Anatomy and Embryology for the Surgical Candidate
Head and neck
The carotid sheath contains the common carotid medially, the internal jugular vein laterally and the vagus posteriorly in the groove between them. The recurrent laryngeal nerve ascends in the tracheo-oesophageal groove; the right hooks beneath the subclavian artery, the left beneath the aortic arch at the ligamentum arteriosum. The external branch of the superior laryngeal nerve descends with the superior thyroid artery and is at risk when that pedicle is ligated flush to the gland - injury causes loss of pitch and voice fatigue, not hoarseness. The thoracic duct enters the venous system at the left internal jugular–subclavian junction.
Thorax
Each intercostal neurovascular bundle lies in the costal groove, ordered vein, artery, nerve from above downwards. A chest drain is placed in the "safe triangle" and entered over the upper border of the rib below to avoid it.
Abdomen and pelvis
Foregut (to the second part of the duodenum) is supplied by the coeliac trunk, midgut by the superior mesenteric artery, hindgut by the inferior mesenteric artery. Calot's triangle is bounded by the cystic duct, the common hepatic duct and the inferior liver edge, and contains the cystic artery. The midgut rotates 270° anticlockwise around the superior mesenteric artery; incomplete rotation leaves the caecum in the right upper quadrant and predisposes to volvulus. The deep inguinal ring lies lateral to the inferior epigastric vessels; direct hernias emerge medial to them through Hesselbach's triangle.
Limbs
The femoral triangle (inguinal ligament, sartorius, adductor longus) contains, lateral to medial, nerve, artery, vein, empty space, lymphatics.
Embryological traps
Examiners favour remnants: vitelline duct (Meckel's), urachus (urachal cyst), thyroglossal duct (midline cyst that moves on tongue protrusion), branchial cleft (anterior to sternocleidomastoid), and proximal oesophageal atresia with distal tracheo-oesophageal fistula as the commonest variant.
Rule of thumb: learn nerves by their relation to a named artery; questions test relations, not names.