WK 6 Spinal Tracks, blood supply to brain Flashcards
What is the internal capsule and where is it found?
An area of white mater where there are fibres running down to the midbrain Found between the lentiform nucleus and the thalamus
What is the ‘regular’ white mater in the brain called?
Corona radiata
What structure connects the two hemispheres of the brain?
The corpus callosum
What is the corticospinal tract?
White mater motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk
The motor neuron fibres in the corticospinal tract cross sides when they reach what?
The motor decussation at the bottom of the medulla
What cranial nerves supply muscles and what muscles are these?
CN III (oculomotor) = extra-ocular muscles CNIV (trochlear) = superior oblique muscle of the eye CN V (trigeminal) = muscles of mastication + others CN VI (abducens) = lateral rectus of the eye (turns the eye out) CN VII (facial) = muscles of facial expression CN IX (glossopharyngeal) = stylopharyngeus CN X (vagus) = muscles of larynx and pharynx CN XI (accessory) = muscles of larynx and pharynx, sternocleidomastoid and trapezius muscle CN XII (hypoglossal) = muscles of the tongue
What cranial nerve cell bodies sit in the midline in the brainstem?
-trochlear nucleus -oculomotor nucleus -abducens nucleus -hypoglossal nucleus
What nucleus’ for cranial nerves sit ‘out to the side’ in the brainstem? Why?
Trigeminal motor nucleus Facial nucleus Nucleus ambiguus Because formed from pharyngeal arches
What are the corticonuclear tracts?
Tracts from the cortex to the cranial nerve nuclei
What kind of input do cranial nerves have? What cell bodies are the exception to this?
Bi-lateral input (from both sides of brain) Exceptions = hypoglossal (unilateral input) and facial nerve (only bi-lateral input to the upper facial muscles)
The 1st pharyngeal arch gives rise to what muscles?
Muscles of mastication
The 2nd pharyngeal arch gives rise to what muscles?
Muscles of facial expression
The 3rd pharyngeal arch gives rise to what muscles?
Small muscle in the pharynx (stylopharyngeus)
The back pharyngeal arches (4 onwards) give rise to what muscles?
Muscles of larynx and pharynx
What blood vessels supply the internal capsule artery?
Lenticulostriate arteries (that come off from middle cerebral artery)
Why is it common for the internal capsule to be damaged in a stroke?
Because it is easy for the lenticulostriate arteries that supply the internal capsule to be blocked as they are small
The brain is composed of 2 hemispheres, connected by what?
Corpus callosum
The hemispheres of the brain are separated by what?
Deep longitudinal fissure
The brain is covered by small grooves called what and what binds these grooves together?
Called sucli and bound together by gyri (ridges)
What is the postcenral gyus also termed? What does the term postcentral gyrus mean?
Primary somato-aesthtic cortex (primary sensory cortex)
The gyrus found after the central sulcus of the brain
What does the postcentral gyrus do?
Sensory info/stimuli are interpreted and put into context
What is the pre-central gryus? What is it responsible for?
The primary motor cortex - coordinated motor response
The primary motor cortex contains what kinds of cells?
Giant pyramidal ceels (cells of Betz)
What is the term used to decribe that particular parts of the brain correspond/are devoted to particular parts of the body?
Somatotopic localisation
Where is somatotopic localisation found?
In both the primary and sensory motor cortex
Where is the motor speech area found in the brain? What is the motor speech area also termed?
On the frontal lobe in the left side only
Bronca’s area
Where is the visual cortex found?
On the medial side of the occipital lobe
Where is the motor speech are found in the brain?
Frontal lobe on the left side only
What is the importance/function of the motor speech area?
Is used to put words together - need it to make words intelligible
Where is the auditory cortex found?
At the transverese temporal gyri
If a patient came in with a paralysed face, upper limb and trunk but spared lower limb, what would be the likely cause?
Why is the lower limb spared?
A stroke affecting the middle cerebral artery
Because the part of the motor nucelus that is dedicated to the lower limb is supplies by the anterior cerebral artery which will be unaffected
Describe/draw the bloody supply to the brain.
Circle of Willus - see notes
The circle of Willus probably does what?
Equalises pressures in arteries (but also means if one part blaocked then can bypas it)
