Joints of Upper Limb — MCQs
In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:
In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:
Painless burn in hand is seen in:
Differential cyanosis is seen in –
What is the characteristic upper limb deformity seen in Erb's palsy?
Which of the following statements about the brachial plexus is true?
Where to look for pre-ductal O2 saturation in PDA in a 3-minute-old infant?
Superior vena cava is derived from:
Pronator drift is a sign of -
Assessment of pre-ductal O₂ saturation in PDA of a 3-minute-old infant is done at?
Joints of Upper Limb Indian Medical PG Practice Questions and MCQs
Question 1: In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:
- A. Coracoacromial ligament
- B. Costoclavicular ligament
- C. Coracoclavicular ligament (Correct Answer)
- D. Coracohumeral ligament
Explanation: ***Coracoclavicular ligament*** - The **coracoclavicular ligament** is a strong extra-articular ligament that connects the **coracoid process** of the scapula to the **inferior surface of the clavicle**, effectively suspending the scapula from the clavicle. - This ligament plays the **primary and crucial role** in transmitting forces from the upper limb through the **scapula and clavicle** to the **axial skeleton**, particularly during weight-bearing activities. - It is the key structure that maintains the connection between the upper limb (via scapula) and the axial skeleton (via clavicle). *Coracoacromial ligament* - The **coracoacromial ligament** forms the roof of the **subacromial space** and is primarily involved in preventing superior displacement of the humeral head. - It does not transmit the weight of the upper limb to the axial skeleton but rather protects structures within the subacromial space by forming the coracoacromial arch. *Costoclavicular ligament* - The **costoclavicular ligament** connects the **first rib to the clavicle**, stabilizing the **sternoclavicular joint**. - While it provides important stability at the sternoclavicular joint (part of the transmission pathway), the primary transmission of upper limb weight occurs through the **coracoclavicular ligament** connecting the scapula to clavicle. *Coracohumeral ligament* - The **coracohumeral ligament** connects the **coracoid process of the scapula** to the **greater and lesser tubercles of the humerus**, reinforcing the shoulder joint capsule. - It primarily helps support the weight of the upper limb when the arm is adducted, but it does not transmit this weight to the axial skeleton.
Question 2: In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:
- A. Coracoclavicular ligament (Correct Answer)
- B. Costoclavicular ligament
- C. Coracohumeral ligament
- D. Coracoacromial ligament
Explanation: ***Coracoclavicular ligament*** - The **coracoclavicular ligament** is a strong fibrous band connecting the **coracoid process** of the scapula to the **undersurface of the clavicle**, effectively suspending the scapula and upper limb from the clavicle. - This ligament is crucial as it transmits the **weight of the upper limb** to the clavicle, which then articulates with the axial skeleton (sternum) via the sternoclavicular joint. *Costoclavicular ligament* - This ligament connects the **first rib** to the **undersurface of the clavicle**, stabilizing the sternoclavicular joint. - While important for sternoclavicular joint stability, it primarily functions to limit **clavicular elevation** and does not directly transmit the primary weight of the upper limb to the axial skeleton in the same way as the coracoclavicular ligament. *Coracohumeral ligament* - The **coracohumeral ligament** is located in the shoulder joint, connecting the **coracoid process of the scapula** to the **greater and lesser tubercles of the humerus**. - Its main roles are to **strengthen the superior part of the joint capsule** and prevent inferior displacement of the humeral head, not to transmit the overall weight of the upper limb to the axial skeleton. *Coracoacromial ligament* - This ligament extends between the **coracoid process** and the **acromion of the scapula**, forming the **coracocromial arch**. - Its primary function is to protect the superior aspect of the **glenohumeral joint** and prevent superior displacement of the humeral head; it does not bear the weight of the upper limb to the axial skeleton.
Question 3: Painless burn in hand is seen in:
- A. SLE
- B. Mononeuritis multiplex
- C. Diabetes mellitus
- D. Syringomyelia (Correct Answer)
Explanation: ***Syringomyelia*** - Syringomyelia is characterized by a fluid-filled cavity (syrinx) within the **spinal cord**, which can damage nerve fibers responsible for pain and temperature sensation. - This damage leads to a **dissociated sensory loss**, where patients lose the ability to feel pain and temperature but retain touch and vibration, making them susceptible to **painless burns** or injuries. *SLE* - **Systemic lupus erythematosus (SLE)** is an autoimmune disease that can affect various organs, but it does not typically cause a dissociated sensory loss leading to painless burns. - Neurological manifestations in SLE are diverse, ranging from headaches to seizures, but they rarely involve selective loss of pain and temperature sensation in a way that causes painless burns. *Mononeuritis multiplex* - **Mononeuritis multiplex** involves damage to at least two distinct nerve areas, often causing pain, weakness, and sensory loss in a patchy distribution, but usually includes pain. - This condition is not typically characterized by a complete and selective loss of **pain and temperature sensation** in a way that would lead to painless burns without other significant sensory deficits. *Diabetes mellitus* - **Diabetic neuropathy** commonly causes sensory loss, often a "stocking-glove" distribution, which can lead to painless injuries due to reduced pain sensation. - However, diabetic neuropathy primarily affects **small fiber nerves** and is more generalized, unlike the more selective **dissociated sensory loss** seen in syringomyelia that specifically explains painless burns.
Question 4: Differential cyanosis is seen in –
- A. PDA (Correct Answer)
- B. VSD
- C. TAPVC
- D. TGV
Explanation: ***PDA*** - **Differential cyanosis** occurs in **patent ductus arteriosus (PDA)** with severe **pulmonary hypertension** leading to **right-to-left shunting** (reversed PDA/Eisenmenger syndrome). - Since the PDA connects the pulmonary artery to the descending aorta **below the origin of the left subclavian artery**, deoxygenated blood from the pulmonary artery perfuses the **lower body** (lower limbs cyanosed) while the **upper body** receives oxygenated blood from the left ventricle (upper limbs and head pink). - This creates the classic pattern: **pink upper extremities, cyanosed lower extremities**. *VSD* - A **ventricular septal defect (VSD)** typically causes **left-to-right shunting**, leading to increased pulmonary blood flow, and does not result in differential cyanosis. - While VSD can eventually lead to **Eisenmenger syndrome** with **generalized cyanosis** (affecting entire body uniformly), it does not specifically cause differential cyanosis because the shunt occurs before blood reaches the systemic circulation. *TAPVC* - **Total anomalous pulmonary venous connection (TAPVC)** is a congenital heart defect where all pulmonary veins drain into the systemic venous circulation, leading to **generalized cyanosis** as mixed blood is delivered throughout the body. - It does not present with differential cyanosis, as the venous return is uniformly deoxygenated and mixes before systemic distribution. *TGV* - **Transposition of the great vessels (TGV)** involves the aorta originating from the right ventricle and the pulmonary artery from the left ventricle, creating two parallel circulations. - This condition presents with **severe generalized cyanosis** shortly after birth unless there is mixing between the two circulations (via PDA, ASD, or VSD), and does not cause differential cyanosis.
Question 5: What is the characteristic upper limb deformity seen in Erb's palsy?
- A. Adduction and lateral rotation of arm
- B. Adduction and medial rotation of arm (Correct Answer)
- C. Abduction and lateral rotation of arm
- D. Abduction and medial rotation of arm
Explanation: ***Adduction and medial rotation of arm*** - Erb's palsy, resulting from injury to the **upper brachial plexus** (C5-C6 nerve roots), primarily affects the **deltoid**, **supraspinatus**, **infraspinatus**, and **biceps** muscles. - The unopposed action of unaffected muscles, such as the **pectoris major** and **latissimus dorsi**, leads to the characteristic **waiter's tip position**, involving **adduction** and **medial rotation** of the arm. *Adduction and lateral rotation of arm* - This position would imply weakness of the **pectoralis major** and **latissimus dorsi** and stronger activity of the **infraspinatus** and **teres minor**, which is contrary to the muscle deficits in Erb's palsy. - **Lateral rotation** of the arm is typically impaired in Erb's palsy due to weakness of the **infraspinatus** and **teres minor**. *Abduction and lateral rotation of arm* - **Abduction** is severely impacted in Erb's palsy due to paralysis of the **deltoid** and **supraspinatus**. - This position would suggest intact function of muscles that are explicitly weakened or paralyzed in Erb's palsy. *Abduction and medial rotation of arm* - While **medial rotation** can be a component of the deformity, **abduction** is a movement that is significantly impaired in Erb's palsy, making this option incorrect. - The inability to abduct the arm is a hallmark of the condition due to weakness of the **deltoid** and **supraspinatus**.
Question 6: 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 7: Where to look for pre-ductal O2 saturation in PDA in a 3-minute-old infant?
- A. Left Upper Limb
- B. Left Lower Limb
- C. Right Upper Limb (Correct Answer)
- D. Right Lower Limb
Explanation: ***Right Upper Limb*** - Pre-ductal oxygen saturation refers to the oxygen saturation in blood before it mixes with deoxygenated blood through the **ductus arteriosus**. The **right upper limb** (specifically, the right hand) receives blood directly from the **brachiocephalic artery**, which branches from the aortic arch **before the ductus arteriosus connection**, making it the ideal site for pre-ductal saturation measurement. - This measurement is critical in screening for **critical congenital heart disease (CCHD)**, especially for conditions like **patent ductus arteriosus (PDA)**, as it reflects systemic oxygenation independent of ductal shunting. - Standard CCHD screening protocols recommend measuring oxygen saturation on the **right hand** for pre-ductal values. *Left Upper Limb* - The **left upper limb** receives blood from the **left subclavian artery**, which branches from the aortic arch. While this is technically before the ductus arteriosus anatomically, it is **not the standard site** for pre-ductal measurement. - The **right upper limb remains the gold standard** because it definitively receives blood before any potential ductal mixing. *Left Lower Limb* - The **left lower limb** receives blood from the **descending aorta after the ductus arteriosus** (post-ductal flow). - Therefore, oxygen saturation measured in the left lower limb will reflect mixed blood after ductal shunting, making it a **post-ductal measurement**, not pre-ductal. - Used as a comparison site to detect differential cyanosis. *Right Lower Limb* - Similar to the left lower limb, the **right lower limb** receives blood from the **descending aorta after the ductus arteriosus (post-ductal)**. - Any oxygen saturation reading from the lower limbs would be considered post-ductal and may reflect desaturation due to a right-to-left shunt through the PDA in conditions like **persistent pulmonary hypertension of the newborn (PPHN)**.
Question 8: Superior vena cava is derived from:
- A. Aortic arch
- B. Pharyngeal arch
- C. Vitelline vein
- D. Cardinal vein (Correct Answer)
Explanation: ***Cardinal vein*** - The **superior vena cava (SVC)** develops primarily from the **right anterior cardinal vein** and the common cardinal veins. [1] - The cardinal veins are the main venous drainage system in the early embryo, eventually forming the major veins of the adult. *Aortic arch* - The **aortic arches** are embryonic structures that contribute to the formation of the **major arteries**, such as the aorta, carotid arteries, and subclavian arteries. - They are involved in the arterial system, not the venous drainage of the superior vena cava. *Pharyngeal arch* - **Pharyngeal arches** are embryonic structures that give rise to various components of the **head and neck**, including skeletal structures, muscles, and nerves. - They are not directly involved in the formation of major blood vessels like the superior vena cava. *Vitelline vein* - The **vitelline veins** are embryonic vessels that drain blood from the **yolk sac** and contribute to the formation of the **portal system**, including the hepatic portal vein and sinusoids. - They are not involved in the development of the systemic veins like the superior vena cava, which drains the upper body.
Question 9: Pronator drift is a sign of -
- A. Dorsal syringomyelia
- B. UMN lesion of upper limb (Correct Answer)
- C. Carpal tunnel syndrome
- D. LMN lesion
Explanation: ***UMN lesion of upper limb*** - **Pronator drift** indicates a **pyramidal tract lesion** (Upper Motor Neuron lesion) affecting the contralateral corticospinal tract, resulting in weakness in supinator muscles. - The affected arm, when extended forward with palms up, will involuntarily pronate and drift downwards due to stronger arm pronator muscles and weaker arm supinator muscles. *Dorsal syringomyelia* - **Syringomyelia** can cause **dissociated sensory loss** (loss of pain and temperature sensation with preserved touch) and muscle weakness, but pronator drift is not a characteristic or primary sign. - It involves a **fluid-filled cyst** (syrinx) within the spinal cord, primarily affecting crossing spinothalamic fibers [1]. *Carpal tunnel syndrome* - This condition involves **compression of the median nerve** at the wrist, leading to **numbness, tingling**, and weakness in the hand muscles innervated by the median nerve. - It does not typically cause pronator drift, which is a sign of central nervous system involvement. *LMN lesion* - A **Lower Motor Neuron (LMN) lesion** causes **flaccid paralysis**, muscle atrophy, fasciculations, and **diminished or absent reflexes** [1]. - While it causes weakness, it does not typically manifest as pronator drift, which is indicative of a specific pattern of weakness seen in UMN lesions.
Question 10: Assessment of pre-ductal O₂ saturation in PDA of a 3-minute-old infant is done at?
- A. Left upper limb
- B. Left lower limb
- C. Right upper limb (Correct Answer)
- D. Right lower limb
Explanation: ***Right upper limb*** - Pre-ductal oxygen saturation is measured in the **right upper extremity** (right hand or wrist) because the blood supply to this limb comes from the **right subclavian artery**, which branches from the brachiocephalic trunk **before the ductus arteriosus**. - This ensures the reading reflects oxygenation of blood that has **not yet mixed with desaturated blood** from the pulmonary artery shunted through a patent ductus arteriosus (PDA). - In newborn screening for critical congenital heart disease, the right hand is the **gold standard site** for pre-ductal saturation measurement. *Left upper limb* - The left upper limb receives blood from the **left subclavian artery**, which branches from the aortic arch closer to the ductus arteriosus insertion point. - This makes it **less reliable** for obtaining a true pre-ductal reading, as it may be influenced by ductal flow patterns depending on PDA size and hemodynamics. - Therefore, the left arm is **not the preferred site** for pre-ductal saturation assessment. *Left lower limb* - Measuring oxygen saturation in the left lower limb provides a **post-ductal reading**. - This value represents blood that has **passed beyond the ductus arteriosus** and potentially mixed with desaturated pulmonary arterial blood if the PDA is patent. - This site is actually useful for **comparison with pre-ductal values** to assess for differential cyanosis. *Right lower limb* - Like the left lower limb, the right lower limb receives **post-ductal blood**. - This measures blood from the descending aorta that has passed the ductus arteriosus and potentially mixed with **deoxygenated blood** from the pulmonary circulation. - Post-ductal measurements are typically done at either foot.
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