Practice 7 structured short- and long-answer medical questions on MBChB/BDS EXAMINATION QUESTIONS AND MARKING SCHEME. Review model answers for exam revision.
Answer: Describe the light microscopic features of the submandibular gland (5 marks) Marking Points: Stroma (2 marks): - Connective tissue capsule - Septae/trabeculae divide the gland into lobules Parenchyma (3 marks): - Lobulated structure - Lobules contain mixed acini (serous and mucous) - Serous acini form the demilunes - Ductal system present ### ( - Outline the arterial blood supply to the nasal septum (5 marks) Marking Points: - Upper part: branches of anterior and posterior ethmoidal arteries - Posterior aspect: branches of sphenopalatine artery - Inferior aspect: branches of greater palatine artery - Anterior aspect: branches of superior labial artery - All arteries anastomose at Little's area (Kiesselbach's plexus) ### ( - Describe the development of the thyroid gland (5 marks) Marking Points: - Begins to form in the endoderm of the dorsum of the tongue (floor of the primordial pharynx) - Proliferation of tissue (thyroid diverticulum) extends downwards - Thyroid descent occurs in front of hyoid bone and larynx - Thyroglossal duct connection forms and later degenerates, leaving the foramen caecum as remnant - Divides into two lobes connected by the isthmus - Invasion/migration of cells from the ultimobranchial body (4th pharyngeal pouch) into the developing gland ### ( - Describe the electron microscopic features of skeletal muscle (5 marks) Marking Points: The sarcomere (any 2 features for 2 marks): - Regular arrangement of actin and myosin filaments - Z-line: attachments of actin filaments - A-band: region containing myosin - I-band: region lacking myosin Other features (any 3 features for 3 marks): - Extensive smooth endoplasmic reticulum (sarcoplasmic reticulum) - Several mitochondria - Cell membrane invaginations (T-tubules) - T-tubules surrounded by terminal cisterns on either side, forming triads - No cell-to-cell junctions ---
Answer: Describe the arterial blood supply to the oesophagus (5 marks) Marking Points: - Cervical segment (2 marks): inferior thyroid artery; deep cervical artery - Thoracic segment (2 marks): oesophageal branches of thoracic aorta; bronchial arteries; posterior intercostal arteries - Abdominal segment (1 mark): left gastric artery ### ( - Describe the histological organization of the tracheal wall (7 marks) Marking Points: - Mucosa (3 marks): pseudostratified columnar ciliated epithelium and lamina propri - Epithelium contains ciliated columnar cells, goblet cells, brush cells, granule cells, and basal cells - Submucosa (1 mark): dense connective tissue and blood vessels - Musculocartilaginous layer (2 marks): C-shaped rings of hyaline cartilage, bridged posteriorly by smooth muscle - Adventitia (1 mark): thin connective tissue ### ( - Describe the development of the thoracic diaphragm (8 marks) Marking Points: - Begins to form in the cervical region and descends to current position, hence innervation by the phrenic nerve (1 mark) - Septum transversum: forms the central tendon (2 marks) - Dorsal mesogastrium (dorsal mesentery): forms the crura (2 marks) - Lateral body wall: forms the lateral aspects (2 marks) - Pleuroperitoneal folds: contribute to the musculature (2 marks) ---
Answer: Describe the lymphatic drainage of the colon (7 marks) Marking Points: - Follows the arteries (1 mark) - Four levels of lymph nodes (4 marks): Epicolic: under the serosa of the gut wall - Paracolic: along the marginal artery - Intermediate: along the superior mesenteric artery (SM - and inferior mesenteric artery (IM - - Principal: at the root of the SMA and IMA - Proximal colon drains mainly to SMA nodes (1 mark) - Distal colon drains mainly to IMA nodes (1 mark) ### ( - Describe the bony organization and stability factors of the elbow joint (7 marks) Marking Points: Bony organization (2 marks): - Trochlear notch of ulna articulates with trochlea of the humerus - Radial head articulates with capitulum of the humerus Stability factors: - Bony congruency (1 mark) - Ligaments (3 marks): Annular ligament - Ulnar collateral ligament - Radial collateral ligament - Surrounding muscles (1 mark) ### ( - Describe the development of the liver (6 marks) Marking Points: - Arises from the endoderm of the distal foregut (1 mark) - Proliferation of endoderm termed hepatic diverticulum extends into the septum transversum (2 marks) - Diverticulum divides into two parts: Pars hepatica: forms the hepatic ducts and liver (1 mark) - Pars cystica: forms the gall bladder and cystic duct - Histogenesis (2 marks): Endoderm: forms hepatocytes and Ito cells - Septum transversum: forms Kupffer cells - Vitelline vein: forms sinusoids ---
Answer: Describe the organization of the rectus sheath below the umbilicus (6 marks) Marking Points: Upper part (3 marks): - Anterior wall: formed by aponeurosis of external oblique abdominis (EO - and anterior lamina of internal oblique abdominis (IO - - Posterior wall: formed by aponeurosis of transversus abdominis (T - and posterior lamina of IOA Lower part (2 marks): - Anterior wall: formed by aponeuroses of all three muscles (EOA, IOA, and T - - Posterior wall: deficient (related to transversalis fasci - - Arcuate line (linea semicircularis): inferior border of the posterior wall (1 mark) ### ( - Describe the histological organization of the pancreas (7 marks) Marking Points: Stroma (2 marks): - Connective tissue covering that sends septae to divide it into lobules - Contains blood vessels Parenchyma: - Has endocrine and exocrine components (1 mark) - Exocrine component (2 marks): Pancreatic acini with acinar cells and centroacinar cells - Extensive ductal system - Endocrine component (2 marks): Islets of Langerhans with alpha, beta, delta, and PP cells - Richly vascularized ### ( - With the help of a diagram, describe the musculofascial compartments of the leg at mid-calf level (7 marks) *[Note: This question requires a diagram which should show the anterior, lateral, superficial posterior, and deep posterior compartments of the leg with their respective muscles and fascial boundaries]* ---
Answer: Describe the distribution of the middle cerebral artery including functional areas supplied (8 marks) Marking Points: - Runs in the lateral sulcus (Sylvian fissur - to supply the lateral surface of the cerebral cortex (2 marks) - Functional areas supplied (any 6 areas for 6 marks): Broca's area - Primary auditory cortex - Primary motor cortex - Primary sensory cortex - Sensory speech area (Wernicke's are - - Premotor cortex - Frontal eye field - Primary gustatory area - Prefrontal cortex ### ( - Describe the structural organization of the Fallopian tube and indicate its blood supply (6 marks) Marking Points: Gross structure (2 marks): - Tubular structure with parts named fimbriae, infundibulum, and ampulla Histological structure (3 marks): - Highly folded mucosal layer - Mucosa lined by simple columnar ciliated epithelium - Smooth muscle in the wall Blood supply (1 mark): - Branches of uterine and ovarian arteries ### ( - Describe the histological organization of the male urethra (6 marks) Marking Points: Prostatic urethra (2 marks): - Lined by transitional epithelium - Has openings for ejaculatory and prostatic ducts Membranous urethra (1 mark): - Lined by stratified or pseudostratified columnar epithelium Penile urethra (3 marks): - Lined by pseudostratified columnar epithelium proximally and stratified squamous epithelium at the distal end - Has openings for ducts of Cowper's and Littré's glands - Adventitia merges with corpus spongiosum # MBChB/BDS EXAMINATION QUESTIONS AND MODEL ANSWERS ## MULTIPLE CHOICE QUESTIONS (MCQs) - ANSWER KEY --- ## SHORT ANSWER QUESTIONS (SAQs)
Answer: The two main components (2 marks) - Decidua basalis - Chorion frondosum #### - One abnormality associated with: - Excessive invasion into the uterine wall (1 mark): Placenta percreta - Implantation in the lower part of the uterus (1 mark): Placenta previa #### - List two types of neurulation and indicate what they form (2 marks) - Primary neurulation: Forms neural tube - Secondary neurulation: Forms filum terminale #### - Name two derivatives of the neural crest cells in the abdomen (2 marks) - Adrenal medulla - Sympathetic ganglia #### - Give two possible causes of oligohydramnios (2 marks) - Renal agenesis - Rupture of membranes
Answer: The closure mechanisms (4 marks) - Soft palate (Passavant's ridge): Closes communication between oropharynx and nasopharynx - Epiglottis: Closes the opening to the larynx #### - The muscles of the tongue involved and their respective role (4 marks) - Genioglossus: Bolus translates posteriorly - Intrinsic muscles: Shape the bolus in transit - Palatoglossus/Hyoglossus/Styloglossus: Push bolus towards isthmus #### - Movements of the hyoid bone and the larynx (2 marks) - Hyoid bone: Geniohyoid pulls it anteriorly - Larynx: Thyrohyoid pulls it anteriorly