Joints of Upper Limb — MCQs
In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:
Fracture shaft of humerus can cause damage to which of the following nerves?
Which muscle is mainly responsible for lateral rotation of the shoulder joint?
Which nerve is damaged in anterior dislocation of shoulder:
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?
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: Fracture shaft of humerus can cause damage to which of the following nerves?
- A. Ulnar nerve
- B. Radial nerve (Correct Answer)
- C. Axillary nerve
- D. Median nerve
Explanation: ***Radial nerve*** - The **radial nerve** runs in the **spiral groove** along the posterior aspect of the humerus shaft, making it highly susceptible to injury during a fracture in this region. - Damage can lead to **wrist drop** and impaired sensation over the posterior forearm and hand. *Ulnar nerve* - The **ulnar nerve** primarily runs along the medial epicondyle of the humerus, making it more vulnerable to injuries around the **elbow joint**, not typically the humeral shaft. - Injury to the ulnar nerve results in a characteristic **"claw hand"** deformity and sensory loss over the medial aspect of the hand. *Axillary nerve* - The **axillary nerve** wraps around the surgical neck of the humerus and is most commonly injured with **shoulder dislocations** or fractures involving the surgical neck, not the shaft. - Damage to the axillary nerve causes weakness in **deltoid abduction** and sensory loss over the lateral shoulder (regimental badge area). *Median nerve* - The **median nerve** travels more anteriorly and medially in the arm and is generally protected from direct injury in a mid-shaft humeral fracture. - Injury to the median nerve can cause a **"ape hand" deformity** and sensory loss over the radial aspect of the palm.
Question 3: Which muscle is mainly responsible for lateral rotation of the shoulder joint?
- A. Subscapularis
- B. Teres major
- C. Infraspinatus (Correct Answer)
- D. Biceps brachii
Explanation: ***Infraspinatus*** - The **infraspinatus** is a key rotator cuff muscle located in the posterior shoulder, primarily responsible for **external (lateral) rotation** of the humerus at the shoulder joint. - It works in conjunction with the **teres minor** to perform this action, as well as to stabilize the humeral head within the glenoid cavity. *Subscapularis* - The **subscapularis** is an anterior rotator cuff muscle that primarily causes **internal (medial) rotation** of the shoulder joint, the opposite action of lateral rotation. - It also aids in adduction and stabilization of the shoulder. *Teres major* - The **teres major** muscle primarily contributes to **adduction**, **extension**, and **internal rotation** of the humerus, not lateral rotation. - It is often referred to as the "lat's little helper" due to its similar actions to the latissimus dorsi. *Biceps brachii* - The **biceps brachii** muscle is primarily involved in **flexion of the elbow** and **supination of the forearm**. - While it has a weak role in shoulder flexion, it does not significantly contribute to lateral rotation of the shoulder joint.
Question 4: Which nerve is damaged in anterior dislocation of shoulder:
- A. Median
- B. Axillary (Correct Answer)
- C. Musculocutaneous
- D. Radial
Explanation: **Axillary** - The **axillary nerve** wraps around the surgical neck of the humerus, which is vulnerable to injury during an **anterior shoulder dislocation**. - Damage to the axillary nerve can lead to **deltoid muscle weakness** (impaired shoulder abduction) and sensory loss over the **regimental badge area**. *Median* - The **median nerve** is typically not directly affected by an anterior shoulder dislocation. - It supplies most of the flexor muscles of the forearm and thenar eminence, and sensory innervation to the lateral palm and digits. *Musculocutaneous* - The **musculocutaneous nerve** innervates the biceps brachii and brachialis muscles, and provides sensory innervation to the lateral forearm. - It is less commonly injured in a shoulder dislocation compared to the axillary nerve. *Radial* - The **radial nerve** typically runs posterior to the humerus in the spiral groove and is more commonly injured in mid-shaft humeral fractures rather than shoulder dislocations. - Damage to the radial nerve manifests as **wrist drop** and sensory loss over the posterior forearm and hand.
Question 5: 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 6: 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 7: 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 8: 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 9: 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 10: 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)**.
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