NN 15. MEDULLA ANATOMY & FUNCTION

Neurology, MBBS Second Year. This chapter is split into 9 topics and has 332 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Transverse Section of Medulla at the Level of Olives 58 questions
2. Transverse Section of Medulla at the Level of Sensory Decussation 51 questions
3. Transverse Section of Medulla at the Level of Pyramidal Decussation 47 questions
4. Cranial Nerves 56 questions
5. Ascending Sensory Pathways: Dorsal Column, Spinothalamic and Trigeminal 26 questions
6. Spinocerebellar, Spino-olivary and Olivocerebellar Pathways 24 questions
7. Vestibular and Cochlear Pathways in the Medulla 23 questions
8. Descending Motor and Autonomic Tracts in the Medulla 25 questions
9. Medullary Lesions and Clinical Correlations 22 questions

Sample questions: NN 15. MEDULLA ANATOMY & FUNCTION

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. The anterior external arcuate fibers represent which fibers, and what do they connect?

• A. Efferent fibers of the inferior olivary nucleus to the cerebellum
• B. Contralateral efferent fibers from the arcuate nucleus, connecting the arcuate nucleus with the ponto-bulbar body(correct answer)
• C. Afferent fibers from the spinal cord to the arcuate nucleus
• D. Ipsilateral fibers from the arcuate nuclei, demarcating the anterior wall of the fourth ventricle

Answer: B.The note states the anterior external arcuate fibers are the contralateral efferent fibers from the arcuate nucleus on each side, providing the connection between the arcuate nucleus and the ponto-bulbar body.

Q2. Which sequence correctly describes the spino-olivary tract as given in the note?

• A. Sensory receptors to the cerebellum, then the cerebellum to the thalamus, then the thalamus to the cortex
• B. Sensory receptors to the inferior olivary nucleus, then directly to the ipsilateral cerebellar hemisphere
• C. Sensory receptors to the dorsal horn, posterior gray horn to the inferior olivary nucleus, then inferior olivary nucleus to the contralateral cerebellar hemisphere(correct answer)
• D. Sensory receptors to the dorsal horn, then to the nucleus gracilis, then to the sensory cortex

Answer: C.The note gives the spino-olivary pathway as first order neuron from sensory receptors to the dorsal horn, second order neuron from the posterior gray horn to the inferior olivary nucleus, and third order neuron from the inferior olivary nucleus to the contralateral cerebellar hemisphere.

Q3. Which of the following structures is listed at the level of the sensory decussation?

• A. The ponto-bulbar body
• B. The inferior salivatory nucleus
• C. The nucleus ambiguus
• D. The beginning of the medial lemniscus(correct answer)

Answer: D.The note lists the beginning of the medial lemniscus among the structures at the level of the sensory decussation; the nucleus ambiguus, inferior salivatory nucleus, and ponto-bulbar body are listed at the level of the olives.

Q4. Which nucleus is found at the level of the olives but NOT listed at the level of the sensory decussation?

• A. The dorsal nucleus of vagus
• B. The hypoglossal nucleus
• C. The nucleus of tractus solitarius
• D. The nucleus ambiguus(correct answer)

Answer: D.The nucleus ambiguus is listed at the level of the olives only, while the hypoglossal nucleus, dorsal nucleus of vagus, and nucleus of tractus solitarius are listed at both the level of the olives and the level of the sensory decussation.

Q5. Which structure is listed at the level of the sensory decussation but NOT at the level of the pyramidal decussation?

• A. The dorsal nucleus of vagus(correct answer)
• B. The fasciculus gracilis
• C. The corticospinal tract
• D. The vestibulospinal tract

Answer: A.The note lists the hypoglossal nucleus, dorsal nucleus of vagus, and nucleus of tractus solitarius at the sensory decussation level, whereas the pyramidal decussation list contains the fasciculus gracilis/cuneatus, corticospinal, vestibulospinal, and other tracts but no vagal or hypoglossal nuclei.

Q6. Which structure is listed at the level of the olives but NOT at the level of the pyramidal decussation?

• A. The nucleus ambiguus(correct answer)
• B. The spino-olivary tract
• C. The tectospinal tract
• D. The rubrospinal tract

Answer: A.The note lists the nucleus ambiguus at the level of the olives, while the pyramidal decussation level list includes the rubrospinal tract, tectospinal tract, and spino-olivary tract but not the nucleus ambiguus.

Q7. Which tract is listed at the level of the olives AND at the level of the pyramidal decussation?

• A. The vestibulo-cerebellar tract
• B. The lateral lemniscus
• C. The corticospinal tract(correct answer)
• D. The trigemino-thalamic tract

Answer: C.The corticospinal tract is included in the structure lists for both the level of the olives and the level of the pyramidal decussation, as are the medial lemniscus-related structures and the spinocerebellar and spinothalamic tracts.

Q8. The glossopharyngeal nerve picks up sensations of the oral cavity using which nucleus and fiber type, and from which structures?

• A. The NTS with general visceral afferent fibers, from the soft palate, pharynx, and posterior one-third of the tongue(correct answer)
• B. The nucleus ambiguus with general visceral efferent fibers, from the epiglottis only
• C. The spinal nucleus of the trigeminal nerve with special visceral afferent fibers, from the anterior two-thirds of the tongue
• D. The inferior salivatory nucleus with general somatic afferent fibers, from the parotid gland

Answer: A.The note states the glossopharyngeal nerve uses the NTS with general visceral afferent fibers to pick up sensations from the soft palate, pharynx, and posterior one-third of the tongue, and also carries fibers from chemoreceptors and baroreceptors.

Q9. Which cranial nerves contribute to the pharyngeal plexus, and by which fibers is it formed?

• A. The vagus, glossopharyngeal, and accessory nerves, formed by fibers from the nucleus ambiguus (special visceral efferent fibers)(correct answer)
• B. The hypoglossal, trigeminal, and facial nerves, formed by fibers from the nucleus tractus solitarius
• C. The oculomotor, trochlear, and trigeminal nerves, formed by fibers from the inferior salivatory nucleus
• D. The abducens, facial, and vestibulocochlear nerves, formed by fibers from the dorsal nucleus of vagus

Answer: A.The note states the pharyngeal plexus is composed of the vagus nerve, glossopharyngeal nerve, and accessory nerve, and is formed by fibers from the nucleus ambiguus carrying special visceral efferent fibers.

Q10. Which of the following is NOT listed among the sensory receptors of the medial lemniscus pathway in the note?

• A. Merkel's discs in the epidermis
• B. Golgi tendon organs in the tendons
• C. Meissner's corpuscles in the skin
• D. Free nerve endings for pain(correct answer)

Answer: D.The receptors for the medial lemniscus include Meissner's corpuscles, Merkel's discs, Pacinian corpuscles, peritrichal endings, Ruffini end organs, muscle spindles and Golgi tendon organs; free nerve endings for pain belong to the spinothalamic pathway.