A rib tubercle is a projection that is postero-inferior and lateral to the neck of a rib which articulates with the transverse process of the corresponding vertebra i.e. of the same number. Therefore, the tubercle of rib 7 articulates with the transverse process of T7 vertebra. The head of the rib 7, on the other hand, articulates with the 6th vertebra superiorly and the 7th vertebra inferiorly.

Fick’s principle states that the total uptake (or release) of a substance by peripheral tissues is equal to the product of the blood flow to the peripheral tissues and the arterial– venous concentration difference (gradient) of the substance. It is used to measure the cardiac output, and the formula is Cardiac output = oxygen consumption divided by arteriovenous oxygen difference. Assuming there are no shunts across the pulmonary system, the pulmonary blood flow equals the systemic blood flow. The arterial and venous blood oxygen content is measured by sampling from the pulmonary artery (low oxygen content) and pulmonary vein (high oxygen content). Peripheral arterial blood is used as a surrogate for the pulmonary vein.

Mithramycin or Plicamycin is a tricyclic pentaglycosidic antibiotic derived from Streptomyces strains. It inhibits RNA and protein synthesis by adhering to DNA. It is used as a fluorescent dye and as an antineoplastic agent. It is also used to reduce hypercalcaemia, especially caused by malignancy. Plicamycin is currently used in multiple areas of research, including cancer cell apoptosis and as a metastasis inhibitor.

Transport maximum (or Tm) refers to the point at which increases in concentration do not result in an increase in movement of a substance across a membrane. Glucose is not secreted, thus excretion = filtration – reabsorption. Both filtration and reabsorption are directly proportional to the concentration of glucose in the plasma. However, reabsorption has a transport maximum of about 300 mg/dl in healthy nephrons, while filtration has effectively no limit (within reasonable physiological ranges). So, if the concentration rises above 300 mg/dl, the body cannot retain all the glucose, leading to glucosuria. Glucosuria is nearly always caused by elevated blood glucose levels, most commonly due to untreated diabetes mellitus.

The most likely diagnosis is appendicitis. The negative vaginal examination (and therefore by definition, the absence of cervical excitation) makes pelvic inflammatory disease unlikely. Given the raised inflammatory markers, the correct course of action is to proceed with surgery. In females, there are considerable advantages of undertaking this laparoscopically as it allows evaluation of the pelvic viscera. Imaging with ultrasound is unlikely to alter management as it has a false negative rate, and given the context of the clinical findings, surgery is likely to occur in any case. Whilst a CT scan would allow for an accurate preoperative diagnosis, it carries a significant radiation dose and again, is unlikely to alter management.

Differential diagnosis of right iliac fossa (RIF) pain includes:
1. Appendicitis
2. Crohn’s disease
3. Mesenteric adenitis
4. Diverticulitis
5. Meckel’s diverticulitis
6. Perforated peptic ulcer
7. Incarcerated right inguinal or femoral hernia
8. Bowel perforation secondary to caecal or colon carcinoma
9. Gynaecological causes—pelvic inflammatory disease/salpingitis/pelvic abscess/Ectopic pregnancy/Ovarian torsion/threatened or complete abortion
10. Urological causes—ureteric colic/urinary tract infection/Testicular torsion
11. Other causes—tuberculosis/typhoid/ infection with herpes zoster

Fat necrosis is necrosis of adipose tissue with subsequent deposition of calcium, giving it a white chalky appearance. It is seen characteristically in trauma to the breast and the pancreas with subsequent involvement of the peripancreatic fat. In the breast it may present as a palpable mass with is usually painless or as an incidental finding on mammogram. Fatty acids are released from the traumatic tissue which combine with calcium in a process known as saponification, this is an example of dystrophic calcification in which calcium binds to dead tissue. The central focus is surrounded by macrophages and neutrophils initially, followed by proliferation of fibroblasts, neovascularization and lymphocytic migration to the site of the insult.

Lymphadenitis is the inflammation or enlargement of a lymph node. Lymph nodes are small, ovoid nodules normally ranging in size from a few millimetres to 2 cm. They are distributed in clusters along the course of lymphatic vessels located throughout the body. The primary function of lymph nodes is to filter out microorganisms and abnormal cells that have collected in lymph fluid. Lymph node enlargement is a common feature in a variety of diseases and may serve as a focal point for subsequent clinical investigation of diseases of the reticuloendothelial system or regional infection. The majority of cases represent a benign response to localized or systemic infection. The red streaks that are noted along the line of lymphatics are indicative of lymphadenitis.

Groin masses are common and include:
Herniae
Lipomas
Lymph nodes
Undescended testis
Femoral aneurysm
Saphena varix

The immediate treatment of hypercalcaemia involves intravenous fluid resuscitation. This may be complemented with the use of bisphosphonates and sometimes, diuretics. However, fluids are administered first. Normal saline is usually preferred for this over other solutions.

Urgent management in hypercalcaemia is indicated if:
1. Serum calcium level >3.5 mmol/L
2. Reduced consciousness
3. Severe abdominal pain
4. Pre-renal failure

Management options include:
1. Intravenous fluid resuscitation with 3–6 litres of 0.9% normal saline in 24 hours
2. Concurrent administration of calcitonin to help lower calcium levels
3. Medical therapy (usually if corrected calcium >3.0mmol/L)

These non specific findings are suggestive of autoimmune disease. Antinuclear antibody (ANA) is the first test that should be performed when autoimmune diseases are suspected and later on more specific tests should be performed. This tests aids in the diagnosis of SLE, scleroderma, Sjogren’s syndrome, Raynaud’s disease, juvenile chronic arthritis, rheumatoid arthritis and antiphospholipid antibody syndrome etc. To confirm the disease a history, physical examination along with specific tests are required.
CPK is more specific for acute conditions.
ESR is a non specific test for inflammation.

Bursae are potential cavities that contain synovial fluid, found in areas where friction occurs. Their function is to minimise friction and facilitate movement. Bursitis is the inflammation of one or more bursae, and they can occur in the shoulder, elbow, knee, ischium, amongst other joints. Acute bursitis can appear after strenuous exercise or activity, and chronic bursitis can develop following previous bursitis or trauma. Acute bursitis causes pain, tenderness, and swelling.

Fick’s principle states that, VO2 = (CO × CAO2) – (CO × CVO2) where VO2 = oxygen consumption, CO = cardiac output, CAO2 = oxygen concentration of arterial blood and CVO2 = oxygen concentration of venous blood. Thus, CO = VO2/CAO2– CVO2, CO = 500/0.24–0.16, CO = 500/0.8, CO = 6.25 l/min. Cardiac output is also given by product of stroke volume and heart rate. Thus, stroke volume = cardiac output / heart rate = 6.25/70 × 1000 stroke volume = 90 ml approximately.

The splenic artery is the large artery that would be found running off the posterior wall of the stomach. It is a branch of the coeliac trunk and sends off branches to the pancreas before reaching the spleen. The gastroduodenal artery on the other hand is found inferior to the stomach, posterior to the first portion of the duodenum. The left gastroepiploic artery runs from the left to the right of the greater curvature of the stomach. The common hepatic artery runs on the superior aspect of the lesser curvature of the stomach, and is a branch of the coeliac trunk. The superior mesenteric artery arises from the abdominal aorta just below the junction of the coeliac trunk.

Nocardia is a Gram-positive aerobic actinomycete. Several species have been identified but the most common human pathogen is Nocardia asteroides. The predominant clinical finding in the majority of patients affected by nocardiosis is pulmonary disease. Predisposing factors for pulmonary nocardiosis include leukaemia, human immunodeficiency virus (HIV) infection, organ transplantation, diabetes and receiving prolonged corticosteroids.

Laparoscopic surgery involves insufflation of a gas (usually carbon dioxide) into the peritoneal cavity producing a pneumoperitoneum. This causes an increase in intra-abdominal pressure (IAP). Carbon dioxide is insufflated into the peritoneal cavity at a rate of 4–6 litre min−1 to a pressure of 10–20 mm Hg. The pneumoperitoneum is maintained by a constant gas flow of 200–400 ml min−1.

Carbon dioxide is the most frequently used gas for insufflation of the abdomen as it is colourless, non-toxic, non-flammable and has the greatest margin of safety in the event of a venous embolus (highly soluble). It is absorbed readily from the peritoneum, causing an increase in PaCO2. This has direct, as well as indirect (by raising catecholamine levels), effects on the cardiovascular system. Thus, tachycardia, increased cardiac contractility and reduction in the diastolic filling can result in decreased myocardial oxygen supply to demand ratio and greater risk of myocardial ischaemia.

Tracheostomy is an operative procedure that creates a surgical airway in the cervical trachea. It is most often performed in patients who have had difficulty weaning off a ventilator, followed by those who have suffered trauma or a catastrophic neurologic insult. High-flow oxygen via tracheostomy may reduce the inspiratory effort and enhance tidal volume by delivering high-flow oxygen and facilitate weaning from prolonged mechanical ventilation in patients with restrictive pulmonary dysfunction.

von Hippel-Lindau (VHL) disease, or von Hippel-Lindau syndrome, is a rare genetic disorder characterized by visceral cysts and benign tumours in multiple organ systems that have a subsequent potential for malignant change.
Clinical hallmarks of VHL disease include the development of retinal and central nervous system (CNS) hemangioblastomas (blood vessel tumours), pheochromocytomas, multiple cysts in the pancreas and kidneys, and an increased risk for malignant transformation of renal cysts into renal cell carcinoma. The wide age range and the pleiotropic manner in which VHL disease presents complicates diagnosis and treatment in affected individuals, as well as their at-risk relatives.

Because VHL disease is a multiple-organ disease that widely varies in clinical presentation, various manifestations may lead to the diagnosis. Criteria are the following:
More than one hemangioblastoma in the CNS (brain, spinal cord) or eye
A single hemangioblastoma in the CNS or retina, plus a visceral manifestation (multiple renal, pancreatic, or hepatic cysts; pheochromocytoma; renal cancer)
Positive family history plus any one of the above clinical manifestations
Elucidation of a deleterious mutation in the VHL gene

Gap junctions are attachments between cells that permit intercellular communication e.g. they permit current flow and electrical coupling between myocardial cells. They allow direct electrical transmission among cells and also permit certain substance to pass through as well. They are either homotypic, formed by two identical hemichannels or heterotypic, formed by different hemichannels.

Intercostal nerves are the ventral primary rami of spinal nerves T1–T11. They give branches which supply the thoracic wall.

The medial epicondyle of the humerus is the site of origin of this group of muscles of the forearm. It originates from the medial epicondyle of the humerus by a common tendon. Fibres from the deep fascia of the forearm, near the elbow and septa, pass from this fascia between the muscles. These muscles include the pronator teres, palmaris longus, flexor carpi radialis, flexor carpi ulnaris and flexor digitorum superficialis.

Repair of an inguinal hernia under local anaesthesia has a short operative time, and patients are usually ambulant immediately after. Furthermore, the family history of this patient is unlikely to be significant and therefore, he is at a very low risk of developing a pulmonary embolism (PE).

Deep vein thrombosis (DVT) may develop insidiously in many surgical patients. If left untreated, it may progress to PE. The following surgical patients are at increased risk of developing DVT:

1. Surgery greater than 90 minutes at any site or greater than 60 minutes if the procedure involves lower limbs or pelvis
2. Acute admissions with inflammatory process involving the abdominal cavity
3. Expected significant reduction in mobility
4. Age over 60 years
5. Known malignancy
6. Thrombophilia
7. Previous thrombosis
8. BMI >30 kg/m2
9. Taking hormone replacement therapy or contraceptive pills
10. Varicose veins with phlebitis

Thromboprophylaxis can be mechanical or therapeutic. The former includes:
1. Early ambulation after surgery: cheap and effective
2. Compression stockings (contraindicated in peripheral arterial disease)
3. Intermittent pneumatic compression devices
4. Foot impulse devices

Therapeutic agents for thromboprophylaxis are:
1. Low-molecular-weight heparin (LMWH)
2. Unfractionated heparin
3. Dabigatran

Goodsall’s rule can be used to clinically predict the course of an anorectal fistula tract. Imagine a line that bisects the anus in the coronal plane (transverse anal line). Any fistula that originates anterior to the line will course anteriorly in a direct route. Fistulae that originate posterior to the line will have a curved path. An exception to the rule are anterior fistulas lying more than 3 cm from the anus, which may open into the anterior midline of the anal canal.

Pyogenic granuloma (lobular capillary haemangioma) is a relatively common benign vascular lesion of the skin and mucosa whose exact cause is unknown
The name pyogenic granuloma is a misnomer since the condition is not associated with pus and does not represent a granuloma histologically. Pyogenic granuloma of the oral cavity is known to involve the gingiva commonly. Extragingivally, it can occur on the lips, tongue, buccal mucosa, palate, and the like. A history of trauma is common in such sites. The aetiology of the lesion is not known, though it was originally believed to be a botryomycotic infection. It is theorized that pyogenic granuloma possibly originates as a response of tissues to minor trauma and/or chronic irritation, thus opening a pathway for the invasion of nonspecific microorganisms, although microorganisms are seldom demonstrated within the lesion. Pathogenesis of pyogenic granuloma is still debatable.
Patients with pyogenic granuloma may report a painless glistening red lesion that bleeds spontaneously or after irritation.

As the stone is smaller in size, there is a strong likelihood (75%) of it to be passed spontaneously. Furthermore, distally sited stones are more likely to pass spontaneously than proximally sited ones. Hence, it should be arranged to review the patient in two weeks with a KUB X-ray.

Urolithiasis affects up to 15% of the population worldwide. The development of sudden-onset, colicky loin to groin pain is a classical feature in the history. It is nearly always associated with haematuria that is either micro- or macroscopic. The most sensitive and specific diagnostic test is helical, non-contrast CT scanning.

Management options for urolithiasis are:
1. Most renal stones measuring <5mm in maximum diameter typically pass within four weeks of onset of symptoms. More intensive and urgent treatment is indicated in the presence of ureteric obstruction, renal developmental abnormality such as horseshoe kidney, and previous renal transplant.
2. Ureteric obstruction due to stones together with infection is a surgical emergency and the system must be decompressed. Options include nephrostomy tube placement, insertion of ureteric catheters, and ureteric stent placement.
3. In the non-emergency setting, the preferred options for treatment include extracorporeal shock wave lithotripsy, percutaneous nephrolithotomy, ureteroscopy, and open surgery (selected cases). Minimally invasive options are the most popular first-line treatment.

Cranial nerve VII, the facial nerve, is found in the internal acoustic canal and runs through this canal into the facial canal before exiting through the stylomastoid foramen. In the case of a bone tumour at the stylomastoid process, the facial nerve is the nerve that will most likely be affected.

In children, more common causes of Urinary tract obstruction include the following:
UPJ or UVJ obstruction
Ectopic ureter
Ureterocoele
Megaureter
Posterior urethral valves

Posterior urethral valves:

During the early stages of embryogenesis, the most caudal end of the wolffian duct is absorbed into the primitive cloaca at the site of the future verumontanum in the posterior urethra. In healthy males, the remnants of this process are the posterior urethral folds, called plicae colliculi. Histologic studies suggest that PUVs are formed at approximately 4 weeks’ gestation, as the wolffian duct fuses with the developing cloaca.
Congenital obstructing posterior urethral membrane (COPUM) was first proposed by Dewan and Goh and was later supported by histologic studies by Baskin. This concept proposes that instead of a true valve, a persistent oblique membrane is ruptured by initial catheter placement and, secondary to rupture, forms a valve like configuration.
Indicators of possible PUVs later in childhood include the following:
Urinary tract infection (UTI)
Diurnal enuresis in boys older than 5 years
Secondary diurnal enuresis
Voiding pain or dysfunction
Abnormal urinary stream

Thyroidectomy has been reported as the most frequent cause of external branch of superior laryngeal nerve (EBSLN) injury.
Diagnosis of EBSLN injury may be difficult because the symptoms are nonspecific in many cases. However, advanced diagnostic techniques have revealed the incidence to be relatively high, ranging from 5 to 28%. Paralysis of the EBSLN causes difficulty with high pitch phonation and decreased pitch range secondary to failure of cricothyroid muscle stimulation and lack of tension in the vocal cord. This symptom may be extremely serious for professional voice users. EBSLN injury can also cause vocal fatigue, hoarseness, breathy sounding voice, and vocal nodules.

Lactobacillus is a Gram-positive facultative bacteria. It is commonly present in the vagina and the gastrointestinal tract. Colonization of Lactobacillus is usually benign and it makes up a small portion of the gastrointestinal flora.

Bile leak may be classified into a minor leak with low output drainage (<300 ml of bile/24 hours) or leaks due to major bile duct injury with high output drainage (>300 ml/24 hours).

The majority of minor bile leak results from Strasberg type A injuries with intact biliary-enteric continuity and includes leaks from cystic duct (CD) stump (55%-71%) or small (less than 3 mm) subsegmental duct in gall bladder (GB) bed (16%) and minor ducts like cholecystohepatic duct or supravesicular duct of Luschka (6%). An injury to the supravesicular duct occurs if the surgeon dissects into the liver bed while separating the gall bladder. This duct does not drain the liver parenchyma.
A leak from the cystic duct stump may occur from clip failure due to necrosis of the stump secondary to thermal injury/pressure necrosis or when clips are used in situations where ties are appropriate (acute cholecystitis) and in a significant majority from distal bile duct obstruction caused by a retained stone and resultant blow out of the cystic stump.
Strasberg type C and type D injuries usually present with a minor leak as well. The former results when an aberrant right hepatic duct (RHD) or right posterior sectoral duct (RPSD) is misidentified as the CD and divided because of the anomalous insertion of CD into either of these ducts.
Type D injuries are lateral injuries to the extrahepatic ducts (EHD) caused by cautery, scissors or clips.

High output biliary fistulas are the result of major transactional injury of EHD (Strasberg type E). Here the common bile duct (CBD) is misidentified as the CD and is clipped, divided and excised. This not only results in a segmental loss of the EHD but often associated with injury or ligation of right hepatic artery as well. Such devastating injuries are peculiar to LC and have been described by Davidoff as “classic laparoscopic biliary injury”.

Early recognition is the most important part of the management of bile leak due to iatrogenic injuries.
Unfortunately, most of the bile duct injuries are not recognized preoperatively. Optimal management of BDI detected postoperatively requires good coordination between the radiologist, endoscopists and an experienced hepatobiliary surgeon.

There is a scope of re-laparoscopy, within 24 hours of surgery, in situations where a low output fistula (<300 ml/day) is confirmed (by reviewing the operative video), to be because of a slipped CD clip. Through lavage, clipping or tying the CD stump with an endoloop may be a simple solution. Such an approach is not useful after 24 hours as inflammatory adhesions and oedema will make the job difficult. If low output controlled biliary fistula is detected after 24 hours, a wait and watch policy should be followed as many of the minor leaks will close within 5 to 7 days. If the leak fails to resolve or if the drainage amount is >300 ml/day (high output), an ERCP should be performed both to delineate the biliary tree and some therapeutic interventions if indicated.

There are two lateral rotators of the arm, the infraspinatus and the teres minor muscles. The infraspinatus muscle receives nerve supply from C5 and C6 via the suprascapular nerve, whilst the teres minor is supplied by C5 via the axillary nerve.

Gastric vasoconstrictors include catecholamines, angiotensin II and vasopressin. Vasodilators include vasoactive intestinal peptide and the hormones; gastrin, cholecystokinin and glucagon.