Introduction to the Human Brain

Question 1

What are the parts of the CNS?

Answer 1

Cerebrum
Consists of two parts:
Outer brain (telencephalon)/Cerebral hemisphere
Inner brain (diencephalon)
Brainstem (Midbrain, pons, medulla oblongata)
Cerebellum
Spinal cord

Question 2

What is the most visible external feature of the human brain?

Answer 2

the cerebrum

Question 3

What separates the cerebral hemispheres ?

Answer 3

Separated by longitudinal fissure

Question 4

What features are present on the surface of the cerebral hemispheres ?

Answer 4

Surface is marked by elevated ridges (gyri) and grooves (sulci

Question 5

What is the role of the sulci and gyri? What type of matter do they contain?

Answer 5

Surface of cerebral hemispheres (i.e cerebral cortex) are heavily folded to increase surface area

Grey matter (cerebral cortex)
Nerve cell bodies
* Note also find collections of grey matter deep within cerebrum

White matter
- Nerve axons

Question 6

What sulci divide the cerebral hemispheres into lobes ?

Answer 6

Specific sulci are used to divide the cerebral hemispheres into lobes (central sulcus; lateral sulcus, parieto-occipital sulcus)

Question 7

What are the 4 lobes of the cerebral hemispheres?

Answer 7

Frontal
Parietal
Occipital
Temporal

Question 8

What is the role of the precentral gyrus?

Answer 8

motor cortex

Question 9

What is the role of the postcentral gyrus?

Answer 9

somatosensory cortex

Question 10

What is the role of the thalamus?

Answer 10

important relay station between brainstem, spinal cord, and the cerebral cortex

Question 11

What is the role of the hypothalamus?

Answer 11

controls the autonomic nervous system (ANS)

Question 12

What makes up the diencephalon?

Answer 12

thalamus and hypothalamus

Question 13

What is the Prosencephalon?

Answer 13

Forebrain
Ai, Telencephalon = Cerebral Hemispheres
Aii, Diencephalon= Diencephalon (ie, Thalamus & Hypothalamus)

Question 14

What is the Mesencephalon?

Answer 14

Midbrain

Mesencephalon= Midbrain

Question 15

What is the Rhombencephalon?

Answer 15

Hindbrain
Ci, Metencephalon= Pons & Cerebellum
Cii, Myelencephalon=Medulla oblongata

Question 16

What happens to the central canal in development?

Answer 16

Ventricles – expanded cavities within the brain
Connecting channels – link ventricles
Vestigial – central canal of spinal cord

Question 17

What is a stroke?

Answer 17

Common neurological deficit of vascular origin

1 in 100 of over 65s

Question 18

How much O2 does the brain use?

Answer 18

20% 02 consumption

Question 19

What are the two layers of dura? What do the allow for?

Answer 19

Outer periosteal layer of dura
Inner meningeal layer of dura

Two layers of dura allow for dural infoldings
Located within the dural infoldings are various venous (dural) sinuses

Question 20

What are the three dural infoldings?

Answer 20

Falx cerebri: between cerebral hemispheres
Tentorium cerebelli: between occipital lobes and cerebellum
Falx cerebelli: between cerebellar hemispheres

Question 21

What is the Dura matter?

Answer 21

Tough, fibrous membrane
Ensheathes brain like loose fitting bag
Two layers: periosteal and meningeal. These are tightly fused together except at dural venous sinuses and various infoldings (reflections).
Two large reflections of dura extend into the cranial cavity between the cerebral hemispheres – falx cerebri, and between the cerebrum and cerebellum – tentorium cerebelli

Question 22

What is the Arachnoid matter?

Answer 22

Soft translucent membrane
Also surrounds the brain
Space between arachnoid and dura = subdural space (very thin)

Question 23

What is the Pia matter?

Answer 23

Microscopically thin, delicate membrane

Tightly adhered to the surface of the brain, following all cavities

Question 24

What are venous (dural) sinuses?

Answer 24

Located within the dural infoldings are various venous (dural) sinuses.

Dural sinuses receive venous blood from the brain and drain into internal jugular veins (IJV)

Question 25

Is the Epidural space real or potential in the brain and SC?

Answer 25

Cranial: potential Spinal: real

Question 26

Is the Subdural space real or potential in the brain and SC?

Answer 26

Cranial: potential Spinal: potential

Question 27

Is the Subarachnoid space real or potential in the brain and SC?

Answer 27

Cranial: real Spinal: real

Question 28

What is a Epidural haemorrhage?

Answer 28

Torn meningeal a

Question 29

What is a Subdural haemorrhage?

Answer 29

Torn bridging veins

Question 30

What is a Subarachnoid haemorrhage?

Answer 30

Torn cerebral a’s

Question 31

What are the Vertebral arteries?

Answer 31

Branch of subclavian arteries Ascend in the neck through transverse foramen of the cervical vertebrae Enter skull via foramen magnum Vertebral arteries fuse at base of brainstem to form basilar artery

Question 32

What are the Internal carotid arteries?

Answer 32

Branch of common carotid arteries | Enter skull via carotid canals

Question 33

What 2 pairs of arteries supply the brain?

Answer 33

Internal carotid arteries | Vertebral arteries

Question 34

What Is the circle of Willis?

Answer 34

Interconnects the internal carotid and vertebral – basilar system Surrounds optic chiasm and hypothalamus Ensures compensation of decreased blood flow if one vessel Constituents: anterior, middle, posterior cerebral a’s. anterior & posterior communicating a’s. internal carotid a’s and the basilar a.

Question 35

What is a Berry Aneurysm?

Answer 35

Abnormal dilations around the circle of Willis or at at the points of arterial branching within the brain ~ 10% of vascular strokes are caused by rupture of a berry aneurysm

Question 36

What does the anterior cerebral artery supply?

Answer 36

Superior and medial areas of frontal and parietal lobes | Corpus callosum

Question 37

What does the middle cerebral artery supply?

Answer 37

Lateral areas of frontal, temporal and parietal lobes

Question 38

What does the posterior cerebral artery supply?

Answer 38

Occipital lobe | Inferior and medial surface of temporal lobe

Question 39

What are Striate arteries? What do they supply?

Answer 39

Deep or Perforating Arteries •Some of these are called Striate arteries (delicate) •Supply structures inside hemisphere oDeep nuclei oDeep grey matter oInternal capsule (major fibre bundle to and from cerebral cortex) oSupply Includes major descending motor pathway

Question 40

What are watershed areas?

Answer 40

Regions that receive blood supply from distal areas of adjacent cerebral arteries Susceptible to ischemia (Watershed stroke)