Anatomy

Question 1

lateral cervical cord lesion

Answer 1

Extramedullary impingement of the lateral cervical cord may cause weakness and upper motor neuron signs in the ipsilateral lower extremity because of the somatotopic organization of sacral and lumbar fibers being most lateral within the lateral corticospinal tract.

Question 2

tensor tympani, anterior belly of digastric and muscles of mastication are supplied by

Answer 2

trigeminal n

Question 3

Initial cortical processing of taste

Answer 3

The insula and the lateral aspect of the postcentral gyrus are primarily involved in the initial cortical processing of taste.

Question 4

thalamus nuclei

Answer 4

The medial lemniscus ascends through the brainstem and terminates in the ventral posterolateral nucleus of the thalamus. The centromedian nucleus, one of the intralaminar nuclei, and the ventral anterior nucleus are involved in basal ganglia circuitry. The ventral lateral nucleus receives input from the deep cerebellar nuclei. The ventral posteromedial nucleus receives sensory input from the face via the trigeminothalamic tract.

Question 5

ventral posteromedial thalamic nucleus

Answer 5

The ventral posteromedial thalamic nucleus receives afferent input from the contralateral spinal trigeminal nucleus, which is responsible for pain and temperature modalities of the face.

Question 6

sympathetic innervation to pupillodialator

Answer 6

Preganglionic sympathetic fibers leave the spinal cord via the ventral roots of T1 and T2 and then join the paravertebral sympathetic chain and synapse in the superior cervical ganglion. Postganglionic fibers follow the carotid plexus, eventually reaching the pupillodilator muscle.

Question 7

peroneal nerve branches

Answer 7

The common peroneal nerve divides into two branches, the deep and superficial peroneal nerves. The deep peroneal nerve innervates the tibialis anterior and extensor digitorum brevis. The peroneus longus and brevis are supplied by the superficial peroneal nerve. The soleus and tibialis posterior muscles are innervated by the tibial nerve.

Question 8

Medial medullary syndrome

Answer 8

The medial medullary syndrome is most commonly associated with infarction in the anterior spinal artery distribution at the level of the medulla. An occlusion at this level may result in ipsilateral CNXII paralysis (fascicle of CNXII), contralateral hemiparesis (pyramid), and contralateral loss of position and vibratory sensation (medial lemniscus). A bilateral lesion in this vascular territory will result in quadriparesis, bilateral loss of proprioception and vibration, and complete paralysis of the tongue.

Question 9

Cheiro-oral syndrome

Answer 9

Cheiro-oral syndrome is a pure sensory lacunar syndrome consisting of numbness of the hemi-mouth and ipsilateral fingertips. It localizes to the junction of the VPL and VPM nuclei of the thalamus.

Question 10

which parts of the brain are affected in alzheimer, MSA, parkinson’s, huntington?

Answer 10

The arrow is indicating the hippocampus which is the structure first affected in the neurodegenerative pathophysiology of Alzheimer disease. Multisystem atrophy involves striatonigral and olivopontocerebellar regions. Parkinson’s disease involves dopaminergic systems. Huntington Disease involves the caudate and putamen.

Question 11

foramen lacerum

Answer 11

foramen lacerum provides entry for the internal carotid artery.

Question 12

What muscles does the sciatic nerve innervate?

Answer 12

The sciatic nerve innervates all of the hamstring muscles and all muscles below the knee via the peroneal and tibial nerve branches.

Question 13

central cord lesion

Answer 13

A central cord lesion which produces pain and temperature dysfunction in a bilateral “shawl” or “cape” distribution is due to involvement of crossing fibers for these modalities in the anterior (a.k.a. ventral) white commissure.

Question 14

blood supply of optic disc

Answer 14

The central retinal artery is a branch of the ophthalmic artery and makes only a minimal contribution to the vascular supply of the optic disc. The short posterior ciliary arteries are branches that also arise from the ophthalmic artery and supply the optic disc and the retro-orbital optic nerve.

Question 15

circumventricular organs

Answer 15

The circumventricular organs - the area postrema, the pineal gland, the subcommissural organ, the subfornical organ, the organum vasculosum, the median eminence and the neurohypophysis all lack a blood-brain barrier. These organs may be sites where the brain monitors a variety of substances contained in the blood. The area postrema serves as a chemoreceptor that triggers vomiting in response to circulating emetic substances. In a patient with nausea with T2 hyperintensity in the area postrema, neuromyelitis optica spectrum disorder should be considered as this is a core clinical presentation.

Question 16

Supraspinatus and infraspinatus innervation and function

Answer 16

The suprascapular nerve innervates the supraspinatus and infraspinatus muscles. The supraspinatus muscle is responsible for the first 15 degrees of humeral abduction, and the infraspinatus muscle externally rotates the arm.

Question 17

foramen ovale

Answer 17

V3 exits via the foramen ovale.

Question 18

CSF flow through the 4th ventricle

Answer 18

The three openings in the 4th ventricle are the two paired lateral apertures (foramina of Luschka) and the median aperture (foramen of Magendie). CSF flows from the 4th ventricle, via these foramina, to reach the subarachnoid space of the cisterna magna.

Question 19

disorders of neuronal migration

Answer 19

Lissencephaly, which is characterized by a reduction in the number of gyri and sulci, is one of the disorders of neuronal migration. Other neuronal migration disorders include polymicrogyria, schizencephaly, and focal cortical dysplasia.

Question 20

posterior cord of the brachial plexus

Answer 20

The posterior cord of the brachial plexus gives off the thoracodorsal and subscapular nerves and terminates by splitting into the axillary and radial nerves. Any muscles innervated by these branches may be weakened with a lesion in the posterior cord of the plexus.

Question 21

what does PCA supply?

Answer 21

The posterior cerebral artery supplies parts of the inferior temporal lobe, occipital lobe, splenium of the corpus callosum and superior parietal lobule.

Question 22

prosopagnosia

Answer 22

Bilateral lesions of the fusiform (occipitotemporal) gyri produce prosopagnosia, the inability to recognize people by looking at their face

Question 23

Gerstmann syndrome

Answer 23

A lesion to the angular gyrus of the dominant parietal lobe can cause Gerstmann syndrome, which is characterized by the dyscalculia, finger agnosia, dysgraphia, and right-left confusion. The angular artery, a branch of the middle cerebral artery supplies this part of the cortex.

Question 24

where do CNs 7, 9, 10, 11 exit?

Answer 24

Cranial nerves 9, 10, and 11 exit through the jugular foramen while cranial nerve 7 exits the skull through the stylomastoid foramen.

Question 25

internal auditory artery

Answer 25

The internal auditory artery (IAA) typically arises from the anterior inferior cerebellar artery (AICA), but may also arise directly from basilar artery. The IAA will then divide into a cochlear and vesitbular branch to supply the labyrinth. AICA ischemia can therefore result in unilateral deafness.

Question 26

Circumventricular ograns

Answer 26

The circumventricular organs, which do not have a blood-brain barrier, are the area postrema, subfornical organ, organum vasculosum, neurohypophysis, median eminence, pineal gland, and subcommissural organ. The area postrema has been implicated as a chemoreceptor trigger zone for vomiting.

Question 27

foramen rotundum

Answer 27

V2 exits via the foramen rotundum

Question 28

nervus intermedius

Answer 28

The nervus intermedius is the portion of the facial nerve carrying all the general visceral efferent, general somatic afferent, and special afferent information. The branchial motor fibers going to the muscles of facial expression travel in a separate bundle. Of the potential answers given, an injury to the nervus intermedius would therefore impair taste from the ipsilateral anterior tongue. Facial muscles would not be affected. The parotid gland is innervated by the glossopharyngeal nerve while the striated muscles of the pharynx are innervated by the vagus nerve.

Question 29

hemiballismus

Answer 29

Ballism is associated with discrete lesions in the subthalamic nucleus. The dyskinesia occurs contralateral to the lesion and is associated with hypotonia. As the hemiballismus improves, the movements are more like chorea. The subthalamic nucleus modulates (suppresses) ipsilateral basal ganglionic activity, which in turn modulates cortical motor outflow to the contralateral effector muscles.

Question 30

suprachiasmatic nucleus

Answer 30

The suprachiasmatic nucleus receives direct inputs from the retina (retinohypothalamic tract). These inputs, from specialized ganglion cells, are involved in entrainment of circadian rhythms on the basis of the light/dark cycle and, via a somewhat indirect route, control melatonin secretion.

Question 31

superior orbital fissure

Answer 31

The third cranial nerve leaves the skull by passing through the superior orbital fissure (as does four, V1, and six)

Question 32

trochlear nerve palsy v vestibular nucleus lesion

Answer 32

A trochlear nerve palsy results in elevation and extorsion of the ipsilateral eye. Patients compensate with a contralateral head tilt. A lesion of the ipsilateral vestibular nucleus will simulate a contralateral body tilt. As a result, the head will tilt ipsilaterally towards the lesion. The eye ipsilateral to the lesion will depress and extort while the eye contralateral to the lesion will elevate and intort.

Question 33

tibial nerve branches

Answer 33

After exiting the tarsal tunnel, the tibial nerve will divide into the medial and lateral plantar nerves. These nerves relay sensation from the plantar skin of the foot. Another branch of the tibial nerve is the calcaneal nerve which innervates the skin over the heel.

Question 34

high cervical cord lesions

Answer 34

In high cervical cord lesions, ipsilateral diminished pain and temperature sensation in the preauricular area of the face is due to involvement of cells in the substantia gelatinosa which is the distal continuation of the descending trigeminal nucleus and tract.

Question 35

intermomediolateral cell column lesions

Answer 35

The interomediolateral cell column contains preganglionic sympathetic neurons. Involvement of this area in the upper thoracic cord may result in an ipsilateral Horner syndrome.

Question 36

Parinaud syndrome

Answer 36

Parinaud syndrome is due to lesion in the dorsal midbrain, involving the quadrigeminal plate, the pretectum and periaqueductal gray matter. Clinical findings include impaired upgaze, convergence retraction nystagmus, eyelid retraction and light-near dissociation

Question 37

where do CN 3 and 4 come off?

Answer 37

The arrow is pointing to the third cranial nerve - which emerges ventrally from the midbrain in the interpeduncular fossa at the level of the superior colliculus. The only other cranial nerve which arises from the midbrain is the fourth and it emerges from the dorsum.

Question 38

weber’s sydnrome

Answer 38

A lesion at the base of the midbrain (cerebral peduncle) will produce an ipsilateral third nerve palsy and contralateral hemiparesis (Weber’s syndrome) as it involves both the descending corticospinal tract (which later mostly crosses to run in the contralateral cord) and the exiting ipsilateral third nerve fibers into the interpeduncular space.

Question 39

lesion of fasiculus gracilis

Answer 39

Proprioceptive and vibratory loss in the lower extremities, due to a spinal cord lesion, involves the fasciculus gracilis which serves these functions below the level of T6.

Question 40

foramen magnum

Answer 40

The spinal cord and the ascending limb of the spinal accessory nerve pass through the foramen magnum.

Question 41

where does MMA exit?

Answer 41

The middle meningeal artery passes through the foramen spinosum.