MBChB/BDS EXAMINATION QUESTIONS AND MARKING OmpathStudy

Question 1 QUESTION 1 (Total: 20 marks) ### ( A. 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 ### ( B. 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) ### ( C. 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 ### ( D. 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: A. 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 ### ( --- Question 2 QUESTION 2 (Total: 20 marks) ### ( A. 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 ### ( B. Describe the histological organization of the tracheal wall (7 marks) Marking Points: - Mucosa (3 marks): pseudostratified columnar ciliated epithelium and lamina propri C. 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 ### ( D. 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: A. 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 ### ( --- Question 3 QUESTION 3 (Total: 20 marks) ### ( A. 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 B. and inferior mesenteric artery (IM C. - 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) ### ( D. 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) ### ( E. Describe the development of the liver (6 marks) Marking Points: -