There are 6 pharyngeal arches, the fifth does not contribute any useful structures and often fuses with the sixth arch. The structures arising from the aortic arches are as follows:First aortic arch: It regresses except for a very small part that gives rise to the maxillary artery.Second aortic arch: It regresses except for a very small part giving rise to the stapedial artery.Third aortic arch: This arch is the source of the common carotid artery and the proximal part of the internal carotid artery, and the external carotid which arises as a bud from this arch.Right Fourth aortic arch: Is the genesis of the proximal part of the right subclavian artery.Left Fourth aortic arch: Gives rise to the medial portion of the arch of the aorta.Fifth aortic arch: The fifth aortic arch regresses completely and very early in the development.Sixth aortic arch: Either of the sixth aortic arches divides into ventral and dorsal segments, and therefore, their derivatives also divide into these two segments.Right Sixth Arch:Ventral: Gives rise to the right pulmonary artery.Dorsal: It degenerates completely and loses its connection with the dorsal aorta.Left Sixth ArchVentral: It gives rise to the left pulmonary artery that goes to the left pulmonary bud.Dorsal: It forms a vital connection during intrauterine life between the left pulmonary artery and the arch of the aorta. This structure is called ductus arteriosus.

Based on the clinical scenario, the most probable diagnosis for this patient is maxillary sinusitis.The maxillary sinus drains from its superior aspect, leaving it prone to infections. It is the most commonly affected sinus in sinusitis.Common symptoms of maxillary sinusitis include postnasal discharge, pain, headache and toothache.Radiological imaging may show a fluid level in the antrum.Common organisms causing maxillary sinusitis include Haemophilus influenzae or Streptococcus pneumoniae.Treatment with antral lavage may facilitate diagnosis and relieve symptoms. Antimicrobial therapy has to be continued for long periods. Antrostomy may be needed.Other options:- Frontal sinusitis more commonly causes intracranial complications, but it is still less frequent than maxillary sinusitis.- The petrosal sinus is not a cavity within bone| rather, it is a venous structure located beneath the brain.- Frontoethmoidal sinusitis: It usually presents with frontal headache, nasal obstruction and altered sense of smell. Inflammation may progress to involve periorbital tissues. Ocular symptoms may occur, and secondary CNS involvement brought about by infection entering via emissary veins. CT scanning is the imaging modality of choice. Early cases may be managed with antibiotics. More severe cases usually require surgical drainage.

In secretory OM, effusion in the middle ear is present which does not produce any pain to the patient in comparison to acute OM which produces otalgia. The family members are the ones to notice hearing loss as the patient usually is not aware of it. On otoscopy, the features described in the question are prominent. Otitis externa is usually painful and it also produces an itching sensation. Chronic otitis media is painful and may interfere with balance problems. Cholesteatoma is an abnormal cystic growth in the middle ear that usually discharges foul-smelling fluids and as it grows, otalgia can appear.

Among the treatment options provided, the most appropriate would be prednisolone 1-2 mg/kg.Other options:- Dexamethasone 0.15 mg per kg is the correct dose based on new trials and BNF guidance.- Inhaled budesonide 2mg would be a more appropriate dose.- Nebulised adrenaline may also be used.Croup:Laryngotracheobronchitis caused most commonly by parainfluenza virus. It most commonly affects children between 6 months to 3 years.Seasonal peaks: Most prevalent in autumn and spring.It starts as viral URTI then progresses to barking cough and a hoarse cry. Stridor and respiratory distress may occur. The illness can last from two days to 2 weeks.Relevant differential diagnoses include epiglottitis (the child will be septic with high temp and drooling) and inhaled foreign body.All children with moderate/severe croup should be given one dose of oral dexamethasone.Further doses may be needed if children have rebound symptoms.

Increasing the volume of the TV and the child’s loss of hearing may suggest that he has otitis media with effusion but the fever and the ear pain and fever strongly points to otitis externa as the diagnosis.

Removal of foreign bodies from the ear is indicated whenever a well-visualized foreign body is identified in the external auditory canal. Insects are better extracted with suction than with forceps or hooks. From the given answers, irrigation with warm water is the most suitable answer.

Upper respiratory tract infection when not treated accordingly can lead to otitis media and the patient presents with severe earache and fever.

With children nosebleeds often occur after nose picking and are benign in nature. For active bleeding, pressing of soft parts of the nose is required to stop the bleeding before doing anything else.

The glossopharyngeal nerve is the primary sensory nerve for the tonsillar fossa. The lesser palatine nerve makes a smaller contribution. Because of this, otalgia may occur following tonsillectomy.Anatomical Rationale:Each palatine tonsil has two surfaces, a medial surface which projects into the pharynx and a lateral surface that is embedded in the wall of the pharynx.The primary arterial supply is from the tonsillar artery, a branch of the facial artery. Its veins pierce the constrictor muscle to join the external palatine or facial veins. The external palatine vein is immediately lateral to the tonsil, which may result in bleeding during a tonsillectomy.Lymphatic drainage is the jugulodigastric node and the deep cervical nodes.TonsillitisThe inflammation of tonsils is usually due to bacterial aetiology (50%) – group A Streptococcus, the remainder of the causes are viral.May be complicated by the development of an abscess (quinsy), which may distort the uvula.Indications for tonsillectomy include recurrent acute tonsillitis, and enlargement causing sleep apnoea.Dissection tonsillectomy is the preferred technique with haemorrhage being the most frequent complication. Delayed otalgia may occur owing to irritation of the glossopharyngeal nerve.

Based on the clinical scenario, the most likely underlying pathogen is the Epstein Barr virus (EBV).An Epstein Barr virus (EBV) infection most commonly results in upper respiratory tract symptoms with fever and sore throat. Lymphadenopathy is frequently palpable on examination. Splenomegaly may also occur, and for this reason, patients diagnosed with glandular fever should be advised to avoid contact sports for one month following diagnosis. The presence of petechiae on the soft palate is also associated with EBV infection. The vast majority of patients with active EBV infection will develop a widespread rash if given amoxicillin, therefore, phenoxymethylpenicillin (Penicillin V) is recommended for the treatment of a suspected bacterial throat infection to prevent this complication occurring for individuals who have EBV infection.Other options:- Coronavirus: This is one of the causes of the common cold and is frequently responsible for sore throats| however, in this case, the presenting features are more suggestive of an EBV infection.- Group A Streptococcus: Streptococci are classified into two main groups| alpha-haemolytic and beta-haemolytic. Group A Streptococcus belongs to the beta-haemolytic group. Group A streptococcal infection is a common cause of bacterial tonsillitis. It is possible that the child, in this case, had streptococcal tonsillitis and has had a drug reaction to the amoxicillin. However her age, flu-like symptoms and petechiae on her palate all point to an EBV infection and amoxicillin resulting in a rash.- Parainfluenza: Parainfluenza viruses are one of many causes of the common cold and can cause pharyngitis. They are the leading cause of viral croup.- Rhinovirus: Rhinoviruses are one of many causes of the common cold and are frequently responsible for sore throats| however, in this case, are other factors suggesting EBV infection.