ANATOMICAL PLANES Flashcards
1
Q
What is an anatomical plane?
A
An anatomical plane is a hypothetical plane used to transect the human body.
2
Q
What are the 3 basic planes used for the central nervous system (CNS)
A
one horizontal (transversal=axial), perpendicular to the neuraxis
two vertical, the coronal = frontal plane and the sagittal = lateral plane (in the midline)
3
Q
What are the directions of the nervous system called?
A
- Medial = towards the midline of the body
- Lateral = away from the midline of the body
- Proximal = nearer to a point of reference
- Distal = away from a point of reference
- Inferior = lower or below
- Superior = upper or above
- Anterior = towards the front
- Posterior = towards the back
- Ventral = towards the abdomen
- Dorsal = towards the back
- Rostral = towards the front
- Caudal = towards the thail
4
Q
Medial
A
towards the midline of the body
5
Q
Lateral
A
away from the midline of the body
6
Q
Proximal
A
nearer the point of reference
7
Q
Distal
A
away from a point of reference
8
Q
Inferior
A
lower or below
9
Q
Superior
A
upper or above
10
Q
Anterior
A
towards the front
11
Q
Posterior
A
towards the back
12
Q
Ventral
A
towards the abdomen
13
Q
Dorsal
A
towards the back
14
Q
Caudal
A
towards the tail
15
Q
Rostral
A
towards the front
16
Q
What are the meninges
A
four membranes surrounding the spinal cord and the brain
17
Q
what are the names of the 3 4 meninges from outer membrane to inner membrane?
A
- The dura mater
- The arachnoid mater
- The pia mater
- The subarachnoid
lymphatic-like membrane (SLYM)
18
Q
What is the dura mater?
A
Tough and fibrous membrane, attached to the bones and
together forming the cranial cavity
19
Q
What is the arachnoid mater?
A
It is a thin spider web-like membrane. The thin arachnoid fills
the space between the dura mater and the pia mater
20
Q
What is the pia mater?
A
It lies directly on the surface of the brain, closely following the outer
structure of the folded pattern of sulci and gyri
21
Q
What is the subarachnoid lymphatic-like membrane (SLYM)
A
Fourth meningeal layer, recently described
22
Q
Epidural space
A
The (potential) space between the bone and the dura
23
Q
Subdural space
A
The (potential) space between the dura and the arachnoid
24
Q
(sub) arachnoidal space
A
The space between the arachnoid and pia mater
25
What are the functions of the meninges?
The meninges have important protective and supportive functions, they play a role in the
circulation and absorption of the cerebral spinal fluid (CSF or liquor), and convey venous
blood to the internal jugular veins.
26
Are/How are meninges relevant to clinical conditions?
The meninges and the CSF system are of great relevance in a number of clinical conditions
including head injuries, intracranial hemorrhages, infections and hydrocephalus.
27
What is the very own arterial system of the meninges called?
meningeal arteries
28
Where are the branches of the middle meningeal arteries running?
They are running
between the inner and outer layers of the dura, providing
the arterial vascularization of the dura. Their distribution
pattern with anterior and posterior branches is visible in the
dura and as impressions on the inner surface of the skull.
29
What happens if there is damage to the middle meningeal arteries?
Damage to these arteries may lead to epi- or extradural
bleeding.
30
What are the two layers of the dura mater?
outer layer = periosteal layer, which is attached to the scull
inner layer = meningeal layer, which follows the two large fissures of the brain ( the longitudinal fissure and the transverse cerebral fissure )
31
What are the two folds formed by the dura?
- the falx cerebri, between left and right hemisphere, at the midline of the brain
- the tentorium cerebelli, between cerebrum and cerebellum
32
what is there at the junction of the outer layer and the folds of the inner layer of the dura? what does this space contain?
At the junction of the outer layer and the folds of the inner layer of the dura, spaces occur, called sinuses. These sinuses contain venous blood.
33
What are the different sinuses called?
- superior sagittal sinus
- inferior sagittal sinus
- transverse and sigmoid sinuses
From the union of these sinuses, the
transverse and sigmoid sinuses
carry the venous blood
to the internal jugular vein, via thejugular foramen and then further to the heart.
34
Epidural hematoma
bleeding from the meningeal artery: between the bone and the outer layer of the dura.
35
Subdural hematoma
occurs when (anchor) veins are sheared during acceleration-deceleration of the head. Mostly commonly at the dorsal part of the brain
36
Subarachnoidal hematoma
bleeding between the inner layer of the dura and the pia, from one of the cerebral arteries. Mostly commonly at the ventral part of the brain
37
What are the cavities known for, where the subarachnoid space widens to form cavities and what are the most important ones?
subarachnoid cisterns
Most important are the:
- cerebello-medullary cistern (cisterna magna)
- the lumbar cistern which is occupied by the nerve roots of the caudal medulla, the cauda equine (horse tail)
37
Hydrocephalus
increased pressure due to an increased volume of CSF (due to e.g. a lack of absorption or due to a blockage of the ventricular system)
38
Meningitis
a viral or a bacterial infection of pia-arachnoid
39
Lumbar puncture
procedure in which a needle is inserted into the spinal canal, between vertebrae L3 – L5. From this cisterna, CSF can be collected for analysis
(cisterna- or lumbar puncture). The lumbar cistern can also be used to administer a spinal anesthetic
40
What are the two artery systems through which extensive blood supply reaches the brain?
Through the internal arteries - internal carotid system (70%), which enter through carotid canal
Through the vertebral arteries - basilar system (30%), which enter the skull through the foramen magnum
41
Caudal to the optic chiasm, when entering the skull through the carotid canal, each internal carotid artery reaches the subarachnoidal space. Which small branches does it give off here? and which two terminal branches does it eventually divide itself to?
- the anterior choroidal arteries, running in a caudolateral direction to supply part of the choroid plexus in the inferior horn of the lateral ventricle
- the posterior communicating arteries, running in a caudal direction to join the posterior cerebral artery.
Next, the internal carotid artery divides into its two main terminal branches:
- the anterior cerebral arteries (ACA)
- the middle cerebral arteries (MCA)
42
The Anterior Cerebral Artery (ACA): how do they branch off and what do they supply?
- The Anterior Cerebral Arteries pass the optic chiasm and branch off:
- Its main branches, the frontal and pericallosal branches, run first rostrally, then caudally above the corpus callosum, towards the parieto-occipital sulcus. These branches supply the medial surfaces of the hemispheres.
- The left and right Anterior Cerebral Arteries are interconnected via the short anterior communicating artery.
- The ACA also supplies the rostral part of the internal capsule.
- The ACA convey blood to the perforating arteries, that supply the hypothalamus and the rostral and basal forebrain.
43
The Middle Cerebral Artery (MCA): how do they branch off and what do they supply?
The Middle Cerebral Artery is the largest branch of the internal carotid artery (conveying
60% to 80% of the carotid blood supply).
The MCA braches off into many perforating arteries: e.g.
- the lateral striate arteries, that run to the thalamus, basal ganglia, and internal capsule.
- the lateral branches, that pass along the depth of the lateral fissure to serve the insula and that continue laterally to emerge on the lateral surface of the hemispheres.
- Branches of the MCA (frontal-, central-, parietal-, temporal- and temporo-occipital
branches) supply at least two-thirds of the lateral surface of the brain.
44
The Basilar system: how do they branch off and what do they supply?
The brainstem and cerebellum receive their blood supply from two vertebral arteries. The
two vertebral arteries enter the skull via the foramen magnum. They unite at the lower
border of the pons to form the basilar artery.
The basilar artery ends when it divides into two branches, the posterior cerebral arteries
(PCAs). These PCAs curve around the lateral aspect of the midbrain to reach the medial and
inferior surfaces of the temporal and occipital lobes.
45
Vertebral arteries: how do they branch off and what do they supply?
The vertebral arteries branch into:
- the (paired) posterior inferior cerebellar arteries (PICAs), serving the dorsolateral
medulla oblongata and the posterior/inferior parts of cerebellum;
- the (unpaired) anterior spinal artery, serving the (para)median parts of the medulla
oblongata, before descending into the vertebral canal.
46
Basilar artery: how does it branch off and what do they supply?
The basilar artery branches into:
- the anterior inferior cerebellar artery (AICA),
supplying the upper medulla and inferior surface of cerebellum
- the pontine and internal auditory (labyrinthine) arteries, supplying the pons and
labyrinth of inner ear
- the superior cerebellar artery (SCA), along the upper border of the pons to superior
surface of cerebellum
47
The Posterior Cerebral Artery (PCA): how does it branch off and what do they supply?
The PCA is connected to the internal carotid
artery through the posterior communicating
artery. It gives off proximal branches to:
- the thalamus and hypothalamus
- the posterior part of the cortex:
lateral (temporal) and medial (occipital,
calcarine and callosal) branches.
48
What is the circle of Willis?
The anterior and posterior communicating arteries connect the carotid arteries and the
basilar system and form a complete arterial circle at the base of the brain: the circulus
arteriosus cerebri or circle of Willis.
49
What is the clinical importance of the circle of Willis?
This circle is of great clinical importance, providing collateral circulation (anastomosis). Thus,
in the event of an occlusion (thrombosis) in one of the contributing arteries, the
consequences are relatively minimal. However, this circular arterial configuration has a high
inter-individual variability and an effective collateral circulation is not possible in all
individuals.
Numerous short perforating branches from the circle of Willis supply the mesencephalon and
hypothalamus.
50
How does the venous drainage of the brain work?
The superficial cerebral veins also lie in the
subarachnoid space and drain into the
intracranial venous sinuses.
A deep cerebral vein curves underneath the
caudal corpus callosum: the great cerebral
vein or vena magna cerebri, draining the
internal cerebral veins into the straight sinus
or sinus rectus. As mentioned before, venous blood flows from the sinuses to the jugular veins and
from there to the heart.
51
What are the four categories of Intracranial hemorrhages (ICH)?
- Epidural hematoma
- Subdural hematoma
- Subarachnoid hemorrhage
- Intracerebral hemorrhage
52
What are CVAs?
Cerebrovascular accidents (CVAs) often occur with involvement of the arteries supplying the
internal capsule, with serious consequences.
In general: symptoms and effects depend on the size and location of the occlusion.
53
List the CVAs mentioned in the book
- Stroke or ischemia
- Hemorrhage or a bleeding
- Transient Ischemic Attack (TIA)
- Angiography.
- Aneurysms
54
What is a Stroke or ischemia caused by?
Stroke or ischemia is caused by an occlusion due to e.g. atherosclerosis, or an embolism.
55
What is hemorhage or bleeding caused by?
Hemorrhage or a bleeding is caused by e.g. a rupture of a blood vessel or traumatic brain
injury.
56
What is a Transient Ischemic Attack?
Transient Ischemic Attack (TIA): temporary local interruption of cerebral blood flow,
often foreboding a major stroke;
57
What is an Angiography?
Angiography: imaging of the vascularization of e.g. the brain by injecting a contrast
medium via a catheter into a vertebral or carotid artery.
58
What is an aneurysm?
Aneurysms in e.g. the circle of Willis may lead to sudden and extensive subarachnoid
hemorrhage.
59
How does the brain develop and what are the structures called that are present in an early brain's development phase?
Initially, the neural tube expands into three brain vescicles:
1. Prosencephalon (forebrain)
2. Mesencephalon (midbrain)
3. Rombencephalon (hindbrain)
The prosencephalon expands
on each side to form the
telencephalon (cerebral
hemispheres) and below to form
the diencephalon.
the rombencephalon is further distinguished into metencephalon and myelencephalon
60
Orbital gyrus
Lateral to gyrus rectus on each frontal lobe
61
Check 4.2
Look at 4.2
62
List the cranial nerves 1- 12
1. Olfactory - Smell
2. Optic - Vision
3. Oculomotor - eye movement and upper eyelid control
4. Trochlear - es the superior oblique, turns the eye downward and laterally
5. Trigeminal - chewing, face and mouth, touch and pain
6. Abducens - turns eye laterally
7. facial - controls most facial expressions, secretion of tears and saliva, taste
8. vestibucochlear - hearing, sense of equilibrium
9. Glossopharyngeal - monitors carotid blood pressure, taste
10. Vagus - monitors aortic blood pressure, decreases heart rate, stimulates digestive organs, taste
11. Accessory - rapezius and sternocleidomastoid muscles
12. Hypoglossal - controls tongue movement
63
Head injuries (cranial nerves)
Head injuries can result in fractures of the base of the skull that can damage several cranial nerves
64
Pituitary adenomas
rising from the adenohypophysis in the sella turcica, may compress the optic chiasm and basal hypothalamus
65
Cerebello-pontine angle tumors – or schwannoma’s
vestibulocochlear
nerve in the internal auditory canal. These tumors may grow into the space between
the lateral side of the pons, the cerebellum, and the posterior surface of the petrous
bone. The expanding tumor may influence the Vth, VIIth, VIIIth, IXth and Xth cranial
nerves as well as cerebellar functions
66
What are the 3 major sulci?
1) the lateral sulcus, or Sylvian fissure, 2) the central sulcus, or Rolandic fissure, and 3) the parieto-occipital sulcus, the lateral hemisphere
67
What are the risk factors for alzheimer's?
- age
- midlife hypertension
- cerebral small vessel disease
- atherosclerosis
- stroke
- atrial fibrillation
- diabetes type II
- hypercholesterolemia
- APOE4 allel
- midlife obesity
- low education
Lifestyle
68
What is hypertension/atherosclerosis
Abnormally elevated arterial blood pressure
69
