The most appropriate management option to consider, after GTN or other topical nitrates have failed, is botulinum toxin injection. In males, a lateral internal sphincterotomy would be an acceptable alternative. In a female who has yet to conceive, this may predispose to an increased risk of sphincter dysfunction. Moreover, division of the external sphincter would result in faecal incontinence and is not a justified treatment for anal fissure.

Anal fissures are a common cause of painful, bright red rectal bleeding. Most fissures are idiopathic and present as a painful mucocutaneous defect in the posterior midline (90% cases). Fissures are more likely to be anteriorly located in females, particularly if they are multiparous. Diseases associated with fissure-in-ano include:
1. Crohn’s disease
2. Tuberculosis
3. Internal rectal prolapse

Diagnostic options are as follows:
In most cases, the defect can be visualised as a posterior midline epithelial defect. Where symptoms are highly suggestive of the condition and examination findings are unclear, an examination under anaesthesia may be helpful. Atypical disease presentation should be investigated by colonoscopy and EUA, with biopsies of the area.

For management of anal fissure:
1. Stool softeners are important as hard stools may tear the epithelium and result in recurrent symptoms. The most effective first-line agents are topically applied GTN (0.2%) or Diltiazem (2%) paste.
2. Resistant cases may benefit from injection of botulinum toxin or lateral internal sphincterotomy. Advancement flaps may be used to treat resistant cases.

Mastectomy should ideally be done in this patient. This patient has extensive spread of disease and tumour margins are unclear which makes radiotherapy the less likely option. Mastectomy is the safest option in this scenario. Patients who have undergone mastectomy may be offered a reconstructive procedure either in conjunction with their primary resection or as a staged procedure at a later date.

Wilms’ tumour is one of the most common malignant tumours of childhood but it can also rarely be found in adults. In biopsy, classical histopathological findings include the triphasic pattern composed by blastemal, epithelial, and stromal elements. First symptoms in children include an abdominal palpable mass, while in adults pain and haematuria are the most common complaints. Deletions of tumours’ suppressor genes on chromosome 11 are usually associated with Wilms’ tumour.

Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC), is a type of inherited cancer syndrome associated with a genetic predisposition to different cancer types. People who have Lynch syndrome have a significantly increased risk of developing colorectal cancer. There is also an increased risk of developing other types of cancers, such as endometrial (uterine), stomach, breast, ovarian, small bowel (intestinal), pancreatic, prostate, urinary tract, liver, kidney, and bile duct cancers. Alterations in several genes involved in DNA mismatch repair that have been linked to Lynch syndrome. They include the genes of MLH1, MSH2, MSH6, PMS2, and EPCAM. A mutation (alteration) in any of these genes gives a person an increased lifetime risk of developing colorectal cancer and other related cancers.

Women also have an increased risk of developing endometrial and ovarian cancers. The safest operative strategy is a pancolectomy and end ileostomy.

Flow in any vessel = Effective perfusion pressure divided by resistance, where effective perfusion pressure is the mean intraluminal pressure at the arterial end minus the mean pressure at the venous end. Thus, in the given problem, resistance = (60 − 20)/200 = 0.2 mmHg/ml per min.

Hashimoto thyroiditis is part of the spectrum of autoimmune thyroid diseases (AITDs) and is characterized by the destruction of thyroid cells by various cell- and antibody-mediated immune processes.
The thyroid gland may become firm, large, and lobulated in Hashimoto’s thyroiditis, but changes in the thyroid can also be nonpalpable. Enlargement of the thyroid is due to lymphocytic infiltration and fibrosis, rather than tissue hypertrophy.

Laboratory studies and potential results for patients with suspected Hashimoto thyroiditis include the following:
– Serum thyroid-stimulating hormone (TSH) levels: Sensitive test of thyroid function; levels are invariably raised in hypothyroidism due to Hashimoto thyroiditis and in primary hypothyroidism from any cause
– Free T4 levels: Needed to correctly interpret the TSH in some clinical settings; low total T4 or free T4 level in the presence of an elevated TSH level further confirms diagnosis of primary hypothyroidism
– T3 levels: Low T3 level and high reverse T3 level may aid in the diagnosis of nonthyroidal illness

Thyroid autoantibodies: Presence of typically anti-TPO (anti-thyroid peroxidase) and anti-Tg (anti-thyroglobulin) antibodies delineates the cause of hypothyroidism as Hashimoto thyroiditis or its variant; however, 10-15% of patients with Hashimoto thyroiditis may be antibody negative.
While their role in the initial destruction of the follicles is unclear, antibodies against thyroid peroxidase (TPO) (also called TPOAb) or thyroglobulin are relevant, as they serve as markers for detecting the disease and its severity. They are hypothesized to be the secondary products of the T cell mediated destruction of the gland.

The ilioinguinal nerve arises together with the iliohypogastric nerve from the first lumbar nerve to emerge from the lateral border of the psoas major muscle just below the iliohypogastric and passing obliquely across the quadratus lumborum and iliacus muscles. It perforates the transversus abdominis, near the anterior part of the iliac crest and communicates with the iliohypogastric nerve between the internal oblique and the transversus. It then pierces the internal oblique to distribute filaments to it and accompanying the spermatic cord through the subcutaneous inguinal ring, is distributed to the skin of the upper and medial parts of the thigh, the skin over the root of the penis and the upper part of the scrotum in man and to the skin covering the mons pubis and labium majus in the woman. As the ilioinguinal nerve runs through the inguinal canal, it could easily be compressed by a hernial sac.
The femoral branch of genitofemoral nerve provides sensory innervation of the upper medial thigh.
The femoral nerve innervates the compartment of the thigh and also has some cutaneous sensory branches to the thigh.
The iliohypogastric nerve innervates the skin of the lower abdominal wall, upper hip and upper thigh. The subcostal nerve innervates the skin of the anterolateral abdominal wall and the anterior scrotal nerve is a terminal branch of the ilioinguinal nerve.

The deep inguinal ring transmits the spermatic cord in the man and the round ligament of the uterus in the female. It is bound below and medially by the inferior epigastric vessels (so these don’t go through it).
The ilioinguinal nerve, although it courses through the inguinal canal, does not pass through it.
The iliohypogastric nerves run between the internal oblique and transversus abdominis in the abdominal wall, piercing the internal oblique at the anterior superior iliac spine to travel just deep to the external oblique.
The inferior epigastric artery runs between the transversus abdominis and the peritoneum forming the lateral umbilical fold.
The medial umbilical ligament is the obliterated umbilical artery that it lies within the medial umbilical fold of peritoneum.

Answer: Hemopericardium

Hemopericardium refers to the presence of blood within the pericardial cavity, i.e. a sanguineous pericardial effusion. If enough blood enters the pericardial cavity, then a potentially fatal cardiac tamponade can occur. There is a very long list of causes but some of the more common are:
-ruptured myocardial infarction
-ruptured left ventricular aneurysm
-aortic dissection
-pericarditis
-trauma
-blunt/penetrating/deceleration
-iatrogenic, e.g. pacemaker wire insertion
-cardiac malignancies
-ruptured coronary artery aneurysm
-post-thrombolysis

Cardiac tamponade is a clinical syndrome caused by the accumulation of fluid in the pericardial space, resulting in reduced ventricular filling and subsequent hemodynamic compromise. The condition is a medical emergency, the complications of which include pulmonary oedema, shock, and death.
Symptoms vary with the acuteness and underlying cause of the tamponade. Patients with acute tamponade may present with dyspnoea, tachycardia, and tachypnoea. Cold and clammy extremities from hypoperfusion are also observed in some patients. Other symptoms and signs may include the following:
Elevated jugular venous pressure

Pulsus paradoxus

Chest pressure

Decreased urine output

Confusion

Dysphoria

Asbestosis is a chronic lung disease which leads to long-term respiratory complications and is caused by the inhalation of asbestos fibres. Symptoms due to long exposure to asbestos usually appear 10 to 40 years after initial exposure and include shortness of breath, cough, weight loss, clubbing of the fingers and chest pain. Typical chest X-ray findings include diffuse lung infiltrates that cause the appearance of shaggy heart borders.

Osteoarthritis is most common in older adults, predominating in women between the ages of 40 and 70; after this age, men and women are affected equally. It affects an entire joint, with disruption and potential loss of joint cartilage, along with other joint changes, including bone hypertrophy (osteophyte formation). The pain is usually gradual and is worse after activity, with occasional joint swelling. X-ray findings include marginal osteophytes, narrowing of the joint space, increased density of the subchondral bone, subchondral cyst formation, bony remodelling and joint effusions.

The superior rectal artery or superior haemorrhoidal artery is the continuation of the inferior mesenteric artery. It descends into the pelvis between the layers of the mesentery of the sigmoid colon, crossing the left common iliac artery and vein.

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.

Retroperitoneal structures are those that are found behind the peritoneum. They include: kidneys, suprarenal glands, bladder, ureter, inferior vena cava, rectum, oesophagus (part of it), part of the pancreas, 2nd, 3rd and 4th parts of the duodenum and ascending and descending parts of the colon.

Transverse sinus: part of pericardial cavity that is behind the aorta and pulmonary trunk and in front of the superior vena cava separating the outflow vessels from the inflow vessels.
Oblique pericardial sinus: is behind the left atrium where the visceral pericardium reflects onto the pulmonary veins and the inferior vena cava. Sliding a finger under the heart will take you to this space.
Cardiac notch: indentation of the ‘of the heart’ on the superior lobe of the left lung.
Hilar reflection: the reflection of the pleura onto the root of the lung to continue as mediastinal pleura.
Costomediastinal recess: part of the pleural sac where the costal pleura transitions to become the mediastinal pleura.
Sulcus terminalis: a groove between the right atrium and the vena cava

Answer: Measurement of faecal calprotectin

Based on Rome criteria, this patient has Irritable Bowel Syndrome (IBS). Irritable bowel syndrome (IBS) is a group of symptoms—including abdominal pain and changes in the pattern of bowel movements without any evidence of underlying damage. These symptoms occur over a long time, often years. It has been classified into four main types depending on whether diarrhoea is common or constipation is common, or both are common, or neither occurs very often (IBS-D, IBS-C, IBS-M, or IBS-U respectively). IBS negatively affects quality of life and may result in missed school or work. Disorders such as anxiety, major depression, and chronic fatigue syndrome are common among people with IBS.

The recommendations for physicians are to minimize the use of medical investigations. Rome criteria are usually used. They allow the diagnosis to be based only on symptoms, but no criteria based solely on symptoms is sufficiently accurate to diagnose IBS. Worrisome features include onset at greater than 50 years of age, weight loss, blood in the stool, iron-deficiency anaemia, or a family history of colon cancer, celiac disease, or inflammatory bowel disease. The criteria for selecting tests and investigations also depends on the level of available medical resources.

Rome criteria
The Rome IV criteria includes recurrent abdominal pain, on average, at least 1 day/week in the last 3 months, associated with two or more of the following criteria:

Related to defecation
Associated with a change in frequency of stool
Associated with a change in form (appearance) of stool.
Physicians may choose to use one of these guidelines or may simply choose to rely on their own anecdotal experience with past patients. The algorithm may include additional tests to guard against misdiagnosis of other diseases as IBS. Such red flag symptoms may include weight loss, gastrointestinal bleeding, anaemia, or nocturnal symptoms. However, red flag conditions may not always contribute to accuracy in diagnosis; for instance, as many as 31% of people with IBS have blood in their stool, many possibly from hemorrhoidal bleeding.

The diagnostic algorithm identifies a name that can be applied to the person’s condition based on the combination of symptoms of diarrhoea, abdominal pain, and constipation. For example, the statement 50% of returning travellers had developed functional diarrhoea while 25% had developed IBS would mean half the travellers had diarrhoea while a quarter had diarrhoea with abdominal pain. While some researchers believe this categorization system will help physicians understand IBS, others have questioned the value of the system and suggested all people with IBS have the same underlying disease but with different symptoms

The main diseases that cause an increased excretion of faecal calprotectin are inflammatory bowel diseases, coeliac disease, infectious colitis, necrotizing enterocolitis, intestinal cystic fibrosis and colorectal cancer.

Although a relatively new test, faecal calprotectin is regularly used as indicator for inflammatory bowel diseases (IBD) during treatment and as diagnostic marker. IBD are a group of conditions that cause a pathological inflammation of the bowel wall. Crohn’s disease and ulcerative colitis are the principal types of inflammatory bowel disease. Inflammatory processes result in an influx of neutrophils into the bowel lumen. Since calprotectin comprises as much as 60% of the soluble protein content of the cytosol of neutrophils, it can serve as a marker for the level of intestinal inflammation. Measurement of faecal calprotectin has been shown to be strongly correlated with 111-indium-labelled leucocytes – considered the gold standard measurement of intestinal inflammation. Levels of faecal calprotectin are usually normal in patients with irritable bowel syndrome (IBS). In untreated coeliac disease, concentration levels of faecal calprotectin correlate with the degree of intestinal mucosal lesion and normalize with a gluten-free diet.

Faecal calprotectin is measured using immunochemical techniques such as ELISA or immunochromatographic assays. The antibodies used in these assays target specific epitopes of the calprotectin molecule.

Gallbladder ultrasonography should be considered if the patient has recurrent dyspepsia or characteristic postprandial pain.

Abdominal computed tomography (CT) scanning is appropriate to screen for tumours, obstruction, and pancreatic disease if these are diagnostic possibilities.

CT and magnetic resonance (MR) enterography or wireless capsule endoscopy are employed if red flags exist to suggest enteritis (small bowel inflammation) or a tumour.

Colonoscopy is appropriate if alarm symptoms are present and in patients who otherwise qualify for screening colonoscopy.

Answer: Spontaneous bacterial peritonitis

The presence of periorbital and facial oedema with normal blood pressure in this toddler indicates that he has nephrotic syndrome. Nephrotic syndrome can be associated with a series of complications that can affect an individual’s health and quality of life:
Spontaneous bacterial peritonitis can develop where there is ascites present. This is a frequent development in children but very rarely found in adults.

Spontaneous bacterial peritonitis (SBP) is the development of a bacterial infection in the peritoneum, despite the absence of an obvious source for the infection. It is specifically an infection of the ascitic fluid – an increased volume of peritoneal fluid. Ascites is most commonly a complication of cirrhosis of the liver. It can also occur in patients with nephrotic syndrome. SBP has a high mortality rate.

The diagnosis of SBP requires paracentesis, a sampling of the peritoneal fluid taken from the peritoneal cavity. If the fluid contains large numbers of white blood cells known as neutrophils (>250 cells/µL), infection is confirmed and antibiotics will be given, without waiting for culture results. In addition to antibiotics, infusions of albumin are usually administered.

Signs and symptoms of spontaneous bacterial peritonitis (SBP) include fevers, chills, nausea, vomiting, abdominal pain and tenderness, general malaise, altered mental status, and worsening ascites. Thirteen percent of patients have no signs or symptoms. In cases of acute or chronic liver failure SBP is one of the main triggers for hepatic encephalopathy, and where there is no other clear causal indication for this, SBP may be suspected.

These symptoms can also be the same for a spontaneous fungal peritonitis (SFP) and therefore make a differentiation difficult. Delay of diagnosis can delay antifungal treatment and lead to a higher mortality rate.

Alpha-fetoprotein (AFP) is a glycoprotein that is normally produced by the yolk sac of the embryo, and then the fetal liver. It is elevated in the new-born and thus, also in the pregnant women. Eventually, it decreases in the first year of life to reach the adult normal value of < 20 ng/ml by 1 year of age. Markedly elevated levels (>500 ng/ml) in a high-risk patient is considered diagnostic for primary hepatocellular carcinoma (HCC). Moreover, due to smaller tumours secreting less quantities of AFP, rising levels can be a better indication. However, not all hepatocellular carcinomas produce AFP. Also, the level of AFP is not a prognostic factor. Populations where hepatitis B and HCC are common (e.g.: sub-Saharan Africans, ethnic Chinese) can see AFP levels as high as 100,000 ng/ml, whereas levels are low (about 3000 ng/ml) in regions with lesser incidences of HCC.
AFP can also be elevated up to 500 ng/ml in conditions like embryonic teratocarcinomas, hepatoblastomas, fulminant hepatitis, hepatic metastases from gastrointestinal tract cancers, some cholangiocarcinomas). Lesser values are seen in acute and chronic hepatitis.
Overall, the sensitivity of AFP value ≥20 ng/ml is 39-64% and the specificity is 76%–91%. Value of 500 ng/ml is considered as the diagnostic cut-off level for HCC.

Diarrhoea can occur due to any of the numerous aetiologies, which include infectious, drug-induced, food related, surgical, inflammatory, transit-related or malabsorption. Four mechanisms have been implicated in diarrhoea: increased osmotic load, increased secretion, inflammation and decreased absorption time. Diarrhoea can result in fluid loss with consequent dehydration, electrolyte loss (Na+, K+, Mg2+, Cl–) and even vascular collapse. Loss of bicarbonate ions can lead to a metabolic acidosis.

Perforins are characteristically found In the granules of CD8+ T cells and natural killer cells. They are cytolytic proteins that insert into the target plasma membrane forming a hole and resulting in lysis. They along with granzyme B induce apoptosis in the target cell.

The glossopharyngeal nerve provides parasympathetic innervation for the parotid salivary gland via the auriculotemporal nerve. The facial nerve supplies the parasympathetic innervation of the lacrimal, nasal, sublingual and submandibular glands.

The inferior sagittal sinus is also known as the inferior longitudinal sinus. It courses along the inferior border of the falx cerebri, superior to the corpus callosum. It is cylindrical in shape and increases in size as it passes backward ending in the straight sinus. It receives blood from the deep and medial aspects of the cerebral hemispheres and drains into the straight sinus.

The jejunum has a wider diameter, is thicker and more vascularized, hence of a deeper colour compared to the ileum. The valvulae conniventes (circular folds) of its mucous membranes are large and thick and its villi are larger than those in the ileum. The jejunum also has sparse aggregates of lymph nodules and most of its part occupies the umbilical and left iliac regions whilst the ileum is mostly in the umbilical, hypogastric, right iliac and pelvic regions.

The description of the patient here fits the diagnosis of obstructive jaundice or cholestasis, which results in conjugated hyperbilirubinemia. Cholestasis occurs due to impairment of bile flow, which can be anywhere from the liver cell canaliculus to the ampulla of Vater. Causes can be divided into intrahepatic and extrahepatic.
– Intrahepatic causes include hepatitis, drug toxicity, alcoholic liver disease, primary biliary cirrhosis, cholestasis of pregnancy and metastatic cancer.
– Extrahepatic causes include common duct stone, pancreatic cancer, benign stricture of the common duct, ductal carcinoma, pancreatitis and sclerosing cholangitis.
There is absence of bile constituents in the intestine, which causes spillage in the systemic circulation. Symptoms include pale stools, dark urine, pruritus, malabsorption leading to steatorrhea and deficiency of fat-soluble vitamins. Chronic cases can result in osteoporosis or osteomalacia due to vitamin D deficiency and Ca2+ malabsorption. Cholesterol and phospholipid retention produces hyperlipidaemia despite fat malabsorption (although increased liver synthesis and decreased plasma esterification of cholesterol also contribute); triglyceride levels are largely unaffected. The lipids circulate as a unique, low-density lipoprotein called lipoprotein X.

Steps involved in leukocyte arrival and function include:
1. margination: cells migrate from the centre to the periphery of the vessel.
2. rolling: selectins are upregulated on the vessel walls.
3. adhesion: upregulation of the adhesion molecules ICAM and VCAM on the endothelium interact with integrins on the leukocytes. Interaction of these results in adhesion.
4. diapedesis and chemotaxis: diapedesis is the transmigration of the leukocyte across the endothelium of the capillary and towards a chemotactic product.
5. phagocytosis: engulfing the offending substance/cell.

The Frykman classification of distal radial fractures is based on the AP appearance and encompasses the eponymous entities of Colles fracture, Smith fracture, Barton fracture, chauffeur fracture.

Colles fractures are very common extra-articular fractures of the distal radius that occur as the result of a fall onto an outstretched hand. They consist of a fracture of the distal radial metaphyseal region with dorsal angulation and impaction, but without the involvement of the articular surface.
Colles fractures are the most common type of distal radial fracture and are seen in all adult age groups and demographics. They are particularly common in patients with osteoporosis, and as such, they are most frequently seen in elderly women.

Smith fractures, also known as Goyrand fractures in the French literature 3, are fractures of the distal radius with associated volar angulation of the distal fracture fragment(s). Classically, these fractures are extra-articular transverse fractures and can be thought of like a reverse Colles fracture.
The term is sometimes used to describe intra-articular fractures with volar displacement (reverse Barton fracture) or juxta-articular fractures

Barton fractures are fractures of the distal radius. It is also sometimes termed the dorsal type Barton fracture to distinguish it from the volar type or reverse Barton fracture.
Barton fractures extend through the dorsal aspect to the articular surface but not to the volar aspect. Therefore, it is similar to a Colles fracture. There is usually associated with dorsal subluxation/dislocation of the radiocarpal joint.

Chauffeur fractures (also known as Hutchinson fractures or backfire fractures) are intra-articular fractures of the radial styloid process. The radial styloid is within the fracture fragment, although the fragment can vary markedly in size.

The pulmonary artery pressure (PA pressure) is a measure of the blood pressure found in the main pulmonary artery. The hydrostatic pressure of the pulmonary circulation refers to the actual pressure inside pulmonary vessels relative to atmospheric pressure. Hydrostatic (blood pressure) in the pulmonary vascular bed is low compared with that of similar systemic vessels. The mean pulmonary arterial pressure is about 15 mmHg (ranging from about 13 to 19 mmHg) and is much lower than the average systemic arterial pressure of 90 mmHg.

Direct inguinal hernias occur because of weakness in the abdominal muscles. The ilioinguinal nerve is important for innervating the muscles of the lower abdominal wall and damage during appendicectomy therefore prevents the man from being able to contract abdominal muscles to pull the falx inguinalis over the weak fascia.
The genitofemoral nerve innervates the cremaster muscle and injury to it would cause inability to elevate the testes.
The subcostal nerve and the ventral primary ramus of T10 innervate the muscles, skin and fascia of the upper abdominal wall.
The iliohypogastric nerve supplies the skin over the upper part of the buttock behind the area supplied by the subcostal nerve.

A patent urachus is one of the spectrum of congenital urachal anomalies. It has occasionally been termed urachal fistula. In an open (or patent) urachus, there is an opening between the bladder and the belly button (navel). The urachus is a tube between the bladder and the belly button that is present before birth. In most cases, it closes along its full length before the baby is born. An open urachus occurs mostly in infants. A patent urachus is often diagnosed in neonates when urine is noted leaking from the umbilicus. The umbilicus may also have an abnormal appearance on physical exam.

A patent urachus predisposes to infection. If the urachal disorder presents with an infection, the infection is treated first. This requires antibiotics, possible admission for intravenous antibiotics, and occasional surgical drainage of any infected cyst or poorly draining cavity. Once the infection is under control, excision of the urachus is usually performed. This can usually be done laparoscopically or with a small incision on the lower abdomen. Patients usually stay in the hospital 1-2 days after the surgery. The urachus can be excised because in normal development it usually obliterates anyway. The umbilicus is not removed.

Omphalitis is an infection of the umbilicus and/or surrounding tissues, occurring primarily in the neonatal period. Omphalitis is primarily a disease of the neonate and is characterized by tenderness, erythema, and induration of the umbilicus and surrounding tissues. Early on, patients may only have superficial cellulitis but, if untreated, this can progress to involve the entire abdominal wall. Patients may also have purulent drainage or be bleeding from the umbilical cord stump. Foul-smelling drainage should raise the suspicion of anaerobic infection.

Patent vitellointestinal or persistent omphalomesenteric duct is a very unusual congenital anomaly which occurs in 2% of population related with the embryonic yolk stalk. A persistent vitellointestinal duct can induce abdominal pain, bowel obstruction, intestinal haemorrhage and umbilical sinus, fistula or hernia which commonly occurs in children.

An umbilical granuloma is a moist, red lump of tissue that can form on a baby’s navel (belly button). It can be seen in the first few weeks of life, after the umbilical cord has dried and fallen off. It’s usually a minor problem that looks worse than it is. An umbilical granuloma does not cause pain. It may ooze a small amount of fluid that can make the skin around it red and irritated.

A stretch reflex is a monosynaptic reflex that causes muscle contraction in response to stretching within that muscle. The sensory apparatus in a muscle that are sensitive to stretch are the muscle spindles. The patellar (knee jerk) reflex is an example. In upper motor neuron lesions, the stretch reflexes tend to be brisk due to loss of inhibitory signals on gamma neurons through the lateral reticulospinal tract.