Anatomy 5: Anatomy of SOLs Flashcards
What is a space-occupying lesion, and what are the two main types?
Abnormal tissue taking up space
Acute or subacute
What are the layers of the scalp?
SCALP Skin CT (artery-rich) Aponeurosis (tendon) Loose CT (thinnest) Pericranium (periostum - outer membrane of bone)
Why do scalp lacerations and incisions bleed excessively?
Scalp arteries form a rich anastomotic network just deep to skin
What two arteries do scalp arteries branch from?
Internal and external carotid
What is the thinnest part of the skull? What type of joint is it? What artery courses just deep to it? Which bones form it?
Pterion
Fibrous joint - suture (H shape)
Middle meningeal artery
Frontal, parietal, temporal, sphenoid bones
List the borders of each of the cranial fossa; anterior, middle and posterior?
Frontal bone - wings of sphenoid
WIngs of sphenoid - petrous temporal bone
Petrous temporal bone - occipital bone
What is the name for the protective coverings of the brain and spinal cord?
Meninges
List the 3 layers of membrane covering the brain and spinal cord, from superficial to deep.
Dura matter ‘hard matter’ (ADHERENT TO SKULL)
Arachnoid matter ‘spidery mother’
(Subarachnoid space)
Pia matter ‘faithful matter’ (ADHERENT TO BRAIN)
What CN is the sensory supply to the dura?
CNV
Which layer of the meninges encloses the dural venous sinuses? What are the main three types of dura?
Dura matter
DIaphragm sellae, tentorium cerebelli, falx cerebri
What is the diaphragm sellae? What does it sit upon?
Tough sheet of dura matter forming a roof over pituitary fossa (on sella turcica)
What is the tentorium cerebelli?
Tough sheet of dura matter tenting over cerebellum, which attaches to ridges of petrous temporal bone
What is the falx cerebri? What are the attachments to the deep aspect of skull?
Midline structure of dura matter that seperates the cerebral hemispheres
Crista galli of ethmoid bone, internal sagittal suture, internal occipital protuberance
Where do the cerebral veins drain into?
Dural venous sinuses
List the main dural venous sinuses that drain blood from the brain, and give their location
Straight sinus (inferior sagittal to confluence of sinus) Superior sagittal sinus (return blood from front brain) Inferior sagittal sinus (return blood from front brain) Transverse sinus (confluence of sinus - sigmoid sinus) Sigmoid 'S' sinus (transverse sinus - IJV)
Where does the sigmoid sinus drain and to what foramen?
IJV at jugular foramen
Where is the confluence of sinuses?
In midline at internal occipital protuberance
What is the danger triangle of the face?
Venous spread of infection from superficial to deep - ophthalmic vein has no valves and can leak backwards = CAVERNOUS SINUS THROMBOSIS
Outline the arterial supply to the brain
- ICA (branch of CCA)
- ECA (branch of CCA)
- VA (branch of SCA)
What route does the vertebral artery take to reach the cranial cavity?
Through transverse foraminae in cervical vertebrae
Through foramen magnum
Outline the branches of the Circle of Willis from bottom to top
Vertebral arteries (connected by anterior spinal)
Basilar artery (anastomosis of two VAs)
(Pontine arteries)
Posterior cerebral arteries (division of basillar artery)
ICAs (connected to PCAs by posterior communicating arteries)
1. Ophthalmic arteries
2. Branch of ICAs = Anterior cerebral arteries (connected by anterior communicating artery)
MCAs (continuation of ICAs)
Which arteries supply the medial, lateral and posterior aspects of the cerebral hemispheres respectively?
ACAs
MCAs
PCAs
Where can the Circle of Willis be found?
Inferior to midbrain, close to the pituitary stalk and optic chiasm in subarachnoid space
What circulates within the subarachnoid space?
CSF
Where does the subarachnoid space terminate?
S2 part of the sacrum
Outline the route taken by CSF from production to reabsorption
- Secreted by choroid plexus
- From right and left lateral ventricles
(via Foraminae of Munro - ONE FOR EACH) - Into midline 3rd ventricle
(Cerebral aqueduct) - Into 4th ventricle
- Into subarachnoid space of brain and cord (and some into central canal)
- Reabsorbed into dural venous sinuses
Where are the lateral ventricles, 3rd ventricle and 4th ventricle located, respectivelly?
Cerebral hemispheres
Diencephalon
Between cerebellum and pons
What reabsorbs CSF back into the dural venous sinuses?
Arachnoid granulations
What is hydrocephalus? How is it managed?
Excess production, obstruction to flow or inadequate reabsorption leading to increased CSF volume
Ventricular peritoneal shunt (connects ventricles to peritoneal cavity)
List the types of bleeding that can occur within the cranial cavity and what causes each of them
EXTRADURAL HAEMORRHAGE (between bone and dura) due to ruptured middle meningeal artery (damage to pterior)
SUBDURAL HAEMORRHAGE (seperates dura from arachnoid) due to torn cerebral veins
SUBARACHNOID HAEMORRHAGE (into CSF of subarachnoid space) due to ruptured CIrcle of WIllis ‘Berry aneurysm’
What can happen if you sustain damage to the extradural venous plexuses?
Epidural haematoma compressing spinal cord or cauda equina
Where is the needle inserted in epidural anaesthesia? Why?
Subarachnoid space where it surrounds cauda equina (spinal nerves not as easily damaged as conus medullaris and vertebrae not fused)
Typically L3/4
What are the four common types of supratentorial herniation?
Cingulate (under falx cerebri)
Central (through tentorium cerebelli)
Uncal (uncus = medial temporal lobe, inferior to tentorium cerebelli)
Transcalvarial (fracture of cranial cavity)
What nerve can be compressed in uncal supratentorial herniation? What is the effect?
Oculomotor nerve
Fixed dilated pupil (ipsilateral)
What are the two common types of infratentorial herniation?
Upward (over tentorium cerebelli)
Downward/ tonsillar herniation (of cerebral tonsils into foramen magnum)
Where is the cerebral aqueduct located anatomically?
In the midbrain
Which cranial nerve is located in the anterior midline of the midbrain?
Oculomotor nerve
Which layer of the meninges is avascular?
Arachnoid matter
