What are sulcus?
crevice/trench on brain surface
What are gyrus?
Ridges on the brain surface
What is the choroid plexus?
A plexus of cells that produces the cerebrospinal fluid, lining the ventricles of the brain
What is the Falx cerebri?
The longitudinal crescent shaped fold of meningeal layer of dura mater between the cerebral hemispheres
What are brain ventricles?
Four cavities located within the brain that contain cerebral spinal fluid (CSF)
What is meant by a sinus?
sac/cavity in organ or tissue. E.g. Frontal sinus, cavity containing air
What is the sella turcica?
The saddle shaped depression in the sphenoid bone, housing the pituitary gland
What is the cerebrum?
Upper most region of the brain nervous system, containing the white and grey matter
It is the seat of personality, memory
and intelligence.
What is the cerebellum?
hindbrain situated at the back of the brain
What are meninges?
‘Membrane’ layers covering the brain consisting of dura, arachnoid and pia
layers
How many bones is the skull composed of?
22 bones
8 form the cranium and 14 form the face
How are the 22 bones of the skull connected?
The joints between the skull bones are an example of
syndesmosis (fibrous joints).
What is the role of the cerebellum?
Concerned with balance, muscular co-ordination and dexterity.
What is the brain stem function?
The brain stem is critical for normal conscious awareness and basic “life support” functions
(e.g. control of breathing and blood pressure)
Name the 3 main brain fissures
- longitudinal fissure
- transverse fissure
- lateral sulcus
Where is the longitudinal fissure located?
Between the two cerebral hemispheres
Where is the transverse fissure found?
Between the cerebrum and cerebellum;
Where is the lateral sulcus?
Between the frontal and temporal lobes.
What functional region is found in the frontal lobe?
Frontal lobe contains the primary motor cortex
Which functional sensory region is in the parietal lobe?
Parietal lobe, containing the primary somatic sensory cortex
What functional region is housed in the occipital lobe?
Occipital lobe contains the primary visual cortex
What region is found in the temporal lobe?
Temporal lobe, containing the primary auditory cortex
Describe the surface of the brain
The surface of the brain consists of a number of folds (gyri) separated by grooves (sulci)
What is the corpus callosum?
This is an impressive bundle of three hundred million nerve fibres linking the two cerebral hemispheres
can be seen in a mid sagittal sectioned brain
Describe the outermost brain meninx
The outermost is dura mater; robust and leathery
Tightly adherent to bone and often remains attached to the inside of the skull during removal of the brain
What is the tentorium cerebelli?
A second dural partition interposed between cerebrum and cerebellum, arching over the posterior fossa like a tent
What are dural venous sinuses?
In places the dura separates into two layers, creating a channel filled with venous blood from the brain
Found in the in the free and attached margins of the falx and tentorium
What is the significance of trauma to the brain?
Trauma can cause bleeding between the skull and the dura mater (extra-dural haemorrhage) which can cause life-threatening pressure on the brain.
Describe the arachnoid mater
The arachnoid is semi-transparent so you can see the cortical vessels beneath it, in the subarachnoid space
What is the subarachnoid space?
This is a very narrow space over the surface of the brain that is filled with cerebrospinal fluid (CSF).
Note that bleeding into the sub-arachnoid space (sub-arachnoid haemorrhage) can be a cause of sudden death.
Where is the pia mater located?
The delicate pia mater closely invests the cortical surface and cannot be identified separately
Why is meningitis so deadly?
In bacterial meningitis there is acute inflammation of the arachnoid and pia with thick, creamy exudate (pus) filling the subarachnoid space and surrounding the vessels.
Note that meningitis can be a life-threatening condition and have severe consequences in those who
survive
Describe the ventricular system of the brain
Each part of the brain contains a fluid-filled cavity or channel corresponding to the lumen of the embryonic neural tube.
This gives rise to the ventricular system.
What are the lateral ventricles?
The large, C-shaped cavities in each cerebral hemisphere are the lateral ventricles.
These drain via the two interventricular foramina to a single, slit-like third ventricle which is located in midline, between the two egg-shaped thalami (plural of thalamus)
Where is the fourth ventricle located?
The diamond-shaped fourth ventricle lies between the brain stem anteriorly and the cerebellum behind.
How are the 3rd and 4th ventricles connected?
The third and fourth ventricles are connected by the narrow cerebral aqeuduct of the midbrain
When is CSF produced?
CSF is continuously secreted by the choroid plexus: a highly vascular structure within each ventricle.
How does CSF reach the subarachnoid space?
It flows towards the fourth ventricle before escaping via three openings to reach the subarachnoid space
How is the flow of CSF kept constant?
CSF is continuously reabsorbed into the superior sagittal sinus (one of the dural venous sinuses).
The rate of absorption matches the rate of production, keeping the CSF volume and pressure constant.
What 3 components is the brainstem formed of?
The brain stem is composed of the midbrain, pons and medulla, from which 10 out of the
12 cranial nerves (peripheral nerves of the head and neck) arise.
What are the 2 pyramid structures coming off the medulla?
The two longitudinally-disposed pyramids on either side of the
midline contain voluntary motor fibres descending from the frontal lobes to the spinal cord
What would be the consequence of damage to the medullary pyramids?
Damage would cause weakness or paralysis
Where is the pons located?
Just above the medulla
Forms a bridge with the cerebellum across the midline
Where is the midbrain situated?
The midbrain is small and partially hidden from view, just above the pons.
Describe the midbrain structure
From the anterior aspect it resembles two Roman pillars: the cerebral peduncles, separated by the interpeduncular fossa