Introduction to the Human Brain Flashcards
What are the parts of the CNS?
Cerebrum
Consists of two parts:
Outer brain (telencephalon)/Cerebral hemisphere
Inner brain (diencephalon)
Brainstem (Midbrain, pons, medulla oblongata)
Cerebellum
Spinal cord
What is the most visible external feature of the human brain?
the cerebrum
What separates the cerebral hemispheres ?
Separated by longitudinal fissure
What features are present on the surface of the cerebral hemispheres ?
Surface is marked by elevated ridges (gyri) and grooves (sulci
What is the role of the sulci and gyri? What type of matter do they contain?
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
What sulci divide the cerebral hemispheres into lobes ?
Specific sulci are used to divide the cerebral hemispheres into lobes (central sulcus; lateral sulcus, parieto-occipital sulcus)
What are the 4 lobes of the cerebral hemispheres?
Frontal
Parietal
Occipital
Temporal
What is the role of the precentral gyrus?
motor cortex
What is the role of the postcentral gyrus?
somatosensory cortex
What is the role of the thalamus?
important relay station between brainstem, spinal cord, and the cerebral cortex
What is the role of the hypothalamus?
controls the autonomic nervous system (ANS)
What makes up the diencephalon?
thalamus and hypothalamus
What is the Prosencephalon?
Forebrain
Ai, Telencephalon = Cerebral Hemispheres
Aii, Diencephalon= Diencephalon (ie, Thalamus & Hypothalamus)
What is the Mesencephalon?
Midbrain
Mesencephalon= Midbrain
What is the Rhombencephalon?
Hindbrain
Ci, Metencephalon= Pons & Cerebellum
Cii, Myelencephalon=Medulla oblongata
What happens to the central canal in development?
Ventricles – expanded cavities within the brain
Connecting channels – link ventricles
Vestigial – central canal of spinal cord
What is a stroke?
Common neurological deficit of vascular origin
1 in 100 of over 65s
How much O2 does the brain use?
20% 02 consumption
What are the two layers of dura? What do the allow for?
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
What are the three dural infoldings?
Falx cerebri: between cerebral hemispheres
Tentorium cerebelli: between occipital lobes and cerebellum
Falx cerebelli: between cerebellar hemispheres
What is the Dura matter?
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
What is the Arachnoid matter?
Soft translucent membrane
Also surrounds the brain
Space between arachnoid and dura = subdural space (very thin)
What is the Pia matter?
Microscopically thin, delicate membrane
Tightly adhered to the surface of the brain, following all cavities
What are venous (dural) sinuses?
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)
Is the Epidural space real or potential in the brain and SC?
Cranial: potential
Spinal: real
Is the Subdural space real or potential in the brain and SC?
Cranial: potential
Spinal: potential
Is the Subarachnoid space real or potential in the brain and SC?
Cranial: real
Spinal: real
What is a Epidural haemorrhage?
Torn meningeal a
What is a Subdural haemorrhage?
Torn bridging veins
What is a Subarachnoid haemorrhage?
Torn cerebral a’s
What are the Vertebral arteries?
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
What are the Internal carotid arteries?
Branch of common carotid arteries
Enter skull via carotid canals
What 2 pairs of arteries supply the brain?
Internal carotid arteries
Vertebral arteries
What Is the circle of Willis?
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.
What is a Berry Aneurysm?
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
What does the anterior cerebral artery supply?
Superior and medial areas of frontal and parietal lobes
Corpus callosum
What does the middle cerebral artery supply?
Lateral areas of frontal, temporal and parietal lobes
What does the posterior cerebral artery supply?
Occipital lobe
Inferior and medial surface of temporal lobe
What are Striate arteries? What do they supply?
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
What are watershed areas?
Regions that receive blood supply from distal areas of adjacent cerebral arteries
Susceptible to ischemia (Watershed stroke)
