Pectoral Region and Axilla — MCQs
Which muscle is affected in winging of the scapula?
What is the vertical extent of the breast along the midclavicular line?
Fascia around the nerve bundles of the brachial plexus is derived from which structure?
Which of the following is not a branch of the cervical plexus?
The largest branch of the axillary artery is which one of the following?
In obstruction of the second part of the axillary artery, the anastomosis between which arteries will maintain the blood supply to the upper limb?
Lesions affecting the terminal duct lobular unit (TDLU) in breast are all except
The lateral boundary of the cubital fossa is formed by
A patient is found to have a melanoma originating in the skin of the left forearm. After removal of the tumor from the forearm, all axillary lymph nodes lateral to the medial edge of the pectoralis minor muscle are removed. Which axillary nodes would not be removed?
Which bone connects the sternum to the scapula?
Pectoral Region and Axilla Indian Medical PG Practice Questions and MCQs
Question 1: Which muscle is affected in winging of the scapula?
- A. Latissimus dorsi
- B. Subscapularis
- C. Serratus anterior (Correct Answer)
- D. Teres minor
Explanation: ***Serratus anterior*** - Damage to the **long thoracic nerve**, which innervates the serratus anterior muscle, leads to paralysis of this muscle. - The **serratus anterior** is crucial for holding the scapula against the thoracic wall and for **scapular protraction**, so its weakness results in a prominent medial border of the scapula, known as **winging**. *Latissimus dorsi* - The **latissimus dorsi** is an important muscle for **adduction**, **extension**, and **internal rotation** of the shoulder. - Injury to this muscle or its innervation (thoracodorsal nerve) primarily affects these movements, not causing scapular winging. *Subscapularis* - The **subscapularis** is part of the rotator cuff and is primarily involved in **internal rotation** of the humerus. - Dysfunction of the subscapularis would manifest as weakness in internal rotation and possibly shoulder instability, but not scapular winging. *Teres minor* - The **teres minor** is another rotator cuff muscle responsible for **external rotation** and stabilization of the humeral head. - Weakness of the teres minor would impair external rotation and contribute to rotator cuff dysfunction, but it is not associated with scapular winging.
Question 2: What is the vertical extent of the breast along the midclavicular line?
- A. 1st to 3rd rib
- B. 2nd to 6th rib (Correct Answer)
- C. 5th to 8th rib
- D. 7th to 10th rib
Explanation: ***2nd to 6th rib*** - The **breast extends vertically** from the 2nd to the 6th rib in the midclavicular line. - This anatomical range is consistent with the typical location of **mammary tissue** in adult females. *1st to 3rd rib* - This range is too high and does not encompass the full vertical extent of the **normal breast tissue**. - The majority of the breast tissue, especially the more inferior portion, would be missed with this description. *5th to 8th rib* - This range is too low and does not include the superior extent of the **breast tissue**, which typically reaches the 2nd or 3rd rib. - While some inferior breast tissue might be in this range, it's not the complete vertical span. *7th to 10th rib* - This range is significantly too low and would describe an area primarily composed of **abdominal wall** or lower chest, rather than normal breast tissue. - It falls outside the anatomical boundaries of the **mammary gland**.
Question 3: Fascia around the nerve bundles of the brachial plexus is derived from which structure?
- A. Deep cervical fascia (Correct Answer)
- B. Pretracheal fascia
- C. Prelaryngeal fascia
- D. Carotid sheath
Explanation: ***Deep cervical fascia*** - The **brachial plexus** is enveloped by a fascial sheath known as the **axillary sheath**, which is a direct continuation of the **prevertebral layer of the deep cervical fascia**. - This fascial extension surrounds the neurovascular structures (subclavian/axillary artery and vein, and brachial plexus) as they exit the neck into the axilla. - The prevertebral fascia extends laterally from the cervical vertebrae to form this protective sheath. *Pretracheal fascia* - The **pretracheal fascia** (middle layer of deep cervical fascia) encloses the trachea, esophagus, and thyroid gland. - It lies anterior to the prevertebral fascia and does not extend laterally to surround the brachial plexus. *Prelaryngeal fascia* - This is not a standard anatomical term for a distinct fascial layer. - The larynx is covered by the investing layer and visceral components of the deep cervical fascia. *Carotid sheath* - The **carotid sheath** is a separate fascial compartment formed by contributions from all three layers of deep cervical fascia. - It encloses the common carotid artery, internal jugular vein, and vagus nerve—not the brachial plexus.
Question 4: Which of the following is not a branch of the cervical plexus?
- A. Suprascapular nerve (Correct Answer)
- B. Supraclavicular nerve
- C. Lesser occipital nerve
- D. Greater auricular nerve
Explanation: ***Suprascapular nerve*** - The **suprascapular nerve** originates from the **brachial plexus** (specifically the upper trunk), not the cervical plexus. - It primarily innervates the **supraspinatus** and **infraspinatus muscles**. *Lesser occipital nerve* - The **lesser occipital nerve** is a cutaneous branch of the **cervical plexus** (C2) that supplies the skin behind the ear. - It provides sensory innervation to the **scalp posterior to the auricle**. *Greater auricular nerve* - The **greater auricular nerve** is a branch of the **cervical plexus** (C2, C3) and provides sensory innervation to the skin over the parotid gland, mastoid process, and auricle. - It supplies sensation to the **external ear** and the **angle of the mandible**. *Supraclavicular nerve* - The **supraclavicular nerves** (C3, C4) are cutaneous branches of the **cervical plexus** that provide sensory innervation to the skin over the shoulder and upper chest. - They provide sensory innervation to the skin overlying the **clavicle** and the **pectoral region**.
Question 5: The largest branch of the axillary artery is which one of the following?
- A. Lateral thoracic artery
- B. Subscapular artery (Correct Answer)
- C. Superior thoracic artery
- D. Thoracoacromial artery
Explanation: ***Subscapular artery*** - The **subscapular artery** is the largest branch of the **axillary artery**, originating from its third part. - It gives off the **circumflex scapular artery** and the **thoracodorsal artery**, both of which supply muscles of the back and shoulder. *Lateral thoracic artery* - The **lateral thoracic artery** typically arises from the second part of the axillary artery and supplies the seratus anterior muscle and pectoral muscles. - While significant, it is generally smaller in caliber and distribution compared to the subscapular artery. *Superior thoracic artery* - The **superior thoracic artery** is usually the first and smallest branch of the **axillary artery**, arising from its first part. - It supplies the first two intercostal spaces and parts of the pectoralis major and minor muscles. *Thoracoacromial artery* - The **thoracoacromial artery** arises from the second part of the axillary artery and divides into pectoral, deltoid, acromial, and clavicular branches. - Although it has multiple branches, its overall size and vascular territory are less extensive than those of the subscapular artery.
Question 6: In obstruction of the second part of the axillary artery, the anastomosis between which arteries will maintain the blood supply to the upper limb?
- A. Dorsal scapular artery and subscapular artery (Correct Answer)
- B. Anterior and posterior circumflex humeral arteries
- C. Posterior circumflex humeral and circumflex scapular arteries
- D. Suprascapular and anterior circumflex humeral arteries
Explanation: Dorsal scapular artery and subscapular artery - This anastomosis forms part of the scapular anastomosis, which is crucial for collateral circulation around the shoulder joint and axillary artery. - The dorsal scapular artery (a branch of the subclavian artery, or occasionally the deep branch of the transverse cervical artery) connects with the subscapular artery (a branch of the third part of the axillary artery) and its circumflex scapular branch, bypassing the obstruction [1]. - This provides effective collateral circulation when the second part of the axillary artery is obstructed. Anterior and posterior circumflex humeral arteries - These arteries originate from the third part of the axillary artery and primarily supply the humeral head and surrounding shoulder joint [1]. - While they anastomose around the surgical neck of the humerus, they are distal to an obstruction in the second part of the axillary artery and do not provide an alternative blood supply around the obstruction. Posterior circumflex humeral and circumflex scapular arteries - The posterior circumflex humeral artery is distal to the obstruction, originating from the third part of the axillary artery. - Although the circumflex scapular artery (a branch of the subscapular artery) participates in the scapular anastomosis, its anastomosis with the posterior circumflex humeral artery would still be affected by an occlusion in the second part of the axillary artery as they are both branches distal to the obstruction. Suprascapular and anterior circumflex humeral arteries - The suprascapular artery (from the thyrocervical trunk) contributes to the scapular anastomosis and is proximal to the obstruction, supplying the supraspinatus and infraspinatus muscles. - However, the anterior circumflex humeral artery arises from the third part of the axillary artery and is distal to an obstruction in the second part, so their anastomosis would not effectively bypass the blockage.
Question 7: Lesions affecting the terminal duct lobular unit (TDLU) in breast are all except
- A. Intraductal papilloma
- B. Fibroadenoma
- C. Blunt duct adenosis
- D. Nipple adenoma (Correct Answer)
Explanation: ***Nipple adenoma*** - **Nipple adenomas** (or florid papillomatosis of the nipple) are uncommon benign epithelial proliferations that specifically originate from the **major lactiferous ducts in the nipple**. - They do **NOT** arise from the **terminal duct lobular unit (TDLU)**, which is the functional unit of the breast parenchyma located peripherally in the breast tissue. - This makes nipple adenoma the correct answer to this "EXCEPT" question. *Intraductal papilloma* - **Intraductal papillomas** can be classified as central (large duct) or peripheral types. - While large solitary papillomas arise from major ducts, **peripheral/multiple papillomas** commonly involve the **smaller ducts and TDLU**. - In the context of breast pathology classification, papillomas are generally considered among lesions that can affect the **TDLU and ductal system**. - They are characterized by **papillary growths** [1] with fibrovascular cores within the ductal lumen. *Fibroadenoma* - **Fibroadenomas** are biphasic benign tumors that classically arise from the **terminal duct lobular unit (TDLU)** [3]. - They result from proliferation of both the **stromal and epithelial components** within the TDLU [3]. - This is the most common benign breast tumor in young women. *Blunt duct adenosis* - **Blunt duct adenosis** is a benign proliferative lesion characterized by an increase in the number of **small ducts and acini within the lobules**, which are components of the TDLU [2]. - It represents proliferation of the **glandular tissue** arising from the TDLU. - It is commonly seen as part of **fibrocystic changes** of the breast [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, pp. 1052-1054. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 445-446. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 448-449.
Question 8: The lateral boundary of the cubital fossa is formed by
- A. Biceps
- B. Brachialis
- C. Brachioradialis (Correct Answer)
- D. Pronator teres
Explanation: ***Brachioradialis*** - The **brachioradialis muscle** forms the **lateral boundary** of the cubital fossa. - It originates from the lateral supracondylar ridge of the humerus and inserts on the distal radius. - This muscle is a **flexor of the elbow** and assists in bringing the forearm to a neutral position from pronation or supination. *Pronator teres* - The **pronator teres muscle** forms the **medial boundary** of the cubital fossa. - It originates from the medial epicondyle of the humerus and coronoid process of the ulna, inserting on the lateral surface of the radius. - This muscle is primarily responsible for **pronation of the forearm** and assists in elbow flexion. *Brachialis* - The **brachialis muscle** forms part of the **floor of the cubital fossa** (along with the supinator muscle). - It lies deep to the biceps brachii and inserts on the coronoid process and ulnar tuberosity. - It is a powerful **elbow flexor**, acting directly on the ulna. *Biceps* - The **biceps brachii** does not form a boundary of the cubital fossa. - Its **tendon passes through the fossa** as content, while the **bicipital aponeurosis** contributes to the roof. - The biceps is a major flexor and supinator of the forearm.
Question 9: A patient is found to have a melanoma originating in the skin of the left forearm. After removal of the tumor from the forearm, all axillary lymph nodes lateral to the medial edge of the pectoralis minor muscle are removed. Which axillary nodes would not be removed?
- A. Central lymph nodes
- B. Lateral lymph nodes
- C. Pectoral lymph nodes
- D. Apical lymph nodes (Correct Answer)
Explanation: ***Apical lymph nodes*** - The **apical lymph nodes** are located **medial** to the **medial border of the pectoralis minor muscle**, at the apex of the axilla (Level III) [2]. - Since the removal was restricted to nodes **lateral** to the medial edge of the pectoralis minor, the apical nodes would **not be removed**. - These nodes receive lymph from all other axillary node groups and drain into the subclavian lymphatic trunk. *Central lymph nodes* - **Central lymph nodes** are located **posterior to (deep to)** the pectoralis minor muscle, within the axillary fat (Level II) [1]. - They lie between the medial and lateral borders of the pectoralis minor and are generally considered to be **lateral** to the medial edge of the pectoralis minor, so they would be removed in this dissection. *Lateral lymph nodes* - **Lateral (humeral) lymph nodes** are found along the **lateral border** of the axilla, following the axillary vein (Level I) [1]. - These nodes drain the majority of the upper limb and are clearly **lateral** to the pectoralis minor muscle, so hese would be included in the dissection. *Pectoral lymph nodes* - **Pectoral (anterior) lymph nodes** lie along the **lower border** of the pectoralis minor muscle and the lateral thoracic vessels (Level I). - They receive lymph from the anterior and lateral thoracic walls and much of the breast. - These nodes are located **lateral** to the medial edge of the pectoralis minor and would be removed as part of the surgical procedure.
Question 10: Which bone connects the sternum to the scapula?
- A. Clavicle (Correct Answer)
- B. First rib
- C. Manubrium
- D. Second rib
Explanation: ***Clavicle*** - The **clavicle**, or collarbone, is the only bone that directly connects the **axial skeleton** (via the sternum) to the **appendicular skeleton** (via the scapula). - It articulates medially with the **manubrium** of the sternum at the sternoclavicular joint and laterally with the **acromion** of the scapula at the acromioclavicular joint. *First rib* - The **first rib** articulates with the **manubrium** of the sternum but does not connect directly to the scapula. - Its primary role is to form part of the **thoracic cage**, protecting internal organs. *Manubrium* - The **manubrium** is the superior part of the **sternum** and articulates with the clavicles and the first two ribs. - It does not directly connect to the **scapula**; rather, the clavicle mediates this connection. *Second rib* - The **second rib** articulates with both the **manubrium** and the body of the sternum at the **sternal angle**. - Like the first rib, it is part of the **thoracic cage** and does not directly connect to the scapula.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free