnoid meninges cover the Spinal Nerve Roots
-Denticulate ligaments (from pia) connect to dura for cord stability *suspend spinal cord in dural sheath
Spinal Meninges- 4 Spaces
- Epidural Space- between vertebral canal and dura (contains fat and venous plexuses)
- Subdural- between dura and arachnoid *potential space
- Subarachnoid Space- between arachnoid and pia (contains CSF)
- Subpial spaces- below pia mater *potential space
What are the ventricles
4 cavities within the brain responsible for deep CSF flow
-2 lateral ventricles, 3rd ventricle, 4th ventricle
Lateral Ventricles (6 Components)
- Anterior horn
- Posterior horn
- Inferior horn
- Body
- Atrium (large triangular space)
- Interventricular Foramen of Munro (connect lateral and 3rd ventricle)
*associated with various lobes of cerebrum (telencephalon)
Third Ventricle (6 Components)
- Anterior wall
- Posterior wall
- Lateral walls
- Roof
- Floor
- Interthalamic adhesion
*associated with thalamus and hypothalamus (diencephalon)
Cerebral Aqueduct
Connects the 3rd and 4th ventricles, passing through midbrain into the pons
Fourth Ventricle
There are 3 apertures in the 4th ventricle:
-2 Lateral (Foramina of Luschka)
-1 Median (Foramen of Magendie)
*associated with the pons (myelencephalon)
Beyond 4th Ventricle
Central canal continues all the way down the spinal cord
-Provides metabolic support to the deep spinal cord
Clinical Connection- Hydrocephalus
-Abnormal enlargements of the ventricles caused by buildup of CSF
-Can be caused by blockages in ventricular foramina (e.g. interventricular foramen)
Choroid Plexus
-Collection of ependymal cells found on walls of all 4 ventricles in specific areas
*produces CSF which flows into the ventricles
Ventricular Flow of CSF
Lateral ventricle -> Interventricular foramen -> 3rd ventricle -> Cerebral aqueduct -> 4th ventricle -> Foramina of Luschka or Magendie (to brain) or Central Canal (to spinal cord)
CSF Flow Exiting the Ventricles
-CSF exits into small subarachnoid spaces called cisterns (small cavities)
-From cisterns, CSF flows along outer cortices of the cerebrum and cerebellum (bathe superficial brain)
-CSF exits subarachnoid space through arachnoid granulations
-These pierce through the dura to drain CSF into dural venous sinuses
Overview of Cranial CSF Flow (11)
- Choroid plexus
- Lateral ventricle
- Interventricular foramen
- Third ventricle
- Cerebral aqueduct
- Fourth ventricle
- Median/Lateral Apertures OR central canal to spinal cord
- Subarachnoid cisterns
- Bathes superficial brain
- Arachnoid granulations
- Dural venous sinuses
Great Vessels of the Heart
Three major branches off the aorta:
1. Brachiocephalic
2. Left common carotid artery
3. Left subclavian artery
*brachiocephalic trunk bifurcates (ends and splits) into right common carotid artery and right subclavian artery
Four Major Arteries to the Brain
Common carotid artery -> internal carotid artery
Subclavian artery -> vertebral artery
*vertebral artery runs through the vertebral foramina of the cervical vertebrae
*goes up and meets in middle (anastomose) to form Basilar artery, which Pontine arteries come off
2 Arteries Through the Skull
-Internal carotid artery goes through carotid canal
-Vertebral artery goes through anterior portion of foramen magnum
Basilar Artery
Left and right vertebral arteries anastomose (join) to form the Basilar artery
-Sits in basilar groove of pons
-Gives off Pontine arteries to supply the pons
Bifurcates into 2 posterior cerebral arteries, which supply the posterior cerebral cortex
What is the Circle of Willis
Anastomosis of arteries providing major cerebral blood supply
Purpose: in the case of a clot in a vertebral or internal carotid artery, maintains cerebral blood flow throughout brain
*is a circle so if there is damage to one part, blood can still be supplied
Circle of Willis (7)
- Basilar artery
- Posterior cerebral arteries
- Posterior communicating arteries
- Internal carotid arteries
- Middle cerebral arteries
- Anterior cerebral arteries
- Anterior communicating artery
*basilar bifurcates into posterior cerebral arteries
*internal carotid artery gives off anterior and middle cerebral arteries, AND the posterior communicating artery (which connects internal carotid with posterior cerebral)
*communicating arteries provide connections
Venous Drainage
Consists of dural venous sinuses that drain the inner structures of the cranial vault
- Superior sagittal sinus
- Confluence of sinuses
- Transverse sinuses (sit in tentorium cerebelli)
Terminal Drainage of Brain
-Transverse sinus becomes Sigmoid sinus when exiting tentorium cerebelli
-Sigmoid sinus drains into Internal Jugular Vein
-Jugular bulb is a superior enlargement of the internal jugular vein
Cavernous Sinus
-Venous plexus sitting lateral to the body of the sphenoid bone
-Drains eye, parts of cerebral cortex and pituitary gland
-Pierced by the internal carotid artery, which then curves up to exit the dura and contribute to circle of willis
Overview Venous Drainage of the Skull (6)
- Superior sagittal sinus
- Confluence of sinuses
- Transverse sinus
- Cavernous sinus *separate
- Sigmoid sinus
- Internal jugular vein
