headaches and anatomy of the head/meninges (A18) Flashcards
1
Q
relationship between frontalis/occipitalis muscles and headaches
A
- these muscles are leading causes of headaches
- usually tension headaches are caused when these muscles are tight and contracting causing a lot of pressure on the bones and nerves
2
Q
muscles involved in tension headaches
A
- frontalis and occipitalis (joined by the epicranial aponeurosis)
- > -usually tension headaches are caused when these muscles are tight and contracting causing a lot of pressure on the bones and nerves
- temporalis and masseter muscles can also be involved in tension headaches (the temporalis attaches onto side of skull, at inferior temporal line, and the coronoid process of the mandible, if contracted they pull on the temporal bones and put pressure on bones and nerves)
3
Q
temporalis muscle
A
- jaw closing muscle
- attaches to inferior temporal line and coronoid process of mandible (coronoid process is the inferior attachment of the temporalis muscle tendon)
4
Q
thinnest part of the skull
A
‘H’ shaped pterion
5
Q
danger of fractures pterion
A
- anterior branches of the middle meningeal artery lie directly beneath
- fracture can cause damage to this artery causing bleeding in cranial cavity (if this happens, the extra blood accumulating increases the pressure which pushes on the brain causing issues)
- > this is a space occupying lesion (SOL) = anything that takes up space in cranial cavity that shouldn’t be there - eg. blood, csf
6
Q
SOL
A
-space occupying lesion
= anything that takes up space in cranial cavity that shouldn’t be there - eg. blood, csf
7
Q
important features of the brain
A
- control center of the nervous system (somatic nervous system, autonomic nervous system, endocrine function - the pituitary gland/the ‘master’ gland)
- somehow makes ‘us’ the individuals that we are
- connects with spinal cord inferiorly
- has anatomical and functional subdivisions
8
Q
central nervous system
A
made up of:
- brain
- spinal cord
9
Q
name of 2 divisions of the brain (when halved down sagittal plane)
A
cerebral (brain) hemispheres (half circle)
10
Q
anatomical features of brain structure that give it the bumpy appearance
A
- gyrus (gyri = part that sticks out)
- sulcus = dip in brain
11
Q
anatomical subdivisions of brain (naming of lobes)
A
- name lobes according to bones that they are lying against:
- frontal lobe
- temporal lobe
- parietal lobe
- occipital lobe
12
Q
visual cortex
A
- located at posterior of occipital lobe
- the part of the cerebral cortex that receives and processes sensory nerve impulses from the eyes
- controls vision
- damage to visual cortex can cause visual impairment
13
Q
cerebellum
A
- posterior and inferior aspect of brain
- ‘little brain’
- contains a lot of fine motor fibers
- controls precise motor activity
- medial aspect looks like a tree
14
Q
brain stem
A
-leads between/joins cerebral hemispheres at the front of the cerebellum
15
Q
divisions of the brainstem
A
- > important divisions with regards to connections with cranial nerves (different cranial nerves attach at different areas)
- > from superior to inferior:
- midbrain
- pons
- medulla oblongata
16
Q
connections/attachments/associations of cranial nerves to divisions of brainstem
A
- CN3 (oculomotor nerve) and CN 4 (trochlear nerve) both associated with midbrain
- CN V (trigeminal nerve) associated with pons
- CN VI (abducens nerve), CN VII (facial nerve) and CN VIII (vestibulocochlear nerve) associated with junction between pons and medulla
- CN IX (glossopharyngeal nerve), CN X (vagus nerve) and CN XII (hypoglossal nerve) associated with medulla oblongata
- CN XI (spinal accessory nerve) comes from spinal cord
17
Q
CN XI
A
- spinal accessory nerve
- supplied SCM and trapezius muscle
18
Q
cranial nerves
A
- 12 pairs
- exit inferior aspect of brain
- CN I = olfactory
- CN II = optic
- CN III = oculomotor
- CN IV = trochlear
- CN V = trigeminal
- CN VI = abducens
- CN VII = facial
- CN VIII = vestibulocochlear
- CN IX = glossopharyngeal
- CN X = vagus
- CN XI = spinal accessory
- CN XII = hypoglossal
19
Q
intra-cranial cause of headache
A
- brain and cranial nerve tumours:
- tumours can cause ‘headache’ pain due to increased pressure within the ‘closed box’ of the skull
20
Q
brain tumours
A
- can affect any part of the brain (even pituitary gland tumours- near midbrain)
- tumours are an example of a ‘space occupying lesion’ which increase intra-cranial pressure
21
Q
acoustic neuroma
A
- associated with CNVIII/ vestibulocochlear nerve is effected
- affects hearing and balance
22
Q
causes of headache due to increased pressure within the skull (intracranial causes of headache)
A
- brain and cranial nerve tumours
- inflammation (creates more extracellular fluid) eg. meningitis
- bleeding inside the skull eg. tear in middle meningeal artery due to fracture of pterion
- hydrocephalus (increase CSF pressure)
23
Q
meningitis
A
- ‘itis’ =inflammation (learn more about it in semester 2)
- meningitis is usually caused by a bacterial or viral infection of the meninges
24
Q
meninges
A
- protective covering of the brain and spinal cord
- ‘meninx’ = membrane
- brain and spinal cord are surrounded in 3 layers of membrane, from superficial to deep they are
- > dura mater
- > arachnoid mater
- > subarachnoid space
- > pia mater
25
Q
dura mater
A
- durable, tough, thick, fibrous layer (latin translation = ‘hard mother’ ie. protective)
- only layer that has innervation (pain) and vascular
- separated into 2 layers (periosteal and meningeal)
26
Q
arachnoid mater
A
- latin translation = ‘spidery mother’ (like cobwebs/loose CT)
- arachnoid granulations (reabsorb CSF)
27
Q
arachnoid granulations
A
reabsorb CSF from subarachnoid space into superior sagittal suture
28
Q
subarachnoid space
A
- space under arachnoid mater
- contains CSF
- ends at the level of S2 vertebra
29
Q
pia mater
A
- latin translation = ‘faithful mother’/pias person is very faithful
- last layer of meninges
- coats brain and the blood vessels/nerves entering/leaving the brain
- only layer that completely covers brain and spinal cord, goes to every sulcus in the brain
- in cerebral sulcus and covering gyrus
30
Q
layers of neurocranium from skin - brain
A
- SCALP:
- > skin
- > connective tissue
- > aponeurosis
- > loose connective tissue
- > pericranium
- PARIETAL BONE
- MENINGES:
- > dura mater
- > arachnoid mater
- > subarachnoid space
- > pia mater
- BRAIN
31
Q
2 layers dura mater
A
- outer periosteal layer/periosteum:
- stuck firmly to the inner aspect of the skull bones
- usually very tightly stuck to bones - inner meningeal layer:
- closer to the meninges
- stuck firmly to the outer layer except: when folded on itself 2 form two structure: the falx cerebri and tentorium cerebelli, and when it separates from the periosteal layer to form the dural venous sinuses
32
Q
middle meningeal artery location within meninges
A
between the 2 layers of the dura mater
33
Q
dural venous sinuses
A
- venous ‘channels’ (not technically actual veins)
- drain the blood from the brain
- basically the 2 layers of dura separate forming a hole for venous drainage
- falxi cerebri and tentorium cerebelli connect to venous network
34
Q
falx cerebri
A
- double layer of meningeal layer of dura mater (when it folds back on itself)
- separates 2 cerebral hemispheres
- anterior attachment = crista galli (the triangular midline process of the ethmoid bone extending superiorly from the cribriform plate)
- Its upper margin is convex, and attached to the inner surface of the skull in the middle line, as far back as the internal occipital protuberance; it contains the superior sagittal sinus. Its lower margin is free and concave, and contains the inferior sagittal sinus
35
Q
tentorium cerebelli
A
- double layer of meningeal layer of dura mater (when it folds back on itself)
- found between cerebral hemispheres and cerebellum
36
Q
globe
A
eyeball
37
Q
sensory nerve supply to/innervation of the dura mater
A
- dura mater is the only layer of meninges innervated
- cause of headache
- mostly innervated by trigeminal nerve branches
- CNVa (at superior orbital fissure)
- CNVb (at foramen rotundum)
- CNVc (at foramen ovale) (all synapse at trigeminal sensory ganglion)
- above info in brackets is not essential, main point = dura is highly innervated layer, by the trigeminal nerve branches at the front and by C2, C3 spinal nerve branches at the back
- middle meningeal artery supplies dura and is located between both layers of dura (at foramen spinosum)
- for completion in the posterior cranial fossa- dura recieves a bit of innervation from C2,C3 (cervical spinal nerves)
38
Q
trigeminal ganglion
A
The large, flattened, sensory ganglion of the trigeminal nerve, lying close to the cavernous sinus along the medial part of the middle cranial fossa
39
Q
bleeding inside the skull
A
can be caused due to tear in any of arteries supplying the brain
40
Q
hydrocephalus
A
- increased CSF pressure
- excessive production or inadequate reabsorption of csf leads to hydrocephalus (associated with headache)
41
Q
blood supply to the brain
A
- vertebral artery branches off of subclavian artery to travel up to cranial cavity via the transverse foramina to supply the brain
- the right and left vertebral arteries join at the base of the brain to form the basilar artery
- the common carotid artery splits into internal and external at the level of the hyoid bone
- > internal carotid artery does not branch and goes straight up into the cranial cavity (external carotid artery branches within the neck and over the face)
- the right and left internal carotid arteries supply the brain
- > internal carotid arteries and basilar artery join together to form circle of willis
42
Q
circle of willis
A
- 2 vertebral arteries form 1 basilar artery when on top of pons
- basilar artery has a branch which comes off and loops around posteriorly to posterior aspect (posterior cerebral artery, a branch of this posterior cerebral artery is one which heads forward (posterior communicating artery) which allows the posterior cerebral artery to communicate with the rest of the circle of willis
- internal carotid arteries join circle of willis to form middle cerebral arteries
- another branch of internal carotid heads anteriorly (anterior cerebral arteries) which supply anterior aspect of the brain
- between these two is a (one) tiny anterior communicating artery
43
Q
dural venous sinuses
A
- top of falx cerebri and underneath sagittal suture is superior sagittal sinus
- inferior sagittal sinus is at the inferior edge of the falx cerebri
- the straight sinus runs straight down from end of inferior sagittal sinus towards confluence of sinuses
- confluence of sinuses is where a lot of sinuses meet at the back (inside of occipital protuberance - at the internal occipital protuberance)
- from the confluence of sinuses, there is a right and left transverse sinus which runs transversely out, around and along cranial cavity laterally
- where the sinus makes a shape to get down to jugular foramen = sigmoid sinus
- superior petrosal sinus runs through petrous part of temporal bone
- cavernous sinus (looks like a big cave) is a collection of a lot of tiny dural venous sinuses around pituitary gland (trigeminal nerve and internal carotid artery pass through here to innervate dura)
- cavernous sinus cools the blood in the internal carotid artery before it reaches the brain
- > confluence of sinuses branches into transverse sinus and superior petrosal sinus
- > transverse sinus leads to sigmoid sinus and sigmoid sinus becomes internal jugular vein at the jugular foramen
- > superior petrosal sinus meets with cavernous sinus
44
Q
venous drainage of the brain to dural venous sinuses
A
- through the cerebral veins
- most drain into superior sagittal sinus
45
Q
cerebro-spinal fluid
A
- secreted by specialized cells within the ventricular system of the brain (400-500ml/day)
- circulates around the brain and spinal cord from the 4 ventricles to the subarachnoid space
- reabsorbed into the dural venous sinuses by specialized cells of the arachnoid mater called arachnoid granulations
- csf cushions the brain (like a waterbed) both internally (the ventricles full of csf) and externally (the subarachnoid space full of csf)
- excessive production or inadequate reabsorption leads to hydrocephalus (associated with headache)
46
Q
ventricular system of the brain
A
- filled with cerebrospinal fluid (csf)
- where csf is produced, circulates and reabsorbed
- lateral ventricles (1 and 2) in the middle of cerebral hemispheres = location of csf production
- 3rd ventricle is the space in the midline, passes down channel (cerebral aqueduct = a fluid-filled canal that runs through the midbrain connecting the third and fourth ventricles) to:
- 4th ventricle then circulates around the brain and passes down spinal canal (filled with csf)
- csf is in subarachnoid space
- arachnoid granulations reabsorb csf
47
Q
spinal tap/lumbar puncture
A
- used to sample csf in suspected cases of meningitis (usually caused by a bacterial or viral infection of the meninges)
- the spinal cord ends at the level of the L2 vertebra however the subarachnoid space doesn’t end until the level of the S2 vertebra therefore this is where you sample the csf from so that you don’t damage any nerves/roots
- > same method is used for epidural and spinal anaesthetic
- > (epidural = on or around the dura mater, in particular (of an anesthetic) introduced into the space around the dura mater of the spinal cord, an epidural anesthetic is used especially in childbirth to produce loss of sensation below the waist)
48
Q
3 types of bleeding outside the brain but within the skull (cranial cavity)
A
- extra-dural
- sub-dural
- sub-arachnoid
49
Q
extra-dural bleeding
A
- same as epi-dural
- between the bone and the dura
- due to injury of middle meningeal artery
- as a result of trauma to the pterion
50
Q
sub-dural bleeding
A
- separates the dura from the arachnoid and pushes these layers apart
- due to injury of cerebral veins
- most commonly due to falls in elderly and those with alcohol problems (in elderly brain smaller veins are pulled thinner therefore are more likely to tear)
51
Q
sub-arachnoid bleeding
A
- into the subarachnoid space where the csf is
- due to injury of the circle of willis (circle of willis forms cerebral arteries which supplies the brain) (‘berry’ aneurysm)
- causes congenital aneurysm
- aneurysm= weaking of walls/burst wall of an artery
