Spinal Cord Anatomy — MCQs

10 questions

In anterior spinal artery syndrome which of the following is spared

A lesion of ventrolateral part of spinal cord will lead to loss of which of the following sensation below the level of lesion?

Which descending motor pathway primarily controls distal limb muscles?

What type of neurological signs would you expect to see in a patient with a cauda equina lesion?

Inferior cerebellar peduncle has all of the following tracts, except which one?

In adults, the spinal cord normally ends at what level?

Dissociated sensory loss in a case of tumor of central Spinal cord is due to lesion of-

TRUE statement regarding nerve supply of adrenal gland:

Which of the following statements about the umbilical cord is incorrect?

Q10

Which of the following is false about spina bifida occulta?

Spinal Cord Anatomy Indian Medical PG Practice Questions and MCQs

Question 1: In anterior spinal artery syndrome which of the following is spared

A. Lateral spinothalamic tract
B. Posterior columns (Correct Answer)
C. Anterior spinothalamic tract
D. Corticospinal tract

Explanation: ***Posterior columns*** - The **anterior spinal artery** supplies the anterior two-thirds of the spinal cord, leaving the **posterior columns** (dorsal columns) and often the dorsal horns with intact blood supply from the **posterior spinal arteries** [1]. - This sparing results in preserved **fine touch**, **vibration**, and **proprioception** (dorsal column function), which are the defining clinical features distinguishing it from other spinal cord syndromes [1]. *Lateral spinothalamic tract* - This tract, responsible for **pain** and **temperature** sensation, is located within the territory supplied by the **anterior spinal artery** [3]. - Damage to this tract leads to bilateral loss of pain and temperature sensation below the level of the lesion [3]. *Anterior spinothalamic tract* - The **anterior spinothalamic tract** mediates crude touch and pressure and is located anteriorly, within the vascular distribution of the **anterior spinal artery**. - Injury to this tract contributes to the overall sensory deficit observed in anterior spinal artery syndrome. *Corticospinal tract* - The **corticospinal tracts** (also known as the pyramidal tracts), responsible for **voluntary motor control**, are situated in the anterior and lateral funiculi of the spinal cord [2]. - These tracts are supplied by the **anterior spinal artery**, leading to **bilateral motor paralysis** below the lesion in anterior spinal artery syndrome.

Question 2: A lesion of ventrolateral part of spinal cord will lead to loss of which of the following sensation below the level of lesion?

A. Proprioception on the contralateral side
B. Proprioception on the ipsilateral side
C. Pain sensation on the ipsilateral side
D. Pain sensation on the contralateral side (Correct Answer)

Explanation: ***Pain sensation on the contralateral side*** - The **ventrolateral part of the spinal cord** contains the **spinothalamic tract**, which transmits **pain and temperature** sensations. - Fibers of the spinothalamic tract **decussate (cross over)** at the level of entry into the spinal cord, meaning a lesion will cause loss of pain sensation on the **contralateral side** below the lesion. *Proprioception on the contralateral side* - **Proprioception** is primarily carried by the **dorsal columns**, which are located more posteriorly in the spinal cord. - Fibers for proprioception from the dorsal columns **decussate in the medulla**, not at the spinal cord level, so a spinal cord lesion would generally affect ipsilateral proprioception. *Proprioception on the ipsilateral side* - While proprioception is indeed carried primarily by the **dorsal columns** (located dorsally), a lesion limited to the ventrolateral part of the spinal cord would primarily affect the spinothalamic tract, not the dorsal columns. - Therefore, isolated **ventrolateral damage** would spare ipsilateral proprioception. *Pain sensation on the ipsilateral side* - This is incorrect because the **spinothalamic tract** fibers transmitting pain sensation **decussate** in the spinal cord close to their entry point. - Therefore, a lesion in the ventrolateral spinal cord would affect the already-crossed fibers, leading to **contralateral**, not ipsilateral, pain loss.

Question 3: Which descending motor pathway primarily controls distal limb muscles?

A. Reticulospinal pathway
B. Vestibulospinal pathway
C. Rubrospinal pathway (Correct Answer)
D. Tectospinal pathway

Explanation: ***Rubrospinal pathway*** - The rubrospinal tract originates in the **red nucleus** and primarily contributes to the control of **flexor muscles**, especially those in the **distal extremities**. - It plays a role in **fine motor control** and **dexterity**, important for manipulating objects. *Reticulospinal pathway* - The reticulospinal tracts are involved in the control of **posture**, **gait**, and **proximal limb movements**. - They provide significant input to **axial and extensor muscles**, which contrast with the distal control function. *Vestibulospinal pathway* - The vestibulospinal tracts are critical for maintaining **balance** and **posture** by controlling **extensor muscles** in response to head movements and gravitational changes. - They primarily influence motor neurons that innervate the **trunk** and **proximal limbs**. *Tectospinal pathway* - The tectospinal tract is involved in coordinating **head and eye movements** in response to visual and auditory stimuli. - It primarily influences the muscles of the **neck** and **upper trunk** rather than distal limb control.

Question 4: What type of neurological signs would you expect to see in a patient with a cauda equina lesion?

A. Upper motor neuron signs
B. Lower motor signs (Correct Answer)
C. Flaccid paralysis
D. Areflexia

Explanation: ***Lower motor signs*** - A **cauda equina lesion** affects the spinal nerves after they exit the conus medullaris, which are part of the **peripheral nervous system**. [1] - As such, damage to these peripheral nerves results in **lower motor neuron (LMN) signs**, including weakness, hypotonia, and atrophy. [1] *Upper motor neuron signs* - **Upper motor neuron lesions** occur within the central nervous system (brain or spinal cord above the conus medullaris). [1] - These lesions are characterized by spasticity, hyperreflexia, and a positive **Babinski sign**. *Flaccid paralysis* - While flaccid paralysis can be seen in cauda equina syndrome due to loss of muscle tone, it is a *symptom* that falls under the broader category of **lower motor neuron signs**. - This option is too general and does not encompass all the neurological signs associated with LMN lesions. *Areflexia* - **Areflexia**, or the absence of reflexes, is another specific symptom commonly seen in cauda equina lesions because the reflex arc is interrupted at the peripheral nerve level. - However, like flaccid paralysis, it is a *component* of lower motor neuron signs rather than the overarching type of neurological signs to expect.

Question 5: Inferior cerebellar peduncle has all of the following tracts, except which one?

A. Olivocerebellar
B. Spinocerebellar
C. Pontocerebellar (Correct Answer)
D. Vestibulocerebellar

Explanation: ***Pontocerebellar*** - The **pontocerebellar tracts** originate from the **pontine nuclei** and project to the contralateral cerebellum exclusively through the **middle cerebellar peduncle** (NOT the inferior cerebellar peduncle). - These tracts are crucial for carrying information about voluntary movements initiated by the cerebral cortex to the cerebellum for motor coordination. - The middle cerebellar peduncle is the largest cerebellar peduncle and consists almost entirely of pontocerebellar fibers. *Olivocerebellar* - The **olivocerebellar tracts** originate from the **inferior olivary nucleus** and pass through the **inferior cerebellar peduncle** to reach the contralateral cerebellar cortex [1]. - These fibers are crucial for motor learning, coordination, and error correction [1]. *Spinocerebellar* - The **posterior spinocerebellar tract** is a major component of the **inferior cerebellar peduncle**, conveying **unconscious proprioception** from the lower limb and lower trunk [1]. - This information helps the cerebellum coordinate posture and movement [1]. *Vestibulocerebellar* - **Vestibulocerebellar tracts** transmit essential information from the **vestibular nuclei** and organs to the cerebellum through the **inferior cerebellar peduncle** [1]. - These fibers contribute to balance, posture, and vestibulo-ocular reflexes [1].

Question 6: In adults, the spinal cord normally ends at what level?

A. Lower border of L3
B. Lower border of S1
C. Lower border of L5
D. Lower border of L1 (Correct Answer)

Explanation: ***Lower border of L1*** - In adults, the **spinal cord** typically terminates at the level of the **L1 vertebral body**, or specifically, its lower border [1]. - This marks the anatomical transition from the solid spinal cord to the **conus medullaris**, which then continues as the **cauda equina** [1]. *Lower border of L3* - While the spinal cord in **newborns** can extend as low as L3, it retracts with growth, and this level is incorrect for adults. - An adult spinal cord ending at L3 would be considered an **abnormal finding**, potentially indicating a **tethered cord syndrome**. *Lower border of S1* - The spinal cord never extends to the S1 level in healthy individuals, even in newborns. - The **sacrum (S1-S5)** is well below the normal termination point of the spinal cord. *Lower border of L5* - The spinal cord typically terminates well above L5 in adults. - The **cauda equina**, not the spinal cord itself, extends through the lumbar and sacral regions to L5 and beyond.

Question 7: Dissociated sensory loss in a case of tumor of central Spinal cord is due to lesion of-

A. Dorsal column fibres
B. Anterior Spinothalamic tract
C. Decussating fibres of lateral spinothalamic tract (Correct Answer)
D. Central spinal centre of spinal cord

Explanation: ***Decussating fibres of lateral spinothalamic tract*** - A tumor in the central spinal cord, such as a **syringomyelia**, primarily affects the decussating fibers of the **lateral spinothalamic tract**. - This typically results in a **dissociated sensory loss**, meaning loss of **pain and temperature sensation** while preserving light touch, proprioception, and vibration. *Dorsal column fibres* - Lesions here would typically cause loss of **proprioception**, **vibration**, and **fine touch**, not primarily dissociated sensory loss involving pain and temperature [1]. - These fibers ascend ipsilaterally and do not decussate in the spinal cord, so they would be less likely to be affected by a central lesion in a dissociated pattern [1]. *Anterior Spinothalamic tract* - This tract primarily mediates **crude touch** and **pressure** and is less commonly the sole cause of dissociated sensory loss as described [1]. - While it does decussate, isolated damage to this tract alone would not typically explain the classic dissociated pain and temperature loss pattern. *Central spinal center of spinal cord* - This is a broad and less specific term; the specific fibers affected within the central spinal cord, leading to dissociated sensory loss, are the **decussating fibers of the lateral spinothalamic tract**. - While a central lesion is the cause, specifying "central spinal center" doesn't precisely identify the neural pathway responsible for the characteristic sensory deficit.

Question 8: TRUE statement regarding nerve supply of adrenal gland:

A. Adrenal cortex has no nerve supply
B. Adrenal medulla has no nerve supply
C. Release of catecholamines is not affected by nerve supply
D. Preganglionic fibres from lower thoracic spinal segments bypass sympathetic chain (Correct Answer)

Explanation: ***Preganglionic fibres from lower thoracic & upper lumbar spinal segments bypass sympathetic chain*** - The adrenal medulla is innervated by **preganglionic sympathetic fibers** originating from the **T5-T11 spinal cord segments**, which travel through the splanchnic nerves and synapse directly on chromaffin cells, effectively bypassing the sympathetic chain ganglia [1], [2]. - This direct innervation allows for a **rapid, systemic catecholamine release** in response to stress. *Adrenal cortex has no nerve supply* - The **adrenal cortex** receives some **autonomic innervation**, primarily sympathetic, though it is less dense and its direct role in steroidogenesis is not fully understood. - While hormonal signals are primary for cortical regulation, nerve fibers are present and may modulate blood flow or cellular activity. *Adrenal medulla has no nerve supply* - The **adrenal medulla** is a modified sympathetic ganglion whose **chromaffin cells** are directly innervated by **preganglionic sympathetic fibers** [1], [2]. - This direct neural input is crucial for its rapid response in releasing **catecholamines** into the bloodstream. *Release of catecholamines is not affected by nerve supply* - The release of **catecholamines** (epinephrine and norepinephrine) from the **adrenal medulla** is directly and primarily controlled by **preganglionic sympathetic innervation** [1], [2]. - Without this nerve supply, the stress-induced release of these hormones would be severely impaired, highlighting the critical role of neural input.

Question 9: Which of the following statements about the umbilical cord is incorrect?

A. Two arteries and one vein
B. Contains Wharton's jelly
C. Typically 50 to 60 cm long
D. Two veins and one artery (Correct Answer)

Explanation: ***Two veins and one artery*** - This statement is incorrect because the typical umbilical cord contains **two umbilical arteries** and **one umbilical vein**. - **Two veins and one artery** would represent a rare anomaly, often associated with other congenital malformations. *Two arteries and one vein* - This is the **normal anatomical configuration** of the umbilical cord, consisting of **two umbilical arteries** and **one umbilical vein**. - The arteries carry deoxygenated blood and waste products from the fetus to the placenta, while the vein carries oxygenated blood and nutrients from the placenta to the fetus. *Contains Wharton's jelly* - **Wharton's jelly** is a gelatinous substance found within the umbilical cord, surrounding the blood vessels. - Its primary function is to protect the umbilical vessels from compression and knotting, ensuring continuous blood flow. *Typically 50 to 60 cm long* - The average length of a term umbilical cord is indeed between **50 and 60 centimeters**. - Variations in length can occur, with excessively short or long cords potentially leading to obstetric complications.

Question 10: Which of the following is false about spina bifida occulta?

A. Presence of a tuft of hair, lipoma, or sinus on the skin indicates a defect in the spinal cord
B. Early surgical repair is usually indicated (Correct Answer)
C. It is a failure of bony fusion of the vertebral column
D. There is skin covering overlying the vertebral defect

Explanation: ***Early surgical repair is usually indicated*** - This statement is **false** because spina bifida occulta is often asymptomatic and discovered incidentally. Most cases do not require early surgical intervention. - Surgical repair is typically reserved for cases with progressive neurological deficits, tethered cord syndrome, or symptomatic lesions. *Presence of a tuft of hair, lipoma, or sinus on the skin indicates a defect in the spinal cord* - This is a **true** statement. Cutaneous stigmata like **hairy patches**, **lipomas**, or **dermal sinuses** over the lumbosacral area often indicate an underlying spinal dysraphism, including spina bifida occulta, and warrant further investigation. - These skin abnormalities suggest a **bony or neural defect** beneath, alerting clinicians to potential neurological involvement. *It is a failure of bony fusion of the vertebral column* - This statement is **true**. Spina bifida occulta is characterized by the **incomplete fusion of the vertebral arches**, typically in the lumbar or sacral regions, leaving a gap. - This bony defect occurs during **embryonic development**, specifically during the ossification of the neural arch. *There is skin covering overlying the vertebral defect* - This is a **true** statement. A key differentiating feature of spina bifida occulta from more severe forms of spina bifida is that the **defect is covered by skin**, and the spinal cord and meninges usually do not protrude. - The intact skin covering prevents direct exposure of neural tissue, which is why it is often asymptomatic.

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