Chapter: Anatomy
Topic: Upper Limb
Subtopic: Muscles of Shoulder and Arm
Keyword Definitions:
Intertubercular sulcus: Groove between the greater and lesser tubercles of the humerus, lodging the tendon of the long head of biceps brachii.
Latissimus dorsi: Large back muscle inserting into the floor of intertubercular sulcus, responsible for adduction, extension, and medial rotation of the arm.
Teres major: Muscle of scapular region inserting into medial lip of intertubercular sulcus.
Pectoralis major: Large anterior chest muscle inserting into lateral lip of intertubercular sulcus.
Deltoid: Shoulder muscle inserting into deltoid tuberosity of humerus.
Medial rotation: Movement turning the anterior surface of limb towards the midline.
Adduction: Movement of limb towards the midline.
Extension (shoulder): Movement of arm backwards in sagittal plane.
Axillary nerve: Nerve supplying deltoid and teres minor muscles.
Thoracodorsal nerve: Nerve supplying latissimus dorsi.
Lead Question - 2012:
Which muscle is inserted into the floor of the intertubercular sulcus of the humerus?
a) Latissimus dorsi
b) Teres major
c) Pectoralis major
d) Deltoid
The correct answer is a) Latissimus dorsi. This large muscle arises from the lower thoracic vertebrae, lumbar fascia, iliac crest, and lower ribs. It passes superiorly and laterally to insert into the floor of the intertubercular sulcus of the humerus. Its insertion site allows it to act as a powerful adductor, extensor, and medial rotator of the arm.
1. The medial lip of the intertubercular sulcus gives insertion to:
a) Teres major
b) Latissimus dorsi
c) Pectoralis major
d) Subscapularis
Answer: Teres major. This muscle assists in medial rotation and adduction of the humerus. Its medial lip insertion is an important anatomical relationship in shoulder surgery.
2. The lateral lip of the intertubercular sulcus is the insertion site for:
a) Latissimus dorsi
b) Pectoralis major
c) Teres major
d) Deltoid
Answer: Pectoralis major. This muscle flexes, adducts, and medially rotates the humerus. Its lateral lip insertion is important in differentiating from latissimus and teres major attachments.
3. Clinical: Injury to the thoracodorsal nerve will impair:
a) Lateral rotation of arm
b) Abduction of arm
c) Adduction and extension of arm
d) Flexion of forearm
Answer: Adduction and extension of arm. The thoracodorsal nerve innervates latissimus dorsi, essential for swimming and climbing movements.
4. Which muscle originates from the iliac crest and inserts into humerus?
a) Latissimus dorsi
b) Teres major
c) Deltoid
d) Pectoralis minor
Answer: Latissimus dorsi. Its broad origin includes the iliac crest, lumbar fascia, and lower thoracic spinous processes.
5. The intertubercular sulcus lodges the tendon of:
a) Long head of triceps
b) Short head of biceps
c) Long head of biceps
d) Brachialis
Answer: Long head of biceps. This tendon passes within the sulcus, stabilized by the transverse humeral ligament.
6. Clinical: During axillary lymph node dissection, damage to which nerve can cause difficulty climbing?
a) Thoracodorsal nerve
b) Axillary nerve
c) Long thoracic nerve
d) Radial nerve
Answer: Thoracodorsal nerve. It lies near axillary lymph nodes and damage impairs latissimus dorsi function.
7. Which movement will be most affected if latissimus dorsi is paralyzed?
a) Shoulder flexion
b) Shoulder extension
c) Elbow extension
d) Wrist flexion
Answer: Shoulder extension. Latissimus dorsi extends the humerus, essential in rowing and pulling actions.
8. The nerve supply of teres major is:
a) Axillary nerve
b) Lower subscapular nerve
c) Thoracodorsal nerve
d) Radial nerve
Answer: Lower subscapular nerve. This innervates teres major, contributing to adduction and medial rotation.
9. Clinical: Weakness in using crutches may be due to paralysis of:
a) Latissimus dorsi
b) Supraspinatus
c) Infraspinatus
d) Subscapularis
Answer: Latissimus dorsi. It plays a role in lifting the body during crutch walking.
10. Which muscle is known as the "swimmer's muscle"?
a) Latissimus dorsi
b) Teres major
c) Deltoid
d) Trapezius
Answer: Latissimus dorsi. Its powerful adduction, extension, and medial rotation are essential for swimming strokes.
Chapter: Embryology
Topic: Early Development
Subtopic: Implantation and Blastocyst Formation
Keyword Definitions:
Blastocyst: Stage of embryonic development after morula, with an inner cell mass and a fluid-filled cavity (blastocoel).
Endometrium: Inner lining of the uterus, prepared for implantation under progesterone influence.
Implantation: Process of embedding the blastocyst into the endometrial lining.
Trophoblast: Outer cell layer of the blastocyst that forms placenta components.
Zona pellucida: Glycoprotein coat surrounding the early embryo, shed before implantation.
Morula: Solid ball of cells formed after cleavage of the zygote.
Hatching: Process by which the blastocyst emerges from the zona pellucida.
Syncytiotrophoblast: Multinucleated trophoblast cells invading the endometrium.
Cytotrophoblast: Inner trophoblast layer with mitotic activity.
Luteal phase: Phase of menstrual cycle dominated by progesterone secretion.
Lead Question - 2012:
Blastocyst makes contact with endometrium on ?
a) < 3 days
b) 5 - 7 days
c) 8 - 11 days
d) 15 -16 days
The correct answer is b) 5 - 7 days. The blastocyst reaches the uterine cavity around day 5 after fertilization and begins attaching to the endometrial epithelium between days 5 and 7. This timing ensures optimal endometrial receptivity, which is hormonally regulated, primarily by progesterone from the corpus luteum.
1. The zona pellucida disappears during which stage?
a) Zygote
b) Morula
c) Early blastocyst
d) Late blastocyst
Answer: Early blastocyst. Hatching occurs when the blastocyst breaks free from the zona pellucida around day 5, enabling direct contact with the endometrium for implantation.
2. Which layer of the trophoblast invades the endometrium?
a) Cytotrophoblast
b) Syncytiotrophoblast
c) Hypoblast
d) Epiblast
Answer: Syncytiotrophoblast. This multinucleated layer secretes enzymes and hCG, aiding in embedding the embryo into maternal tissue.
3. Clinical: A woman undergoes IVF and embryo transfer. The best day for transfer to mimic natural implantation is:
a) Day 2
b) Day 3
c) Day 5
d) Day 10
Answer: Day 5. A day-5 blastocyst transfer aligns with the natural implantation window, increasing pregnancy rates.
4. The inner cell mass of the blastocyst forms:
a) Placenta
b) Amniotic sac only
c) Embryo proper
d) Decidua basalis
Answer: Embryo proper. The inner cell mass differentiates into epiblast and hypoblast, forming all embryonic tissues.
5. Which hormone maintains endometrial receptivity for implantation?
a) Estrogen
b) Progesterone
c) LH
d) FSH
Answer: Progesterone. Secreted by the corpus luteum, it converts the endometrium to a secretory phase, crucial for implantation.
6. The decidua basalis develops from:
a) Embryonic mesoderm
b) Maternal endometrium
c) Chorionic villi
d) Cytotrophoblast
Answer: Maternal endometrium. The decidua basalis is the maternal portion of the placenta, forming at the site of implantation.
7. Clinical: An ectopic pregnancy in the fallopian tube occurs because implantation happens:
a) Too early
b) Too late
c) Before blastocyst reaches uterus
d) After corpus luteum regression
Answer: Before blastocyst reaches uterus. If zona pellucida sheds prematurely, implantation can occur in abnormal sites like the fallopian tube.
8. Which of the following occurs last in early embryonic development?
a) Cleavage
b) Morula formation
c) Blastocyst formation
d) Implantation
Answer: Implantation. Cleavage → morula → blastocyst → implantation is the correct sequence.
9. The blastocoel is:
a) Space between amnion and chorion
b) Cavity within blastocyst
c) Fluid-filled yolk sac
d) Maternal blood-filled lacuna
Answer: Cavity within blastocyst. It helps separate the inner cell mass from the trophoblast layer.
10. Clinical: Which marker confirms trophoblastic activity soon after implantation?
a) Progesterone
b) Estrogen
c) hCG
d) Inhibin B
Answer: hCG. Secreted by syncytiotrophoblast cells, detectable in maternal blood within days after implantation.
Chapter: Embryology
Topic: Development of External Genitalia
Subtopic: Female External Genitalia Derivatives
Keyword Definitions:
Labia majora: Paired folds of skin in the female external genitalia derived from genital swellings.
Urogenital sinus: Endodermal structure forming parts of the urethra, vagina, and vestibule.
Müllerian duct: Paramesonephric duct forming uterus, fallopian tubes, and upper vagina.
Genital ridge: Mesodermal structure giving rise to gonads.
Genital swelling: Embryonic structure forming labia majora in females and scrotum in males.
Labia minora: Derived from genital folds (urogenital folds).
Clitoris: Derived from genital tubercle.
Hypospadias: Urethral opening defect due to incomplete fusion of urogenital folds in males.
Neuroectoderm: Specialized ectoderm forming CNS structures.
Mesoderm: Middle germ layer forming muscles, connective tissue, and some reproductive structures.
Lead Question - 2012:
Development of labia majora is from -
a) Urogenital sinus
b) Mullerian duct
c) Genital ridge
d) Genital swelling
The correct answer is d) Genital swelling. In females, genital swellings enlarge and form the labia majora. In males, these swellings fuse in the midline to form the scrotum. This is an important embryological distinction when differentiating homologous male and female structures in developmental anatomy.
1. Labia minora are derived from:
a) Genital tubercle
b) Genital folds
c) Genital swelling
d) Urogenital sinus
Answer: Genital folds. The urogenital folds in females persist as the labia minora, while in males they fuse to form the penile urethra. This is a classic example of sexual homology in embryology.
2. The clitoris develops from:
a) Genital folds
b) Genital swelling
c) Genital tubercle
d) Urogenital sinus
Answer: Genital tubercle. The genital tubercle elongates to form the clitoris in females and the penis in males. Its growth is influenced by sex hormones during development.
3. The male homolog of the labia majora is:
a) Penis
b) Scrotum
c) Urethra
d) Glans penis
Answer: Scrotum. Genital swellings fuse in males to form the scrotum, making it the male counterpart of the labia majora in females.
4. Which structure arises from the urogenital sinus in females?
a) Clitoris
b) Lower vagina
c) Labia majora
d) Mons pubis
Answer: Lower vagina. The lower one-third of the vagina develops from the endodermal urogenital sinus, while the upper two-thirds come from the Müllerian ducts.
5. A newborn female presents with fused labia majora. This condition is likely due to:
a) Excess estrogen exposure
b) Androgen excess in utero
c) Müllerian agenesis
d) Gonadal dysgenesis
Answer: Androgen excess in utero. Virilization due to congenital adrenal hyperplasia can cause fusion of labia majora and other masculinization features.
6. Which embryonic structure forms the mons pubis?
a) Genital swelling
b) Genital folds
c) Genital tubercle
d) Urogenital sinus
Answer: Genital swelling. Along with forming the labia majora, genital swellings contribute to the development of the mons pubis in females.
7. The male homolog of the clitoris is:
a) Glans penis
b) Corpus spongiosum
c) Urethra
d) Scrotum
Answer: Glans penis. Both glans penis and clitoris originate from the genital tubercle, highlighting their homologous nature.
8. Which germ layer primarily contributes to the genital swellings?
a) Endoderm
b) Ectoderm
c) Mesoderm
d) Neural crest cells
Answer: Mesoderm. External genitalia structures like genital swellings are mesodermal in origin, with surface ectoderm covering.
9. A 46,XY DSD newborn has bifid scrotum resembling labia majora. This is due to:
a) Müllerian agenesis
b) Incomplete fusion of genital swellings
c) Failure of genital tubercle elongation
d) Cloacal membrane persistence
Answer: Incomplete fusion of genital swellings. In males, unfused genital swellings result in bifid scrotum, resembling female labia majora.
10. In androgen insensitivity syndrome (AIS), the labia majora develop from:
a) Müllerian ducts
b) Urogenital folds
c) Genital swellings
d) Genital tubercle
Answer: Genital swellings. Even in AIS where testes are present, external genitalia develop along the female pathway, with labia majora from genital swellings.
Chapter: Embryology
Topic: Germ Layer Derivatives
Subtopic: Ectoderm, Mesoderm, and Endoderm Origins
Keyword Definitions:
Ectoderm: The outermost germ layer forming skin, nervous system, and certain sensory organs.
Endoderm: The innermost germ layer forming gastrointestinal tract lining and respiratory epithelium.
Mesoderm: The middle germ layer forming muscles, bones, blood vessels, and connective tissues.
Hypophysis (pituitary gland): Formed partly from ectoderm (Rathke’s pouch) and partly from neuroectoderm.
Retina: Derived from neuroectoderm of the forebrain.
Spinal cord: Derived from neuroectoderm.
Adrenal cortex: Derived from mesoderm, specifically intermediate mesoderm.
Neural crest cells: Specialized ectodermal cells giving rise to diverse structures including melanocytes and adrenal medulla.
Surface ectoderm: Ectoderm forming epidermis, hair, nails, and glands of the skin.
Neuroectoderm: Specialized ectoderm forming the brain, spinal cord, and retina.
Lead Question - 2012:
All are derived from ectoderm except -
a) Hypophysis
b) Retina
c) Spinal cord
d) Adrenal cortex
The correct answer is d) Adrenal cortex. The adrenal cortex is derived from mesoderm, while the adrenal medulla comes from neural crest cells (ectoderm). Hypophysis, retina, and spinal cord are all ectodermal derivatives, specifically neuroectoderm or surface ectoderm in the case of Rathke’s pouch. This distinction is key in embryology MCQs.
1. The adrenal medulla is derived from:
a) Surface ectoderm
b) Neuroectoderm
c) Neural crest cells
d) Mesoderm
Answer: Neural crest cells. The medulla’s chromaffin cells originate from neural crest ectoderm, explaining their neuroendocrine function in secreting catecholamines like epinephrine and norepinephrine.
2. Rathke’s pouch gives rise to which structure?
a) Neurohypophysis
b) Adenohypophysis
c) Pineal gland
d) Retina
Answer: Adenohypophysis. Rathke’s pouch is an ectodermal outgrowth from the roof of the mouth, forming the anterior pituitary, which secretes hormones like GH, ACTH, and prolactin.
3. Which germ layer forms the lens of the eye?
a) Surface ectoderm
b) Neuroectoderm
c) Mesoderm
d) Endoderm
Answer: Surface ectoderm. The lens develops from a placode of surface ectoderm induced by the optic vesicle derived from neuroectoderm.
4. Which of the following is a mesodermal derivative?
a) Retina
b) Dermis of skin
c) Epidermis of skin
d) Anterior pituitary
Answer: Dermis of skin. While epidermis is from ectoderm, dermis is largely mesodermal in origin except in certain craniofacial regions.
5. Which embryonic layer forms the thyroid follicular cells?
a) Ectoderm
b) Endoderm
c) Mesoderm
d) Neural crest cells
Answer: Endoderm. Follicular cells derive from endodermal epithelium of the pharyngeal floor, while parafollicular cells come from neural crest cells.
6. Melanocytes originate from:
a) Surface ectoderm
b) Mesoderm
c) Neural crest cells
d) Endoderm
Answer: Neural crest cells. Melanocytes are pigment-producing cells found in the skin, hair, and eyes, and their origin explains disorders like vitiligo.
7. A newborn presents with aniridia (absence of iris). This defect most likely involves which embryonic derivative?
a) Neuroectoderm
b) Surface ectoderm
c) Mesoderm
d) Endoderm
Answer: Neuroectoderm. The iris stroma is mesodermal, but the iris epithelium and muscles are from neuroectoderm, explaining the visual defect.
8. The spinal cord originates from:
a) Surface ectoderm
b) Neuroectoderm
c) Mesoderm
d) Endoderm
Answer: Neuroectoderm. It forms from the neural tube, which develops from ectoderm after neural plate folding during neurulation.
9. The epithelial lining of the respiratory tract is derived from:
a) Surface ectoderm
b) Neuroectoderm
c) Endoderm
d) Mesoderm
Answer: Endoderm. Endoderm forms the epithelium of the respiratory and gastrointestinal tracts, while mesoderm forms their connective and muscular tissues.
10. Which embryonic origin best explains congenital absence of sweat glands (anhidrosis)?
a) Mesoderm
b) Surface ectoderm
c) Neuroectoderm
d) Endoderm
Answer: Surface ectoderm. Sweat glands are epidermal derivatives, and ectodermal dysplasia can lead to absence or dysfunction of these glands.
Chapter: Embryology
Topic: Pharyngeal Arches
Subtopic: Skeletal Derivatives of Pharyngeal Arches
Keyword Definitions:
Pharyngeal arches: Mesodermal and neural crest cell-derived structures in the embryonic head and neck region.
Second pharyngeal arch: Also called the hyoid arch, contributes to parts of the hyoid bone, stapes, and facial muscles.
Malleus: Middle ear ossicle derived from the first pharyngeal arch.
Incus: Middle ear ossicle derived from the first pharyngeal arch.
Stapes: Middle ear ossicle partly derived from the second pharyngeal arch.
Maxilla: Upper jaw bone derived from the first pharyngeal arch.
Reichert’s cartilage: Cartilage of the second arch forming specific skeletal elements.
Hyoid bone: Bone in the neck supporting the tongue and swallowing muscles.
Facial nerve (CN VII): Nerve of the second pharyngeal arch, supplying facial muscles.
Styloid process: Bony projection from temporal bone derived from the second pharyngeal arch.
Lead Question - 2012:
Skeletal derivative of 2nd pharyngeal arch -
a) Malleus
b) Incus
c) Stapes
d) Maxilla
The correct answer is c) Stapes. The second pharyngeal arch, also known as the hyoid arch, contains Reichert’s cartilage. It forms the stapes of the middle ear, styloid process of the temporal bone, stylohyoid ligament, and parts of the hyoid bone (lesser horn and upper body). Malleus and incus are first arch derivatives.
1. The nerve associated with the second pharyngeal arch is:
a) Trigeminal nerve
b) Facial nerve
c) Glossopharyngeal nerve
d) Vagus nerve
Answer: Facial nerve. The second arch is innervated by cranial nerve VII, responsible for motor supply to muscles of facial expression and taste from the anterior two-thirds of the tongue via the chorda tympani.
2. Reichert’s cartilage develops from which pharyngeal arch?
a) First
b) Second
c) Third
d) Fourth
Answer: Second. Reichert’s cartilage gives rise to several skeletal derivatives including stapes, styloid process, and part of the hyoid bone, highlighting the role of the second pharyngeal arch in craniofacial development.
3. The lesser horn of the hyoid bone is derived from:
a) First arch
b) Second arch
c) Third arch
d) Fourth arch
Answer: Second arch. The lesser horn and upper part of the body of the hyoid bone are derivatives of Reichert’s cartilage from the second pharyngeal arch.
4. Which arch anomaly is associated with congenital stapes fixation?
a) First
b) Second
c) Third
d) Fourth
Answer: Second arch. Abnormal development of Reichert’s cartilage can lead to stapes fixation, resulting in conductive hearing loss.
5. Which muscle group arises from the second pharyngeal arch?
a) Muscles of mastication
b) Muscles of facial expression
c) Pharyngeal constrictors
d) Intrinsic tongue muscles
Answer: Muscles of facial expression. The second arch forms muscles for facial expressions, stapedius, stylohyoid, and posterior belly of the digastric.
6. The stapes footplate is related embryologically to:
a) First arch mesoderm
b) Second arch cartilage
c) Otic capsule
d) Nasal capsule
Answer: Otic capsule. While the stapes suprastructure comes from the second arch, the footplate originates from the otic capsule surrounding the developing inner ear.
7. Which pharyngeal arch abnormality can cause microtia with middle ear anomalies?
a) First arch
b) Second arch
c) Third arch
d) Fourth arch
Answer: Second arch. Malformations can affect auricular hillocks (external ear) and ossicles like stapes, causing hearing defects.
8. The stylohyoid ligament develops from:
a) First arch
b) Second arch
c) Third arch
d) Fourth arch
Answer: Second arch. The stylohyoid ligament is derived from Reichert’s cartilage, which also forms the styloid process and parts of the hyoid bone.
9. Which cranial nerve is affected in Bell’s palsy, a condition involving muscles of facial expression?
a) CN V
b) CN VII
c) CN IX
d) CN X
Answer: CN VII (Facial nerve). Bell’s palsy is a lower motor neuron lesion affecting the nerve of the second arch, leading to unilateral facial muscle weakness.
10. In development, the second pharyngeal arch overgrows the third and fourth arches to form:
a) Cervical sinus
b) External auditory canal
c) Submandibular gland
d) Carotid sheath
Answer: Cervical sinus. This overgrowth creates a temporary space that normally disappears; persistence can cause branchial cleft cysts.
Chapter: Embryology
Topic: Development of Gastrointestinal Tract
Subtopic: Development of Rectum and Anal Canal
Keyword Definitions:
Rectum: terminal part of the large intestine between sigmoid colon and anal canal.
Cloaca: common cavity in embryo for urinary, genital, and digestive tracts.
Hindgut: posterior portion of primitive gut tube giving rise to distal colon and rectum.
Allantois: embryonic diverticulum involved in early urine collection.
Urogenital sinus: embryonic structure that develops into urinary bladder and urethra.
Anal canal: terminal part of digestive tract distal to rectum.
Proctodeum: ectodermal depression forming lower anal canal.
Pectinate line: junction between endodermal and ectodermal anal canal.
Imperforate anus: congenital absence of anal opening.
Cloacal membrane: embryonic membrane separating cloaca from exterior.
Lead Question - 2012:
Rectum develops from
a) Cloaca
b) Hind gut
c) Allantoic remnants
d) Urogenital sinus
The correct answer is b) Hind gut. The rectum develops from the endodermal hindgut. During embryogenesis, the cloaca divides into the urogenital sinus and the anorectal canal by the urorectal septum. The upper anal canal and rectum are derived from hindgut, whereas lower anal canal is from ectodermal proctodeum.
1. The cloaca is divided into the urogenital sinus and anorectal canal by:
a) Cloacal membrane
b) Urorectal septum
c) Pectinate line
d) Allantoic duct
Answer: Urorectal septum. It is a mesodermal structure that grows to separate the cloaca into the anterior urogenital sinus and posterior anorectal canal, preventing communication between urinary and digestive tracts in normal development.
2. The lower anal canal develops from:
a) Hindgut
b) Cloaca
c) Proctodeum
d) Allantois
Answer: Proctodeum. The lower one-third of the anal canal originates from the ectodermal proctodeum, which invaginates to meet the endodermal upper canal at the pectinate line.
3. Which embryonic germ layer forms the epithelium of the rectum?
a) Mesoderm
b) Endoderm
c) Ectoderm
d) Neural crest
Answer: Endoderm. The lining epithelium of the rectum and most of the anal canal above the pectinate line arises from the endoderm of the hindgut.
4. A newborn with imperforate anus likely has failure of:
a) Cloacal membrane rupture
b) Pectinate line formation
c) Proctodeum invagination
d) Hindgut rotation
Answer: Cloacal membrane rupture. Normally, the cloacal membrane degenerates to create an opening; persistence leads to imperforate anus, often associated with other anomalies.
5. Hirschsprung’s disease results from failure of migration of:
a) Mesodermal cells
b) Neural crest cells
c) Endodermal epithelium
d) Myoblasts
Answer: Neural crest cells. Absence of ganglion cells in the distal colon leads to functional obstruction due to failure of peristalsis.
6. Which structure marks the junction of endodermal and ectodermal parts of the anal canal?
a) Dentate line
b) Pectinate line
c) Anocutaneous line
d) Anal verge
Answer: Pectinate line. This line is important for differences in blood supply, innervation, and lymphatic drainage between upper and lower anal canal.
7. Which artery supplies the upper rectum?
a) Superior rectal artery
b) Middle rectal artery
c) Inferior rectal artery
d) Internal pudendal artery
Answer: Superior rectal artery. It is a continuation of the inferior mesenteric artery and supplies the rectum above the pectinate line.
8. The anorectal canal is lined by:
a) Simple squamous epithelium
b) Columnar epithelium above, stratified squamous below
c) Transitional epithelium
d) Pseudostratified ciliated columnar
Answer: Columnar epithelium above, stratified squamous below. This change occurs at the pectinate line, correlating with embryonic origin.
9. Which venous drainage is associated with internal hemorrhoids?
a) Inferior rectal vein
b) Middle rectal vein
c) Superior rectal vein
d) External pudendal vein
Answer: Superior rectal vein. It drains into the portal system, and its dilatation above the pectinate line causes internal hemorrhoids.
10. The urogenital sinus gives rise to all except:
a) Urinary bladder
b) Urethra
c) Lower anal canal
d) Prostate
Answer: Lower anal canal. This structure arises from the proctodeum, not the urogenital sinus. The urogenital sinus forms urinary and part of reproductive structures.
Chapter: Embryology
Topic: Development of Breast
Subtopic: Congenital Anomalies of the Mammary Gland
Keyword Definitions:
Amastia: complete absence of breast tissue and nipple.
Polymastia: presence of more than two breasts.
Polythelia: presence of additional nipples without extra breast tissue.
Mastitis: inflammation of breast tissue, usually due to infection.
Mammary ridge: embryonic thickening of ectoderm from which breasts develop.
Congenital anomaly: defect present at birth due to developmental disturbance.
Galactorrhea: inappropriate milk secretion unrelated to pregnancy.
Accessory breast tissue: extra breast tissue along the mammary line.
Hypoplasia: underdevelopment of a tissue or organ.
Neonatal mastitis: breast inflammation in newborns, often due to staphylococcal infection.
Lead Question - 2012:
Which of the following is not a congenital anomaly?
a) Amastia
b) Polymastia
c) Polythelia
d) Mastitis
The correct answer is d) Mastitis. Mastitis is an acquired inflammatory condition, most commonly due to bacterial infection during lactation. Amastia, polymastia, and polythelia result from developmental abnormalities of the mammary ridge. Mastitis can occur at any age and is not a structural defect present at birth.
1. Amastia occurs due to failure of:
a) Mammary ridge formation
b) Mammary ridge involution
c) Nipple eversion
d) Milk duct formation
Answer: Mammary ridge formation. If the mammary ridge fails to develop during embryogenesis, breast tissue and nipple are absent. This may occur unilaterally or bilaterally and can be associated with other syndromes such as ectodermal dysplasia.
2. Polymastia results from persistence of:
a) Entire mammary ridge
b) Single mammary placode
c) Accessory milk ducts
d) Nipple-areola complex
Answer: Entire mammary ridge. Normally, the mammary ridge regresses except at the site of future breasts. Failure of regression in other areas leads to accessory breasts.
3. Which is the most common congenital breast anomaly?
a) Amastia
b) Polymastia
c) Polythelia
d) Hypoplasia
Answer: Polythelia. Extra nipples without associated glandular tissue are the most frequent anomaly. They often occur along the “milk line” and are usually asymptomatic.
4. In which syndrome is amastia commonly seen?
a) Poland syndrome
b) Turner syndrome
c) Klinefelter syndrome
d) Marfan syndrome
Answer: Poland syndrome. This rare congenital condition involves unilateral chest wall and breast muscle hypoplasia or absence, sometimes associated with amastia.
5. Mastitis is most common in which period?
a) Neonatal
b) Puberty
c) Lactational
d) Post-menopause
Answer: Lactational. Cracks in the nipple during breastfeeding allow bacterial entry, leading to inflammation and infection, usually by Staphylococcus aureus.
6. Which breast condition can present as a midline chest wall swelling at birth?
a) Polymastia
b) Polythelia
c) Amastia
d) Mastitis neonatorum
Answer: Mastitis neonatorum. Caused by maternal hormones crossing the placenta, it can result in breast enlargement and sometimes infection in newborns.
7. Polythelia may be mistaken for:
a) Lipoma
b) Mole
c) Sebaceous cyst
d) All of the above
Answer: All of the above. Supernumerary nipples can be small, pigmented, and mistaken for skin lesions; histology confirms nipple structures.
8. Breast tissue along the axilla is usually due to:
a) Polymastia
b) Lymphadenopathy
c) Fibroadenoma
d) Fat necrosis
Answer: Polymastia. Accessory breast tissue can develop in the axilla and respond to hormonal changes during puberty and pregnancy.
9. Which hormone stimulates breast development during puberty?
a) Estrogen
b) Progesterone
c) Prolactin
d) Oxytocin
Answer: Estrogen. It stimulates ductal growth, while progesterone promotes lobuloalveolar development. Both act synergistically for breast maturation.
10. Which congenital breast anomaly is associated with urinary tract malformations?
a) Polythelia
b) Amastia
c) Polymastia
d) Hypoplasia
Answer: Polythelia. Embryologically, mammary and urinary systems may share developmental signaling pathways; polythelia has been linked to renal anomalies in some cases.
Chapter: Embryology
Topic: Vertebral Column Development
Subtopic: Role of Notochord and Sclerotome
Keyword Definitions:
Notochord: rod-like embryonic structure inducing neural tube development and forming the nucleus pulposus.
Sclerotome: portion of somite forming vertebrae, ribs, and annulus fibrosus.
Annulus fibrosus: outer fibrous ring of the intervertebral disc.
Nucleus pulposus: gelatinous inner core of the intervertebral disc.
Neural tube: embryonic precursor to the brain and spinal cord.
Somites: segmented mesodermal blocks forming musculoskeletal structures.
Mesoderm: germ layer giving rise to muscle, bone, and connective tissues.
Vertebral arch: posterior element of vertebra enclosing the spinal cord.
Chondrification centers: initial sites of cartilage formation before ossification.
Ossification: process of bone tissue formation from cartilage or fibrous tissue.
Lead Question - 2012:
Which of the following is true about vertebral development?
a) The notochord forms the annulus fibrosus
b) The sclerotome forms the nucleus pulposus
c) The sclerotome surrounds the notochord only
d) The sclerotome surrounds the notochord and the neural tube
The correct answer is d) The sclerotome surrounds the notochord and the neural tube. In vertebral embryogenesis, sclerotome cells migrate medially to encircle both structures. The notochord persists as the nucleus pulposus, while the sclerotome forms vertebral bodies, arches, and annulus fibrosus. This organization is vital for spinal support and nerve protection.
1. Which embryonic structure forms the nucleus pulposus?
a) Notochord
b) Sclerotome
c) Dermomyotome
d) Myotome
Answer: Notochord. It persists in the adult as the gelatinous nucleus pulposus, cushioning the spine and enabling movement. Its embryonic role also includes inducing neural plate formation through signaling molecules.
2. The annulus fibrosus is derived from:
a) Notochord
b) Neural crest
c) Sclerotome
d) Endoderm
Answer: Sclerotome. Mesenchymal cells from sclerotome wrap around the notochord to form the annulus fibrosus, which supports and encloses the nucleus pulposus.
3. The myotome of the somite develops into:
a) Vertebrae
b) Skeletal muscles
c) Dermis
d) Nucleus pulposus
Answer: Skeletal muscles. The myotome gives rise to voluntary muscles of the trunk and limbs, distinct from sclerotome (bone) and dermatome (skin dermis).
4. Congenital vertebral fusion in Klippel-Feil syndrome is due to failure of:
a) Notochord segmentation
b) Sclerotome resegmentation
c) Myotome migration
d) Neural tube closure
Answer: Sclerotome resegmentation. This step allows for nerve root exit and intervertebral disc formation. Failure results in fused cervical vertebrae with limited neck motion.
5. Sclerotome differentiation is induced by signals from:
a) Neural crest
b) Ectoderm
c) Notochord and neural tube floor plate
d) Endoderm
Answer: Notochord and neural tube floor plate. They secrete Sonic hedgehog (Shh), triggering sclerotome gene expression for vertebral development.
6. First chondrification centers in vertebrae appear in:
a) Centrum and neural arches
b) Spinous process
c) Transverse process
d) Costal elements
Answer: Centrum and neural arches. These primary cartilage centers fuse later to form complete vertebrae.
7. A tumor from persistent notochordal tissue is:
a) Osteosarcoma
b) Chordoma
c) Meningioma
d) Astrocytoma
Answer: Chordoma. This slow-growing malignant tumor occurs in midline locations such as sacrum and clivus, reflecting its notochordal origin.
8. Failure of vertebral arch fusion leads to:
a) Spina bifida
b) Scoliosis
c) Kyphosis
d) Lordosis
Answer: Spina bifida. In this defect, the vertebral arch remains incomplete, potentially exposing spinal structures.
9. Vertebral column originates from which germ layer?
a) Ectoderm
b) Endoderm
c) Paraxial mesoderm
d) Intermediate mesoderm
Answer: Paraxial mesoderm. This mesoderm forms somites, which later specialize into sclerotome, myotome, and dermatome.
10. Ossification of vertebrae begins in which fetal month?
a) 1st month
b) 2nd month
c) 3rd month
d) 5th month
Answer: 3rd month. Ossification centers appear in the centrum and arches, enabling vertebral maturation before birth.
Chapter: Respiratory System Anatomy
Topic: Trachea and Bronchial Tree
Subtopic: Anatomical Landmarks of Trachea
Key Term Definition
Trachea: A tubular airway extending from the larynx to the carina, conducting air to the bronchi.
Carina: Ridge at the tracheal bifurcation, highly sensitive and triggers the cough reflex.
Bifurcation: Division of the trachea into right and left primary bronchi.
T4 vertebra: Thoracic vertebra marking the level of tracheal bifurcation.
Sternal angle: Surface landmark anteriorly corresponding to T4–T5 vertebral level.
Primary bronchi: First branches of the trachea leading to each lung.
Right main bronchus: Shorter, wider, more vertical bronchus—common site of aspiration.
Left main bronchus: Longer, narrower, more horizontal bronchus.
Bronchoscopy: Endoscopic examination of the airways using a bronchoscope.
Mediastinum: Central compartment of the thoracic cavity containing heart, trachea, esophagus, etc.
Lead Question - 2012:
At what level does the trachea bifurcate?
a) Upper border of T4
b) Lower border of T4
c) 27.5 cm from the incisors
d) Lower border of T5
The correct answer is Lower border of T4. The trachea ends by dividing into right and left main bronchi at the lower border of the T4 vertebra, aligning with the sternal angle anteriorly. This landmark is important in bronchoscopy, thoracic surgery, and chest imaging. It shifts slightly with respiration and posture.
1. Which surface landmark indicates tracheal bifurcation anteriorly?
a) Jugular notch
b) Sternal angle
c) Xiphisternal joint
d) Clavicle
Answer: Sternal angle. The junction between the manubrium and the body of the sternum corresponds to the T4–T5 intervertebral disc level. Clinically, it is a key reference point for rib counting, mediastinal anatomy, and airway localization in surgery or trauma settings.
2. In bronchoscopy, the carina appears:
a) Sharp and well-defined
b) Blunt and indistinct
c) Invisible
d) Covered by epiglottis
Answer: Sharp and well-defined. A normal carina is a distinct ridge; blunting may indicate malignancy or chronic inflammation. Its appearance is crucial during bronchoscopy for diagnosing tumors, lymphadenopathy, or airway compression.
3. Which bronchus is more prone to foreign body aspiration?
a) Right main bronchus
b) Left main bronchus
c) Both equally
d) None
Answer: Right main bronchus. Its shorter, wider, and more vertical course makes it more likely for aspirated objects to enter, especially in children. This anatomical feature explains the distribution of aspiration pneumonia patterns.
4. Which nerve provides sensory innervation to the trachea?
a) Glossopharyngeal nerve
b) Recurrent laryngeal nerve
c) Superior laryngeal nerve
d) Vagus nerve directly
Answer: Recurrent laryngeal nerve. This branch of the vagus nerve supplies sensation to the tracheal mucosa, enabling protective airway reflexes like coughing. Damage can cause impaired reflexes and aspiration risk.
5. Which tracheal layer contains the C-shaped cartilage rings?
a) Mucosa
b) Submucosa
c) Adventitia
d) Fibromuscular membrane
Answer: Adventitia. This outer connective tissue layer contains hyaline cartilage rings, which prevent airway collapse. Posteriorly, the trachea is membranous, allowing expansion of the esophagus during swallowing.
6. In neck flexion, the tracheal bifurcation moves:
a) Upward
b) Downward
c) Remains same
d) Forward only
Answer: Upward. Neck flexion shortens the trachea and elevates the carina, which is relevant during airway management. Excessive movement can complicate tube positioning in intubated patients.
7. Arterial supply of the upper trachea is primarily via:
a) Inferior thyroid artery
b) Superior thyroid artery
c) Bronchial arteries
d) Vertebral artery
Answer: Inferior thyroid artery. This vessel supplies blood to the cervical portion of the trachea, supporting mucosal health and healing. Lower portions receive blood from bronchial arteries.
8. Widening of the carinal angle is suggestive of:
a) Pneumothorax
b) Left atrial enlargement
c) Asthma
d) Emphysema
Answer: Left atrial enlargement. Seen in conditions like mitral stenosis, it causes downward displacement of the carina, visible on imaging and often correlating with clinical symptoms of pulmonary congestion.
9. Structure lying directly posterior to tracheal bifurcation:
a) Esophagus
b) Left atrium
c) Descending aorta
d) Right pulmonary artery
Answer: Esophagus. The esophagus runs behind the trachea and continues posterior to the left main bronchus after bifurcation, important during transesophageal procedures.
10. If an endotracheal tube enters the right bronchus, the consequence is:
a) Hypoventilation of right lung
b) Hypoventilation of left lung
c) Collapse of both lungs
d) Bronchospasm
Answer: Hypoventilation of left lung. The tube bypasses the left bronchus, ventilating only the right lung. This can cause collapse of the left lung if unrecognized during anesthesia or critical care.
Chapter: Respiratory System Anatomy
Topic: Larynx and Airway Landmarks
Subtopic: Cricoid Cartilage and Related Structures
Keyword Definition
Cricoid cartilage: A complete ring-shaped cartilage located below the thyroid cartilage at the C6 vertebral level, forming part of the larynx.
C6 vertebra: A cervical vertebral level marking anatomical landmarks like the cricoid cartilage and start of trachea and esophagus.
Larynx: Voice box containing vocal cords, located in the neck, functioning in phonation, airway protection, and breathing.
Trachea: Airway tube starting below the larynx at C6 and extending to the carina.
Esophagus: Muscular tube posterior to trachea, beginning at C6 level, conveying food to the stomach.
Thyroid cartilage: Largest laryngeal cartilage forming the laryngeal prominence or Adam's apple.
Recurrent laryngeal nerve: Branch of vagus nerve supplying motor function to all intrinsic laryngeal muscles except cricothyroid.
Emergency cricothyrotomy: A lifesaving airway procedure performed through the cricothyroid membrane.
Pharynx: Musculomembranous tube connecting nasal and oral cavities to the larynx and esophagus.
Laryngopharynx: Lowest part of the pharynx, extending from the hyoid bone to the cricoid cartilage.
Lead Question - 2012:
Cricoid cartilage lies at which vertebral level?
a) C3
b) C6
c) T1
d) T4
The correct answer is C6. The cricoid cartilage marks the junction of the larynx and trachea anteriorly and the beginning of the esophagus posteriorly. This landmark is vital in clinical medicine for procedures like cricothyrotomy and intubation. It also correlates with the lower border of the pharynx and entry of the recurrent laryngeal nerves into the larynx.
1. Which structure lies directly posterior to the cricoid cartilage?
a) Trachea
b) Esophagus
c) Thyroid gland
d) Vertebral artery
Answer: Esophagus. The esophagus begins at the level of the cricoid cartilage (C6) and lies directly behind it. This relationship is critical in endoscopy, nasogastric tube insertion, and esophageal surgeries.
2. During emergency airway access, the preferred site below the thyroid cartilage is:
a) Cricothyroid membrane
b) Tracheal rings
c) Thyrohyoid membrane
d) Hyoid bone
Answer: Cricothyroid membrane. This site is accessed in cricothyrotomy due to its superficial location and minimal vascularity, lying between the thyroid cartilage and cricoid cartilage.
3. Which muscle attaches to the posterior lamina of the cricoid cartilage?
a) Posterior cricoarytenoid
b) Cricothyroid
c) Lateral cricoarytenoid
d) Thyroarytenoid
Answer: Posterior cricoarytenoid. This is the only muscle that abducts the vocal cords and is critical for maintaining an open airway.
4. At the C6 vertebral level, which of the following structures is also present?
a) Bifurcation of trachea
b) Beginning of esophagus
c) Termination of aorta
d) Diaphragmatic opening of IVC
Answer: Beginning of esophagus. This level also marks the end of the pharynx and the transition to the esophagus posteriorly.
5. In infants, the narrowest part of the airway is:
a) Vocal cords
b) Cricoid cartilage
c) Thyroid cartilage
d) Tracheal rings
Answer: Cricoid cartilage. In pediatric anatomy, this is the narrowest region and is relevant in airway management, sizing endotracheal tubes, and avoiding post-intubation stenosis.
6. Which nerve is closely related to the cricoid cartilage?
a) Hypoglossal nerve
b) Recurrent laryngeal nerve
c) Phrenic nerve
d) Accessory nerve
Answer: Recurrent laryngeal nerve. This nerve ascends in the tracheoesophageal groove to enter the larynx just behind the cricoid cartilage.
7. Which clinical maneuver involves applying pressure over the cricoid cartilage to prevent aspiration during intubation?
a) Heimlich maneuver
b) Sellick’s maneuver
c) Jaw thrust
d) Chin lift
Answer: Sellick’s maneuver. It occludes the esophagus against the vertebral body to reduce the risk of regurgitation during airway instrumentation.
8. Which ligament connects the cricoid cartilage to the first tracheal ring?
a) Cricothyroid ligament
b) Cricotracheal ligament
c) Thyrohyoid ligament
d) Annular ligament
Answer: Cricotracheal ligament. It provides stability between the cricoid and the trachea while allowing minimal movement.
9. Which imaging modality best visualizes cricoid cartilage in suspected airway trauma?
a) X-ray
b) CT scan
c) MRI
d) Ultrasound
Answer: CT scan. It provides high-resolution images of laryngeal cartilage, detecting fractures or displacement.
10. Which type of cartilage is the cricoid composed of?
a) Elastic cartilage
b) Fibrocartilage
c) Hyaline cartilage
d) Mixed cartilage
Answer: Hyaline cartilage. It maintains airway patency but can ossify with age, becoming more visible on imaging in older individuals.