The first brachial arch (mandibular) gives rise to the mandibular and maxillary processes. Muscles and bones of this process originate within the arch’s mesoderm. The first arch cartilage (Meckel’s) ossifies to form the incus and malleus of the middle ear. Its perichondrium gives rise to he sphenomandibular ligament and through intermembraneous ossification after the mandible forms, the rest of the cartilage disappears. Muscles of the first arch include: mylohyoid, tensor tympany and palati, temporalis, masseter and lateral pterygoids and the anterior belly of the epigastric. This first arch is supplied by the trigeminal nerve.

Precocious Puberty is the development of secondary sexual characteristics before the age of 8 in females, and 9 in males. The first sign of early puberty in males is testicular enlargement, followed by growth of the penis and the scrotum at least a year after. Precocious puberty in boys in uncommon and usually has an organic cause leading to excess secretion of testosterone. These can be gonadotrophin dependent in the case of an inter cranial lesion, where the testes would be bilaterally enlarged, or from excess production from the adrenal gland in the case of adrenal hyperplasia or a tumour.

A peripheral blood film in iron deficiency anaemia can reveal the following morphologically variant RBCs:- Microcytic cells- Hypochromic cells- Pencil cells- Target cellsOther options:- Schistocytes can be caused by mechanical heart valves. – Rouleaux can be seen in chronic liver disease and malignant lymphoma. – Tear-drop poikilocytes can be seen in myelofibrosis. – Acanthocytes can be seen in liver disease and McLeod blood group phenotype.Pathological red cell forms include:- Target cells: Sickle-cell/thalassaemia, iron-deficiency anaemia, hyposplenism, and liver disease.- Tear-drop poikilocytes: Myelofibrosis- Spherocytes: Hereditary spherocytosis and autoimmune haemolytic anaemia- Basophilic stippling: Lead poisoning, thalassaemia, sideroblastic anaemia, and myelodysplasia- Howell-Jolly bodies: Hyposplenism- Heinz bodies: G6PD deficiency and alpha-thalassaemiaSchistocytes (‘helmet cells’): Intravascular haemolysis, mechanical heart valve, and disseminated intravascular coagulation- Pencil poikilocytes: Iron deficiency anaemia- Burr cells (echinocytes): Uraemia and pyruvate kinase deficiency – Acanthocytes: Abetalipoproteinemia

Also known as the hyoid arch, it forms the side and front of the neck. From its cartilage develops the styloid process, stylohyoid ligament and lesser cornu of the hyoid bone. The muscular derivatives include the muscles of facial expression, stapedius, stylohyoid and the posterior belly of the digastric. All these are innervated by cranial nerve VII but migrate into the area of the mandibular arch.

The presenting features and the surgical site provided in the clinical scenario are highly suggestive of ipsilateral hypoglossal nerve injury.Note:Three cranial nerves may be injured during submandibular gland excision.- Marginal mandibular branch of the facial nerve- Lingual nerve- Hypoglossal nerveHypoglossal nerve damage may result in the paralysis of the ipsilateral aspect of the tongue. The nerve itself lies deep to the capsule surrounding the gland and should not be injured during an intracapsular dissection. The lingual nerve is probably at higher risk of injury. However, the effects of lingual nerve injury are predominantly sensory rather than motor.Thus, the most appropriate answer is the hypoglossal nerve.

Mumps presents with a prodromal phase of general malaise and fever. On examination there is usually painful parotid swelling which has high chances of becoming bilateral. In OM with effusion there are no signs of infection and the only symptom is usually hearing loss. Acute otitis externa produces otalgia as well as ear discharge and itching. Acute OM produces otalgia and specific findings upon otoscopy. In acute mastoiditis the patient experiences ear discharge, otalgia, headache, hearing loss and other general signs of inflammation.

While the cause for Bell’s palsy is still under debate, it is observed that Bell’s palsy is often preceded by a viral infection. Bell’s Palsy:Bell’s palsy (idiopathic facial palsy) is an acute unilateral lower motor neurone palsy. It typically occurs two weeks after viral infection such as Epstein-Barr, herpes simplex, herpes zoster or mumps. A careful assessment may suggest an alternative aetiology for the acute onset of weakness, e.g. acute otitis media, Lyme disease, hypertension. Causes:In childhood, Bell’s palsy is probably a post-infectious (i.e. immune-mediated) phenomenon, while in adults, there is increasing evidence that the majority of cases follow reactivation of previous HSV infection. Management:The prognosis is generally good in childhood with full recovery in the majority. However, permanent weakness is observed in around 5%. Steroids and acyclovir may have some benefit in adults with recent onset of weakness, but the evidence of the treatment benefit is much less convincing in childhood. Exposure keratitis is an important complication and children should be managed with eye drops and taping of the eyelid at night until recovery is complete.

Vesicoureteric reflex (VUR) is described as the retrograde flow of urine from the bladder into the ureter due to an incompetent uterovesical junction. In primary VUR the lower urinary tract functions normally, while secondary VUR is associated with a poorly functioning lower urinary tract. The incidence of VUR is highest in new-born girls. They can present with hydronephrosis, or urinary tract infections.

The main aim of randomisation in a clinical trial is to remove the bias and avoid any potential confounding variables. While in double blind studies both the investigators and the patients are not aware of which group they belong in, being blind is not essential in carrying out a randomized study, nor is it essential that the randomisation be done away from the study centre. A placebo also does not facilitate randomisation, which can be done in single centre and multi-centre trials.

History is suggestive of a possible hearing impairment. As the baby is vocalizing and has normal motor development, an isolated hearing problem is possible. A hearing test will confirm the diagnosis.

The patient has bloody diarrhoea that sounds like a food poisoning in the clinical scenario. Campylobacter is the most common cause of this in the United Kingdom. This is then followed by Salmonella and Shigella. The symptoms are usually self limiting. This is more likely to be bacterial from the food than a viral gastroenteritis.

EPICure is a series of studies of survival and later health among babies and young people who were born at extremely low gestations -from 22 to 26 weeks.Boost II is a double-blind randomised controlled trial (RCT) comparing the effects of targeting arterial oxygen saturations between 85% and 89% versus 91% and 95% in preterm infants.OSCAR Xe is not the name of a study. Baby-OSCAR is an RCT to determine whether a confirmed large patent ductus arteriosus in very premature babies should be treated with ibuprofen within 72 hours of birth.SafeBoosC is a trial to examine if it is possible to stabilise the cerebral oxygenation of extremely preterm infants in the first 72 hours of life with the use of NIRS oximetry and a clinical treatment guideline. TOBY Xe is an RCT looking at the neuroprotective effects of hypothermia combined with inhaled xenon following perinatal asphyxia.

Frequent regurgitation of milk and microcytic anaemia is suggestive of a hiatus hernia. The reflux causes regurgitation of milk and frequent ulceration of the lower oesophageal mucosa potentially resulting in blood loss and anaemia. Duodenal atresia usually presents with bilious vomiting and pyloric stenosis presents with projectile vomiting. Alpha 1 antitrypsin deficiency and cystic fibrosis usually do not present with vomiting.

Still’s disease is a rare systemic disorder that accounts for 10% of cases of juvenile idiopathic arthritis (JIA). The aetiology is unknown. It affects boys and girls equally up to the age of five years of age, following which, girls are more commonly affected. Clinical features of this disease include:- Fever- Maculopapular rash- Myalgia- Generalised lymphadenopathy- Hepatosplenomegaly- Pericarditis and pleuritis Laboratory investigations reveal raised ESR and CRP. There can also be coexisting neutrophilia and thrombocytosis. Anti-nuclear autoantibodies and rheumatoid factor are usually negative in patients with Still’s disease.On the rare case that they are present, their titres are generally low.

Histology of psoriasis is characterised by parakeratosis (cell nuclei within stratum corneum) and thickened projections of the prickle cell layer of keratinocytes (psoriasiform hyperplasia or acanthosis). Orthokeratosis refers to the formation of a pathological anuclear keratin layer in the skin.The stratum granulosum is actually thinned or absent in patients with psoriasis.

The Green Book guidelines report in an active infection (HBeAg+ and HBsAg+) to give the vaccine as well as immunoglobulin. If antibodies are present it is not active infection (anti-Hbe) and then in that case only the vaccine, and no immunoglobulin, would be given. The presence of HBeAg means a person is infectious and can transmit to other people.

While the clinical scenario and the anosmic presentation of the child are highly suggestive of Kallmann’s syndrome, reduced testosterone, FSH and LH levels can confirm the diagnosis.Kallman’s syndrome is a recognised cause of delayed puberty secondary to hypogonadotropic hypogonadism. It is usually inherited as an X-linked recessive trait. Kallman’s syndrome is thought to be caused by a failure of GnRH-secreting neurons to migrate to the hypothalamus.Clinical features of Kallmann’s syndrome include:- Delayed puberty- Hypogonadism, cryptorchidism- Anosmia- Low sex hormone levels – Inappropriately low/normal LH and FSH levels- Some patients can present with associated cleft lip/palate and visual/hearing defects.

Puberty is the general term for the transition from sexual immaturity to sexual maturity. There are two main physiological events in puberty:- Gonadarche is the activation of the gonads by the pituitary hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH).- Adrenarche is the increase in production of androgens by the adrenal cortex. It is the term for the maturational increase in adrenal androgen production that normally becomes biochemically apparent at approximately six years of age in both girls and boysA number of other terms describe specific components of puberty:- Thelarche is the appearance of breast tissue, which is primarily due to the action of oestradiol from the ovaries. – Menarche is the time of first menstrual bleed. – Pubarche is the appearance of pubic hair, which is primarily due to the effects of androgens from the adrenal gland. The term is also applied to first appearance of axillary hair, apocrine body odour, and acne.The earliest detectable secondary sexual characteristic on physical examination in most girls is breast/areolar development (thelarche). Ovarian enlargement and growth acceleration typically precede breast development but are not apparent on a single physical examination. Oestrogen stimulation of the vaginal mucosa causes a physiologic leukorrhea, which is a thin, white, non-foul-smelling vaginal discharge that typically begins 6 to 12 months before menarche. Menarche occurs, on average, 2 to 2.5 years after the onset of puberty

Androgen insensitivity syndrome (AIS), previously referred to as testicular feminization, is an X-linked disorder in which the patients are genotypically male (possessing and X and Y chromosome) and phenotypically female. This disorder is rare, with reported incidences from 1 in 20,000 to 1 in 60,000 live male births, and is the result of a missing gene on the X chromosome that is responsible for the cytoplasmic or nuclear testosterone receptor. In its absence, the gonad, which is a testis, produces normal amounts of testosterone; however, the end tissues are unable to respond due to the deficient receptors leading to the external genitalia developing in a female fashion. Anti-Mullerian hormone, which is produced by the testis, is normal in these patients, leading to regression of the Mullerian duct. Wolffian duct development, which depends on testosterone, does not occur as the ducts lack the receptors. The cumulative effect is a genotypic male with normal external female genitalia (without pubic or axillary hair), no menses, normal breast development, short or absent vagina, no internal sex organs, and the presence of testis. Frequently, these patients have bilateral inguinal hernias in childhood, and their presence should arouse suspicion of the diagnosis.

6 month old babies that go through normal developmental milestones, should enjoy playing with others and especially their parents.The other milestones are expected of a 9-month-old.

The gastrocolic reflex is a physiological reflex that involves increase in colonic motility in response to stretch in the stomach and by-products of digestion in the small intestine. It is shown to be uneven in its distribution throughout the colon, with the sigmoid colon affected more than the right side of the colon in terms of a phasic response. Various neuropeptides have been proposed as mediators of this reflex, such as serotonin, neurotensin, cholecystokinin and gastrin.

Cleansing and debridement is paramount in dealing with tetanus-prone wounds (severe crushing injuries, piercing wounds, blisters and burns are outstanding examples, particularly if contaminated with dirt, grass or other debris).Prophylaxis then is relatively easy in persons who have been actively immunized by toxoid injections. For them, a boosterť injection is indicated. There is experimental evidence that antibiotics of the tetracycline group, given soon after injury, may have prophylactic effect against tetanus.

Prednisone is used for the treatment of myasthenia gravis if there is no initial response to the anticholinesterase medications. Pyridostigmine can make the symptoms of myasthenia gravis worse if used  in the initial stages of treatment. 

The most common cause for acute bloody diarrhoea in a 10-year-old child is Campylobacter.Note:Campylobacter is the most common bacterial cause of gastroenteritis in the UK. It typically presents with bloody diarrhoea, fever, abdominal pain and vomiting. The primary source of Campylobacter is uncooked poultry. Treatment is generally supportive unless the child is immunosuppressed or the symptoms are persistent.Other options:- E. coli 0157:H7: It causes acute haemorrhagic diarrhoea, usually afebrile. It can lead to haemolytic uremic syndrome (haemolytic anaemia, acute renal failure and thrombocytopenia), which is the commonest cause of acute renal failure in children.- Rotavirus: It rarely causes bloody diarrhoea.- Salmonella and Yersinia: While they can cause bloody diarrhoea, they are much less common compared to Campylobacter.

The differentiation between type 1 and type 2 epithelia in the developing lung buds is evident from 16-24 weeks of gestation.Development of the respiratory tract has five stages:- Embryonic (at 4 – 5 weeks of gestation):Formation of lung buds, trachea and mainstem bronchi occur. These structures are formed from a ventral outpouching of foregut pharynx. At this stage, the beginnings of the five lung lobes are present.- Pseudoglandular (at 5 – 16 weeks of gestation):Formation of terminal bronchioles, cartilage and smooth muscles occur in this stage. – Canalicular (at 16-24 weeks gestation): Differentiation of type I and II epithelial cells can be done in this stage. There is also an increase in the size of proximal airways).- Saccular (at 24 – 40 weeks of gestation): Terminal saccule formation occurs. Production of surfactant takes place at this stage with an increase in the number of goblet cellsUp to half the adult number of alveoli are in place by this stage.- Alveolar (occurs between 32 weeks of gestation till the post-natal age 8): Formation of alveoli and septation occurs with the expansion of air spaces.

Distal renal tubular acidosis (dRTA) is characterised by a decreased hydrogen ion excretion from the alpha intercalated cells of the collecting duct of the distal nephron. The resultant acidosis causes Ca and phosphates to be released from bones to buffer the acidosis causing hypercalciuria, thus precipitating calcium compounds in the kidney. Other consequences of the dRTA in children include rickets, hypokalaemia, and polyuria. While dRTA can occur as a result of various pathologies including autoimmune disease, proximal renal tubular acidosis often presents as part of Fanconi’s syndrome. One way to differentiate between the two conditions is with an acid challenge test. In proximal RTA offering the child an acid load will decrease the urinary ph whereas in distal disease the pH will be unaffected due to impairment in hydrogen ion secretion.

Although some individuals with Anorexia Nervosa exhibit no laboratory abnormalities, the semistarvation characteristic of this disorder can affect most major organ systems and produce a variety of disturbances. The induced vomiting and abuse of laxatives, diuretics, and enemas can also cause a number of disturbances leading to abnormal laboratory findings.Haematology: Leukopenia and mild anaemia are common; thrombocytopenia occurs rarely.Chemistry: Dehydration may be reflected by an elevated blood urea nitrogen (BUN). Hypercholesterolemia is common. Liver function tests may be elevated.Hypomagnesemia, hypozincaemia, hypophosphatemia, and hyperamylasaemia are occasionally found. Induced vomiting may lead to metabolic alkalosis (elevated serum bicarbonate), hypochloraemia, and hypokalaemia, and laxative abuse may cause a metabolic acidosis. Serum thyroxine levels are usually in the low-normal range; triiodothyronine levels are decreased. Hyperadrenocorticism and abnormal responsiveness to a variety of neuroendocrine challenges are common.In females, low serum oestrogen levels are present, whereas males have low levels of serum testosterone. There is a regression of the hypothalamic-pituitary-gonadal axis in both sexes in that the 24-hour pattern of secretion of luteinizing hormone (LH) resembles that normally seen in prepubertal or pubertal individuals.

Possible Zika virus infections have been identified in breastfeeding babies, but Zika virus transmission through breast milk has not been confirmed. Additionally, we do not yet know the long-term effects of Zika virus on young infants infected after birth. Because current evidence suggests that the benefits of breastfeeding outweigh the risk of Zika virus spreading through breast milk, CDC continues to encourage mothers to breastfeed, even if they were infected or lived in or travelled to an area with risk of Zika.

Primary amenorrhea is defined as the total absence of menarche in a girl of 14 years of age if the secondary sexual characteristics are also absent or in a girl of 16 years of age in whom normal secondary sexual characteristics are present. There are multiple causes of primary amenorrhea, but the most common are constitutional delay, imperforate hymen, congenital adrenal hyperplasia, hypothalamic failure, and testicular feminization. Cushing’s syndrome leads to secondary amenorrhea, which is defined as the absence of a menstrual period for 6 consecutive cycles in a girl who has achieved menarche.

The mnemonic STUMPED is helpful for remembering the differential diagnosis for congenital corneal opacities: – Sclerocornea- Tears in Descemet membrane (usually due to forceps trauma or congenital glaucoma)- Ulcers (e.g. infection – rubella)- Metabolic (e.g., mucopolysaccharidosis)- Peters anomaly- oEdema – Dermoids (e.g. Goldenhar’s syndrome)