Chapter: Thorax & Mediastinum
Topic: Sternum & Xiphoid Process
Subtopic: Ossification and Fusion of Xiphoid
Keyword Definitions:
Xiphoid process: Small inferior cartilaginous/ossified part of the sternum, variable in shape and fusion time.
Sternum: Midline anterior thoracic bone formed by manubrium, body, and xiphoid process.
Ossification: Process of cartilage turning into bone during growth and maturation.
Fusion: The bony union of xiphoid with sternal body, completes skeletal continuity.
Epigastrium: Region overlying xiphoid; clinical landmark for subxiphoid procedures.
Lead Question - 2014
Xiphoid fuses with sternum by what age ?
a) 30 years
b) 35 years
c) 40 years
d) 45 years
Explanation: The xiphoid process usually ossifies and fuses with the sternal body in middle adulthood; most commonly fusion is complete by around forty years of age. Clinically this is relevant for subxiphoid landmarks and variations; correct answer: c) 40 years.
Guessed Questions for NEET PG (1–10)
1) The xiphoid process is derived from which embryologic tissue?
a) Neural crest
b) Paraxial mesoderm (somites)
c) Lateral plate mesoderm (somatic layer)
d) Endoderm
Explanation: The sternum, including the xiphoid, arises from paired sternal bars derived from the somatic (lateral plate) mesoderm that fuse in the midline during embryogenesis. This explains congenital sternal defects. Correct answer: c) Lateral plate mesoderm (somatic layer).
2) Which structure lies immediately posterior to the xiphoid process in the epigastrium?
a) Right lobe of liver
b) Left lobe of liver
c) Stomach
d) Transverse colon
Explanation: The xiphoid process overlies the superior surface of the left lobe of the liver and the epigastric region; care is required for subxiphoid approaches. In trauma, xiphoid fractures risk liver injury. Correct answer: b) Left lobe of liver.
3) Clinical: A patient has a sharp midline inferior sternal pain after CPR with lower sternal tenderness. Likely injury is to the:
a) Manubrium
b) Sternal body
c) Xiphoid process
d) Costal cartilage
Explanation: Forceful chest compressions can fracture or displace the xiphoid process, causing localized inferior sternal pain and tenderness; this may also injure underlying liver. Clinical suspicion after CPR should include xiphoid injury. Correct answer: c) Xiphoid process.
4) Which of the following muscles attaches to the xiphoid process?
a) Rectus abdominis
b) Transversus thoracis
c) Diaphragm
d) All of the above
Explanation: Multiple muscles anchor to the xiphoid: rectus abdominis fibers attach inferiorly, the diaphragm has a central tendon near it, and transversus thoracis attaches to lower sternum. These attachments explain pain referral patterns. Correct answer: d) All of the above.
5) Straight anatomy: The sternal angle (Angle of Louis) is at the junction of which parts?
a) Manubrium and body of sternum
b) Body and xiphoid process
c) Manubrium and clavicle
d) Xiphoid and costal cartilage
Explanation: The sternal angle is the junction between the manubrium and the body of the sternum and corresponds to the level of the second costal cartilage and the T4/T5 vertebral level—important surface landmark. Correct answer: a) Manubrium and body of sternum.
6) Clinical: During subxiphoid pericardial window, the surgeon should avoid which structure immediately deep to the xiphoid?
a) Pericardium and right ventricle
b) Stomach body
c) Inferior vena cava
d) Splenic flexure
Explanation: A subxiphoid approach reaches the pericardium lying deep and slightly posterior to xiphoid; care avoids injuring the right ventricle and pericardial sac. Knowledge of xiphoid anatomy reduces cardiac injury risk. Correct answer: a) Pericardium and right ventricle.
7) Which ossification pattern is common for the xiphoid in adults?
a) Remains cartilaginous throughout life
b) Ossifies and fuses variably, sometimes bifid or perforated
c) Always fuses by puberty
d) Is absent congenitally in all cases
Explanation: The xiphoid shows variable ossification: it may remain cartilaginous for years, ossify and fuse in middle age, or present anatomical variants like bifid or foraminal xiphoid. These variants can mimic epigastric masses on exam. Correct answer: b) Ossifies and fuses variably, sometimes bifid or perforated.
8) Straight anatomy: Which costal cartilages articulate directly with the body of the sternum (not xiphoid)?
a) 1st and 2nd
b) 2nd to 7th
c) 7th only
d) 8th to 10th
Explanation: The body of the sternum articulates with the 2nd to 7th costal cartilages. The 1st joins the manubrium, and 8th–10th fuse with each other indirectly to the sternum via the 7th. Correct answer: b) 2nd to 7th.
9) Clinical: A palpable bony projection below the sternum is found; xiphoid is angled anteriorly causing discomfort when pressed. This condition is called:
a) Xiphoidalgia
b) Costochondritis
c) Sternal cleft
d) Pectus excavatum
Explanation: Painful anterior projection or tenderness of xiphoid is termed xiphoidalgia (xiphoid syndrome). It may follow trauma, heavy lifting, or be positional; treatment is conservative or local steroid if persistent. Correct answer: a) Xiphoidalgia.
10) Straight anatomy: Fusion of xiphoid to sternal body is complete by which decade in most adults?
a) Second decade
b) Third decade
c) Fourth decade
d) Sixth decade
Explanation: While variable, most textbooks note xiphoid ossification and fusion to the sternal body occurs by the fourth decade of life. This is clinically relevant for forensic age estimation and surgical landmarks. Correct answer: c) Fourth decade (≈ 40 years).
Subtopic: Bronchopulmonary Segments
Keyword Definitions:
Bronchopulmonary segment: A distinct, functionally independent unit of a lung, supplied by its own bronchus and artery.
Lobes of lung: The right lung has three lobes, while the left has two lobes due to the position of the heart.
Segmental bronchus: The tertiary bronchus supplying each bronchopulmonary segment.
Pulmonary circulation: The blood flow between the heart and lungs for oxygenation.
Lead Question (2014):
Bronchopulmonary segments in right and left lungs respectively?
a) 9, 11
b) 11, 9
c) 10, 10
d) 8, 10
Explanation:
Each lung is divided into bronchopulmonary segments — 10 on the right and 8–10 on the left. These segments are separated by connective tissue and have independent blood supply and airways. Answer: c) 10, 10. This structural independence allows surgical removal of one segment without affecting others.
1)
Which bronchopulmonary segment of the right lung is most prone to aspiration of foreign bodies in a supine patient?
a) Apical
b) Posterior
c) Superior segment of lower lobe
d) Medial basal
In supine position, aspirated material often enters the superior segment of the right lower lobe due to the bronchus’ vertical orientation. Answer: c) Superior segment of lower lobe. This segment’s airway is a direct continuation of the bronchus, making it the commonest aspiration site.
2)
Which of the following statements about bronchopulmonary segments is true?
a) Veins lie within the segments
b) Arteries are intersegmental
c) Veins are intersegmental
d) Each segment shares arteries
Pulmonary veins are intersegmental, draining blood between segments, while arteries and bronchi are segmental. Answer: c) Veins are intersegmental. This distinct arrangement facilitates anatomical lung resections with minimal bleeding and segmental preservation during surgery.
3)
A 40-year-old man undergoes segmentectomy for localized bronchiectasis. Which feature helps the surgeon identify the diseased segment?
a) Segmental artery
b) Lymphatic drainage
c) Intersegmental veins
d) Bronchioles pattern
During surgery, intersegmental veins mark the boundaries between bronchopulmonary segments. Answer: c) Intersegmental veins. These veins run in connective tissue planes separating adjacent segments and act as important anatomical landmarks in lung segmental resections.
4)
How many bronchopulmonary segments are present in the left lung?
a) 9
b) 10
c) 8–10
d) 11
The left lung has 8–10 segments, commonly described as 8 due to fusion of some segments. Answer: c) 8–10. The left upper lobe segments are often fused, such as apicoposterior, leading to minor variations in segment counts among individuals.
5)
A patient with tuberculosis develops localized cavitation in the apical segment of the upper lobe. This infection affects which lung region?
a) Apex of right lower lobe
b) Apical segment of right upper lobe
c) Superior segment of middle lobe
d) Anterior basal segment
Tuberculosis commonly involves the apical segment of the upper lobe due to higher oxygen tension supporting bacterial growth. Answer: b) Apical segment of right upper lobe. This region has better aeration and is less perfused, creating a favorable environment for Mycobacterium tuberculosis.
6)
Each bronchopulmonary segment is supplied by which of the following?
a) Primary bronchus
b) Secondary bronchus
c) Tertiary bronchus
d) Terminal bronchiole
Each bronchopulmonary segment receives air through a tertiary or segmental bronchus, along with its own artery. Answer: c) Tertiary bronchus. This independent supply allows selective surgical removal of diseased segments without compromising adjacent lung areas or causing collapse.
7)
A 50-year-old chronic smoker presents with localized carcinoma confined to one bronchopulmonary segment. What type of surgical procedure is most suitable?
a) Lobectomy
b) Segmentectomy
c) Pneumonectomy
d) Wedge resection
Segmentectomy is removal of a bronchopulmonary segment while preserving the rest of the lobe. Answer: b) Segmentectomy. It is preferred when the lesion is confined to a single segment, ensuring preservation of maximal healthy lung tissue for respiratory function.
8)
Which structure separates bronchopulmonary segments from one another?
a) Elastic tissue
b) Connective tissue septa
c) Bronchial cartilage
d) Pleural folds
Each bronchopulmonary segment is separated by thin connective tissue septa containing intersegmental veins. Answer: b) Connective tissue septa. This separation permits selective surgical resection and defines the anatomic boundaries between individual functional lung units.
9)
A CT scan reveals consolidation limited to the medial basal segment of the right lower lobe. Which bronchus is affected?
a) Tertiary bronchus of right middle lobe
b) Medial basal segmental bronchus
c) Superior segmental bronchus
d) Posterior basal bronchus
Each segment has its own bronchus, and infection in the medial basal segment implies involvement of the medial basal segmental bronchus. Answer: b) Medial basal segmental bronchus. Such localized findings help radiologists identify exact sites of pulmonary infection or tumor growth.
10)
Which of the following statements about surgical importance of bronchopulmonary segments is correct?
a) They cannot be removed independently
b) Each segment has its own venous drainage
c) Segments are not functionally separate
d) They share bronchi among lobes
Each segment is functionally independent, supplied by its own bronchus and artery, allowing isolated removal. Answer: b) Each segment has its own venous drainage. This independence makes bronchopulmonary segmentation crucial in surgical planning and pulmonary disease localization.
Subtopic: Nerves of Thorax – Vagus and Phrenic Nerves
Keyword Definitions:
Vagus nerve: The tenth cranial nerve supplying parasympathetic fibers to thoracic and abdominal viscera.
Phrenic nerve: Arises from C3–C5 spinal roots, providing motor supply to the diaphragm.
Arch of aorta: The curved portion of the aorta giving rise to major arteries of the upper body.
Thoracic cavity: The chest space containing lungs, heart, and major vessels.
Lead Question (2014):
At the level of Arch of aorta, the relationship of left vagus nerve and left phrenic nerve?
a) Phrenic nerve anterior, vagus nerve posterior
b) Phrenic nerve posterior, vagus nerve anterior
c) Both in same plane anteroposteriorly
d) Variable in relationship
Explanation:
At the level of the aortic arch, the left phrenic nerve lies anterior to the left vagus nerve. Answer: a) Phrenic nerve anterior, vagus nerve posterior. The vagus nerve gives off the left recurrent laryngeal branch here, looping under the arch near the ligamentum arteriosum.
1)
The left recurrent laryngeal nerve hooks around which structure in the thorax?
a) Right subclavian artery
b) Arch of aorta
c) Pulmonary trunk
d) Left subclavian vein
The left recurrent laryngeal nerve hooks under the arch of the aorta, close to the ligamentum arteriosum. Answer: b) Arch of aorta. This explains why enlargement of mediastinal nodes or aneurysm can cause hoarseness due to recurrent laryngeal nerve compression.
2)
Which of the following nerves carries parasympathetic fibers to the thoracic and abdominal organs?
a) Phrenic nerve
b) Vagus nerve
c) Intercostal nerve
d) Sympathetic trunk
The vagus nerve provides parasympathetic supply to most thoracic and abdominal viscera. Answer: b) Vagus nerve. It slows heart rate, enhances gastrointestinal motility, and modulates glandular secretions through its autonomic fibers descending through the thorax into the abdomen.
3)
A 60-year-old man with hoarseness of voice is found to have an aortic aneurysm. Which nerve is most likely compressed?
a) Right phrenic
b) Left phrenic
c) Left recurrent laryngeal
d) Right vagus
An aortic arch aneurysm can compress the left recurrent laryngeal nerve as it loops beneath the arch. Answer: c) Left recurrent laryngeal. This causes hoarseness due to paralysis of the left vocal cord supplied by this branch of the vagus nerve.
4)
Phrenic nerve arises from which spinal segments?
a) C1–C3
b) C2–C4
c) C3–C5
d) C4–C6
The phrenic nerve originates mainly from cervical spinal nerves C3, C4, and C5. Answer: c) C3–C5. Its mnemonic “C3, 4, and 5 keep the diaphragm alive” emphasizes its importance in diaphragmatic contraction and maintenance of respiratory function.
5)
In thoracic surgery, which nerve must be carefully preserved to avoid diaphragmatic paralysis?
a) Vagus
b) Intercostal
c) Phrenic
d) Recurrent laryngeal
The phrenic nerve supplies the diaphragm motor fibers. Injury during surgery may cause hemidiaphragm paralysis and breathing difficulty. Answer: c) Phrenic. Its anterior location on the pericardium makes it vulnerable in cardiac or mediastinal procedures.
6)
The right vagus nerve passes posterior to which thoracic structure?
a) Right pulmonary root
b) Left pulmonary root
c) Arch of aorta
d) Pulmonary trunk
The right vagus nerve passes posterior to the right pulmonary root, whereas the left vagus lies anterior to the left root. Answer: a) Right pulmonary root. These relations are clinically important during lung and mediastinal surgeries to avoid nerve injury.
7)
A trauma patient presents with left hemidiaphragmatic paralysis. Which nerve is most likely injured?
a) Left vagus
b) Left phrenic
c) Right vagus
d) Left intercostal
Diaphragmatic paralysis on one side indicates phrenic nerve damage. Answer: b) Left phrenic. The phrenic nerve runs along the pericardium and can be injured by penetrating trauma or mediastinal compression, leading to elevation of the hemidiaphragm on chest X-ray.
8)
Which branch of the vagus nerve contributes to the cardiac plexus?
a) Superior cardiac branch
b) Recurrent laryngeal branch
c) Cervical cardiac branch
d) Pulmonary branch
The cervical cardiac branches of the vagus nerve descend to form part of the cardiac plexus, supplying parasympathetic fibers to the heart. Answer: c) Cervical cardiac branch. These fibers help decrease heart rate and modulate conduction through the atrioventricular node.
9)
A mediastinal tumor compressing the left phrenic nerve would cause which symptom?
a) Hoarseness
b) Dysphagia
c) Dyspnea on exertion
d) Loss of cough reflex
Compression of the left phrenic nerve results in paralysis of the left diaphragm, producing breathlessness on exertion. Answer: c) Dyspnea on exertion. This occurs because the affected hemidiaphragm fails to contract effectively, reducing lung expansion during inspiration.
10)
The vagus nerve forms which plexus on the esophagus before entering the abdomen?
a) Pulmonary plexus
b) Cardiac plexus
c) Esophageal plexus
d) Gastric plexus
Before passing through the diaphragm, the vagus nerve forms the esophageal plexus around the esophagus. Answer: c) Esophageal plexus. These fibers then reorganize into anterior and posterior vagal trunks that continue into the abdomen to supply visceral organs.
Subtopic: Pericardium and Pericardial Sinuses
Keyword Definitions:
Pericardium: The fibroserous sac enclosing the heart and the roots of great vessels.
Transverse pericardial sinus: A passage between arterial and venous ends of the heart formed by pericardial reflections.
Oblique pericardial sinus: A blind recess behind the left atrium formed by serous pericardium.
Great vessels: Major arteries and veins entering and leaving the heart, such as aorta, pulmonary trunk, SVC, and IVC.
Lead Question (2014):
Posterior to transverse pericardial sinus?
a) Aorta
b) Pulmonary trunk
c) SVC
d) Left atrium
Explanation:
The transverse pericardial sinus lies between the arterial and venous ends of the heart. Anteriorly it’s related to the aorta and pulmonary trunk, and posteriorly to the left atrium. Answer: d) Left atrium. Surgeons can pass a finger through this sinus during cardiac procedures to isolate great vessels.
1)
The transverse pericardial sinus is located between which two groups of structures?
a) Arteries and veins
b) Veins and nerves
c) Right and left atria
d) Aorta and pulmonary veins
The transverse sinus separates the arterial trunks (aorta and pulmonary trunk) anteriorly from the venous structures (SVC and left atrium) posteriorly. Answer: a) Arteries and veins. It forms due to pericardial reflections around the great vessels during cardiac development.
2)
During cardiac surgery, a surgeon can pass a finger behind which vessels through the transverse pericardial sinus?
a) Aorta and pulmonary trunk
b) SVC and IVC
c) Pulmonary veins
d) Coronary sinus
The surgeon passes a finger behind the aorta and pulmonary trunk through the transverse sinus, isolating them from venous structures. Answer: a) Aorta and pulmonary trunk. This helps in clamping or cannulating the great arteries during cardiopulmonary bypass surgery.
3)
Which of the following structures forms the anterior boundary of the transverse pericardial sinus?
a) SVC
b) Aorta and pulmonary trunk
c) Left atrium
d) Pulmonary veins
The transverse pericardial sinus is bounded anteriorly by the ascending aorta and pulmonary trunk. Answer: b) Aorta and pulmonary trunk. These arterial trunks pass upward from the heart and are covered by serous pericardium forming the anterior wall of this sinus.
4)
The oblique pericardial sinus is located posterior to which cardiac chamber?
a) Right atrium
b) Left atrium
c) Right ventricle
d) Left ventricle
The oblique pericardial sinus lies behind the left atrium, formed by reflection of serous pericardium around pulmonary veins and IVC. Answer: b) Left atrium. It forms a cul-de-sac where pericardial fluid may collect in pericardial effusion cases.
5)
A cardiac surgeon uses the transverse pericardial sinus to control blood flow. What vessels are clamped during this procedure?
a) SVC and IVC
b) Pulmonary veins
c) Aorta and pulmonary trunk
d) Coronary arteries
During cardiac surgery, the transverse sinus allows passage of a clamp behind the ascending aorta and pulmonary trunk to control arterial outflow. Answer: c) Aorta and pulmonary trunk. This isolation is vital during cardiopulmonary bypass procedures for safe cardiac manipulation.
6)
The pericardial cavity is located between which two layers?
a) Parietal and visceral pericardium
b) Fibrous and parietal pericardium
c) Serous and fibrous pericardium
d) Epicardium and myocardium
The pericardial cavity is the potential space between the parietal and visceral layers of serous pericardium containing lubricating fluid. Answer: a) Parietal and visceral pericardium. It allows frictionless cardiac movement within the pericardial sac during heartbeats.
7)
A pericardial effusion compressing the left atrium would most likely accumulate in which sinus?
a) Coronary sinus
b) Oblique pericardial sinus
c) Transverse pericardial sinus
d) Costomediastinal recess
Fluid tends to accumulate in the oblique pericardial sinus posterior to the left atrium, especially in supine patients. Answer: b) Oblique pericardial sinus. This collection can compress pulmonary veins and impair cardiac filling, producing symptoms of cardiac tamponade.
8)
Which pericardial sinus lies behind the left atrium and between the pulmonary veins?
a) Oblique pericardial sinus
b) Transverse pericardial sinus
c) Coronary sinus
d) Pleural recess
The oblique pericardial sinus lies behind the left atrium and between pulmonary veins. Answer: a) Oblique pericardial sinus. It forms a blind recess, allowing expansion of the left atrium during increased venous return without friction against pericardial surfaces.
9)
In a patient with pericardial effusion, which structure allows surgical drainage without injuring pleura?
a) Left 2nd intercostal space
b) Right 5th intercostal space
c) Infrasternal angle
d) Left midaxillary line
The infrasternal angle or subxiphoid approach allows needle insertion into the pericardial cavity without damaging pleura. Answer: c) Infrasternal angle. This route provides direct access to pericardial fluid in emergencies such as cardiac tamponade.
10)
A 50-year-old male undergoing open-heart surgery—what is the clinical significance of the transverse pericardial sinus?
a) Allows passage of coronary vessels
b) Used to clamp great arteries during bypass
c) Site of venous drainage
d) Receives pulmonary veins
The transverse pericardial sinus enables surgeons to pass a clamp or tube behind great arteries to isolate them from veins. Answer: b) Used to clamp great arteries during bypass. It serves as an important landmark during cardiac surgeries involving cardiopulmonary bypass setup.
Topic: Reflex Arcs
Subtopic: Cremasteric Reflex
Keyword Definitions:
Cremasteric Reflex: A superficial reflex that causes elevation of the testis on stroking the inner thigh.
Genitofemoral Nerve: A mixed nerve from L1–L2 spinal segments, with genital and femoral branches.
Afferent Limb: The sensory pathway carrying impulse to spinal cord.
Efferent Limb: The motor pathway carrying impulse to muscle.
Lead Question - 2014
True about cremasteric reflex?
a) Afferent: genital branch of genitofemoral nerve
b) Efferent: genital branch of genitofemoral nerve
c) Efferent: femoral branch of genitofemoral nerve
d) Afferent: pudendal nerve
Explanation: The cremasteric reflex has an afferent limb through the femoral branch of the genitofemoral nerve and the ilioinguinal nerve, and an efferent limb through the genital branch of the genitofemoral nerve causing contraction of the cremaster muscle. Answer: b) Efferent: genital branch of genitofemoral nerve.
1. Absence of cremasteric reflex indicates lesion at which spinal level?
a) T10–T11
b) L1–L2
c) S1–S2
d) C5–C6
The cremasteric reflex is mediated through L1–L2 spinal segments. Its absence suggests a lesion involving these levels, as in spinal cord injury or testicular torsion. Answer: b) L1–L2.
2. Cremaster muscle is derived from which layer of the abdominal wall?
a) External oblique
b) Internal oblique
c) Transversus abdominis
d) Fascia transversalis
The cremaster muscle is a continuation of the internal oblique muscle fibers and forms part of the spermatic cord. Its contraction elevates the testis. Answer: b) Internal oblique.
3. Which nerve carries the sensory component of the cremasteric reflex?
a) Femoral branch of genitofemoral nerve
b) Genital branch of genitofemoral nerve
c) Pudendal nerve
d) Iliohypogastric nerve
The sensory (afferent) limb of the cremasteric reflex is carried mainly by the femoral branch of the genitofemoral nerve and partially by the ilioinguinal nerve. Answer: a) Femoral branch of genitofemoral nerve.
4. In testicular torsion, cremasteric reflex is:
a) Exaggerated
b) Absent
c) Normal
d) Delayed
In testicular torsion, the cremasteric reflex is typically absent on the affected side due to compromised nerve supply and pain inhibition. This is a key clinical diagnostic feature. Answer: b) Absent.
5. Which muscle contraction is responsible for the cremasteric reflex?
a) Dartos muscle
b) Cremaster muscle
c) External oblique
d) Transversus abdominis
The cremasteric reflex involves contraction of the cremaster muscle, causing elevation of the testis. This muscle is innervated by the genital branch of the genitofemoral nerve. Answer: b) Cremaster muscle.
6. Clinical case: A 25-year-old male presents after trauma to the upper thigh with absent cremasteric reflex. Which nerve is likely injured?
a) Ilioinguinal nerve
b) Genitofemoral nerve
c) Pudendal nerve
d) Obturator nerve
Damage to the genitofemoral nerve disrupts both the afferent and efferent limbs of the cremasteric reflex, leading to its absence. Answer: b) Genitofemoral nerve.
7. A newborn has undescended testes and absent cremasteric reflex. What is the most likely cause?
a) Cryptorchidism
b) Hydrocele
c) Hernia
d) Varicocele
In cryptorchidism, the testis fails to descend into the scrotum, leading to absent cremasteric reflex due to abnormal nerve and muscle development. Answer: a) Cryptorchidism.
8. Afferent fibers of cremasteric reflex travel through:
a) Femoral branch of genitofemoral nerve
b) Ilioinguinal nerve
c) Both a and b
d) None
Both the femoral branch of the genitofemoral nerve and ilioinguinal nerve contribute sensory input from the inner thigh to the spinal cord. Answer: c) Both a and b.
9. Which reflex is mediated at the spinal level S1–S2?
a) Cremasteric reflex
b) Anal reflex
c) Abdominal reflex
d) Plantar reflex
The anal reflex, not the cremasteric reflex, is mediated at the S1–S2 level. The cremasteric reflex is L1–L2. Answer: b) Anal reflex.
10. Clinical case: A man with spinal cord injury above L1–L2 shows absent cremasteric reflex but intact anal reflex. Which statement is correct?
a) Reflex arc of cremasteric is intact
b) Reflex arc of cremasteric is interrupted
c) Pudendal nerve involved
d) Reflex mediated by S2–S4
The cremasteric reflex arc is interrupted in lesions above L1–L2, abolishing the reflex, while the anal reflex (S2–S4) remains intact. Answer: b) Reflex arc of cremasteric is interrupted.
Topic: Male Urethra
Subtopic: Prostatic Urethra and Urethral Crest
Keyword Definitions:
Urethral Crest: A longitudinal mucosal fold in the posterior wall of the prostatic urethra containing the prostatic utricle and ejaculatory ducts.
Prostatic Urethra: The widest part of the male urethra passing through the prostate gland.
Prostatic Glands: Compound tubuloalveolar glands secreting prostatic fluid into the urethra.
Trigone: A smooth triangular area on the posterior wall of the urinary bladder.
Lead Question - 2014
Urethral crest is an elevation seen in urethra due to:
a) Prostatic glands
b) Insertion of detrusor muscle
c) Insertion of trigone
d) Preprostatic internal sphincter
Explanation: The urethral crest is a longitudinal mucosal ridge in the prostatic urethra formed by the median lobe of the prostate containing prostatic glands and the prostatic utricle. It helps in the closure of the urethra during ejaculation. Answer: a) Prostatic glands.
1. Which structure opens on each side of the prostatic utricle?
a) Ejaculatory ducts
b) Bulbourethral glands
c) Prostatic sinuses
d) Ducts of Cowper’s glands
The ejaculatory ducts open on each side of the prostatic utricle within the prostatic urethra. These ducts convey sperm and seminal fluid from the seminal vesicles and vas deferens. Answer: a) Ejaculatory ducts.
2. The urethral crest is located in which part of the male urethra?
a) Membranous urethra
b) Spongy urethra
c) Prostatic urethra
d) Penile urethra
The urethral crest is a prominent mucosal elevation found in the posterior wall of the prostatic urethra. It is absent in the membranous and penile urethra. Answer: c) Prostatic urethra.
3. Clinical case: A 65-year-old man with benign prostatic hyperplasia shows obstruction at the level of the urethral crest. Which lobe is responsible?
a) Median lobe
b) Anterior lobe
c) Posterior lobe
d) Lateral lobe
The median lobe of the prostate lies between the ejaculatory ducts and urethra, forming the urethral crest. Its hypertrophy causes urethral obstruction in benign prostatic hyperplasia. Answer: a) Median lobe.
4. The depression on either side of the urethral crest is called:
a) Prostatic sinus
b) Urethral groove
c) Urethral recess
d) Prostatic sac
On either side of the urethral crest are the prostatic sinuses, into which the ducts of the prostate gland open. These sinuses convey prostatic secretions into the urethra. Answer: a) Prostatic sinus.
5. The prostatic utricle is a remnant of which embryological structure?
a) Mesonephric duct
b) Paramesonephric duct
c) Urogenital sinus
d) Cloacal membrane
The prostatic utricle is a vestigial remnant of the paramesonephric (Müllerian) duct in males and opens at the summit of the urethral crest. Answer: b) Paramesonephric duct.
6. Clinical case: A male patient has infection extending from the urethra to the prostate via prostatic ducts. Which region is primarily affected?
a) Urethral crest
b) Membranous urethra
c) External sphincter
d) Ureteric orifice
Infection can spread through the ducts opening into the prostatic sinuses adjacent to the urethral crest, leading to prostatitis. Answer: a) Urethral crest.
7. Which part of the urethra passes through the deep perineal pouch?
a) Prostatic urethra
b) Membranous urethra
c) Penile urethra
d) Bulbous urethra
The membranous urethra passes through the deep perineal pouch surrounded by the external urethral sphincter. Answer: b) Membranous urethra.
8. The external urethral sphincter is innervated by:
a) Pelvic splanchnic nerves
b) Pudendal nerve
c) Inferior hypogastric plexus
d) Ilioinguinal nerve
The external urethral sphincter is supplied by the pudendal nerve (S2–S4), providing voluntary control over micturition. Answer: b) Pudendal nerve.
9. Clinical case: A 50-year-old male presents with difficulty in urination. Cystoscopy reveals hypertrophy near the urethral crest. Likely diagnosis?
a) Benign prostatic hyperplasia
b) Bladder carcinoma
c) Urethral stricture
d) Cystitis
Hypertrophy of the median lobe near the urethral crest compresses the urethra, typical of benign prostatic hyperplasia. Answer: a) Benign prostatic hyperplasia.
10. The posterior urethral wall in the prostatic part shows:
a) Colliculus seminalis
b) Fossa navicularis
c) Bulbar enlargement
d) Lacuna magna
The colliculus seminalis (verumontanum) is a raised area on the posterior urethral wall representing the urethral crest with openings of ejaculatory ducts and utricle. Answer: a) Colliculus seminalis.
Topic: Muscles of Anterior Abdominal Wall
Subtopic: Nerve Supply of Pyramidalis Muscle
Keyword Definitions:
Pyramidalis: A small triangular muscle anterior to the rectus abdominis that tenses the linea alba.
Rectus Sheath: Fibrous covering formed by aponeuroses of abdominal muscles enclosing rectus abdominis and pyramidalis.
Subcostal Nerve: Twelfth thoracic spinal nerve supplying muscles of abdominal wall and overlying skin.
Iliohypogastric Nerve: Arises from L1, supplying skin above pubis and lower abdominal muscles.
Ilioinguinal Nerve: Branch of L1 nerve that supplies the groin region and upper thigh skin.
Genitofemoral Nerve: From L1–L2, divides into genital and femoral branches for cremaster and thigh skin.
Lead Question – 2014
Pyramidalis is supplied by?
a) Subcostal nerve
b) Ilioinguinal nerve
c) Iliohypogastric nerve
d) Genitofemoral nerve
Explanation: The pyramidalis muscle is a small triangular structure in front of the rectus abdominis that tenses the linea alba. It is supplied by the subcostal nerve (T12). It may be absent in some individuals and acts as a surgical landmark for rectus sheath termination. (Answer: a)
1) The rectus sheath encloses all except:
a) Pyramidalis
b) Rectus abdominis
c) Inferior epigastric vessels
d) Transversus abdominis
Explanation: The rectus sheath encloses the rectus abdominis, pyramidalis, and epigastric vessels, but not transversus abdominis, which contributes to its aponeurotic formation. (Answer: d)
2) Linea alba extends between:
a) Xiphoid process and umbilicus
b) Umbilicus and pubic crest
c) Xiphoid process and pubic symphysis
d) Costal margin and iliac crest
Explanation: The linea alba is a fibrous midline raphe extending from the xiphoid process to the pubic symphysis. It is used in surgical incisions because of its avascular nature. (Answer: c)
3) The pyramidalis muscle lies:
a) Behind rectus abdominis
b) In front of rectus abdominis
c) Between rectus and transversus abdominis
d) Deep to linea alba
Explanation: The pyramidalis muscle lies anterior to rectus abdominis within the rectus sheath. It helps tense the linea alba and may be absent in some people. (Answer: b)
4) The subcostal nerve is the:
a) T11 nerve
b) T12 nerve
c) L1 nerve
d) L2 nerve
Explanation: The subcostal nerve is derived from the ventral ramus of the twelfth thoracic nerve (T12). It supplies muscles and skin of the anterior abdominal wall. (Answer: b)
5) Which of the following muscles flexes the trunk and stabilizes the pelvis?
a) Pyramidalis
b) Rectus abdominis
c) Transversus abdominis
d) External oblique
Explanation: The rectus abdominis flexes the vertebral column, stabilizes the pelvis, and compresses abdominal viscera. (Answer: b)
6) (Clinical) A 38-year-old man undergoes abdominal surgery. A small triangular muscle anterior to rectus abdominis is identified. Its nerve supply is from:
a) Ilioinguinal nerve
b) Subcostal nerve
c) Genitofemoral nerve
d) Femoral nerve
Explanation: The pyramidalis muscle is supplied by the subcostal nerve (T12) and serves as a landmark for lower rectus sheath termination. (Answer: b)
7) (Clinical) A midline incision through the linea alba is preferred because it is:
a) Highly vascular
b) Avascular
c) Thick and muscular
d) Contains major nerves
Explanation: The linea alba is an avascular fibrous raphe, which allows midline surgical incisions with minimal bleeding. (Answer: b)
8) (Clinical) A surgeon finds absence of pyramidalis during laparotomy. This indicates:
a) Nerve injury
b) Congenital absence (normal variant)
c) Muscle atrophy
d) Hernia risk
Explanation: The pyramidalis is sometimes congenitally absent. It is a normal anatomical variant and not clinically significant. (Answer: b)
9) (Clinical) During cesarean section, incision is taken in the linea alba because:
a) It has abundant blood vessels
b) It has fewer nerves and vessels
c) It provides muscle access
d) It prevents scar formation
Explanation: The linea alba is chosen for surgical incisions because it is avascular and less painful, providing direct access to the abdominal cavity. (Answer: b)
10) (Clinical) The pyramidalis muscle helps the surgeon identify:
a) Inguinal canal
b) Lower rectus sheath
c) Umbilicus
d) Pubic tubercle
Explanation: The pyramidalis muscle marks the lower end of the rectus sheath near the pubic symphysis and is used as a landmark during abdominal surgeries. (Answer: b)
Topic: Large Intestine Anatomy
Subtopic: Appendices Epiploicae
Keyword Definitions:
Appendices epiploicae: Small fat-filled pouches of peritoneum projecting from the colon’s serosal surface, absent in duodenum, jejunum, and stomach.
Colon: Major part of large intestine including ascending, transverse, descending, and sigmoid segments.
Mesocolon: Peritoneal fold that attaches colon to the posterior abdominal wall.
Taenia coli: Longitudinal bands of smooth muscle on colon forming haustra.
Haustra: Sacculations of colon formed due to taenia coli.
Lead Question – 2014
Appendices epiploicae is a feature of?
a) Duodenum
b) Stomach
c) Colon
d) Jejunum
Explanation: Appendices epiploicae are small fat-filled peritoneal pouches projecting from the serosal surface of the colon, especially along the transverse and sigmoid colon. They are absent in duodenum, jejunum, and stomach. Clinically, they may undergo torsion causing epiploic appendagitis. (Answer: c)
1) Taenia coli are:
a) Longitudinal bands of colon
b) Circular muscle of small intestine
c) Fatty appendages
d) Peritoneal folds
Explanation: The taenia coli are three longitudinal bands of smooth muscle on the colon’s surface that create sacculations called haustra. They do not exist in the small intestine. (Answer: a)
2) Haustra are formed due to:
a) Circular muscle contraction
b) Longitudinal taenia coli
c) Fatty appendices
d) Mesocolon tension
Explanation: Haustra are sacculations of the colon formed because the taenia coli are shorter than the colon length, producing puckered segments. (Answer: b)
3) Clinical case: A patient presents with localized left lower quadrant pain. Imaging shows inflamed appendices epiploicae. Diagnosis is likely:
a) Diverticulitis
b) Epiploic appendagitis
c) Appendicitis
d) Crohn’s disease
Explanation: Inflammation of appendices epiploicae causes acute localized abdominal pain mimicking diverticulitis but without systemic symptoms, termed epiploic appendagitis. (Answer: b)
4) Appendices epiploicae are absent in:
a) Ascending colon
b) Transverse colon
c) Rectum
d) Sigmoid colon
Explanation: Appendices epiploicae are found along colon but absent in the rectum. They are fat-filled pouches attached to the colon’s serosal surface. (Answer: c)
5) The mesocolon is:
a) Fold attaching small intestine
b) Fold attaching colon to posterior wall
c) Fold covering stomach
d) Fold of duodenum
Explanation: The mesocolon is a peritoneal fold that suspends parts of the colon from the posterior abdominal wall and provides passage for vessels, nerves, and lymphatics. (Answer: b)
6) (Clinical) A 45-year-old male has acute right-sided abdominal pain. CT shows a small fatty mass attached to the colon. Most likely structure involved:
a) Taenia coli
b) Appendices epiploicae
c) Meckel’s diverticulum
d) Cecum wall
Explanation: Acute localized pain due to inflamed appendices epiploicae often mimics appendicitis. CT shows fat-density mass on colon surface, confirming epiploic appendagitis. (Answer: b)
7) The longitudinal bands of smooth muscle on colon are called:
a) Haustra
b) Teniae coli
c) Appendices epiploicae
d) Circular bands
Explanation: The teniae coli are three longitudinal bands of smooth muscle along colon surface that produce sacculations (haustra). They are absent in rectum. (Answer: b)
8) (Clinical) A patient’s sigmoid colon shows multiple epiploic appendices torsion. This may cause:
a) Systemic infection
b) Localized abdominal pain
c) Hemorrhage
d) Vomiting
Explanation: Torsion of appendices epiploicae leads to localized ischemic pain without systemic signs. It is a benign, self-limited cause of acute abdomen. (Answer: b)
9) (Clinical) During colonoscopy, fatty appendages seen along colon indicate:
a) Crohn’s disease
b) Normal appendices epiploicae
c) Diverticulosis
d) Ulcerative colitis
Explanation: Appendices epiploicae are normal anatomical fat-filled pouches projecting from the serosal surface of the colon, commonly visualized during colonoscopy. (Answer: b)
10) Clinical significance of appendices epiploicae includes:
a) Appendicitis origin
b) Torsion causing localized pain
c) Site of ulceration
d) Absorption of nutrients
Explanation: The appendices epiploicae can undergo torsion or infarction causing localized abdominal pain, mimicking diverticulitis or appendicitis. They are otherwise clinically insignificant. (Answer: b)
Topic: Large Intestine Anatomy
Subtopic: Appendices Epiploicae Distribution
Keyword Definitions:
Appendices epiploicae: Small peritoneal fat-filled pouches projecting from the colon’s serosal surface; absent in rectum.
Colon: Large intestine segments: cecum, ascending, transverse, descending, sigmoid colon.
Caecum: Initial part of large intestine connecting ileum to colon.
Sigmoid colon: S-shaped distal colon connecting descending colon to rectum.
Transverse colon: Horizontally placed middle segment of colon between hepatic and splenic flexures.
Haustra: Sacculations of colon caused by taenia coli shortening.
Lead Question – 2014
Appendices epiploicae is seen in all part of large intestine except -
a) Sigmoid colon
b) Ascending colon
c) Caecum
d) Transverse colon
Explanation: Appendices epiploicae are fat-filled peritoneal pouches projecting from the colon’s surface. They are present on the cecum, ascending, transverse, descending, and sigmoid colon, but absent in the rectum. This makes them important anatomical landmarks and potential sites for epiploic appendagitis. (Answer: Rectum)
1) Taenia coli are:
a) Longitudinal smooth muscle bands
b) Circular muscle bands
c) Fatty appendices
d) Peritoneal folds
Explanation: The taenia coli are three longitudinal bands of smooth muscle along the colon. They contract to form sacculations called haustra and are absent in the rectum. They are key anatomical landmarks in colon identification. (Answer: a)
2) Haustra are formed due to:
a) Circular muscle contraction
b) Shorter taenia coli
c) Fatty appendices
d) Mesocolon tension
Explanation: Haustra are sacculations of the colon formed because the taenia coli are shorter than the colon length. This gives the colon its segmented appearance. (Answer: b)
3) Clinical case: A patient presents with left lower quadrant pain. Imaging shows inflamed appendices epiploicae. Likely diagnosis:
a) Diverticulitis
b) Epiploic appendagitis
c) Appendicitis
d) Colitis
Explanation: Inflammation of appendices epiploicae causes localized abdominal pain without systemic symptoms. CT shows a fat-density mass attached to colon. This condition is known as epiploic appendagitis, a self-limiting cause of acute abdomen. (Answer: b)
4) Appendices epiploicae are absent in:
a) Ascending colon
b) Sigmoid colon
c) Rectum
d) Transverse colon
Explanation: Appendices epiploicae are present along the colon except in the rectum, where they are absent. Their absence helps distinguish rectum from other colon segments during imaging or surgery. (Answer: c)
5) The mesocolon is:
a) Fold attaching colon to posterior wall
b) Fold attaching small intestine
c) Fold covering stomach
d) Fold of duodenum
Explanation: The mesocolon is a peritoneal fold suspending parts of the colon to the posterior abdominal wall, transmitting blood vessels, lymphatics, and nerves. It stabilizes colon position and allows mobility. (Answer: a)
6) (Clinical) A 40-year-old male has sudden left lower quadrant pain. CT shows small fat-density lesion attached to colon. Structure involved is:
a) Taenia coli
b) Appendices epiploicae
c) Meckel’s diverticulum
d) Sigmoid wall
Explanation: Torsion of appendices epiploicae leads to acute localized abdominal pain, often mimicking diverticulitis or appendicitis. CT confirms fat-density lesion attached to colon surface. (Answer: b)
7) The longitudinal bands of colon are:
a) Haustra
b) Taenia coli
c) Appendices epiploicae
d) Circular bands
Explanation: Taenia coli are three longitudinal muscle bands on colon surface forming haustra. They are absent in rectum. Appendices epiploicae are fat-filled pouches projecting from serosa. (Answer: b)
8) (Clinical) Torsion of appendices epiploicae may cause:
a) Systemic infection
b) Localized abdominal pain
c) Hemorrhage
d) Vomiting
Explanation: Torsion or infarction of appendices epiploicae produces localized abdominal pain without systemic symptoms. It is self-limiting and may mimic diverticulitis. (Answer: b)
9) (Clinical) During colonoscopy, fatty appendages along colon indicate:
a) Crohn’s disease
b) Normal appendices epiploicae
c) Diverticulosis
d) Ulcerative colitis
Explanation: Appendices epiploicae are normal anatomical fat-filled pouches projecting from colon serosa. Visualization during colonoscopy confirms normal anatomy. (Answer: b)
10) Clinical significance of appendices epiploicae includes:
a) Appendicitis origin
b) Torsion causing localized pain
c) Ulceration site
d) Nutrient absorption
Explanation: Appendices epiploicae can undergo torsion or infarction, producing localized abdominal pain mimicking diverticulitis or appendicitis. They have no major physiological role. (Answer: b)
Topic: Blood Supply of Anal Canal
Subtopic: Inferior Rectal Artery
Keyword Definitions:
Inferior rectal artery: Branch of internal pudendal artery supplying anal canal below pectinate line and perianal skin.
Internal pudendal artery: Branch of internal iliac artery supplying perineum, external genitalia, and anal canal.
Superior rectal artery: Terminal branch of inferior mesenteric artery supplying rectum above pectinate line.
Pectinate line: Anatomical line dividing upper (visceral) and lower (somatic) anal canal.
Anal canal: Terminal part of large intestine extending from rectum to anus.
Inferior mesenteric artery: Branch of abdominal aorta supplying hindgut structures including upper rectum.
Lead Question – 2014
Inferior rectal artery is a branch of?
a) Inferior mesenteric artery
b) Superior mesenteric artery
c) Coeliac trunk
d) Internal pudendal artery
Explanation: The inferior rectal artery arises from the internal pudendal artery, a branch of the internal iliac artery. It supplies the lower anal canal below the pectinate line, anal sphincters, and perianal skin. The superior rectal artery arises from inferior mesenteric artery. (Answer: d)
1) Superior rectal artery is a continuation of:
a) Inferior mesenteric artery
b) Internal pudendal artery
c) Coeliac trunk
d) Superior mesenteric artery
Explanation: The superior rectal artery is the terminal branch of the inferior mesenteric artery. It supplies rectum above pectinate line, anastomosing with middle and inferior rectal arteries. (Answer: a)
2) Middle rectal artery arises from:
a) Internal iliac artery
b) External iliac artery
c) Inferior mesenteric artery
d) Superior mesenteric artery
Explanation: The middle rectal artery arises from internal iliac artery, supplying rectum, prostate, seminal vesicles in males, and vagina in females. It forms anastomoses with superior and inferior rectal arteries. (Answer: a)
3) (Clinical) A patient with internal hemorrhoids has bleeding above pectinate line. Blood supply is mainly from:
a) Inferior rectal artery
b) Superior rectal artery
c) Middle rectal artery
d) Internal pudendal artery
Explanation: Internal hemorrhoids occur above the pectinate line. Their arterial supply is from the superior rectal artery, a branch of inferior mesenteric artery, which forms a rich anastomotic network. (Answer: b)
4) Inferior rectal artery supplies:
a) Upper rectum
b) Lower anal canal and perianal skin
c) Sigmoid colon
d) Rectosigmoid junction
Explanation: The inferior rectal artery supplies the lower anal canal below pectinate line, anal sphincters, and perianal skin. It is a branch of internal pudendal artery. (Answer: b)
5) Pectinate line divides:
a) Upper and lower rectum
b) Visceral and somatic innervation
c) Ascending and descending colon
d) Sigmoid and rectum
Explanation: The pectinate line marks the junction of hindgut and proctodeum, separating visceral (above) and somatic (below) innervation, lymphatic drainage, and arterial supply. Inferior rectal artery supplies below it. (Answer: b)
6) (Clinical) A surgeon ligates inferior rectal artery during perianal surgery. This artery is a branch of:
a) Inferior mesenteric artery
b) Internal pudendal artery
c) External iliac artery
d) Middle rectal artery
Explanation: During perianal procedures, the inferior rectal artery from internal pudendal artery may be ligated to control bleeding. It supplies lower anal canal, anal sphincters, and skin. (Answer: b)
7) (Clinical) Patient has external hemorrhoids. Painful swelling is supplied by:
a) Superior rectal artery
b) Inferior rectal artery
c) Middle rectal artery
d) Superior mesenteric artery
Explanation: External hemorrhoids are located below the pectinate line, supplied by the inferior rectal artery, which is a branch of the internal pudendal artery. They are painful due to somatic innervation. (Answer: b)
8) Internal pudendal artery arises from:
a) External iliac artery
b) Internal iliac artery
c) Common iliac artery
d) Inferior mesenteric artery
Explanation: The internal pudendal artery branches from the internal iliac artery, exiting the pelvis via the greater sciatic foramen, supplying perineum, external genitalia, and inferior rectal artery. (Answer: b)
9) (Clinical) Bleeding from lower anal canal is supplied by:
a) Superior rectal artery
b) Inferior rectal artery
c) Middle rectal artery
d) Coeliac trunk
Explanation: The inferior rectal artery supplies the lower anal canal below the pectinate line and perianal skin. Bleeding in this region originates from this branch of internal pudendal artery. (Answer: b)
10) Anastomosis of rectal arteries ensures:
a) Only venous drainage
b) Collateral circulation to anal canal
c) Supply to small intestine
d) Supply to sigmoid colon only
Explanation: Superior, middle, and inferior rectal arteries form an anastomotic network ensuring collateral arterial supply to the anal canal, providing protection against ischemia. Inferior rectal artery contributes to lower anal canal supply. (Answer: b)