Gross Anatomy of the CNS & Neurocranium Flashcards
Coronal Section
Label ventricles, basal ganglia and gross structures


Label gross brain stuctures


Label the Circulus Arteriosus


What three branches originate from the internal carotid artery before it joins the circulus arteriosus/
Ophthalmic Artery
Anterior Choroidal Artery
Hypophyseal Arteries
Detail the territory of Cerebral Arteries


Label the Venous drainage of the brain


List the 5 layers of the scalp
- S = Skin
- C = Connective tissue
- A = Aponeurosis
- L = Loose connective tissue
- P= Pericranium
Why will scalp lacerations bleed excessively?
the scalp arteries form a rich anastomotic network just deep to the skin – scalp lacerations & incisions can bleed excessively

How do sutures, in mature skulls, protect the neurocranium?
- Sutures (fibrous joints) help prevent skull fractures from spreading
- Minimise propagation
Describe the Pterion
- H-shaped
- Frontal, parietal, temporal and sphenoid bones
- Thinnest part of skull
- Overlies the middle meningeal artery
Label the sutures and other remarkable points


Label the key features to the Base of the Cranial Cavity


Describe the meninges and their structural layering
(“meninx” = membrane)

- DURA MATER: “hard mother”!! (protector)
- tough/fibrous
- has a sensory nerve supply mainly from CN V
- encloses the dural venous sinuses
- ARACHNOID MATER: “spidery mother”!
- arachnoid granulations (reabsorb CSF)
- SUBARACHNOID SPACE
- contains the circulating CSF
- PIA MATER: “faithful mother”!
- adherent to the brain and the blood vessels & nerves entering or leaving brain
Label and describe parts of the dura mater


Describe and detail the falx cerebri
- a midline structure
- made of dura mater
- attaches to the deep aspect of the skull:
- the crista galli of the ethmoid bone anteriorly
- the internal aspect of the sagittal suture
- the internal occipital protruberance of the occipital bone posteriorly
- separates the right & left cerebral hemispheres

Regarding the Subarachnoid space:
(i) where is it located and what is its function
(ii) what does it contain and how does this flow
(iii) where can it be accessed safely?
(iv) At what level does it end?
(i) Between arachnoid mater and pia mater
- completely surrounds both brain & spinal cord
- continuous
- cushions and protects
(ii) Contains circulating cerebrospinal fluid (CSF)
- 400-500 mls/day
- produced inside the brain by the choroid plexus of the ventricles
- reabsorbed into the dural venous sinuses via arachnoid villi
(iii) Can be accessed via lumbar puncture at L3/4 or L4/5 IV disc levels to obtain a sample of CSF
(iv) Ends/closes inferiorly at the level of the S2 part of the sacrum
Label the diagram of the ventricular system


What is hydrocephalus?
(water in the head)
excessive production, obstruction to flow or inadequate reabsorption leads to an increased CSF volume

Label the daigram of the Superior Sagittal Sinus


Describe an extradural heamorrhage
- between the bone & the dura
- ruptured middle meningeal artery
- trauma to the pterion

Describe a subdural haemorrhage
- separates the dura from the arachnoid
- torn cerebral veins
- falls in the elderly & those with problem drinking

Describe a subarachnoid haemorrhage
- into the CSF of the subarachnoid space
- ruptured Circle of Willis (“berry”) aneurysm
- congenital aneurysm

Label the diagram of Lumbar Puncture


What is the rare and serious complication of Lumbar Puncture?
Damage to the extradural venous plexus can result in an epidural haematoma compressing the spinal cord or cauda equina
What is the usual level for attempting lumbar puncture and why?
L3/ L4
- Region of cauda equina so spinal cord will not be punctured (->L2)
- Above level of fused sacrum
In raised ICP what forms of brain herniation occur?
Supratentorial herniation
Infratentorial herniation
Describe the events of supratentorial herniation
- cingulate (subfalcine)
- central
- uncal - the uncus (medial part) of the temporal lobe herniates inferior to the tentorium cerebelli
- transcalvarial
Describe events in infratentorial herniation
- upward
- downward or tonsillar herniation
(herniation of the cerebellar tonsils):
the cerebellar tonsils herniate into the foramen magnum
What nerve, and therefore what sign, are commonly seen in herniation
compression of the oculomotor nerve by an uncal herniation leads to an ipsilateral fixed dilated pupil (a “blown” pupil)