Upper Limb Practice Questions

Q: What is true about the blood supply of the scaphoid bone?

Major supply from the dorsal surface. The scaphoid is the most commonly fractured carpal bone [1], and its unique vascular anatomy is a high-yield topic for NEET-PG. [2] ### **Explanation of the Correct Answer** The scaphoid receives approximately **70–80% of its blood supply from the dorsal carpal branch of the radial artery**. These vessels enter the bone through the **dorsal ridge** (non-articular surface) and supply the proximal two-thirds of the bone via **retrograde flow**. This makes the dorsal surface the primary site of vascular entry. ### **Analysis of Incorrect Options** * **Option A:** The blood supply is derived almost exclusively from the **radial artery**, not the ulnar artery. * **Option B:** While some minor vessels enter the distal tubercle on the volar (ventral) side, the **major** supply is dorsal. * **Option C (Correct):** As stated, the dorsal carpal branch of the radial artery is the dominant source. * **Option D:** The blood supply to the proximal pole is **retrograde** (distal-to-proximal). There is no direct antegrade supply to the proximal pole, which is why it is highly susceptible to ischemia. [2] ### **Clinical Pearls for NEET-PG** * **Retrograde Blood Flow:** Because the vessels enter distally and travel proximally, a fracture at the **waist of the scaphoid** often severs the blood supply to the proximal fragment. [1] * **Avascular Necrosis (AVN):** The proximal pole is the most common site for AVN (Preiser’s disease is idiopathic AVN, but post-traumatic AVN is more common). [2] * **Anatomical Snuffbox:** Tenderness here is pathognomonic for a scaphoid fracture. * **Non-union:** Due to the precarious retrograde supply, scaphoid fractures have a high risk of non-union and delayed healing. [2]

Q: In ulnar nerve injury in the arm, all of the following are seen except?

Adduction of thumb. **Explanation:** The ulnar nerve (C8-T1) is the "musician’s nerve," responsible for fine motor movements of the hand. To solve this question, one must understand the muscular innervation of the thumb. **Why "Adduction of thumb" is the correct answer:** The **Adductor Pollicis** muscle is innervated by the deep branch of the ulnar nerve [1]. In an ulnar nerve injury, this muscle is paralyzed, leading to a **loss of thumb adduction** [1]. Patients compensate for this loss by flexing the thumb at the interphalangeal joint (using the Flexor Pollicis Longus, innervated by the median nerve) when asked to grip a piece of paper—a clinical sign known as **Froment’s Sign**. Therefore, adduction is lost, not preserved. **Analysis of Incorrect Options:** * **Hypothenar atrophy:** The ulnar nerve supplies the hypothenar muscles (Abductor, Flexor, and Opponens digiti minimi). Denervation leads to visible wasting of the medial palm. * **Loss of sensation (medial 1/3):** The ulnar nerve provides sensory innervation to the medial one and a half fingers and the corresponding medial third of the palm and dorsum of the hand. * **Claw hand:** This occurs due to paralysis of the medial two lumbricals and all interossei [1]. This leads to hyperextension at the MCP joints and flexion at the IP joints of the 4th and 5th digits. **High-Yield Clinical Pearls for NEET-PG:** * **Ulnar Paradox:** A high lesion (at the elbow) results in a *less* prominent clawing than a low lesion (at the wrist) because the Flexor Digitorum Profundus (medial half) is also paralyzed in high lesions, reducing the flexion at the IP joints. * **Innervation Rule:** The ulnar nerve supplies all intrinsic muscles of the hand **except** the "LOAF" muscles (Lateral two lumbricals, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis), which are supplied by the Median nerve [1].

Q: What is true about the pectoralis major muscle?

Its blood supply is by the thoracoacromial artery.. ### Explanation **1. Why Option C is Correct:** The **pectoralis major** is a large, fan-shaped muscle of the anterior chest wall. Its primary arterial supply is the **thoracoacromial artery** (specifically its pectoral branch), which is a branch of the second part of the axillary artery. Additional supply comes from the lateral thoracic artery. **2. Why the Other Options are Incorrect:** * **Option A:** The pectoralis major is an **adductor** and **medial (internal) rotator** of the humerus, not an abductor. Its clavicular head also helps in the flexion of the humerus. * **Option B:** While the internal thoracic artery provides some minor supply via its perforating branches, the **dominant** and primary blood supply is the thoracoacromial artery. In surgical contexts (like the PMMC flap), the thoracoacromial artery is the definitive pedicle. * **Option D:** The nerve supply of the pectoralis major is derived from the **medial and lateral pectoral nerves** (C5–T1), which arise from the brachial plexus [1]. The intercostal nerves supply the skin and intercostal muscles, not the pectoralis major [1]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Dual Nerve Supply:** It is one of the few muscles supplied by both the medial and lateral pectoral nerves (named based on their origin from the cords of the brachial plexus) [1]. * **Poland Syndrome:** A congenital condition characterized by the unilateral absence of the pectoralis major, often associated with syndactyly. * **Surgical Flap:** The Pectoralis Major Myocutaneous (PMMC) flap is a "workhorse" flap in reconstructive head and neck surgery, based on the **pectoral branch of the thoracoacromial artery**. * **Insertion:** It inserts into the **lateral lip of the bicipital groove** of the humerus. (Mnemonic: "A Lady between two Majors" — Latissimus dorsi in the floor, Pectoralis major on the lateral lip, and Teres major on the medial lip).

Q: In Erb's palsy, what is the typical position of the affected limb?

Extended, medially rotated, pronated. ### Explanation **Erb’s Palsy** (Waiter’s Tip or Policeman’s Tip deformity) results from an injury to the **upper trunk of the brachial plexus (C5-C6)**, most commonly due to birth trauma or a fall on the shoulder [1]. #### Why Option C is Correct: The deformity is caused by the loss of function in specific muscle groups, leading the limb to take a position dictated by the unopposed action of the surviving muscles: 1. **Extended Elbow:** Loss of the **Biceps brachii** and **Brachialis** (flexors). 2. **Medially Rotated Arm:** Loss of the **Supraspinatus** and **Infraspinatus** (lateral rotators), leaving the subscapularis and pectoralis major unopposed. 3. **Pronated Forearm:** Loss of the **Biceps brachii** (the powerful supinator) and **Supinator** muscle. 4. **Adducted Shoulder:** Loss of the **Deltoid** and **Supraspinatus** (abductors). #### Why Other Options are Incorrect: * **Options A & B (Laterally rotated):** Incorrect because the lateral rotators (Infraspinatus/Teres minor) are paralyzed; the arm is pulled medially by the intact subscapularis. * **Options B & D (Supinated):** Incorrect because the primary supinator (Biceps) is paralyzed; the forearm remains fixed in pronation. #### High-Yield Clinical Pearls for NEET-PG: * **Site of Injury:** **Erb’s Point** (junction of 6 nerves: C5, C6 roots; Suprascapular n.; N. to Subclavius; Anterior and Posterior divisions of the upper trunk). * **Nerves Involved:** Suprascapular nerve, Axillary nerve, and Musculocutaneous nerve [1]. * **Sensory Loss:** A small area of anesthesia over the **lower part of the deltoid** (regimental badge area). * **Reflexes:** The **Biceps and Supinator reflexes** are characteristically lost. * **Contrast:** Compare with **Klumpke’s Paralysis (C8-T1)**, which presents with a "Claw Hand" and potential Horner’s Syndrome.

Question 1

What is true about the blood supply of the scaphoid bone?

Accepted Answer

Major supply from the dorsal surface

Answer

Mainly through the ulnar artery

Answer

Major supply from the ventral surface

Answer

Proximal supply in antegrade fashion

Question 2

In ulnar nerve injury in the arm, all of the following are seen except?

Accepted Answer

Adduction of thumb

Answer

Hypothenar atrophy

Answer

Loss of sensation of the medial one-third of the hand

Answer

Claw hand

Question 3

What is true about the pectoralis major muscle?

Accepted Answer

Its blood supply is by the thoracoacromial artery.

Answer

It is an abductor and internal rotator of the shoulder.

Answer

Its blood supply is by the perforating branch of the internal thoracic artery.

Answer

Its nerve supply is by the intercostal artery.

Question 4

Loss of extension of the little finger and hypothenar atrophy are seen in an injury of which nerve?

Accepted Answer

Ulnar nerve

Answer

Posterior interosseous nerve

Answer

Radial trunk

Answer

Median nerve

Question 5

In Erb's palsy, what is the typical position of the affected limb?

Accepted Answer

Extended, medially rotated, pronated

Answer

Extended, laterally rotated, pronated

Answer

Extended, laterally rotated, supinated

Answer

Extended, medially rotated, supinated

Upper Limb — MCQs

Upper Limb — MCQs

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