1. Microscopic structure of the duodenum, with a labelled diagram
2. Types of epiphysis, with examples
3. Left coronary artery: origin, course, branches and applied anatomy
4. Verbal and non-verbal communication (AETCOM)

1. Why the umbilicus is called the watershed line
2. Why scalp injuries bleed profusely
3. Why cholecystitis pain is referred to the right shoulder
4. Why extravasated urine does not enter the thigh
5. Steps of karyotyping

• Duodenum: It has the four usual layers: mucosa, submucosa, muscularis externa and serosa or adventitia. The distinguishing features are broad leaf-like villi, Brunner's glands in the submucosa (these are specific to the duodenum), and few goblet cells.
• Epiphysis: Pressure epiphyses (e.g., femoral head) take weight. Traction epiphyses (e.g., greater trochanter) are the sites of muscle pull. Atavistic epiphyses (e.g., coracoid process) are phylogenetically separate bones. Aberrant epiphyses are present only in some individuals (e.g., the head of the first metacarpal).
• Left coronary artery: It arises from the left aortic sinus and runs between the pulmonary trunk and the left auricle. It divides into the anterior interventricular (LAD) and circumflex arteries. Applied anatomy covers myocardial infarction, angina and bypass grafting.
• Verbal and non-verbal communication: Verbal communication is spoken or written words. Non-verbal communication is body language, eye contact, tone, touch and posture, and the diagram is a communication model.
• Watershed line: Above the umbilicus, lymph, venous blood and nerve supply drain towards the axilla. Below it, they drain towards the groin.
• Scalp bleeding: The scalp is very vascular. The vessel walls are held open by dense fibrous tissue in the superficial fascia, so they cannot retract or collapse. There are also rich anastomoses.
• Cholecystitis pain: The diaphragm is irritated, and the phrenic nerve (C3 to C5) carries the pain. It is felt at the shoulder because the supraclavicular nerves (C3 to C4) share those segments.
• Extravasated urine: Deep fascia, Colles' fascia and the fascia lata fuse at the inguinal ligament. This blocks spread into the thigh, so urine goes up into the anterior abdominal wall.
• Karyotyping: The steps are culture, arrest at metaphase with colchicine, a hypotonic solution, fixation, slide preparation, banding and microscopy.

1. Microscopic structure of the duodenum, with a labelled diagram
2. Types of epiphysis, with examples
3. Left coronary artery: origin, course, branches and applied anatomy
4. Verbal and non-verbal communication (AETCOM)

1. Why the umbilicus is called the watershed line
2. Why scalp injuries bleed profusely
3. Why cholecystitis pain is referred to the right shoulder
4. Why extravasated urine does not enter the thigh
5. Steps of karyotyping

• Duodenum: It has the four usual layers: mucosa, submucosa, muscularis externa and serosa or adventitia. The distinguishing features are broad leaf-like villi, Brunner's glands in the submucosa (these are specific to the duodenum), and few goblet cells.
• Epiphysis: Pressure epiphyses (e.g., femoral head) take weight. Traction epiphyses (e.g., greater trochanter) are the sites of muscle pull. Atavistic epiphyses (e.g., coracoid process) are phylogenetically separate bones. Aberrant epiphyses are present only in some individuals (e.g., the head of the first metacarpal).
• Left coronary artery: It arises from the left aortic sinus and runs between the pulmonary trunk and the left auricle. It divides into the anterior interventricular (LAD) and circumflex arteries. Applied anatomy covers myocardial infarction, angina and bypass grafting.
• Verbal and non-verbal communication: Verbal communication is spoken or written words. Non-verbal communication is body language, eye contact, tone, touch and posture, and the diagram is a communication model.
• Watershed line: Above the umbilicus, lymph, venous blood and nerve supply drain towards the axilla. Below it, they drain towards the groin.
• Scalp bleeding: The scalp is very vascular. The vessel walls are held open by dense fibrous tissue in the superficial fascia, so they cannot retract or collapse. There are also rich anastomoses.
• Cholecystitis pain: The diaphragm is irritated, and the phrenic nerve (C3 to C5) carries the pain. It is felt at the shoulder because the supraclavicular nerves (C3 to C4) share those segments.
• Extravasated urine: Deep fascia, Colles' fascia and the fascia lata fuse at the inguinal ligament. This blocks spread into the thigh, so urine goes up into the anterior abdominal wall.
• Karyotyping: The steps are culture, arrest at metaphase with colchicine, a hypotonic solution, fixation, slide preparation, banding and microscopy.

IV. Short notes

9. Microscopic structure of the duodenum

1. Mucosa
   • Epithelium: simple columnar with a brush border (absorptive cells, enterocytes). Goblet cells are scattered among them.
   • Villi: broad, leaf-like projections. They become taller and thinner from proximal to distal duodenum (Yamada's Textbook of Gastroenterology).
   • Crypts of Lieberkühn: these open between villi. They contain stem cells, Paneth cells and enteroendocrine cells (secretin and CCK cells).
   • Lamina propria: loose connective tissue with lymphoid cells and a lacteal in each villus.
   • Muscularis mucosae: thin smooth muscle layer.
2. Submucosa: it contains Brunner's glands. These are branched tubuloacinar mucous glands whose ducts open into the crypts. They secrete alkaline mucus (pH 8 to 9), which neutralises gastric acid. They also secrete urogastrone (EGF), which inhibits gastric acid. The Histology: A Text and Atlas textbook calls them "a distinctive feature of the duodenum".
3. Muscularis externa: inner circular and outer longitudinal smooth muscle layers. The myenteric (Auerbach's) plexus lies between them.
4. Serosa or adventitia: the outermost layer.

10. Types of epiphysis, with examples

11. Left coronary artery

• Origin: left posterior aortic sinus, just above the left cusp of the aortic valve.
• Course: it is about 1 to 2.5 cm long. It passes forward and to the left, behind the pulmonary trunk, and emerges between the pulmonary trunk and the left auricle. It then divides into two terminal branches.
  • The anterior interventricular artery (LAD) runs in the anterior interventricular groove to the apex. It then turns round the inferior border to anastomose with the posterior interventricular artery.
  • The circumflex artery runs in the left atrioventricular groove to the posterior surface.
• Branches of the LAD: left conus artery, diagonal branches, anterior ventricular branches, and septal branches (supplying the anterior two-thirds of the interventricular septum and part of the conducting system).
• Branches of the circumflex: left marginal artery (the largest), atrial branches, and anterior and posterior ventricular branches. It gives the SA nodal artery in about 40% of people. In left-dominant hearts it gives the posterior interventricular artery.
• Area supplied: left atrium, most of the left ventricle, part of the right ventricle, and the anterior two-thirds of the interventricular septum.
• Applied anatomy:
  • LAD occlusion is the "widow maker". It causes anterior wall myocardial infarction and septal damage with bundle branch block.
  • Narrowing causes angina. Treatment is angioplasty with stenting, or CABG using the internal thoracic artery or great saphenous vein.
  • Coronary arteries are functional end arteries. Slow occlusion allows collateral channels to develop.
  • The artery is imaged by coronary angiography.
  • Branching variation is common. A 2026 meta-analysis of left coronary branching patterns found it varies, which does not change the standard description above.

12. Verbal and non-verbal communication (AETCOM)

• Examples: taking a history, explaining a diagnosis, informed consent, discharge summaries, written prescriptions.
• Principles: use simple language without jargon, ask open-ended questions, check understanding, and speak at a suitable pace and tone.

• Eye contact.
• Facial expression.
• Posture and gesture (kinesics).
• Touch (haptics).
• Personal space (proxemics).
• Tone, pitch and pauses (paralanguage).
• Appearance and dress.
• Examples: sitting at the patient's level, nodding, not looking at a computer screen throughout, a gentle touch during bad news.

V. Reasoning questions

13. Why the umbilicus is called the watershed line

• Lymph: superficial lymphatics above the umbilicus drain to the axillary nodes. Those below it drain to the superficial inguinal nodes.
• Veins: above the umbilicus, blood drains by the lateral thoracic vein to the axillary vein. Below it, it drains by the superficial epigastric vein to the great saphenous vein.
• Clinical use: cancers of the skin above the umbilicus spread to the axillary nodes, and those below spread to the inguinal nodes.

14. Why scalp injuries bleed profusely

• The scalp has five layers (SCALP): skin, dense connective tissue, aponeurosis (galea), loose areolar tissue, pericranium.
• The vessels lie in the dense connective tissue layer. They are held open by its fibrous septa, so cut vessels cannot retract or collapse, and bleeding continues.
• There is rich anastomosis between the arteries, across the midline and between branches of the internal and external carotid systems. A vessel cut at one point continues to be fed from the other end.
• A transverse cut through the galea gapes because the occipitofrontalis pulls the edges apart, keeping vessels open.

• Supratrochlear and supraorbital: from the ophthalmic artery (internal carotid).
• Superficial temporal, posterior auricular and occipital: from the external carotid.

15. Why cholecystitis pain is referred to the right shoulder

• The gallbladder is supplied by visceral afferents running with the sympathetic nerves (T7 to T9). Early pain from the gallbladder itself is felt in the epigastrium or right hypochondrium.
• As inflammation spreads, it irritates the parietal peritoneum covering the diaphragm. The central part of the diaphragm is supplied by the phrenic nerve (C3, C4, C5).
• The skin over the shoulder is supplied by the supraclavicular nerves (C3, C4), which share the same spinal segments. The brain interprets the pain as coming from the shoulder tip, which is a referred pain (somatic pain from a visceral cause).

16. Why extravasated urine does not enter the thigh

• It spreads into the scrotum and penis, then up over the pubis into the lower anterior abdominal wall, deep to the membranous layer (Scarpa's) of the superficial fascia.
• Spread into the thigh is blocked because Scarpa's fascia fuses with the deep fascia of the thigh (fascia lata) about one finger's breadth below the inguinal ligament. Colles' fascia also fuses laterally with the pubic arch and the fascia lata (Campbell-Walsh Urology).
• It cannot enter the ischioanal fossa because Colles' fascia is attached to the posterior border of the perineal membrane and to the ischiopubic rami.
• Clinical point: the perineum, scrotum and lower abdomen swell, but the thigh does not.

17. Steps of karyotyping

1. Sample collection: peripheral blood (lymphocytes), amniotic fluid, chorionic villi or bone marrow.
2. Culture: cells are grown in medium for 48 to 72 hours, with phytohaemagglutinin (PHA) to stimulate lymphocytes to divide.
3. Arrest in metaphase: add colchicine or colcemid, which blocks spindle formation.
4. Hypotonic treatment: swells the cells (KCl solution) so the chromosomes spread.
5. Fixation: with methanol and acetic acid (3:1).
6. Slide preparation: drop the cells onto slides to spread the chromosomes.
7. Banding: G-banding (trypsin then Giemsa) gives a characteristic band pattern for each chromosome.
8. Microscopy and photography: analyse and photograph a metaphase spread.
9. Arrangement: pair homologues and arrange them by size, centromere position and banding in groups A to G (autosomes 1 to 22, then sex chromosomes X and Y). Report as, for example, 46,XY.