SDL 3 - Brain, Meninges & Blood Supply Flashcards
What is meant by ‘rostral’ and ‘caudal’?
Rostral:
- this is used to describe the position of a structure with reference to the nose
- Occurring near the front end of the body
Caudal:
- towards the tail end or the posterior part of the body
What is meant by the cephalic flexure?
The axis of the adult brain bends at an angle of 100 degrees between the midbrain and the diencephalon
this is the cephalic flexure
What terms are used to describe structures in the brain, relating to the cephalic flexure?
What does this mean?
The terms dorsal and ventral are used as though the flexure did not exist and the CNS was still a straight tube (as in the early embryo)
In the spinal cord and brainstem, dorsal means posterior
In the forebrain, dorsal means superior
Label the aspects of the forebrain and spinal cord
Label the diagram of the neurone
What is the difference between grey matter and white matter?
Grey matter:
- contains neuronal cell bodies
- also contains neuropil, glial cells, synapses and capillaries
White matter:
- contains axons coated in a myelin sheath
What is meant by ‘neuropil’?
Dendrites, as well as myelinated and non-myelinated axons
What is meant by the cortex?
Cortex is the outermost (or superficial) layer of an organ
The cerebral cortex is the outer portion of the cerebrum that is covered by the meninges, often referred to as grey matter
What is meant by nucleus?
A nucleus is a cluster of neurones within the CNS
they are located deep within the cerebral hemispheres and the brainstem
What is meant by ‘tract’ in neuroanatomy?
A bundle of nerve fibres (axons) connecting nuclei of the CNS
What is meant by ganglion?
A group of neurone cell bodies within the PNS
Label the ventral view of the brain
Label the midsagittal view of the brain
Which subdivisions of the brain make up the forebrain (or cerebrum)?
Telencephalon:
- contains cerebral cortex (2 cerebral hemispheres)
Diencephalon:
- contains the thalamus and hypothalamus
Which subdivisions of the brain make up the brainstem?
- Medulla oblongata
- Pons
- Midbrain
Label the lobes and structures of the brain
Are the cerebral lobes functional or descriptive subdivisions?
Functional
the cerebellum has four functionally and spatially defined lobes:
- Parietal
- Occipital
- Temporal
- Frontal
What is the formation of the dura mater like?
What structures does it form periodically?
It is formed from the periosteum lining the inside of the skull, together with a fibrous inner layer
throughout most of the cranial cavity, the two layers are tightly fused together
at some sites, the fibrous inner layer of dura separates from the periosteum to enclose blood-filled spaces - dural venous sinuses
What is contained within the dural venous sinuses?
Venous blood flows into them from the brain
At two sites of separation of the 2 layers of dura, what is formed?
The fibrous inner layer of dura projects into the cranial cavity to form a dural reflection (fold/septum)
this extends into the fissures between the major components of the brain
What is the name of the dural septum that extends down between the two cerebral hemispheres?
Falx cerebri
What is the name of the dural septum that extends between the occipital lobes of the hemispheres and the cerebellum?
Tentorium cerebelli
What is the function of the two dural septa?
They restrict rotary displacement of the brain
Label the structures indicated on the diagram
What occupies space A, and what is its function?
Subarachnoid space
it contains cerebrospinal fluid (CSF) that acts as a cushion/shock absorber
it provides a passage for blood vessels and nerves in the brain
What are the arachnoid villi and what is their function?
They are small protrusions of arachnoid mater in the outer layer of the dura mater
They reduce pressure on the CNS
they allow CSF to pass from the subarachnoid space into the venous system
Which vessel provides the arterial supply to the dura mater?
Middle meningeal artery
This is a branch of the maxillary artery
An injured middle meningeal artery is the most common cause of an epidural haematoma
Which two pairs of blood vessels provide the arterial supply to the brain?
- Vertebral arteries
- internal carotid arteries
What is the course of the vertebral artery as it ascends to enter the skull?
- Arises from the subclavian artery
- Passes through the transverse foramina of the cervical vertebrae
- Passes through the foramen magnum and into the skull
- The vertebral arteries then fuse to form the basilar artery
What is the course of the internal carotid artery like as it passes into the skull?
- Arises at the level of C4, where the common carotid artery bifurcates
- it passes through the carotid canal to enter the skull
- it arises on the floor of the skull, on either side of the optic chiasma
Label the circle of Willis in the brain
Which vessels are A and B?
Which brain regions are supplied by each pair of arrows?
Label the distribution of the anterior, middle and posterior cerebral arteries
Label the distributions of the anterior, middle and posterior cerebral arteries
Blue = anterior cerebral artery
Orange = posterior cerebral artery
Pink = middle cerebral artery
Which brain regions are supplied by which pairs of cerebral arteries?
Posterior cerebral artery:
- occipital lobe
- inferior & medial surface of temporal lobe
Anterior cerebral artery:
- corpus callosum
- superior & medial surfaces of frontal & parietal lobes
Middle cerebral artery:
- lateral areas of frontal, temporal and parietal lobes
What is meant by ‘perforating arteries’?
What is an alternative name for them?
Penetrating arterial branches that arise from around the arterial circle and pass into the substance of the brain
Those arising from the MCA are also called striate arteries
What do striate arteries supply?
- Arise from middle and anterior cerebral arteries
- supply deep structures in the cerebrum including basal ganglia and internal capsule
What are the 2 sets of veins that drain blood from the brain?
Superficial and deep veins
What is the passage of superficial veins like?
Where do they drain into?
They run over the surface of the hemispheres
the majority of superficial veins drain into the superior sagittal sinus
What is the passage of the deep veins like?
They converge on the internal cerebral veins
these eventually unite to form the great cerebral vein
Complete the venous drainage of the brain
What are the 3 main types of intracranial haemorrhages?
- Extradural
- Subdural
- Subarachnoid
Rupture of which vessels leads to an extradural, subdural and subarachnoid haemorrhage?
Extradural haemorrhage:
- also known as epidural haematoma
- Usually caused by torn middle meningeal artery
Subdural haemorrhage:
- usually caused by tearing of the bridging veins that cross the subdural space
Subarachnoid haemorrhage:
- usually caused by ruptured berry aneurysm
What is the proper name for a stroke?
Why do they occur?
Cerebrovascular accident
they occur when a blood vessel is occluded and brain tissue becomes infarcted
the symptoms depend on which artery has been occluded and which area of the brain has been damaged
