The vagus nerve, ‘the wanderer’, contains motor fibres (to the palate and vocal cords), sensory components (posterior and floor of external acoustic meatus) and visceral afferent and efferent fibres.

Palatal weakness can cause nasal speech and nasal regurgitation of food. The palate moves asymmetrically when the patient says ‘ahh’. Recurrent nerve palsy results in hoarseness, loss of volume and ‘bovine cough’.

An eosinophil leucocytosis is defined as an increase in blood eosinophils above 0.4 x 109/L.It is most frequently due to:
Allergic diseases (e.g. bronchial asthma, hay fever, atopic dermatitis, urticaria)
Parasites (e.g. hookworm, ascariasis, tapeworm, schistosomiasis)
Skin diseases (e.g. psoriasis, pemphigus, urticaria, angioedema)
Drug sensitivity

The arrangement of micelles is such that hydrophobic lipid molecules lie in the centre, surrounded by hydrophilic bile acids that are arranged in the outer region. This arrangement allows the entry of micelles into the aqueous layers surrounding the microvilli. As a result, the products of fat digestion (fatty acids and monoglycerides), cholesterol and fat-soluble vitamins (such as vitamin D) can then diffuse passively into the enterocytes. The bile salts are left within the lumen of the gut where they are reabsorbed from the ileum or excreted in faeces.

Factors causing bronchoconstriction:Via muscarinic receptorsParasympathetic stimulationStimulation of irritant receptorsInflammatory mediators e.g. histamine, prostaglandins, leukotrienesBeta-blockers

Meckel’s lies on the antimesenteric surface of the middle-to-distal ileum, approximately 2 feet proximal to the ileocaecal junction. It appears as a blind-ended tubular outpouching of bowel, about 2 inches long, occurring in about 2% of the population, and may contain two types of ectopic tissue (gastric and pancreatic). The rich blood supply to the diverticulum is provided by the superior mesenteric artery.Proximal to the major duodenal papilla the duodenum is supplied by the gastroduodenal artery (branch of the coeliac trunk) and distal to the major duodenal papilla it is supplied by the inferior pancreaticoduodenal artery (branch of superior mesenteric artery). The arterial supply to the jejunoileum is from the superior mesenteric artery.

Aspirin works by inhibiting cyclo-oxygenase in an irreversible manner, resulting in a decrease in prostaglandin and thromboxane production. As a result, platelet activation and aggregation are reduced.

The purine nucleoside adenosine is used to diagnose and treat paroxysmal supraventricular tachycardia. Adenosine works by stimulating A1-adenosine receptors and opening potassium channels that are sensitive to acetylcholine. This causes the atrioventricular (AV) node’s cell membrane to become hyperpolarized, slowing conduction by inhibiting calcium channels.
Patients who have had a heart transplant are extremely sensitive to the effects of adenosine and should start with a lower dose of 3 mg, then 6 mg, and finally 12 mg.

Dipyridamole potentiates the effects of adenosine, so it should be used with caution in patients who are taking it.

The use of adenosine is contraindicated in the following situations:
Asthma
COPD (chronic obstructive pulmonary disease)
Decompensated heart failure 
Long QT syndrome
AV block in the second or third degree
Sinusitis is a condition in which the sinuses become (unless pacemaker fitted)
Hypotension that is severe

Each motor unit contracts in an all or nothing fashion, i.e. if a motor unit is excited, it will stimulate all of its muscle fibres to contract. The force of contraction of a muscle is controlled by varying the motor unit recruitment (spatial summation), and by varying the firing rate of the motor units (temporal summation). During a gradual increase in contraction of a muscle, the first units start to discharge and increase their firing rate, and, as the force needs to increase, new units are recruited and, in turn, also increase their firing rate. For most motor units, the firing rate for a steady contraction is between 5 and 8 Hz. Because the unitary firing rates for each motor unit are different and not synchronised, the overall effect is a smooth force profile from the muscle. Increasing the firing rate of motor units is temporal summation where the tension developed by the first action potential has not completely decayed when the second action potential and twitch is grafted onto the first and so on. If the muscle fibres are stimulated repeatedly at a faster frequency, a sustained contraction results where it is not possible to detect individual twitches. This is called tetanus.

Polycythaemia vera (PCV), which is also referred to as polycythaemia rubra vera, is a clonal haematological malignancy in which the bone marrow produces too many red blood cells. It may also result in the overproduction of white blood cells and platelets. It is most commonly seen in the elderly and the mean age at diagnosis is 65-74 years.
Patients can be completely asymptomatic and it is often discovered as an incidental finding on a routine blood count. Approximately 1/3 of patients present with symptoms due to thrombosis, of these 3/4 have arterial thrombosis and 1/4 venous thrombosis. Features include stroke, myocardial infarction, deep vein thrombosis and pulmonary embolism.
The other clinical features of PCV include:
Plethoric appearance
Lethargy and tiredness
Splenomegaly (common)
Pruritis (in 40% – particularly after exposure to hot water)
Headaches, dizziness and sweating (in 30%)
Gouty arthritis (in 20%)
Budd-Chiari syndrome (in 5-10%)
Erythromyalgia (in <5% – burning pain and red/blue discolouration of hands and feet)
Increased incidence of peptic ulcer disease (possibly related to increased histamine release from mast cells)
The diagnosis of PCV requires two major criteria and one minor criterion, or the first major criterion and two minor criteria:
Major criteria:
HB > 18.5 g/dl in men, 16.5 g/dl in women
Elevated red cell mass > 25% above mean normal predicted value
Presence of JAK2 mutation

Minor criteria:
Bone marrow biopsy showing hypercellularity with prominent erythroid, granulocytic and megakaryocytic proliferation
Serum erythropoietin level below normal range
Endogenous erythroid colony formation in vitro
The main aim of treatment is to normalize the full blood count and prevent complications such as thrombosis. Venesection is the treatment of choice but hydroxyurea can also be used to help control thrombocytosis.

Opponens pollicis is a small, triangular muscle that forms part of the thenar eminence. It originates from the flexor retinaculum and the tubercle of trapezium bone and inserts into the whole length of the first metacarpal bone on its radial side.
Opponens pollicis is innervated by the recurrent branch of the median nerve and receives its blood supply from the superficial palmar arch.
The main action of opponens pollicis is to flex the first metacarpal bone at the carpometacarpal joint, which opposes the thumb towards the centre of the palm. It also medially rotates the first metacarpal bone at the carpometacarpal joint.

The following approaches have some benefit in adult patients with reflux:

Weight loss or weight management for individuals who are overweight
Head of bed elevation is important for individuals with nocturnal or laryngeal symptoms, but its value for other situations is unclear.
The following lifestyle approaches also are used frequently. There is some evidence that these lifestyle changes improve laboratory measures of reflux (such as lower oesophageal sphincter pressure).
Dietary modification – A practical approach is to avoid a core group of reflux-inducing foods, including chocolate, peppermint, and alcohol, which may reduce lower oesophageal sphincter pressure. Acidic beverages, including colas with caffeine and orange juice also may exacerbate symptoms.
Avoiding the supine position soon after eating.
Promotion of salivation by either chewing gum or using oral lozenges. Salivation neutralizes refluxed acid, thereby increasing the rate of oesophageal acid clearance.
Avoidance of tobacco (including passive exposure to tobacco smoke) and alcohol. Nicotine and alcohol reduce lower oesophageal sphincter pressure, and smoking also diminishes salivation.

Angina pectoris is the most common symptom of ischemic heart disease and presents with chest pain relieved by rest and nitro-glycerine.

Nitrates are the first-line treatment to relieve chest pain caused by angina. The commonly used nitrates are:
1. Glyceryl trinitrate
2. Isosorbide dinitrate

Side effects to nitrate therapy are common especially
The most common side effects are:
1. Headaches
2. Feeling dizzy, weak, or tired
3. Nausea
4. Flushing

The serious but less likely to occur side effects are:
1. Methemoglobinemia (rare)
2. Syncope
3. Prolonged bleeding time
4. Exfoliative dermatitis
5. Unstable angina
6. Rebound hypertension
7. Thrombocytopenia

Dry eyes, bradycardia, and metabolic acidosis have not been reported.

Megaloblastic anemia results from inhibition of DNA synthesis during red blood cell production. When DNA synthesis is impaired, the cell cycle cannot progress from the growth stage to the mitosis stage. This leads to continuing cell growth without division, which presents as macrocytosis, with an increase in mean corpuscular volume (MCV). The defect in red cell DNA synthesis is most often due to hypovitaminosis, specifically vitamin B12 deficiency or folate deficiency.
Folate is an essential vitamin found in most foods, especially liver, green vegetables and yeast. The normal daily diet contains 200 – 250 μg, of which about 50% is absorbed. Daily adult requirements are about 100 μg. Absorption of folate is principally from the duodenum and jejunum. Stores of folate are normally only adequate for 4 months and so features of deficiency may be apparent after this time.

A low pH in the stomach inhibits gastrin secretion, therefore when the stomach is empty or when acid has been secreted for some time after food has entered it, there is inhibition of acid secretion. However, when food first enters the stomach, the pH rises, and this leads to release of the inhibition and causes a maximum secretion of gastrin. Thus gastric acid secretion is self-regulating.

The glenohumeral joint possesses the capability of allowing an extreme range of motion in multiple planes.

Flexion – Defined as bringing the upper limb anterior in the sagittal plane. The usual range of motion is 180 degrees. The main flexors of the shoulder are the anterior deltoid, coracobrachialis, and pectoralis major. Biceps brachii also weakly assists in this action.

Extension—Defined as bringing the upper limb posterior in a sagittal plane. The normal range of motion is 45 to 60 degrees. The main extensors of the shoulder are the posterior deltoid, latissimus dorsi, and teres major.

Internal rotation—Defined as rotation toward the midline along a vertical axis. The normal range of motion is 70 to 90 degrees. The internal rotation muscles are the subscapularis, pectoralis major, latissimus dorsi, teres major, and the anterior aspect of the deltoid.

External rotation – Defined as rotation away from the midline along a vertical axis. The normal range of motion is 90 degrees. Primarily infraspinatus and teres minor are responsible for the motion.

Adduction – Defined as bringing the upper limb towards the midline in the coronal plane. Pectoralis major, latissimus dorsi, and teres major are the muscles primarily responsible for shoulder adduction.

Abduction – Defined as bringing the upper limb away from the midline in the coronal plane. The normal range of motion is 150 degrees. Due to the ability to differentiate several pathologies by the range of motion of the glenohumeral joint in this plane of motion, it is essential to understand how different muscles contribute to this action.

Flexion of the index and middle fingers at the IPJs is lost due to paralysis of the flexor digitorum superficialis and the lateral half of the flexor digitorum profundus. Flexion of the MCPJs of the index and middle fingers are lost due to paralysis of the lateral two lumbrical muscles. Flexion of the ring and little fingers are preserved as these are supported by the medial half of the flexor digitorum profundus and the medial two lumbrical muscles, innervated by the ulnar nerve.

High-dose NSAIDs are the first-line treatment for acute gout. In the absence of any contraindications, Naproxen 750 mg as a stat dose followed by 250 mg TDS is commonly used.

Aspirin is contraindicated in gout. It reduces the urinary clearance of urate and also interferes with the action of uricosuric agents.

Colchicine is preferred in patients with heart failure or in those who are intolerant of NSAIDs. It is as effective as NSAIDs in relieving acute attacks.

Colchicine acts on the neutrophils, binding to tubulin to prevent neutrophil migration into the joint. Where Allopurinol is not tolerated, it has a role in prophylactic treatment of gout.

Allopurinol should not be started in the acute phase of gout as it increases the severity and duration of symptoms. It is used as a prophylaxis in preventing future attacks and acts by reducing serum uric acid levels.

Cardiac output (CO) is calculated by multiplying stroke volume (SV) by heart rate (HR):
CO = HR x SV

As a result, both stroke volume and heart rate are exactly proportional to cardiac output. There will be an increase in cardiac output if the stroke volume or heart rate increases, and a reduction in cardiac output if the stroke volume or heart rate lowers.

​Primary hyperparathyroidism the commonest cause of hypercalcaemia. It is commonest in women aged 50 to 60.
The commonest cause of primary hyperparathyroidism is a solitary adenoma of the parathyroid gland (approximately 85% of cases).

Primary hyperparathyroidism may present with features of hypercalcaemia such as polyuria, polydipsia, renal stones, bone and joint pain, constipation, and psychiatric disorders.

In primary Hyperparathyroidism:
PTH is elevated
Calcium is elevated
Phosphate is lowered

In secondary Hyperparathyroidism:
PTH is elevated
Calcium is low or low-normal
Phosphate is raised in CRF

In tertiary Hyperparathyroidism:
PTH is elevated
Calcium is elevated
Phosphate is lowered in CRF

Acute lymphoblastic leukaemia (ALL) is caused by an accumulation of lymphoblasts in the bone marrow and is the most common malignancy of childhood. The incidence of ALL is highest at 3 – 7 years, with 75% of cases occurring before the age of 6. There is a secondary rise after the age of 40 years. 85% of cases are of B-cell lineage and have an equal sex incidence; there is a male predominance for the 15% of T-cell lineage.

Damage to the long thoracic nerve results in weakness/paralysis of the serratus anterior muscle causing difficulty abducting the upper limb above 90 degrees and giving a ‘winged ‘ scapula appearance where the medial border, particularly the inferior angle, of the scapula moves laterally and posteriorly away from the thoracic wall (this becomes more pronounced if the patient presses the upper limb against a wall).

The earliest biochemical change seen in hypothyroidism is an increase in thyroid-stimulating hormone (TSH) levels.

Triiodothyronine (T3) and thyroxine (T4) levels are normal in the early stages.

TBG levels are generally unchanged in primary hypothyroidism.

At rest the right dome of the diaphragm lies slightly higher than the left; this is thought to be due to the position of the liver. In normal expiration, the normal upper limits of the superior margins are the fifth rib for the right dome, the fifth intercostal space for the left dome and the xiphoid process for the central tendon.

The following are the mechanisms of breathing during inspiration and expiration, whether normal or forced.

Normal inspiration is an active process, with the diaphragm as the main muscle. The diaphragm descends, ribs move upward and outward, and the lungs become wider and taller.

In forced inspiration, which commonly occurs during exercise, the external intercostals and accessory muscles, such as the sternocleidomastoid, anterior serrati, scalenes, alae nasi, genioglossus and arytenoid are involved. The ribs move upward and outward, and the abdominal contents move downward.

Normal expiration is a passive process, while in forced expiration, the internal intercostals and abdominal muscles, such as the rectus abdominis, internal and external obliques and transversus abdominis are involved. The ribs move downward and inward, and the abdominal contents move upward.

Dopamine is a neurotransmitter and a metabolic precursor of the catecholamines. It acts on beta1-receptors in cardiac muscle increasing cardiac contractility, and increases renal perfusion by stimulating dopamine receptors in the renal vasculature. This is of benefit in cardiogenic shock where deterioration of renal function is common.

The Loop of Henle connects the proximal tubule to the distal convoluted tubule and lies parallel to the collecting ducts. It consists of three major segments, including the descending thin limb, the ascending thin limb, and the ascending thick limb. These segments are differentiated based on structure, anatomic location, and function.

The main function of the loop of Henle is to recover water and sodium chloride from urine. When fluid enters the loop of Henle, it has an osmolality of approximately 300 mOsm, and the main solute is sodium.

The thin descending limb has a high water permeability but a low ion permeability. Because it lacks solute transporters, it cannot reabsorb sodium. Aquaporin 1 (AQP1) channels are used to passively absorb water in this area. The peritubular fluid becomes increasingly concentrated as the loop descends into the medulla, causing water to osmose out of the tubule. The tubular fluid in this area now equalizes to the osmolality of the peritubular fluid, to a maximum of approximately 1200 mOsm in a long medullary loop of Henle and 600 mOsm in a short cortical loop of Henle.

The thin ascending limb is highly permeable to ions and impermeable to water. It allows the passive movement of sodium, chloride, and urea down their concentration gradients, so urea enters the tubule and sodium and chloride leave. Reabsorption occurs paracellularly due to the difference in osmolarity between the tubule and the interstitium.

The thick ascending limb is also impermeable to water but actively transports sodium, potassium, and chloride out of the tubular fluid. The osmolality of the tubular fluid is lower compared to the surrounding peritubular fluid. This area is water impermeable. This results in tubular fluid leaving the loop of Henle with an osmolality of approximately 100 mOsm, which is lower than the osmolality of the fluid entering the loop, and urea being the solute.

There is a high suspicion of a thyroid crisis in this patient and emergent treatment should be initiated even before the results of TFT’s have returned. Antiadrenergic drugs like IV propranolol should be administered immediately to minimise sympathomimetic symptoms. Antithyroid medications like propylthiouracil or carbimazole should be administered to block further synthesis of thyroid hormones. After thionamide therapy has been started to prevent stimulation of new hormone synthesis, there should then be delayed administration of oral iodine solution. Hydrocortisone administration is also recommended as it treats possible relative adrenal insufficiency while also decreases peripheral conversion of T4 to T3.

Ketamine is a dissociative anaesthetic with analgesic, amnesic, and hypnotic effects. It is the only anaesthetic agent which causes all three of these effects.

Ketamine exerts its action by non-competitive antagonism at the NMDA (N-methyl-D-aspartate) receptor. Due to its analgesic property, Ketamine is given so that patients do not retain memories of short term procedures. Ketamine is used for the induction and maintenance of anaesthesia in general surgery and for treating burn wounds, battlefield injuries, and children who cannot tolerate other anaesthetic or analgesic agents.

It can be given by both intravenous and intramuscular routes. Ketamine causes cardiac stimulation by increasing the sympathetic tone. The major side effect is increased intracranial pressure as an increase in the sympathetic tone causes vasoconstriction and an increase in the MAP.

In foreign body aspiration, the foreign body is more likely to enter the right main bronchus because it is shorter, wider and more vertical than the left main bronchus. In a patient who is standing or sitting, the foreign body tends to become lodged in the posterobasal segment of the inferior lobe of the right lung.

Short vessels called arteriovenous anastomoses (AVAs) link tiny arteries and veins. They have a large lumen diameter. The strong and muscular walls allow AVAs to completely clog the vascular lumen, preventing blood flow from artery to vein (acting like a sphincter). When the AVAs open, they create a low-resistance connection between arteries and veins, allowing blood to flow into the limbs’ superficial venous plexuses. There is no diffusion of solutes or fluid into the interstitium due to their strong muscle walls.

AVAs are densely innervated by adrenergic fibres from the hypothalamic temperature-regulation centre. High sympathetic output occurs at normal core temperatures, inducing vasoconstriction of the AVAs and blood flow through the capillary networks and deep plexuses. When the temperature rises, sympathetic output decreases, producing AVA vasodilation and blood shunting from the artery to the superficial venous plexus. Heat is lost to the environment as hot blood rushes near to the skin’s surface.
AVAs are a specialized anatomical adaptation that can only be found in large quantities in the fingers, palms, soles, lips, and pinna of the ear.