Neuroanatomy Flashcards
Acute onset of paralysis and sensory loss in leg, lack of initiative, urinary incontinence is caused by occlusion in this vascular territory.
Anterior Cerebral Artery Occlusion causes this syndrome.
Facial droop, arm weakness, face/arm sensation loss, expressive aphasia, is caused by an occlusion of this vascular territory.
Occlusion of the superior division of the MCA which serves the sensory cortex, motor cortex, Broca’s area (inferior frontal gyrus) if it is on the dominant hemisphere will cause these symptoms.
Explain the anatomy and function of the rubrospinal tract
It is an extra-pyramidal tract that is a major motor control pathway, for upper limbs only. It facilitates flexion of upper ext and therefore plays a role in decorticate posturing. It originates in the red nucleus of the bidbrain, then crosses to the other side of the midbrain, and descends in the lateral part of the brainstem tegmentum. It runs very laterally
Describe intracerebral venous circulation
There are essentially 3 drainages:
1) Superficial drainage from the dural venous sinuses: The superior sagittal sinus drains to the torcula
2) Deep drainage: the inferior sagittal sinus and the thalamostriates -> vein of galen (aka great cerebral vein) both drain into the straight sinus which then drains into the torcula.
The anastamosis of Trolard goes between the deep and the superficial circulation. Labbe drains into the transverse sinus.
From the torcula, the drainage passes through the transverse sinus and into the sigmoid, then into the jugular and the superior vena cava.
3) The Cavernous sinus drains to the petrosal sinus, then directly into the sigmoid and into the jugular vein.
What are the components of the basal ganglia?
1) Striatum (caudate - oculomotor and prefrontal information - and putamen)
2) Globus pallidus
3) Substantia nigra
4) Subthalamic nucleus
Limbic sector - involved with reward learning; highly addictive drugs including cocaine, amphetamine, nicotine work here:
1) Nucleus accumbens - receives input from limbic system and orbitofrontal cortex. Anticipates rewards and is implicated in substance abuse and addiction
2) Ventral pallidum
3) Ventral tegmental area
Embryologically, what is derived from the basal vs the alar plate?
A is behind B
Alar: Sensory tracts. Also olivary nuclei and solitary nuclei. Superior and inferior colliculi
Basal: Motor tracts such as the hypoglossal nucleus. Red nuclei, CN III and IV nuclei, reticular nuclei, substantia nigra
What syndrome and anatomic area is involved in a patient with socially inappropriate behaviors as well as poor impulse control with disinhibition?
Orbitofrontal syndrome
What syndrome and antomic correlate are involved in dysexecutive symptoms?
The “lateral convexity” syndrome, AKA dorsolateral or prefrontal
What syndrome and anatomic correlate are associated with amotivation?
Mesial Frontal Syndrome (such as is seen in ACA stroke)
Which cranial nerves carry general visceral efferent information?
- Oculomotor - Edinger-Westphal nucleus supplies parasympathetics to the eye via the ciliary ganglion controlling the sphincter pupillae and ciliary muscles (pupillary constriction and accomodation)
- Facial - parasympathetic fibers to submandibular and sublingual glands via the chorda tympani, increasing salivary flow. Also parasympathetics to nasal mucosa and lacrimal gland via pterygopalatine ganglion.
- Glossopharyngeal - parasympathetic innervation of parotid gland
- Vagal - dorsal nucleus gives parasympathetic output to the viscera, i.e. intestines. Nucleus ambiguus gives parasympathetics to the heart
Where is the spinal cord vulnerable to vascular insult?
T1-T4 is the vascular boundary zone between ascending and descending sources of blood supply to the spinal cord. The great anterior artery of Adamkiewicz arises between T9 and L2 and supplies the lumbar enlargement.
Where besides the frontal lobe can frontal syndromes be caused?
The dorsomedial nucleus of the thalamus. It provides innervation to the whole prefrontal cortex including the paralimbic orbitofrontal region and the associative dorsolateral region. You can get disinhibition and poor executive function with dorsomedial thalamus lesions. If you get an anterior nucleus of the thalamus lesion you get amnesia but not a frontal syndrome.
What arterial territory is this, and what structures are affected?
This is the anterior choroidal artery territory that arises from the ICA. It feeds the globus pallidus, putamen, and PLIC.
Syndrome is hemiplegia, hemianesthesia, and hemianopia contralateral to the side of the lesion
Stroke syndrome involving hemiplegia, hemianesthesia, and hemianopia contralateral to side of lesion
anterior choroidal artery infarct
Describe the hippocampal projections
The entorhinal cortex projects to the dentate.
The dentate gyrus consists of 3 layers of neurons: molecular, granular, and polymorphic. The middle layer is most prominent and contains granule cells that project via mossy fibers to CA3 of the hippocampus, which in turn projects to CA1
Describe the anatomy of the pain and temperature sensation.
Pain and temperature are spinothalamic tract. Primary nociceptive afferents from the dorsal root ganglion synapse in the posteromarginal nucleus then immediately deccusate to the contralateral side. They travel in the lateral medulla in the STT, then join the dorsal columns in the medial lemniscus once it reaches the midbrain. It then reaches the ventral posterior nucleus of the thalamus and finally the primary somatosensory cortex.
An ipsilateral CN III palsy and contralateral hemiparesis is caused by what lesion and what is the eponym?
Base of the midbrain (cerebral peduncle). This is called weber’s syndrome.
Describe the anatomy of CN VII
The motor nucleus, superior salivatory nucleus (gives rise to preganglionic autonomic fibers), and nucleus of fasciculus solitarius all originate in the ponto-medullary junction and form a nerve together.
The fibers travel to the geniculate ganglion. The motor and parasympathetic fibers pass through the GG without synapsing. The motor fibers innervate the stapedius muscle, then pass through the stylomastoid foramen to innervate the facial muscles. The parasympathetic fibers do not pass through the stylomastoid formane, but rather travel on to the submandibular ganglion, then innervate the submandibular and sublingual glands.
Sensory fibers that originate from the external auditory canal and the tympanic membrane as well as fibers conveying taste all have cell bodies that reside in the GG.
Describe the neuroanatomy of circadian rhythms
The suprachiasmatic nucleus inhibits the paraventricular nucleus of the hypothalamus which decreases paraventricular driving of the superior cervical ganglion, thereby decreasing sympathetic drive onto the pineal gland
What is the end organ for sensing vibration, and where are they found?
Pacinian corpuscles found in the subcutaneous tissue and in the periosteum
What is the ventral tegmental area? What types of neurons are found there and where do they travel?
Mesolimbic and mesocortical projections arise from the ventral tegmental area of the midbrain. The fibers are dopaminergic and travel to the cerebral cortex and limbic structures such as the amygdala
What is the ciliary ganglion and what runs through it?
Parasympathetic neurons in the ciliary ganglion project fibers to the ciliary muscles to change the shape of the lens for accomodation. Also, a small number of fibers project to the iris sphincter to constrict the pupil.
Sympathetic fibers run through the ciliary ganglion, but they do not synapse there. Their activation results in pupillary dilation.
What is the course of the parasympathetic fibers of CN IX?
The glossopharyngeal, or ninth cranial nerve, is derived from the inferior salivary nucleus. These parasympathetic fibers synapse in the otic ganglion and then innervate the parotid gland.
It also receives general sensory fibers from the tonsils, pharynx, middle ear, and posterior 1/3 of the tongue.
Visceral sensory fibers from the carotid bodies and sinus
Motor fibers to stylopharyngeus muscle (the only motor component of this CN)
What is the fornix and what passes through it?
Pre and post commissural fibers pass through the fornix
The precommissural fibers innervate the septal area and the anterior hypothalamus (nucleus accumbens)
The post-commissural fibers pass through the hypothalamus to innervate the mammillary bodies, then to the anterior nuclei of the thalamus, maps to cingulate cortex
What does the inferior parietal lobule contain?
The angular and supramarginal gyrus
