Anatomy Flashcards
Where do most aneurysms occur?
In the arterial circle
What are the two divisions that make up the circulation to the brain?
The anterior circulation and the posterior circulation.
What makes up the posterior circulation to the brain?
The two vertebral arteries that conjoin to form the basilar artery
What makes up the anterior circulation to the brain?
The internal carotid artery
What branches does the Basilar artery give off?
Forms the posterior cerebral artery then the posterior communication artery to join the circle of willis
What branches does the internal carotid give off
The middle cerebral artery is a direct continuation of the internal carotid.
Before the middle cerebral artery an opthalmic artery is given off and an anterior cerebral artery joined to the contralateral anterior cerebral artery by an anterior communicating artery
If the internal carotid artery became blocked what kind of affects would likely be seen?
One-sided blindness (homonymous hemianopsia)
If on dominant side for speech global aphasia would be seen
If on non-dominant side then contralateral hemineglect and motor contralateral hemiparesis or hemiplegia
If the Posterior circulation was affected what kind of syndromes would be seen? give examples
Brainstem syndromes:
Lateral medullary syndrome/medial medullary syndrome
What is alternating hemiplegia?
Seen in brainstem syndromes, when the cranial nerve on the ipsilateral side is affected and the motor long tract on the contralateral side is affected.
What are the two pathways of the spinothalamic tract?
The Direct and Indirect pathways
What fibres are involved in the direct and indirect pathways of the spinothalamic tract what are the characteristics of these fibres?
Direct: A δ fibres: Fast
Indirect: C-Fibres: Slow
Where in the grey matter of the spinal cord does the first neurone of both pathways of the spinothalamic tract synpase?
The Dorso-lateral fasciculus
What is the difference in the indirect pathway of the spinothalamic tract once it leaves the dorso-lateral fasciculus in the grey matter of the spinal cord?
The indirect pathway ascends ipsilaterally to synapse in the reticular formation, which is involved in arousal. It then synapses in the thalamus. It is a 4 neurone system
The direct pathway synapses in the VPL of the thalamus and then on to the primary sensory cortex. It is a 3 neurone system.
What is the paracentral lobule?
An area of the brain that includes both the Primary sensory cortex and the primary motor cortex.
What are the two areas of the pre-frontal cortex and their different roles?
DLPFC (Dorsal Lateral Pre-Frontal Cortex) Involved mainly in planning
VMPFC (Ventral Medial Pre-Frontal Cortex) Involved mainly in personality
The Association motor cortex is made up of what two areas? What are their individual roles?
Premotor Cortex and The supplementary motor area
The premotor cortex is involved in processing motor function involving visual cues
The supplementary motor area is involved in planning activity (e.g. the order of movements)
Briefly how is the sympathetic supply to the head achieved (from the hypothalamus to the sympathetic chain?)
The hypothalamus sends fibres down the DLF (dorsal lateral fasciculus)
To the Reticular formation in the brainstem
This travels down the reticulospinal tract to nuclei in the grey matter of the spinal cord
These then send fibres that ascend the sympathetic chain all the way to the superior cervical ganglion
From the superior cervical ganglion how do sympathetic fibres reach the head?
They leave the superior cervical ganglion and wrap themselves around the internal carotid artery and travel up through the carotid canal and then onto areas in the head
What is an example of a structure supplied by sympathetics in the head?
Dilator pupillae muscles
What are the two layers of the dura in the head?
The endosteal layer
The meningeal layer
What is inside the subarachnoid space in the head?
Cerebral arteries
cerebral Veins
CSF
What are the subarachnoid, subdural and extradural spaces located inbetween? which is the only non-potential space?
Extradural - inbetween skull and dura (potential)
Subdural - inbetween Meningeal layer of dura and the Arachnoid layer (potential)
Subarachnoid - between the arachnoid and the pia (non-potential - actually exists at all times)
Where are the venous sinuses located?
Across both the endosteal and meningeal layers of the dura
Which space is the middle meningeal artery located in?
The extra-dural space
Which space in the middle cerebral artery located in?
Subarachnoid space
Who usually gets subdural haemorrhages?
Very young/Very old
Which types of meningeal haemorrhage is arterial and which venous?
Extradural - arterial
Subdural - venous (bridging veins)
Subarachnoid (normally causes stroke - arterial normally)
What are the roles of the thalamus?
Sensory roles (not olfactory):
Modulation
Integration
Relay of info
Gateway/gatekeeper (can change what is being put through)
Three main divisions of the thalamus?
Where are the main clinically important nuclei?
Anterior
Lateral
Medial
Lateral
What divisions of the lateral part of the thalamus?
Going anterior to posterior:
VA: Ventral anterior nucleus VL: Ventral Lateral nucleus VPL: Ventral posterior lateral nucleus VPM: Ventral Posterior Medial nucleus LGN: lateral geniculate nucleus
Roles of the LGN?
Integration of optic functions
The VPL and VPM both are involved in receiving sensory input, from where?
VPL - Body
VPM - Head
What are the three cerebellar peduncles (name them)?
Superior, middle and inferior.
Three main functions of the cerebellum?
Equilibrium - stability and balance
Position of muscles/tone, joint position (proprioception)
Co-ordination
Clinical problems associated with cerebellar dysfunction? (don’t need to get all)
Loss of co-ordination Loss of ability to alternate between movements Intention tremor Ataxic gait Falls Hypotonia Slurred/expolsive speech Nystagmus
What are the muscles involved in the buccal phase of swallowing (bolus compression)? what are they innervated by?
Intrinsic tongue muscles (XII)
Ant. belly of digastric (V)
Tensor veli palatini (V)
Levator veli palatini (X)
Muscles which elevate the larynx (Pharyngeal phase of swallowing) and their innervations?
Stylohyoid (VII)
Mylohyoid (VII)
Posterior belly of digastric (VII)
Stylopharyngeus (X)
geniohyoid (C1)
What nerves control peristalis and the gag reflex?
Afferent: IX
Efferent: X
What nerve specifically innervates the cough reflex?
Internal laryngeal branch of Vagus
General functions of the basal ganglia?
Facilitate voluntary muscle movement
Suppress unwanted movement
control/adjust tone
Regulating background patterns of movement
What does the VAN of the thalamus do?
Submits movement information
What do the indirect and direct pathway for movement of the basal ganglia normally do? in parkinsons what happens?
Normally:
Direct facilitates efficient and targeted movement
Indirect cuases superfluous behaviour
Normally direct is facilitated and indirect is inhibited (with dopamine)
In parkinsons the direct becomes inhibited = less targeted movement
indirect is less inhibited (encouraged) = more superfluous behaviour
What nerve precisely innervates the omohyoid, sternohyoid and sternothyroid muscles?
Ansa Cervicalis
What is the innervation to the Ansa Cervicalis
C1, 2 and 3
What spinal root supplies geniohyoid thyrohyoid muscles?
C1
Name the 6 main sinuses
Superior saggital
Inferior saggital
Right/left transverse sinus
Straight sinus
Cavernous sinus
What are emissary veins?
Veins that pass through cranial openings and connect venous sinuses and extracranial veins
What are the main layers of the eyeball, what do they contain?
An outer fibrous coat: Tough sclera, the cornea (continuous with the conjunctiva)
A middle vascular coat: choroid, Ciliary body, Iris, Pupil
An inner coat: retina
Where does the cavernous sinus drain?
The transverse sinus
If the ciliary body contracts, what is the effect on the lens?
The suspensory ligaments relax and so the lens becomes more convex
Two chambers of the anterior segment of the eye?
Anterior - between cornea and iris
Posterior - between the iris and lens
Where do the muscles of the eye originate?
The common tendinous ring
What is the function of vallat, filliform and fungiform papillae?
Filliform - increase friction between food and tongue
Fungiform - taste buds
Vallate - also taste buds in the sulcus terminalis
What is the arterial supply to the thyroid?
The Superior thyroid artery which branches off the external carotid
The inferior thyroid artery which branches off the thyrocervical trunk
What is the venous supply to the thyroid?
The superior and middle thyroid veins drain to the internal jugular
The inferior descends in front of the trachea and joins the brachiocephalic vein
What is the name of the space between the arterial wall and the pia mater?
perivascular space
Where is the uncus?
The most medial part of the parahippocampal gyrus on the inferior part of the temporal lobe
2 parts of the brain that may become herniated with a SOL in one cerebral hemisphere?
uncus, cerebellar tonsil
How does interstitial fluid and AB get drained from the brain?
Along the blood vessel basement membrane in blood vessel walls
Atrophy of what area of the brain is normally seen in Huntington disease?
The basal ganglia
What is used in the treatment of Alzheimer’s disease?
AchEI - Donepezil
