Neuroanatomy 1

Question 1

Layers of the SCALP (5)

Answer 1

Skin
Connective tissue
Aponeurosis
Loose connective tissue
Periosteum

*superficial to deep

Question 2

“Scalp Proper”

Answer 2

-First 3 layers of the scalp, they are all connected and move together

Skin
Connective tissue
Aponeurosis

Question 3

Deep Scalp

Answer 3

-Deepest 2 layers

Loose connective tissue
Periosteum

*emissary veins in the LCT provide a potential infection pathway into the cranial vault

Question 4

Aponeurosis function

Answer 4

Helps prevent stretching of the scalp

Question 5

What are the Meninges

Answer 5

3 layers of tissue, provide protection and support to the spinal cord (CNS)

Superficial to deep:
-Dura mater
-Arachnoid mater
-Pia mater

Question 6

Dura Mater

Answer 6

-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

Question 7

2 Layers of Dura Mater

Answer 7

1. Periosteal layer
2. 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

Question 8

2 Spaces of Dura Mater

Answer 8

1. Epidural space
2. Subdural space

*these spaces are potential spaces (not found unless trauma/disease cause separation if them)

Question 9

Arachnoid Mater

Answer 9

-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

Question 10

Cerebrospinal Fluid (CSF) Functions

Answer 10

Help to metabolically and physically support the brain

Metabolically- exchange medium
Physically- buoyancy and cushion

Question 11

Pia Mater

Answer 11

-Closely covers cortical sulci and gyri
-Subpial space exists b/t pia and cortex
(another potential space not normally present)

Question 12

Spinal Meninges

Answer 12

-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

Question 13

Spinal Meninges- 4 Spaces

Answer 13

1. Epidural Space- between vertebral canal and dura (contains fat and venous plexuses)
2. Subdural- between dura and arachnoid *potential space
3. Subarachnoid Space- between arachnoid and pia (contains CSF)
4. Subpial spaces- below pia mater *potential space

Question 14

What are the ventricles

Answer 14

4 cavities within the brain responsible for deep CSF flow
-2 lateral ventricles, 3rd ventricle, 4th ventricle

Question 15

Lateral Ventricles (6 Components)

Answer 15

1. Anterior horn
2. Posterior horn
3. Inferior horn
4. Body
5. Atrium (large triangular space)
6. Interventricular Foramen of Munro (connect lateral and 3rd ventricle)

*associated with various lobes of cerebrum (telencephalon)

Question 16

Third Ventricle (6 Components)

Answer 16

1. Anterior wall
2. Posterior wall
3. Lateral walls
4. Roof
5. Floor
6. Interthalamic adhesion

*associated with thalamus and hypothalamus (diencephalon)

Question 17

Cerebral Aqueduct

Answer 17

Connects the 3rd and 4th ventricles, passing through midbrain into the pons

Question 18

Fourth Ventricle

Answer 18

There are 3 apertures in the 4th ventricle:
-2 Lateral (Foramina of Luschka)
-1 Median (Foramen of Magendie)

*associated with the pons (myelencephalon)

Question 19

Beyond 4th Ventricle

Answer 19

Central canal continues all the way down the spinal cord

-Provides metabolic support to the deep spinal cord

Question 20

Clinical Connection- Hydrocephalus

Answer 20

-Abnormal enlargements of the ventricles caused by buildup of CSF
-Can be caused by blockages in ventricular foramina (e.g. interventricular foramen)

Question 21

Choroid Plexus

Answer 21

-Collection of ependymal cells found on walls of all 4 ventricles in specific areas

*produces CSF which flows into the ventricles

Question 22

Ventricular Flow of CSF

Answer 22

Lateral ventricle -> Interventricular foramen -> 3rd ventricle -> Cerebral aqueduct -> 4th ventricle -> Foramina of Luschka or Magendie (to brain) or Central Canal (to spinal cord)

Question 23

CSF Flow Exiting the Ventricles

Answer 23

-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

Question 24

Overview of Cranial CSF Flow (11)

Answer 24

1. Choroid plexus
2. Lateral ventricle
3. Interventricular foramen
4. Third ventricle
5. Cerebral aqueduct
6. Fourth ventricle
7. Median/Lateral Apertures OR central canal to spinal cord
8. Subarachnoid cisterns
9. Bathes superficial brain
10. Arachnoid granulations
11. Dural venous sinuses

Question 25

Great Vessels of the Heart

Answer 25

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

Question 26

Four Major Arteries to the Brain

Answer 26

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

Question 27

2 Arteries Through the Skull

Answer 27

-Internal carotid artery goes through carotid canal -Vertebral artery goes through anterior portion of foramen magnum

Question 28

Basilar Artery

Answer 28

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

Question 29

What is the Circle of Willis

Answer 29

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

Question 30

Circle of Willis (7)

Answer 30

1. Basilar artery 2. Posterior cerebral arteries 3. Posterior communicating arteries 4. Internal carotid arteries 5. Middle cerebral arteries 6. Anterior cerebral arteries 7. 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

Question 31

Venous Drainage

Answer 31

Consists of dural venous sinuses that drain the inner structures of the cranial vault 1. Superior sagittal sinus 2. Confluence of sinuses 3. Transverse sinuses (sit in tentorium cerebelli)

Question 32

Terminal Drainage of Brain

Answer 32

-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

Question 33

Cavernous Sinus

Answer 33

-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

Question 34

Overview Venous Drainage of the Skull (6)

Answer 34

1. Superior sagittal sinus 2. Confluence of sinuses 3. Transverse sinus 4. Cavernous sinus *separate 5. Sigmoid sinus 6. Internal jugular vein