Spinal Cord & Long Tracts
This specific gray matter region contains lower motor neuron cell bodies whose destruction produces flaccid weakness, atrophy, and fasciculations.
What is the anterior (ventral) horn?
This dorsal caudal point of the fourth ventricle serves as the anatomical landmark dividing the closed medulla from the open medulla.
What is the obex?
This massive peduncle, the largest of the cerebellar connections, transmits crossed pontocerebellar fibers from the pons into the cerebellum.
What is the middle cerebellar peduncle (brachium pontis)?
This dorsal portion of the midbrain contains the superior and inferior colliculi.
What is the tectum?
This extraocular cranial nerve is unique among all twelve because it is the only one that emerges from the dorsal aspect of the brainstem and decussates prior to exit.
What is Cranial Nerve IV (Trochlear nerve)?
These sensory modalities ascend ipsilaterally in the fasciculus gracilis and cuneatus and are classically spared in anterior spinal artery occlusion
What are vibration, conscious proprioception, and discriminative (fine) touch?
Second-order neurons carrying dorsal column modalities originate in these dorsal medullary nuclei before crossing as internal arcuate fibers.
What are the nucleus gracilis and nucleus cuneatus?
Complete bilateral infarction of the basilar/ventral pons typically leads to this terrifying state where a patient is quadriplegic and anarthric but retains consciousness and vertical gaze
What is locked-in syndrome?
Degeneration of dopaminergic neurons in this midbrain structure leads to resting tremor, bradykinesia, and cogwheel rigidity.
What is the substantia nigra (pars compacta)?
These are the specific afferent (sensory) and efferent (motor) cranial nerves that mediate the gag reflex.
What are Cranial Nerve IX (Glossopharyngeal, afferent) and Cranial Nerve X (Vagus, efferent)?
Syringomyelia classically damages these crossing fibers first, leading to a bilateral "cape-like" loss of pain and temperature sensation.
What is the anterior white commissure?
This non-cranial-nerve structure near the floor of the fourth ventricle acts as the chemoreceptor trigger zone for vomiting.
What is the area postrema?
An AICA (lateral inferior pontine) infarction causes ipsilateral facial paralysis and hearing loss by affecting these two cranial nerves, distinguishing it from PICA infarction.
What are Cranial Nerve VII (Facial) and Cranial Nerve VIII (Vestibulocochlear)?
A rostral dorsal midbrain lesion that causes upward vertical gaze palsy, bilateral light-near dissociation, and convergence-retraction nystagmus produces this classic syndrome.
What is Parinaud syndrome (dorsal midbrain syndrome)?
A patient with complete unilateral weakness of both the upper and lower face has this type of motor neuron lesion, contrasting with forehead-sparing cortical deficits.
What is a Lower Motor Neuron (LMN) facial palsy?
A spinal hemisection causes this specific triad below the level of the lesion: ipsilateral UMN weakness, ipsilateral loss of vibration/proprioception, and this sensory deficit on the opposite side.
What is contralateral loss of pain and temperature sensation?
Medial medullary syndrome (Dejerine syndrome) is classically caused by occlusion of this specific blood vessel or its paramedian branches.
What is the anterior spinal artery (or paramedian vertebral branches)?
A lesion isolated to the midline cerebellar vermis predominantly impairs posture and gait rather than limb coordination, producing this clinical presentation.
What is truncal (or gait) ataxia?
Ipsilateral CN III palsy accompanied by contralateral hemiparesis from damage to the basis pedunculi defines this classic alternating midbrain stroke pattern.
What is Weber syndrome?
Compression of CN III by an uncal herniation or posterior communicating artery aneurysm initially affects these superficial fibers, resulting in early pupillary dilation.
What are parasympathetic (preganglionic / Edinger-Westphal) fibers?
This large anterior segmental medullary artery, which usually arises in the lower thoracic or upper lumbar region on the left, puts the lower spinal cord at high risk for infarction during aortic repair.
What is the Artery of Adamkiewicz?
In Wallenberg (lateral medullary) syndrome, damage to this specific branchial motor nucleus explains why patients develop dysphagia, hoarseness, and a diminished gag reflex
What is the nucleus ambiguus?
A lesion located at this specific dorsal caudal pontine landmark causes combined ipsilateral lower-motor-neuron facial weakness and ipsilateral horizontal conjugate gaze palsy.
What is the facial colliculus?
Occlusion of posterior cerebral artery perforators damaging the CN III fascicles, red nucleus, and surrounding cerebellothalamic fibers produces this midbrain tegmental syndrome characterized by third nerve palsy and contralateral chorea/tremor/ataxia
What is Benedikt syndrome?
The corneal blink reflex arc travels via this specific division of CN V for the afferent limb and relies on this bilateral cranial nerve to contract the orbicularis oculi muscles.
What are CN V1 (Ophthalmic division) and CN VII (Facial nerve)?