SDL 3 - Brain, Meninges & Blood Supply

Question 1

What is meant by ‘rostral’ and ‘caudal’?

Answer 1

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

Question 2

What is meant by the cephalic flexure?

Answer 2

The axis of the adult brain bends at an angle of 100 degrees between the midbrain and the diencephalon

this is the cephalic flexure

Question 3

What terms are used to describe structures in the brain, relating to the cephalic flexure?

What does this mean?

Answer 3

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

Question 4

Label the aspects of the forebrain and spinal cord

Answer 4

Question 5

Label the diagram of the neurone

Answer 5

Question 6

What is the difference between grey matter and white matter?

Answer 6

Grey matter:

• contains neuronal cell bodies
• also contains neuropil, glial cells, synapses and capillaries

White matter:

• contains axons coated in a myelin sheath

Question 7

What is meant by ‘neuropil’?

Answer 7

Dendrites, as well as myelinated and non-myelinated axons

Question 8

What is meant by the cortex?

Answer 8

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

Question 9

What is meant by nucleus?

Answer 9

A nucleus is a cluster of neurones within the CNS

they are located deep within the cerebral hemispheres and the brainstem

Question 10

What is meant by ‘tract’ in neuroanatomy?

Answer 10

A bundle of nerve fibres (axons) connecting nuclei of the CNS

Question 11

What is meant by ganglion?

Answer 11

A group of neurone cell bodies within the PNS

Question 12

Label the ventral view of the brain

Answer 12

Question 13

Label the midsagittal view of the brain

Answer 13

Question 14

Which subdivisions of the brain make up the forebrain (or cerebrum)?

Answer 14

Telencephalon:

• contains cerebral cortex (2 cerebral hemispheres)

Diencephalon:

• contains the thalamus and hypothalamus

Question 15

Which subdivisions of the brain make up the brainstem?

Answer 15

1. Medulla oblongata
2. Pons
3. Midbrain

Question 16

Label the lobes and structures of the brain

Answer 16

Question 17

Are the cerebral lobes functional or descriptive subdivisions?

Answer 17

Functional

the cerebellum has four functionally and spatially defined lobes:

1. Parietal
2. Occipital
3. Temporal
4. Frontal

Question 18

What is the formation of the dura mater like?

What structures does it form periodically?

Answer 18

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

Question 19

What is contained within the dural venous sinuses?

Answer 19

Venous blood flows into them from the brain

Question 20

At two sites of separation of the 2 layers of dura, what is formed?

Answer 20

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

Question 21

What is the name of the dural septum that extends down between the two cerebral hemispheres?

Answer 21

Falx cerebri

Question 22

What is the name of the dural septum that extends between the occipital lobes of the hemispheres and the cerebellum?

Answer 22

Tentorium cerebelli

Question 23

What is the function of the two dural septa?

Answer 23

They restrict rotary displacement of the brain

Question 24

Label the structures indicated on the diagram

Answer 24

Question 25

What occupies space A, and what is its function?

Answer 25

**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

Question 26

What are the arachnoid villi and what is their function?

Answer 26

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

Question 27

Which vessel provides the arterial supply to the dura mater?

Answer 27

**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

Question 28

Which two pairs of blood vessels provide the arterial supply to the brain?

Answer 28

* Vertebral arteries * internal carotid arteries

Question 29

What is the course of the vertebral artery as it ascends to enter the skull?

Answer 29

* 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**

Question 30

What is the course of the internal carotid artery like as it passes into the skull?

Answer 30

* 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**

Question 31

Label the circle of Willis in the brain

Answer 31

Question 32

Which vessels are A and B? Which brain regions are supplied by each pair of arrows?

Answer 32

Question 33

Label the distribution of the anterior, middle and posterior cerebral arteries

Answer 33

Question 34

Label the distributions of the anterior, middle and posterior cerebral arteries

Answer 34

Blue = anterior cerebral artery Orange = posterior cerebral artery Pink = middle cerebral artery

Question 35

Which brain regions are supplied by which pairs of cerebral arteries?

Answer 35

**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

Question 36

What is meant by 'perforating arteries'? What is an alternative name for them?

Answer 36

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**

Question 37

What do striate arteries supply?

Answer 37

* Arise from middle and anterior cerebral arteries * supply deep structures in the cerebrum including basal ganglia and internal capsule

Question 38

What are the 2 sets of veins that drain blood from the brain?

Answer 38

Superficial and deep veins

Question 39

What is the passage of superficial veins like? Where do they drain into?

Answer 39

They run over the surface of the hemispheres the majority of superficial veins drain into the superior sagittal sinus

Question 40

What is the passage of the deep veins like?

Answer 40

They converge on the internal cerebral veins these eventually unite to form the **great cerebral vein**

Question 41

Complete the venous drainage of the brain

Answer 41

Question 42

What are the 3 main types of intracranial haemorrhages?

Answer 42

1. Extradural 2. Subdural 3. Subarachnoid

Question 43

Rupture of which vessels leads to an extradural, subdural and subarachnoid haemorrhage?

Answer 43

**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

Question 44

What is the proper name for a stroke? Why do they occur?

Answer 44

**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