The scalp is the anatomical area bordered by the face at the front, and by the neck at the sides and back. The scalp is usually described as having five layers:
1. The skin which contains numerous sebaceous glands and hair follicles.
2. The connective tissue, a dense subcutaneous layer of fat and fibrous tissue that lies beneath the skin, containing the nerves and vessels of the scalp.
3. The aponeurosis or galea aponeurotica, a tough layer of dense fibrous tissue which runs from the frontalis muscle anteriorly to the occipitalis posteriorly.
4. The loose areolar connective tissue layer provides an easy plane of separation between the upper three layers and the pericranium.
5. The pericranium is the periosteum of the skull bones and provides nutrition to the bone and the capacity for repair.

The navicular bone is situated at the medial side of the tarsus, between the talus and the cuneiform bones. Its medial surface presents a rounded tuberosity, the lower part of which gives attachment to part of the tendon of the tibialis posterior.

Hepatitis A is a viral liver disease that can cause mild to severe illness. The hepatitis A virus (HAV) is transmitted through ingestion of contaminated food and water or through direct contact with an infectious person.
The risk of hepatitis A infection is associated with a lack of safe water, and poor sanitation and hygiene (such as dirty hands). Unlike hepatitis B and C, hepatitis A does not cause chronic liver disease and is rarely fatal, but it can cause debilitating symptoms and fulminant hepatitis (acute liver failure), which is often fatal.
Prodrome
In the prodrome, patients may have mild flulike symptoms of anorexia, nausea and vomiting, fatigue, malaise, low-grade fever (usually < 39.5°C), myalgia, and mild headache. Smokers often lose their taste for tobacco, like persons presenting with appendicitis. Icteric phase
In the icteric phase, dark urine appears first (bilirubinuria). Pale stool soon follows, although this is not universal. Jaundice occurs in most (70%-85%) adults with acute HAV infection; it is less likely in children and is uncommon in infants. The degree of icterus also increases with age. Abdominal pain occurs in approximately 40% of patients. Itching (pruritus), although less common than jaundice, is generally accompanied by jaundice.

Arthralgias and skin rash, although also associated with acute HAV infection, are less frequent than the above symptoms. Rash more often occurs on the lower limbs and may have a vasculitic appearance.

Relapsing hepatitis A
Relapsing hepatitis A is an uncommon sequela of acute infection, is more common in elderly persons, and is characterized by a protracted course of symptoms of the disease and a relapse of symptoms and signs following apparent resolution.

The blood–brain barrier is a membrane that controls the passage of substances from the blood into the central nervous system. It is a physical barrier between the local blood vessels and most parts of the central nervous system and stops many substances from travelling across it. During meningitis, the blood–brain barrier may be disrupted. This disruption may increase the penetration of various substances (including either toxins or antibiotics) into the brain. A few regions in the brain, including the circumventricular organs, do not have a blood–brain barrier.

The rate of filtration at any point along a capillary depends on a balance of forces sometimes called Starling’s forces after the physiologist who first described their operation in detail. The Starling principle of fluid exchange is key to understanding how plasma fluid (solvent) within the bloodstream (intravascular fluid) moves to the space outside the bloodstream (extravascular space). Fluid movement = k[(pc– pi)–(Πc– Πi)] where k = capillary filtration coefficient, pc = capillary hydrostatic pressure, pi= interstitial hydrostatic pressure, Πc = capillary colloid osmotic pressure, Πi = interstitial colloid osmotic pressure. Therefore: 1 × [capillary hydrostatic pressure (17) – interstitial fluid hydrostatic pressure (–3)] – [plasma colloid osmotic pressure (28) – interstitial fluid colloid osmotic pressure (8)] = 0 mmHg

An Anal fissure is a cut or a tear in the anal canal typically caused by passing a hard stool. Patients often complain of severe anal pain and bleeding with bowel movements. On physical examination, you may see the fissure or just the sentinel tag. If the examination appears normal, you can elicit point tenderness. We recommend against continuing the digital rectal examination or anoscopy if the patient is having pain during the examination.
The primary goals of therapy are to properly bulk the stool with adequate fibre and relax the anal muscle. Specific steps include the following:
Properly bulk the stool with adequate fibre to minimize constipation and diarrhoea; both frequent bowel movements and hard bowel movements can lead to an anal fissure.
Temporary use of laxatives such as daily Miralax or senna. The dose of Miralax can be titrated up or down to achieve desired results. As the patient’s fibre supplementation increases, the need for Miralax will diminish.
Chronic use of laxatives should be avoided because it can lead to worsening colonic function and constipation.
Diltiazem 2% ointment is to be placed on the anal muscle 3 times daily—continue for a minimum of 8 weeks, even if symptoms improve earlier.
If a patient cannot tolerate diltiazem or is breastfeeding or pregnant, 0.2% nitroglycerin-compounded ointment can be prescribed. However, the proper dose of nitroglycerin is important as too high of a dose can cause severe headaches.
Do NOT prescribe haemorrhoid ointments or suppositories, especially steroid-based ones. Steroid ointments do not help. They do cause perianal skin thinning and dermatitis. At best, they act as a placebo, but they often are used chronically and cause unpleasant perianal skin changes.
Use mental anal muscle relaxation: Actively thinking about relaxing sphincter tone.
Consider sitz baths: Soaking the anal area in warm water induces relaxation. Warmer water induces more relaxation. No additives are needed.
Surgical intervention (such as Botox injections or sphincterotomy) is considered for patients whose symptoms do not improve with the above management strategies. It is imperative that the patient increases fibre and water intake so bowel movements are very soft before the surgical intervention to maximize chances of postoperative healing.

Lung metastases occur when a cancer started in another part of the body (primary site) spreads to the lungs. The lungs are among the most common site where cancer can spread due to its rich systemic venous drainage, almost every type of cancer can spread to the lung. The most common types of cancer that spread to the lung are breast, colorectal, kidney, testicular, bladder, prostate, head and neck cancers.

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.

Acute renal failure (ARF) is a rapid loss of renal function due to damage to the kidneys, resulting in retention of nitrogenous (urea and creatinine) and non-nitrogenous waste products that are normally excreted by the kidney. This accumulation may be accompanied by metabolic disturbances, such as metabolic acidosis and hyperkalaemia, changes in body fluid balance and effects on many other organ systems. Metabolic acidosis and hyperkalaemia are the two most serious biochemical manifestations of acute renal failure and may require medical treatment with sodium bicarbonate administration and antihyperkalaemic measures. If not appropriately treated these can be life-threatening. ARF is diagnosed on the basis of characteristic laboratory findings, such as elevated blood urea nitrogen and creatinine, or inability of the kidneys to produce sufficient amounts of urine.

Crohn’s disease is a chronic, inflammatory disease that can affect any part of the gastrointestinal tract but is usually seen in the distal ileum and colon. It is transmural and symptoms include chronic diarrhoea, abdominal pain, fever, anorexia and weight loss. On examination, there is usually abdominal tenderness with a palpable mass or fullness seen occasionally. Rectal bleeding is uncommon (except in isolated colonic involvement) which manifests like ulcerative colitis. Differential diagnosis includes acute appendicitis or intestinal obstruction. 25%-33% patients also have perianal disease in the form of fissure or fistulas.
Extra intestinal manifestations predominate in children, and include: arthritis, pyrexia, anaemia or growth retardation. Histologically, the disease shows crypt inflammation and abscesses initially, which progress to aphthoid ulcers. These eventually develop into longitudinal and transverse ulcers with interspersed mucosal oedema, leading to the characteristic ‘cobblestoned appearance’. Transmural involvement leads to lymphoedema and thickening of bowel wall and mesentery, leading to extension of mesenteric fat on the serosal surface of bowel and enlargement of mesenteric nodes. There can also be hypertrophy of the muscularis mucosae, fibrosis and stricture formation, which can cause bowel obstruction. Abscesses are common and the disease can also leas to development of fistulas with various other organs, anterior abdominal wall and adjacent muscles. Pathognomonic non-caseating granulomas are seen in 50% cases and they can occur in nodes, peritoneum, liver, and in all layers of the bowel wall. The clinical course does not depend on the presence of granulomas. There is sharp demarcation between the diseased and the normal bowel (skip areas).
35% cases show only the ileal involvement, whereas in 45% cases, both the ileum and colon are involved with a predilection for right side of colon. 20% cases show only colonic involvement, often sparing the rectum (unlike ulcerative colitis). In occasional cases, there is jejunoileitis – involvement of the entire small bowel. The stomach, duodenum and oesophagus are rarely involved, although there has been microscopic evidence of disease involving the gastric antrum in younger patients. The affected small bowel segments show increased rick of cancer. Moreover, patients with colonic disease show a long-term risk of cancer similar to that seen in ulcerative colitis.