There are usually 3 perforating arteries:
The first gives branches to the adductor brevis and magnus, biceps femoris and gluteus maximus and anastomoses with the inferior gluteal, medial and lateral femoral circumflex.
The second artery supplies the posterior femoral muscles and anastomose with the first and third perforating vessels.
The third supplies the posterior femoral muscles.

Percutaneous coronary intervention (PCI), also known as coronary angioplasty, is a nonsurgical technique for treating obstructive coronary artery disease, including unstable angina, acute myocardial infarction (MI), and multivessel coronary artery disease (CAD).

Inferior STEMI is usually caused by occlusion of the right coronary artery, or less commonly the left circumflex artery, causing infarction of the inferior wall of the heart.

The ECG findings of an acute inferior myocardial infarction include the following:
ST segment elevation in the inferior leads (II, III and aVF)
Reciprocal ST segment depression in the lateral and/or high lateral leads (I, aVL, V5 and V6)

The peroneus brevis is supplied by the fourth and fifth lumbar and first sacral nerves through the superficial peroneal nerve which is one of the two terminal branches of the common peroneal nerve. The common peroneal nerve winds around the neck of the fibula and can be injured in cases of fractured neck of fibula.

Increased alkaline phosphatase is indicative of cholestasis, with a 4x or greater increase seen 1-2 days after biliary obstruction. Its level can remain elevated several days after the obstruction is resolved due to the long half life (7 days). Increase up to three times the normal level can be seen in hepatitis, cirrhosis, space-occupying lesions and infiltrative disorders. Raised alkaline phosphatase with other liver function tests being normal can occur in focal hepatic lesions like abscesses or tumours, or in partial/intermittent biliary obstruction. However, alkaline phosphatase has several isoenzymes, which originate in different organs, particularly bone. An isolated rise can also be seen in malignancies (bronchogenic carcinoma, Hodgkin’s lymphoma), post-fatty meals (from the small intestine), in pregnancy (from the placenta), in growing children (from bone growth) and in chronic renal failure (from intestine and bone). One can differentiate between hepatic and non-hepatic cause by measurement of enzymes specific to the liver e.g. gamma-glutamyl transferase (GGT).
In an elderly, asymptomatic patient, isolated rise of alkaline phosphatase usually points to bone disease (like Paget’s disease). Presence of other symptoms such as jaundice, pale stools, weight loss suggests obstructive jaundice, most probably due to pancreatic carcinoma.

Anal fissure is a tear in the anoderm distal to the dentate line. It is the most common cause of severe anal pain. It is equally one of the most common reasons for bleeding per anus in infants and young children. The pain of an anal ulcer is intolerable and always disproportionate to the severity of the physical lesion. It may be so severe that patients may avoid defecation for days together until it becomes inevitable. This leads to hardening of the stools, which further tear the anoderm during defecation, setting a vicious cycle. The fissures can be classified into 1] Acute or superficial and 2] Chronic fissure in ano.

Initial therapy for an anal fissure is medical, and more than 80% of acute anal fissures resolve without further therapy.
The goals of treatment are to relieve the constipation and to break the cycle of hard bowel movement, associated pain, and worsening constipation. Softer bowel movements are easier and less painful for the patient to pass.

First-line medical therapy consists of therapy with stool-bulking agents, such as fibre supplementation and stool softeners. Laxatives are used as needed to maintain regular bowel movements. Mineral oil may be added to facilitate passage of stool without as much stretching or abrasion of the anal mucosa, but it is not recommended for indefinite use. Sitz baths after bowel movements and as needed provide significant symptomatic relief because they relieve some of the painful internal sphincter muscle spasm.
Recurrence rates are in the range of 30-70% if the high-fibre diet is abandoned after the fissure is healed. This range can be reduced to 15-20% if patients remain on a high-fibre diet.

Second-line medical therapy consists of intra-anal application of 0.4% nitroglycerin (NTG; also called glycerol trinitrate) ointment directly to the internal sphincter.
Some physicians use NTG ointment as initial therapy in conjunction with fibre and stool softeners, and others prefer to add it to the medical regimen if fibre and stool softeners alone fail to heal the fissure. NTG ointment is thought to relax the internal sphincter and to help relieve some of the pain associated with sphincter spasm; it also is thought to increase blood flow to the anal mucosa.
Unfortunately, many people cannot tolerate the adverse effects of NTG, and as a result, its use is often limited. The main adverse effects are headache and dizziness; therefore, patients should be instructed to use NTG ointment for the first time in the presence of others or directly before bedtime.
Analogous to the use of NTG intra-anal ointment, nifedipine ointment is also available for use in clinical trials. It is thought to have similar efficacy to NTG ointment but with fewer adverse effects.

Botulinum toxin has been used to treat acute and chronic anal fissures. It is injected directly into the internal anal sphincter, in effect performing a chemical sphincterotomy. The effect lasts about 3 months, until nerve endings regenerate. This 3-month period may allow acute fissures (and sometimes chronic fissures) to heal and symptoms to resolve. If botulinum toxin injection provides initial relief of symptoms but there is a recurrence after 3 months, the patient may benefit from surgical sphincterotomy.

Surgical therapy is usually reserved for acute anal fissures that remain symptomatic after 3-4 weeks of medical therapy and for chronic anal fissures.
Sphincter dilatation
Lateral internal sphincterotomy

Vitamin B6 is required for collagen cross-links.
Vitamin A is required for epithelial cell proliferation.
Zinc is required for RNA and DNA synthesis.
Copper is required for cross-linking of collagen.

Lambert–Eaton myasthenic syndrome is a rare disorder of the neuromuscular junction. It can occur as a solitary diagnosis but it can also occur as a paraneoplastic syndrome associated with lung cancer, particularly small-cell histology. It can also be associated with other cancers such as lymphoma, non-Hodgkin’s lymphoma, T-cell leukaemia, non-small-cell lung cancer, prostate cancer and thymoma.

The sciatic nerve supplies both gemellae, quadratus femoris, semitendinosus, semimembranosus, both heads of the biceps femoris, the hamstring half of abductor magnus and obturator internus. Obturator externus is supplied by the obturator nerve.

At the upper and back part of the ulna, there exists a curved eminence which is the olecranon process. This process lodges in the olecranon fossa of the humerus. It’s posterior surface is subcutaneous and this triangular area is what you rest your elbow upon.

Answer: Hyperchloremic acidosis

Hyperchloremic acidosis is a form of metabolic acidosis associated with a normal anion gap, a decrease in plasma bicarbonate concentration, and an increase in plasma chloride concentration. In general, the cause of a hyperchloremic metabolic acidosis is a loss of base, either a gastrointestinal loss or a renal loss.

1) Gastrointestinal loss of bicarbonate (HCO3-)
-Severe diarrhoea (vomiting will tend to cause hypochloraemic alkalosis)
-Pancreatic fistula with loss of bicarbonate rich pancreatic fluid
-Nasojejunal tube losses in the context of small bowel obstruction and loss of alkaline proximal small bowel secretions
-Chronic laxative abuse
2) Renal causes
-Proximal renal tubular acidosis with failure of (HCO3-) resorption
-Distal renal tubular acidosis with failure of H+
secretion
-Long-term use of a carbonic anhydrase inhibitor such as acetazolamide
3) Other causes
-Ingestion of ammonium chloride, hydrochloric acid, or other acidifying salts
-The treatment and recovery phases of diabetic ketoacidosis
-Volume resuscitation with 0.9% normal saline provides a chloride load, so that infusing more than 3-4L can cause acidosis
-Hyperalimentation (i.e., total parenteral nutrition).

This patient received 6L of 0.9% normal saline which lead to hyperchloremic acidosis.

The lowest part of the pleural cavity is the costodiaphragmatic recess and it the space in which the pleural fluid will accumulate when the patient sits up.
The cupola is part of the pleural cavity that extends into the root of the neck above the first rib.
The costomediastinal recess is the junction at which the costal pleura becomes the mediastinal pleura.
The middle mediastinum is the part of the mediastinum that is occupied by the heart.
The hilar reflection is the point where the mediastinal pleura is reflected to continue on as the visceral pleura.

The umbilicus has a relatively consistent position in humans and thus serves as an important land mark. The skin around the waist at the level of the umbilicus is supplied by the tenth thoracic spinal nerve (T10 dermatome).

The phrenic nerve originates in the neck between C3-C5, mostly C4 spinal root. It enters the thoracic cavity past the heart and lungs to the diaphragm. In the neck, this nerve begins at the lateral border of the anterior scalene muscle, its course then continues inferiorly on the anterior aspect of the anterior scalene muscle as it moves towards the diaphragm.

The patient suffers from hyperkalaemia as an adverse effect of RBCs transfusion, which causes his ECG changes.
The potassium concentration of blood increases during storage, by as much as 5–10 mmol u−1. After the transfusion, the RBC membrane Na+–K+ ATPase pumping mechanism is re-established and cellular potassium reuptake occurs rapidly. Hyperkalaemia rarely occurs during massive transfusions unless the patient is also hypothermic and acidotic.
The total extracellular potassium load, which is <0.5 mmol for fresh RBC units and only 5-7 mmol for units at expiration, rarely causes problems in the recipient because of rapid dilution, redistribution into cells, and excretion. An abnormally high potassium level (>5 mmol/l or ≥1.5 mmol/l net increase) within an hour of transfusion is classified as transfusion-associated hyperkalaemia.
Irradiation enhances potassium leakage.

The fourth ventricle, is a cavity of the brains ventricular system in which the cerebrospinal fluid is formed. This cavity is located behind the pons and upper half of the medulla oblongata. It extends from the cerebral aqueduct, to its connection to the third ventricle, and to the obex- which is the caudal tip of the fourth ventricle. The floor of the fourth ventricle consists of three parts – superior, intermediate and inferior. This inferior aspect of the floor of the fourth ventricle has the nucleus of the abducens nerve, CN VI which is looped over by the facial nerve.

Hyperbilirubinemia can be caused due to increased bilirubin production, decreased liver uptake or conjugation, or decreased biliary excretion. Normal bilirubin level is less than 1.2 mg/dl (<20 μmol/l), with most of it unconjugated. Elevated unconjugated bilirubin (indirect bilirubin fraction >85%) can occur due to haemolysis (increased bilirubin production) or defective liver uptake/conjugation (Gilbert syndrome). Such increases are less than five-fold usually (<6 mg/dl or <100 μmol/l) unless there is coexistent liver disease.

The lateral femoral cutaneous nerve of the thigh arises from the dorsal division of the lumbar plexus of the second and the third lumbar nerves (L2 – L3). Spinal injuries at this level are likely to affect the lateral femoral cutaneous nerve. The lateral femoral cutaneous nerve innervates the skin on the lateral aspect of the thigh.

Membranous glomerulonephritis or nephropathy, is a renal disorder with insidious course and usually affects people aged 30-50 years. 85% cases are primary (or idiopathic). The other 15% are secondary to autoimmune conditions like SLE, infections like malaria or hepatitis B, drugs like captopril and NSAIDs, or malignancies (particularly lung or colonic carcinoma). This disease is caused due to circulating immune complexes which are said to form by binding of antibodies to antigens in glomerular basement membrane. This antigens could be endogenous or derived from systemic circulation. This immune complex triggers the complement system, resulting in formation of membrane attack complex (MAC) on glomerular epithelial cells. This further results in release of proteases and oxidants which damage the capillaries making them ‘leaky’. Moreover, the epithelial cells also secrete a mediator to reduce nephron synthesis and distribution.

The markedly increased haematocrit, along with thrombocytosis and the leucocytosis suggest a myeloproliferative disorder.
Polycythaemia vera is the commonest myeloproliferative disorders occurring more often in males (about 1.4 to 1). The mean age at diagnosis is 60 years (range 15–90 years) with 5% of patients below 40 years at onset. It involves increased production of all cell lines, including red blood cells (independent of erythropoietin), white blood cells and platelets. If confined only to red blood cells, it is known as ‘primary erythrocytosis’. There is an increase in blood volume and hyperviscosity occurs, predisposing to thrombosis. Increased bleeding occurs due to abnormal functioning of platelets. Patients become hypermetabolic, and increased cell turnover leads to hyperuricaemia.
Usually asymptomatic, occasionally symptoms include weakness, pruritus, headache, light-headedness, visual disturbances, fatigue and dyspnoea. Face appears red with engorged retinal veins. Lower extremities appear red and painful, along with digital ischaemia (erythromelalgia). Hepatomegaly is common and massive splenomegaly is seen in 75% patients. Thrombosis can lead to stroke, deep venous thrombosis, myocardial infarction, retinal artery or vein occlusion, splenic infarction (often with a friction rub) or Budd–Chiari syndrome. Gastrointestinal bleeding is seen in 10-20% patients. Hypermetabolism can lead to low-grade fevers and weight loss. Late features include complications of hyperuricaemia (e.g. gout, renal calculi). 1.5% to 10% cases transform to acute leukaemia.

A greenstick fracture is a fracture in a young, soft bone in which the bone bends and breaks. Greenstick fractures occur most often during infancy and childhood when bones are soft.
Some clinical features of a greenstick fracture are similar to those of a standard long bone fracture – greenstick fractures normally cause pain at the injured area. As these fractures are specifically a paediatric problem, an older child will be protective of the fractured part and babies may cry inconsolably. As per a standard fracture, the area may be swollen and either red or bruised. Greenstick fractures are stable fractures as a part of the bone remains intact and unbroken so this type of fracture normally causes a bend to the injured part, rather than a distinct deformity, which is problematic.
Radiographic features
-usually mid-diaphyseal
-occur in tandem with angulation
-incomplete fracture, with cortical breach of only one side of the bone

Non-gonococcal urethritis is most commonly caused by Chlamydia trachomatis (50% cases). Less common organisms include Mycoplasma genitalium, Urea urealyticum and Trichomonas vaginalis. Chlamydia is also the commonest cause of non-gonococcal cervicitis in women and proctitis in both sexes.

The rectus capitis anterior is a short, flat muscle, situated immediately behind the upper part of the longus capitis. It is also known as the obliquus capitis superior. It aids in flexion of the head and the neck. Nerve supple is from C1 and C2.

Staghorn calculi refer to branched stones that fill all or part of the renal pelvis and branch into several or all of the calyces. They are most often composed of struvite (magnesium ammonium phosphate) and/or calcium carbonate apatite. These stones are often referred to as ‘infection stones’ since they are strongly associated with urinary tract infections with urea splitting organisms. Small struvite and/or calcium carbonate apatite stones can grow rapidly over a period of weeks to months into large staghorn calculi involving the calyces and entire renal pelvis. If left untreated, this can lead to deterioration of kidney function and end-stage renal disease. In addition, since the stones often remain infected, there is a risk of developing sepsis. Thus, most patients require definitive surgical treatment.

Struvite stones account for 15% of renal calculi. They are associated with chronic urinary tract infection (UTI) with gram-negative, urease-positive organisms that split urea into ammonia, which then combines with phosphate and magnesium to crystalize into a calculus. Usual organisms include Proteus, Pseudomonas, and Klebsiella species. Escherichia coli is not capable of splitting urea and, therefore, is not associated with struvite stones. Because ammonia, a base, is produced during the catalytic process, the urine pH is typically greater than 7.
Underlying anatomical abnormalities that predispose patients to recurrent kidney infections should be sought and corrected. UTI does not resolve until the stone is removed entirely.
This patient has a urine pH of 7.8 which is very alkaline.

The linea alba is the point where this incision was made. It is a tendinous raphe in the midline of the abdomen extending between the xiphoid process and the symphysis pubis. It is placed between the medial borders of the recti and is formed by the blending of the aponeuroses of the external and internal obliques and transversi.
The linea aspera is a vertical ridge on the posterior surface of the femur.
The arcuate line is the inferior border of the posterior rectus sheath behind the rectus abdominis muscle.
The semilunar line is the lateral margin of the rectus abdominis.
The iliopectineal line is a line on the pelvic bones formed by the arcuate line of the ilium and the pectineal line of the pubis.

Myoglobin is a pigmented globular protein made up of 153 amino acids with a prosthetic group containing haem around which the apoprotein folds. It is the primary oxygen carrying protein of the muscles. The binding of oxygen to myoglobin is unaffected by the oxygen pressure as it has an instant tendency to bind given its hyperbolic oxygen curve. It releases oxygen at very low pO2 levels.

Signs and symptoms of thalamic syndrome include contralateral hemi anaesthesia, burning or aching sensation in one half of a body (hyperaesthesia), often accompanied by mood swings.

Airway obstruction: In the first 24 hours it is most likely from a compressive hematoma. After 24 hours consider laryngeal dysfunction secondary to hypocalcaemia.
In this patient, the most likely cause is a haematoma.
Definitive therapy is opening the surgical incision to evacuate the hematoma. Re-intubation may be lifesaving for persistent airway obstruction. Consider awake fibreoptic intubation.

The ileum is a part of the small intestine and has a pH of around 7-8 (neutral or slightly alkaline). Its main function is absorption of products of digestion. The ileal wall has multiple villi, which in turn have numerous microvilli. This increases the surface area available for absorption significantly. The cells lining the ileum contain multiple enzymes such as protease and carbohydrase, which aid in the final stages of digestion. Villi contain lacteals which absorb the products of fat digestion, fatty acids and glycerol. Thus, ileal resection will lead to their decreased absorption and increased fat content in the stool. The ileum is also responsible for absorption of vitamin B12.
Maximum water absorption occurs in the colon followed by the jejunum. Hence, ileal resection is less likely to lead to fluid volume deficiency. Also, most minerals (like calcium, iron etc.) are absorbed in the duodenum, and thus will not be affected by ileal resection.

Pacinian corpuscles are a type of mechanoreceptor, sensitive to deep pressure, touch and high-frequency vibration. The Pacinian corpuscles are ovoid and about 1 mm long. In the centre of the corpuscle is the inner bulb, which is a fluid-filled cavity with a single afferent unmyelinated nerve ending. Any deformation in the corpuscle causes the generation of action potentials by opening of pressure-sensitive sodium ion channels in the axon membrane. This allows influx of sodium ions, creating a receptor potential (independent of potassium channels).

An anal fissure is a painful linear tear or crack in the distal anal canal, which, in the short term, usually involves only the epithelium and, in the long term, involves the full thickness of the anal mucosa. Typically, the patient reports severe pain during a bowel movement, with the pain lasting several minutes to hours afterward. The pain recurs with every bowel movement, and the patient commonly becomes afraid or unwilling to have a bowel movement, leading to a cycle of worsening constipation, harder stools, and more anal pain. Approximately 70% of patients note bright-red blood on the toilet paper or stool. Occasionally, a few drops may fall in the toilet bowl, but significant bleeding does not usually occur with an anal fissure.
Second-line medical therapy consists of intra-anal application of 0.4% nitro-glycerine (NTG; also called glycerol trinitrate) ointment directly to the internal sphincter. Nitro-glycerine rectal ointment is approved by the US Food and Drug Administration (FDA) for moderate-to-severe pain associated with anal fissures and may be considered when conservative therapies have failed.