anats Flashcards
Primary Somatosensory cortex
POST CENTRAL GYRUS
Sensory homunculus
brodmanns areas 1,2,3,
Secondary somatosensory cortex
Adjacent to head region of primary somatosensory cortex
Extends posteriorly along parietal cortex buried in lateral fissure
Somatosensory association cortex
Located posterior to primary somatosensory cortex in superior part of parietal lobe
brodmann’s area 5
Thalamus
either of two masses of grey matter lying between the cerebral hemispheres on either side of the third ventricle, relaying sensory information and acting as a centre for pain perception.
What is the pathway for fine touch and conscious proprioception
Dorsal Column-Medial Lemniscal Pathway, DCML
describe the dorsal column medial lemniscal pathway
First order neurone ascends the spinal cord via the cuneate fasciuclus ( upper limb) or gracile fascicles( lower limb) before synapsing with the gracile or cuneate nucleus in the medulla oblongata
Second order neurone decussates and ascends via the medial leminscus to the thalamus
3rd order neurone ascends via the internal capsule to synapse in the primary somatosensory cortex
How many neurones in the dorsal medial lemniscal pathway
3
WHERE do fibres of the dorsal columns pathway decussate
MEDULLA OBLONGATA
WHAT IS THE PATHWAY for pain sensation
Spinothalamic tract
Pathway of the spinothalamic tract
1st order neurone ascend or descends 1-2 spinal levels through lissauers tract before synapsing in the substantial gelatinous, at the tip of the dorsal horn
2nd order neurones decussate and ascend to the thalamus via either the anterior( crude touch) or lateral ( pain and temperature) spinothalamic tract
3rd order neurone ascends through internal capsule to primary somatosensory cortex
anterior vs lateral of spinothalamic tract
anterior = crude touch lateral = pain and temp
Difference in place of decussation in spinothalamic vs DCML
DCML = medulla oblongata Spinothalamic = level of the spine cord
Central sulcus
Separates precentral motor cortex (frontal lobe) and postcentral sensory cortex (parietal lobe)
Primary motor cortex
(Brodmann’s area 4): precentral gyrus and area immediately in front of it
Premotor cortex
(area 6): immediately in front of motor cortex and has close connections with it
Supplementary motor area
lies on medial surface of hemisphere above cingulate sulcus
Areas of the motor cortex
Upper/medial part: lower limb and perineum
Lower/lateral part: trunk, of upper limb, neck and head
Paracentral lobule: cortical control of micturition and defecation
Frontal eye field: voluntary eye movement (lesions cause paralysis of voluntary contralateral gaze)
PRE CENTRAL gyrus
surface of the posterior frontal lobe of the brain.
primary motor cortex
Corticospinal tract
Voluntary control of skilled movement
2 neurone pathway
Pathway of corticospinal tract `
first order neurone descends from the primary motor cortex via the internal capsule
Enters the brainstem through the crus cerebri
75-90% of fibres decussate at the pyramids in the medulla oblongata; those that decussate descend down the lateral corticospinal tract before exiting the spinal cord via the ventral root
Those that don’t decussate (10-15%) descend ipsilaterally down the ventral corticospinal tract before decussating near their termination site
Rubrocospinal tract
starts in red nucelus( midbrain ) controlling limb flexors
Tectospinal tract
originates from contralateral superior colliculi( midbrain)- reflex response to visual stimuli
Vestibulospinal tract
lateral and medial, originates from ipsilateral vestibular nuceli. Lateral = mediate excitation of proximal limb extensors, medial = head and neck posture
Reticulospinal tract
originates in pons and medulla, involved in reflex, tone and vital functions
Corticonucelear fibers ( additional to corticospinal tract,
terminate (mainly bilaterally) in motor nuclei of cranial nerves of pons and medulla or within the reticular formation of brainstem. Often referred to as corticobulbar tract and relates to chewing, talking and swallowing.
Corticopontine fibers
terminate ipsilaterally in pontine nuclei then travel to cerebellum via cerebellar peduncle. Carries ‘copies’ of the executive motor plan from cortex to cerebellum
Basal nuclei
• Functionally and anatomically-related group of forebrain nuclei concerned with modulation of movement and behaviour, including muscle tone and posture
3 integrated nuclei of the basal ganglia
caudate nucleus, putamen and globus pallidus. Caudate and putamen together often referred to as ‘corpus striatum’.
Origin of dopamine fibres to basal nuclei
substantia nigra (midbrain)