Cervical Plexus — MCQs
All are infraclavicular branches of brachial plexus except ?
All are true regarding brachial plexus injury, except:
Which spinal nerves are affected in Klumpke's paralysis?
Most common complication of celiac plexus block:
A 55-year-old male, known smoker, complains of calf pain while walking. He experiences calf pain while walking but can continue walking with effort. Which grade of claudication does this patient fall under?
Which nerve is responsible for supplying the posterior semicircular canal?
Which of the following statements about the brachial plexus is true?
Inferior cerebellar peduncle has all of the following tracts, except which one?
The fascia around the nerve bundle of the brachial plexus is derived from?
Adson's test is positive in -
Cervical Plexus Indian Medical PG Practice Questions and MCQs
Question 1: All are infraclavicular branches of brachial plexus except ?
- A. Axillary nerve
- B. Thoracodorsal nerve
- C. Long thoracic nerve (Correct Answer)
- D. Ulnar nerve
Explanation: Long thoracic nerve - The long thoracic nerve originates directly from the roots (C5, C6, C7) of the brachial plexus, making it a supraclavicular branch. - It does not arise from the cords of the brachial plexus, which are located infraclavicularly. Ulnar nerve - The ulnar nerve arises from the medial cord of the brachial plexus, which is an infraclavicular structure. - It supplies many intrinsic hand muscles and the ulnar half of the flexor digitorum profundus. Axillary nerve - The axillary nerve is a branch of the posterior cord of the brachial plexus, classifying it as an infraclavicular branch. - It innervates the deltoid and teres minor muscles. Thoracodorsal nerve - The thoracodorsal nerve also originates from the posterior cord of the brachial plexus, making it an infraclavicular branch [1]. - It provides motor innervation to the latissimus dorsi muscle [1].
Question 2: All are true regarding brachial plexus injury, except:
- A. In Klumpke's palsy, Horner's syndrome may be present on the ipsilateral side
- B. Preganglionic lesions have a better prognosis than postganglionic lesions (Correct Answer)
- C. Erb's palsy causes paralysis of the abductors and external rotators of the shoulder
- D. Histamine test is useful to differentiate between the preganglionic and postganglionic lesions
Explanation: ***Preganglionic lesions have a better prognosis than postganglionic lesions*** - **Preganglionic lesions** involve the avulsion of nerve roots from the spinal cord, making nerve regeneration and surgical repair more challenging, therefore resulting in a **worse prognosis**. - In contrast, **postganglionic lesions** involve damage to the nerves distal to the dorsal root ganglion, which often allows for **spontaneous recovery** or more successful surgical intervention, leading to a better prognosis. *In Klumpke's palsy, Horner's syndrome may be present on the ipsilateral side* - **Klumpke's palsy** results from injury to the **lower trunk** of the brachial plexus (C8-T1), which can involve the sympathetic fibers that exit at T1. - Damage to these fibers can lead to **Horner's syndrome** (miosis, ptosis, anhydrosis) on the ipsilateral side. *Erb's palsy causes paralysis of the abductors and external rotators of the shoulder* - **Erb's palsy** involves injury to the **upper trunk** of the brachial plexus (C5-C6), affecting muscles innervated by these roots. - This results in paralysis of muscles such as the deltoid (abductor) and supraspinatus/infraspinatus (external rotators), leading to the characteristic "waiter's tip" posture. *Histamine test is useful to differentiate between the preganglionic and postganglionic lesions* - The **histamine test** (or histamine wheal test) is used to assess the integrity of peripheral unmyelinated postganglionic sympathetic fibers. - If a wheal and flare reaction occurs, it suggests intact postganglionic fibers, indicating a **preganglionic lesion**; absence of a reaction suggests a **postganglionic lesion**.
Question 3: Which spinal nerves are affected in Klumpke's paralysis?
- A. C3-C6
- B. C6-C7
- C. C8-T1 (Correct Answer)
- D. C4-C5
Explanation: ***C8-T1*** - **Klumpke's paralysis** results from damage to the lower trunks of the brachial plexus, specifically involving the **C8 and T1 spinal nerves**. - This injury often leads to a characteristic "claw hand" deformity due to paralysis of the **intrinsic hand muscles** and **flexors of the wrist and fingers**, along with potential **Horner's syndrome** if the T1 sympathetic fibers are affected. *C3-C6* - Involvement of these spinal nerves would typically affect the **upper and middle trunks of the brachial plexus**, leading to different patterns of paralysis, such as those seen in **Erb's palsy**. - This range does not specifically define Klumpke's paralysis, which is localized to the lower brachial plexus. *C6-C7* - Injury to these nerves primarily affects the **upper and middle trunks**, responsible for movements like shoulder abduction and elbow flexion. - This pattern of involvement is associated with different neurological deficits and is not characteristic of Klumpke's paralysis. *C4-C5* - Damage to these spinal nerves would primarily affect the **upper trunk of the brachial plexus**, leading to conditions like **Erb's palsy**. - This would result in paralysis of the shoulder and biceps muscles, distinct from the hand and wrist deficits seen in Klumpke's paralysis.
Question 4: Most common complication of celiac plexus block:
- A. Retroperitoneal hemorrhage
- B. Intra-arterial injection
- C. Pneumothorax
- D. Postural hypotension (Correct Answer)
Explanation: ***Postural hypotension*** - This is the most common complication due to the **vasodilation** that occurs from blocking the sympathetic nerves in the celiac plexus. - It results from the temporary loss of sympathetic tone, leading to a drop in blood pressure, especially upon standing. *Retroperitoneal hemorrhage* - While possible, a retroperitoneal hemorrhage is a less common complication compared to postural hypotension. - It typically results from **trauma to blood vessels** during needle insertion, especially in patients with coagulopathies. *Pneumothorax* - Pneumothorax is a rare complication of celiac plexus block, as the procedure generally avoids the thoracic cavity. - It can occur if the needle is advanced too far superiorly or laterally, piercing the **diaphragm and pleura**. *Intra-arterial injection* - Intra-arterial injection is an uncommon but serious complication that can lead to **ischemia or vascular spasm**. - This risk is mitigated by careful aspiration before injection and the use of imaging guidance.
Question 5: A 55-year-old male, known smoker, complains of calf pain while walking. He experiences calf pain while walking but can continue walking with effort. Which grade of claudication does this patient fall under?
- A. Grade I (Mild claudication)
- B. Grade II (Moderate claudication) (Correct Answer)
- C. Grade III (Severe claudication)
- D. Grade IV (Ischemic rest pain)
Explanation: ***Grade II (Moderate claudication)*** - **Grade II claudication** is characterized by **intermittent claudication** where the patient experiences pain while walking but can **continue walking with effort**. - This level of claudication reflects a moderate degree of peripheral arterial disease, where blood flow is sufficiently compromised to cause pain with exertion but not severe enough to force immediate cessation of activity. - The patient in this scenario can continue ambulation despite discomfort, which is the defining feature of this grade. *Grade I (Mild claudication)* - **Grade I claudication** involves discomfort or pain that the patient can **tolerate without significantly altering their gait or pace**. - In this stage, the pain is minimal, and the patient may perceive it as a dull ache or mild fatigue rather than true pain. - Walking can continue without significant effort or limitation. *Grade III (Severe claudication)* - **Grade III claudication** is marked by pain that is **severe enough to stop the patient from walking within a short distance** (typically less than 200 meters). - The pain forces the patient to rest and recover before they can resume walking. - This represents significant functional limitation in daily activities. *Grade IV (Ischemic rest pain)* - **Grade IV**, also known as **critical limb ischemia**, involves **pain even at rest**, especially in the feet or toes, often worsening at night when the limb is elevated. - This stage indicates severe arterial obstruction and is frequently associated with **ulcers, non-healing wounds, or gangrene**. - This represents advanced peripheral arterial disease requiring urgent intervention. **Note:** This grading system is a simplified clinical classification. The standard medical classifications for peripheral arterial disease are the **Fontaine classification** (Stages I-IV) and **Rutherford classification** (Categories 0-6).
Question 6: Which nerve is responsible for supplying the posterior semicircular canal?
- A. Superior vestibular nerve supplying posterior semicircular canal
- B. Superior vestibular nerve supplying anterior semicircular canal
- C. Inferior vestibular nerve supplying posterior semicircular canal (Correct Answer)
- D. Inferior vestibular nerve supplying anterior semicircular canal
Explanation: ***Inferior vestibular nerve supplying posterior semicircular canal*** - The **inferior vestibular nerve** innervates the **posterior semicircular canal** and the saccule. - This nerve transmits information about changes in **angular acceleration** in the plane of the posterior canal and **linear acceleration** from the saccule [1]. - This is the correct answer to the question. *Superior vestibular nerve supplying posterior semicircular canal* - This is **anatomically incorrect**. - The **superior vestibular nerve** innervates the **anterior (superior) and lateral (horizontal) semicircular canals** and the utricle. - It does **not** supply the posterior semicircular canal. *Superior vestibular nerve supplying anterior semicircular canal* - While this statement is **anatomically correct**, it does not answer the question. - The question specifically asks for the nerve supplying the **posterior semicircular canal**, not the anterior canal. - The superior vestibular nerve does supply the anterior semicircular canal, but this is irrelevant to the question asked. *Inferior vestibular nerve supplying anterior semicircular canal* - This is **anatomically incorrect**. - The **inferior vestibular nerve** supplies the **posterior semicircular canal** and the saccule only. - The **anterior semicircular canal** is innervated by the **superior vestibular nerve**, not the inferior vestibular nerve.
Question 7: Which of the following statements about the brachial plexus is true?
- A. Formed by spinal nerves C5-C8 and T1 (Correct Answer)
- B. The radial nerve arises from the medial cord of the brachial plexus.
- C. Injury to the brachial plexus may occur during shoulder dystocia, often affecting the lower trunk.
- D. The lower trunk is a common site of injury in brachial plexus trauma.
Explanation: ***Formed by spinal nerve C5- C8 and T1*** - The brachial plexus is indeed formed by the **ventral rami** of spinal nerves **C5, C6, C7, C8, and T1**. - These roots then arrange into **trunks, divisions, cords, and branches** to innervate the upper limb. *The radial nerve arises from the medial cord of the brachial plexus.* - The **radial nerve** is the largest branch of the **posterior cord** of the brachial plexus, not the medial cord. - The **ulnar nerve** and medial root of the median nerve arise from the medial cord. *Injury to the brachial plexus may occur during shoulder dystocia, often affecting the lower trunk.* - **Shoulder dystocia** typically causes injury to the **upper roots (C5-C6)**, leading to **Erb's palsy**, not the lower trunk. - Injury to the lower trunk (C8-T1) is more commonly associated with **Klumpke's palsy**, which is rarer and often due to traction on an abducted arm. *The lower trunk is a common site of injury in brachial plexus trauma.* - The **upper trunk (C5-C6)** is the most common site of injury in brachial plexus trauma, especially in conditions like **Erb's palsy**. - While the lower trunk can be injured, it is much less frequent than upper trunk injuries.
Question 8: 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 9: The fascia around the nerve bundle of the brachial plexus is derived from?
- A. Superficial cervical fascia
- B. Pretracheal fascia
- C. Investing layer
- D. Prevertebral fascia (Correct Answer)
Explanation: ***Prevertebral fascia*** - The **brachial plexus** and the subclavian artery emerge between the **anterior and middle scalene muscles**. - As they exit the neck, they become surrounded by a tubular sheath derived from the **prevertebral fascia**, forming the **axillary sheath**. *Pretracheal fascia* - This fascia surrounds the **trachea**, esophagus, thyroid gland, and infrahyoid muscles. - It lies anterior to the vertebral column and has no direct involvement in forming the sheath around the brachial plexus. *Investing layer* - The investing layer of deep cervical fascia encircles the entire neck, enclosing the **sternocleidomastoid** and **trapezius muscles**. - While it's a superficial layer of deep cervical fascia, it does not specifically form the immediate sheath around the brachial plexus. *Superficial cervical fascia* - This layer is synonymous with the **subcutaneous tissue** of the neck and contains the platysma muscle. - It is superficial to the deep cervical fascia layers and does not contribute to the fibrous sheath of the brachial plexus.
Question 10: Adson's test is positive in -
- A. Cervical rib (Correct Answer)
- B. Cervical spondylosis
- C. Cervical fracture
- D. Cervical dislocation
Explanation: ***Cervical rib*** - **Adson's test** assesses for **thoracic outlet syndrome (TOS)**, which can be caused by a cervical rib compressing the **subclavian artery** or **brachial plexus**. - A positive test occurs when the radial pulse diminishes or disappears upon specific head and arm maneuvers, indicating neurovascular compression. *Cervical spondylosis* - This condition involves **degenerative changes** in the cervical spine, such as bone spurs and disc herniation. - While it can cause neurological symptoms, it typically does not lead to a positive Adson's test, as the compression site is different from that assessed by the test. *Cervical fracture* - A cervical fracture is a **traumatic injury** to the bones of the neck. - Adson's test is not indicated for diagnosing fractures and performing it could exacerbate the injury. *Cervical dislocation* - Cervical dislocation is a severe injury where cervical vertebrae are **displaced from their normal alignment**. - Similar to fractures, Adson's test is not appropriate for diagnosing or evaluating dislocations and carries a risk of further injury.
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