gross anatomy
somatosensory pathways
vasculature
motor pathways
spinal cord + ventricles
100
Which structure is more anterior, the optic tract or optic nerve?
optic nerve
structures anterior to posterior: optic nerve--> optic chiasm --> optic tract
100
What is the somatotopic organization within the primary somatosensory cortex (conscious somatosensation)?
medial somatosensory cortex = contralateral legs and trunk
lateral = contralateral arms, neck, head
100
What is the definition of an anastomosis? What are named examples of natural anastomises?
A connection between two arteries, results in two pathways of arterial flow to the same target.
- anterior communicating artery: connects bilateral anterior cerebral arteries.
- posterior communicating artery: connects vertebrobasilar and internal carotid systems via connecting the internal carotid artery with the posterior cerebral artery.
100
Which two tracts end at the cervical spinal cord level?
*both are motor tracts*
Rubrospinal Tract: excites flexors of proximal upper limb, inhibits extensors of proximal upper limb.
Medial vestibulospinal tract: acts on neck mm
- Fibers of MVST runs within medial longitudinal fasciculus (MLF) of cervical spinal cord
100
What is the filum terminale and what is its function?
Inferior projection of pia mater, anchors spinal cord inferiorly.
** Remember - denticulate ligaments are part of Pia mater as well and anchor the spinal cord laterally**
200
Which two gyri comprise Wernicke's area?
LEFT angular and supramarginal gyri
200
What sensations (modalities) are carried within the fast (PCML) and slow (ALS) somatosensory systems?
**remember "fast" and "slow" are not the true names for these modalities, just a way to group them together**
Fast SS: proprioception, vibration, and discriminative touch
Slow SS: pain, temperature, and crude touch
200
What areas are supplied by the Posterior Inferior Cerebellar Artery (PICA)?
Posterior inferior cerebellum and medulla.
200
Does the lateral corticospinal tract cross midline? If yes, where?
Yes, decussation of the pyramids!
200
There is a blockage at the mesencephalic aqueduct, making CSF unable to travel downstream. This will result in what pathology and where?
hydrocephalus and enlarged lateral and third ventricles (CSF would accumulate upstream of the blockage)
300
What is the purpose of the massa intermedia/interthalamic adhesion?
Connects the left and right thalami
300
Name the parts of the posterior column which carries conscious somatosensation from the lower limbs and the lower limbs.
Lower limbs: fasciculus gracilis (more medial)
Upper limbs: fasciculus cuneatus (more lateral)
300
Which named arteries give rise to the spinal arteries (3)?
Anterior spinal artery (1): bilateral vertebral arteries
Posterior spinal arteries (2): PICA (75%) or vertebral artery (25%)
300
Fully walk us through the myotatic reflex, including reciprocal inhibition.
Myotatic reflex: Stretch receptor -->primary sensory afferent -->lower motor neuron (agonist group) --> skeletal muscle
Reciprocal inhibition: Stretch receptor --> primary sensory afferent --> inhibitory interneuron --> DIFFERENT lower motor neuron (antagonist group) --> skeletal muscle
300
The Posterior (dorsal) root ganglia is associated with what modality (sensory, motor, both)?
Sensory only.
400
What's the venous drainage of the brain, starting from superior sagittal sinus?
superior sagittal sinus --> confluence of sinus --> transverse sinus --> sigmoid sinus --> internal jugular vein (travels through jugular foramen)
400
Does slow somatosensory information cross midline? If yes, where?
Slow somatosensory is carried by the anterolateral system (ALS), in which the secondary/projection neuron crosses midline at the anterior white commissure, ultimately ending up in the thalamus.
*the primary sensory afferent doesn't cross midline, since it terminates at the posterior horn**
400
A patient comes into your ER with symptoms of sensory deficits in the legs, but reflexes are unaltered. Which major artery might you suspect is damaged? What area of the nervous system is effected?
Anterior cerebral artery, specifically the portion that supplies the posterior paracentral gyrus.
400
What is the crossed extensor reflex?
Stimulus causes simultaneous and opposite patterns of activity in limbs:
ex. right side flexors are activated to bend the knee and avoid noxious stimulus while left side extensors fire to support quick weight shift
400
Name the real meningeal spaces found within the spinal cord.
1) epidural space (filled with fat)
2) subarachnoid space (filled with CSF)
*subdural space is never real, in spinal cord nor cranium*
*epidural space is real in the spinal cord but NOT in the cranium*
500
Name all the cranial nerves and their modalities.
On Old Olympus Towering Top, A Fin And German Viewed A Hop
Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear(Auditory), Glossopharyngeal, Vagus, Accessory, Hypoglossal
other pneumonic for modalities: Some Say Money Matters, But My Brother Says Big Brains Matter Most
500
Which tract leaves its projection neuron cell bodies within the nucleus dorsalis?
cell bodies of the posterior/dorsal spinocerebellar tract
-thus, cell bodies found in nucleus dorsals are involved in UNCONSIOUS proprioception of LOWER LIMB
500
Walk us through the pathway a red blood cell would take to reach the choroid plexus of the lateral ventricle, starting at the vertebral artery.
vertebral artery --> basilar artery --> posterior cerebral artery --> posterior communicating artery --> internal carotid artery --> middle cerebral artery --> anterior choroidal artery
500
Compare and contrast lateral vs medial reticulospinal and vestibulospinal tracts (4 total)
LRST: bilateral, medullary reticular formations
MRST: ipsilateral, pontine reticular formations
*both reticulospinal tracts innervate antigravity muscles for posture*
LVST: ipsilateral, innervates antigravity muscles for posture and balance
MVST: descends bilateral, innervates neck muscles (only goes to cervical level)
500
Walk us through the pathway of CSF flow, from lateral ventricle to venous sinus.
lateral ventricle--> interventricular foramen --> third ventricle --> mesencephalic aqueduct --> fourth ventricle --> central canal of the spinal cord OR apertures --> subarachnoid space --> arachnoid villi/granulations --> venous system (via superior sagittal sinus)
*remember that the venous sinuses are located between the two layers of dura in the cranium -meninigal and periosteal.*