Lecture 3 & 4: Neuroanatomy Flashcards
How many layers does the scalp have?
5 layers
What are the 5 layers of the scalp?
- Skin
- Connective Tissue
- Aponeurosis
- Loose connective tissue
- Periosteum
What does the Scalp Proper Consist of?
3 superficial layers:
1. Skin
2. Connective tissue
3. Aponeurosis
*all 3 layers are connected and move together
4 aponeurosis of the skull
-frontalis
-Epicranial aponeururosis
-occipitofrontalis
-occipitalis
what is the main function of the aponeurosis of the skull?
help prevent stretching of the scalp
fucntion of frontalis aponeurosis
raise eyebrows and scrunch forehead
function of the occipitalis aponeurosis
retract scalp
Contents of the deep scalp
Loose connective tissue and Periosteum
What is considered the danger zone of the scalp?
the Loose connective tissue; because emmissary veins (bridging veins) in the loose connective tissue provide a potential infection pathway into the cranial vault
What are the meninges for?
3 layers of connective tissue to provide protection and support to the CNS (brain and spinal cord)
Name the meninges from 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 blood from the cranial vault
The three invaginations that the dura mater forms within the cranial vault
- Falx cerebri
- Tentorium Cerebelli
- Fslx Cerebelli
What does the falx cerebri attach anteriorly
the crista galli of the ethmoid bone
2 layers of the dura mater
- Periosteal layer
- Meningeal layer (deeper)
what is the purpose of the layers of the dura mater splitting?
to form the dural venous sinuses
2 spaces of the dura mater
- Epidural space
- Subdural space
Key characteristic of the 2 spaces of the dura mater
they are POTENTIAL spaces; they are not found unless trauma/disease cause separation of the 2 layers
Where does the dura mater split
at the edge of the skull and at the foramen magnum
Where does each layer of the dura mater travel?
Periosteal layer: edge of the skull
Meningeal Layer: around the spinal cord
Arachnoid mater
-sits deep to the dura, on the dura
where is the subarachnoid space?
subarachnoid space between arachnoid and pia; thsi contains CSF
Cerebrospinal Fluid purpose
-helps metabolically (exchange medium) and physically (buoyancy and cushion) support brain
Arachnoid mater Granulations
drain CSF through the dura
Arachnoid mater trabeculae
support the arachnoid mater (against underlying pia)
Pia Mater
-closely covers cortical sulci and gyri
Subpial space
exists between Pia and Cortex (potential space)
Spinal Meninges
3 layers of tissue to provide protection and support to the spinal cord:
-Dura mater
-Arachnoid mater
-Pia Mater
What do the dura and arachnoid meninges cover to physically support and protect
Spinal Nerve Roots
Denticulate Ligaments
-from the pia and connect to dura for cord stability
What does the epidural space contain
fat and venous plexuses
what does the subarachnoid space contain
CSF
what are the two potential spaces
subdural and subpial
what are the 4 ventricles responsible for
deep CSF flow
Lateral ventricles
space assocaited with the cerebrum (telencephalon)
features of the lateral ventricles
-Anterior horn
-Inferior horn
-Posterior horn
-Body
-Atrium
-interventricular foramen
what does the body of the lateral ventricle connect
-anterior horn and atrium
what does the atrium of the lateral ventricles connect
all 3 horns
Interventricular foramen
helps with CSF flow from lateral ventricles
third ventricle
space associated with the thalamus and the hypothalamus (the diencephalon)
Features of the third ventricle
-Anterior wall
-Roof
-Posterior wall
-Lateral walls (2)
-floor
-interthalamic adhesion
-cerebral aqueduct
Cerebral aqueduct
connects the third and fourth ventricles passing through the midbrain into the pons (where the fouth ventricle is located
Fourth ventricle
space associated with the pons (the myelencephalon)
Features of the fourth ventricle
-Foramina of luschka
-Foramen of magendie
What is beyond the fourth ventricle
-the central canal continues all the way down the spinal cord
Purpose of the central canal
provides metabolic support to the deep spinal cord
Hydrocephalus
abnormal enlargement of the ventricles cause by a buildup of CSF
WHat can hydrocephalus be caused by
blockages in the ventricular formaina
Choroid Plexus
collection of ependymal cells found on the walls of all 4 ventricles in specific areas
*produces CSF
path of ventricular flow
- Lateral Ventricle
- Interventricular Foramen
- Third Ventricle
- Cerebral aqueduct
- Fourth ventricle
- Foramina of Luschka, Central CAnal, Foramen of Magendie
Exiting the ventricles
CSF exits into small subarachnoid spaces called cisterns, then flows along the outer cortices of the cerebrum and cerebellum
Arachnoid Granulations
-CSF exits through subarachnoid space through arachnoid granulations which pierce through dura to drain CSF into dural venous sinuses
Cranial CSF Flow
- Choroid Plexus
- Lateral Ventricle
- Interventricular foramen
- Third ventricle
- Cerebral Aqueduct
- Fourth Ventricle
- Median/Lateral Apertures
- Subarachnoid Cisterns
- Bathes Superficial Brain
- Arachnoid Granulations
- Dural Venous Sinuses
Spinal CSF flow
- Choroid PLexus
- Lateral VEntricle
- Interventricular foramen
- Third ventricle
- Cerebral Aqueduct
- Fourth Ventricle
- Central Canal
Three major branches of the aorta
-brachiocephalic trunk
-Left Common carotid artery
-Left Subclavian artery
The brachiocephalic trunk bifurcates into:
the right common carotid artery and the subclavian artery
FOur major arteries to the brain
Common carotid artery –> Internal Carotid Artery
Subclavian artery –> Vertebral artery
which artery runs through the vertebral foramina of the cervical vertebrae
the vertebral artery
Which opening of the skull does the internal carotid artery run through
carotid canal
which opening of the skull does the vertebral artery run through
anterior portion of foramen magnum
Basilar artery
-left and right vertebral arteries anastomose to form the basilar artery
-sits in basilar groove on pons
-gives off pontine arteries to supply the pons
Bifurcation of basilar artery
basilalr artery bifurcates into 2 posterior cerebral arteries; these supply the posterior cerebral cortex
*both arteries supply respective sides
Where does the circle of willis supply blood to
cerebrum
Circle of Willis order
- Basilar artery
- Posterior cerebral arteries
- Posterior communicating ateries
- Internal Carotid arteries
- Middle cerebral arteries
- Anterior cerebral arteries
- Anterior communicating artery
In the circle of willis, what does the internal carotid artery give off?
the anterior and middle cerebral arteries, and the posterior communicating artery
Purpose of communicating arteries
provide connections
In the circle of willis, what are the anterior cerebral arteries connected by
anterior communicating artery
smallest artery in circle of willis
anterior communicating artery
What supplies blood to the lateral surfaces of the cerebral hemispheres
middle cerebral artery
Purpose of the circle of willis
in the case of a clot, in a vertebral or internal carotid artery, cerebral blood flow is maintained therefore it is a compensatory mechanism
Venous Drainage
dural venous sinuses that drain the inner structures of the cranial vault
Superior Sagittal Sinus
lies along mid sagittal plane in falx cerebri
order of venous drainage
- Superior sagittal sinus
- Confluence of sinuses
- Transverse sinuses
Confluence of sinuses
multiple sinuses drain into this area; splits into transverse sinuses
where does the transverse sinuses sit
in the tentorium cerebelli
WHne does the transverse sinus become sigmoid sinus
when exiting tentorium cerebelli
where does sigmoid sinus drain
into the internal jugular vein
What is the jugular bulb?
it is a superior enlargement of the internal jugular vein
Cavernous Sinus
venous plexus sitting lateral to body of sphenoid bone that drain eye, parts of cerebral cortex and pituitary gland
what is the cavernous sinus pierced by
internal carotid artery
Diencephalon
From brain stem to cerebrum and surrounds the third ventricle:
-Epithalamus
-Thalamus
-Hypothalamus
Thalamus
-makes up 80% of diencephalon
-major relay olfactory centre
-paired oval masses of nuclei
connected by interthalamic adhesion
Where do axons pass through in the thalamus
internal capsule
Hypothalamus
-controls and integrates autonomic activities
-major regulator of homeostasis
-produces hormones
-creates caracadian rhythyms
What is inferior to the hypothalamus
infundibulum and pituitary gland
Epithalamus
contains the habenular nuclei and pineal gland
Habenular nuclei function
olfaction and emotional response to others
Pineal gland function
part of the endocrine that secretes melatonin
Components of the brainstem
Midbrain, Pons and Medulla Oblongata
Medulla Oblongata
-continuation of the superior aspect of spinal cord
-forms inferior part of the brainstem
-contains all sensory (ascending) and motor (decending) tracts that connect the spinal cord to the brain
Pyramids of the medulla fucntion
-90% of axons cross to opposite side
-crossing is known as the decussation of pyramids
-allows for contralateral control
**explains how moving right hand uses the left side of the brain
Pons
-superior to the medualla and anterior to the cerebellum
-contains a control center for respiration
Midbrain
-extends upwards from pons to diencephalon
-involved in the auditory and visual pathway
which part of the brainstem surrounds the cerebral aqueduct
midbrain
features and function of the midbrain
Superior Colliculi: vision
Inferior Colliculi: Audition
protective structures of the spinal cord
-vertebral column
-spinal meninges
-cerebrospinal fluid
Makeup of the vertebral column
-7 cervical vertebrae
-12 thoracic vertebrae
-5 lumbar vertebrae
-5 fused sacral vertebrae
-4 fused coccygeal vertebrae
Spinal Meninges
**continuous with cranial meninges
1. Dura Mater (outermost)
2. Arachnoid Mater (middle)
3. Pia mater (deepest)
Where is the epidural space and what does it contain
between vertebral canal and dura and contains fat
where is the subdural space and what does it contain
between dura mater and arachnoid mater and contains interstitial fluid
where is the subarachnoid space and what does it contain
between arachnoid mater and pia mater and contains CSF
where are denticulate ligaments
suspend spinal cord in dural sheath
purpose of denticulate ligaments
membranous extensions of pia mater and fuse with arachnoid mater to protectand prevent sudden movements and displacement
Spinal Cord enlargements
- Cervical enlargement
- Lumbosacral enlargement
cervical enlargement
-C4-T1
-supplies upper extremeties
lumbosacral enlargement
-T9-T12
-supplies lower extremeties
Conus Medullaris
-termination of the spinal cord
-located between first and second lumbar vertebrae
Filum terminale
-extension of the pia mater
-attaches spinal cord to the coccyx.
Cauda Equina
-lumbar, sacral % coccygeal spinal nerves
-base of vertebral column
Lumbar Puncture
needle inserted into the lumbar cistern will pass among nerve roots, allowing safe sampling of CSF
-use L4 area as spinal cord has ended here
-flexed position to allow space between spinous processes
features of internal structure of spinal cord
-posterior median sulcus
-white matter
-grey matter
-central canal (extends full length of spinal cord and contains CSF)
-anterior median fissure
Grey matter of spinal cord
-posterior horn
-lateral horn
-anterior horn
Posterior horn of grey matter
contains cell bodies and axons of nuclei for sensory function
lateral horn of grey matter
contains autonomic nuclei to control smooth muscle for involuntary control
anterior horn of grey matter
contains somatic motor nuclei for skeletal muscle
white matter of the spinal cord
-posterior funiculus
-lateral funiculus
-anterior funiculus
