The middle cerebral artery is a part of the circle of Willis system of anastomosis within the brain, and the most often affected by brain pathology. The primary function of the middle cerebral artery is providing oxygenated blood to related regions of the brain. It achieves this by giving off different branches to supply different brain regions, namely: The cortical branches: which supplies the primary motor and somatosensory cortical areas of some parts of the face, trunk and upper limbs. The small central branches: which supply the basal ganglia and internal capsule via the lenticulostriate vessels. The superior division: which supplies the lateral inferior frontal lobe, including the Broca area which is responsible for production of speech, language comprehension, and writing. The inferior division: which supplies the superior temporal gyrus, including Wernicke’s area which controls speech comprehension and language development.

The fifth cervical nerve passes between the fourth and fifth cervical vertebrae, and the fourth thoracic nerve passes between the fourth and fifth thoracic vertebrae. Therefore, when the cancer metastasizes in this area, they are most likely affected.

The pterygoid hamulus is a hook-like process at the lower extremity of the medial pterygoid plate of the sphenoid bone around which the tendon of the tensor veli palatini passes.

The oculomotor nerve controls most of the eye muscles. It also controls the constriction of the pupils and thickening of the lens of the eye. This can be tested in two main ways. By moving a finger toward a person’s face to induce accommodation, their pupils should constrict or shining a light into one eye should result in equal constriction of the other eye. The neurons in the optic nerve decussate in the optic chiasm with some crossing to the contralateral optic nerve tract. This is the basis of the swinging-flashlight test. Loss of accommodation and continued pupillary dilation can indicate the presence of a lesion of the oculomotor nerve.

The anterior triangle is the triangular area of the neck found anteriorly to the sternocleidomastoid muscle. It is formed by the anterior border of sternocleidomastoid laterally, the median line of the neck medially and by the inferior border of the mandible superiorly. The apex of the anterior triangle extends towards the manubrium sterni. The anterior triangle contains: Muscles: thyrohyoid, sternothyroid, sternohyoid muscles Organs: thyroid gland, parathyroid glands, larynx, trachea, esophagus, submandibular gland, caudal part of the parotid gland Arteries: superior and inferior thyroid, common carotid, external carotid, internal carotid artery (and sinus), facial, submental, lingual arteries Veins: anterior jugular veins, internal jugular, common facial, lingual, superior thyroid, middle thyroid veins, facial vein, submental vein, lingual veins Nerves: vagus nerve (CN X), hypoglossal nerve (CN XII), part of sympathetic trunk, mylohyoid nerve The posterior triangle is a triangular area found posteriorly to the sternocleidomastoid muscle. It has three borders; anterior, posterior and inferior borders. The anterior border is the posterior margin of the sternocleidomastoid muscle. The posterior border is the anterior margin of the trapezius muscle, while the inferior border is the middle one-third of the clavicle. The investing layer of deep cervical fascia and integument forms the roof of the space, while the floor is covered with the prevertebral fascia along with levator scapulae, splenius capitis and the scalene muscles. The inferior belly of omohyoid subdivides the posterior triangle into a small supraclavicular, and a large occipital, triangle. Contents: Vessels: the third part of the subclavian artery, suprascapular and transverse cervical branches of the thyrocervical trunk, external jugular vein, lymph nodes Nerves: accessory nerve (CN XI), the trunks of the brachial plexus, fibers of the cervical plexus

A tonsillar sinus or fossa is a space that is bordered by the triangular fold of the palatoglossal and palatopharyngeal arches in the lateral wall of the oral cavity. The palatine tonsils are in these sinuses. The glossopharyngeal nerve is the main sensory nerve for the tonsillar fossa. The tonsillar branches of the glossopharyngeal nerve supply the palatine tonsils forming a plexus around it. Filaments from this plexus are distributed to the soft palate and fauces where they communicate with the palatine nerves. A lesser contribution is made by the lesser palatine nerve. Because of this otalgia may occur following tonsillectomy.

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.

Hutchinson sign relates to involvement of the tip of the nose from facial herpes zoster. It implies involvement of the external nasal branch of the nasociliary nerve which is a branch of the ophthalmic division of the trigeminal nerve. The nasociliary branch of the trigeminal nerve innervates the apex and lateral aspect of the nose, as well as the cornea. Therefore, lesions on the side or tip of the nose should raise suspicion of ocular involvement.

Infrahyoid muscles are also known as “strap muscles” which connect the hyoid, sternum, clavicle and scapula. They are located below the hyoid bone on the anterolateral surface of the thyroid gland and are involved in movements of the hyoid bone and thyroid cartilage during vocalization, swallowing and mastication. They are composed of four paired muscles, organized into two layers. Superficial layer consists of the sternohyoid and omohyoid Deep layer consists of the sternothyroid and thyrohyoid.

The superior cerebral veins are predominantly located on the superior aspect of the brain. They are 8 to 12 in number and they drain the lateral, medial and superior aspects of the cerebral hemispheres. These veins drain into the superior sagittal sinus, also known as the superior longitudinal sinus – which is located along the attached margin of the falx cerebri.

The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. A large number of muscles attach to the hyoid: Superiorly – the middle pharyngeal constrictor muscle, hyoglossus muscle, genioglossus, intrinsic muscles of the tongue and suprahyoid muscles. Inferiorly – the thyrohyoid muscle, omohyoid muscle and sternohyoid muscle.

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.

The paired sublingual glands are major salivary glands in the mouth. They are the smallest, most diffuse, and the only unencapsulated major salivary glands. They provide only 3-5% of the total salivary volume. The gland receives its blood supply from the sublingual and submental arteries. The sublingual artery is a branch of the lingual artery, thus damage to the lingual artery will decrease the blood flow to the sublingual gland.

The superior thyroid artery is the first branch of the external carotid artery. The other branches of the external carotid artery are: 1. Superior thyroid artery 2. Ascending pharyngeal artery 3. Lingual artery 4. Facial artery 5. Occipital artery 6. Posterior auricular artery 7. Maxillary artery 8. Superficial temporal artery The inferior thyroid artery is derived from the thyrocervical trunk.

Cholesteatoma is a special form of chronic otitis media in which keratinizing squamous epithelium grows from the tympanic membrane or the auditory canal into the middle ear mucosa or mastoid. The presence of abnormal epithelium in an abnormal location triggers an inflammatory response that can destroy surrounding structures such as the ossicles. Cholesteatomas may be congenital or acquired later in life. Acquired cholesteatomas are usually associated with chronic middle ear infection. Cardinal symptoms are painless otorrhea and progressive hearing loss. Important diagnostic procedures include mastoid process x-rays, temporal bone CT scans, and audiometric tests. Left untreated, erosion of the surrounding bone by a cholesteatoma can lead to facial nerve palsy, extradural abscess, and/or sigmoid sinus thrombosis. Therefore, even if a cholesteatoma is asymptomatic, surgery is always indicated. Surgical treatment involves tympanomastoidectomy to excise the cholesteatoma, followed by repair of the damaged middle ear structures.

The lateral pterygoid or external pterygoid is a muscle of mastication with two heads. It lies superiorly to the medial pterygoid. When acting alone, it will shift the mandible laterally and to the right.

The sternocleidomastoid muscle divides the neck into anterior and posterior triangles on both sides of the neck. The posterior triangle has the following boundaries: anteriorly – sternocleidomastoid muscle posteriorly – trapezius roof – investing layer of deep cervical fascia floor – prevertebral fascia overlying splenius capitis, levator scapulae, and the scalene muscles The contents of the posterior triangle are: 1. fat 2. lymph nodes (level V) 3. accessory nerve 4. cutaneous branches of the cervical plexus – greater auricular nerve, transverse cervical nerve, lesser occipital nerve, supraclavicular nerve (A major branch of this plexus is the phrenic nerve, which arises from the anterior divisions of spinal nerves C3-C5) 5. inferior belly of omohyoid 6. branches of the thyrocervical trunk (transverse cervical and suprascapular arteries) 7. third part of the subclavian artery 8. external jugular vein

The digastric muscle is a small muscle located under the jaw. It lies below the body of the mandible, and extends, in a curved form, from the mastoid process to the symphysis menti. The digastric divides the anterior triangle of the neck into three smaller triangles:- The submaxillary triangle, bounded above by the lower border of the body of the mandible and a line drawn from its angle to the sternocleidomastoid, below by the posterior belly of the digastric and the stylohyoid and in front by the anterior belly of the digastric- The carotid triangle, bounded above by the posterior belly of the digastric and stylohyoid, behind by the sternocleidomastoid and below by the omohyoid- The suprahyoid or submental triangle, bounded laterally by the anterior belly of the digastric, medially by the midline of the neck from the hyoid bone to the symphysis menti and inferiorly by the body of the hyoid bone.

The middle meatus is a nasal passageway located inferior to the middle concha and superior to the inferior concha. On the superior aspect of this meatus is a bulge produced by the middle ethmoidal cells known as the bulla ethmoidalis. Below this bulge is a curved fissure, the hiatus semilunaris, which is also bordered inferiorly by the edge of the uncinate process of the ethmoid. It is through this curved fissure, hiatus semilunaris, that the middle meatus communicates with the frontal sinus. It first forms a communication with a curved passage way known as the infundibulum. The infundibulum anteriorly communicates with the anterior ethmoidal cells and continues upward as the frontonasal duct into the frontal sinus.

The anterior triangle is the triangular area of the neck found anteriorly to the sternocleidomastoid muscle. It is formed by the anterior border of sternocleidomastoid laterally, the median line of the neck medially and by the inferior border of the mandible superiorly. The apex of the anterior triangle extends towards the manubrium sterni. The anterior triangle contains: Muscles: thyrohyoid, sternothyroid, sternohyoid muscles Organs: thyroid gland, parathyroid glands, larynx, trachea, esophagus, submandibular gland, caudal part of the parotid gland Arteries: superior and inferior thyroid, common carotid, external carotid, internal carotid artery (and sinus), facial, submental, lingual arteries Veins: anterior jugular veins, internal jugular, common facial, lingual, superior thyroid, middle thyroid veins, facial vein, submental vein, lingual veins Nerves: vagus nerve (CN X), hypoglossal nerve (CN XII), part of sympathetic trunk, mylohyoid nerve The posterior triangle is a triangular area found posteriorly to the sternocleidomastoid muscle. It has three borders; anterior, posterior and inferior borders. The anterior border is the posterior margin of the sternocleidomastoid muscle. The posterior border is the anterior margin of the trapezius muscle, while the inferior border is the middle one-third of the clavicle. The investing layer of deep cervical fascia and integument forms the roof of the space, while the floor is covered with the prevertebral fascia along with levator scapulae, splenius capitis and the scalene muscles. The inferior belly of omohyoid subdivides the posterior triangle into a small supraclavicular, and a large occipital, triangle. Contents: Vessels: the third part of the subclavian artery, suprascapular and transverse cervical branches of the thyrocervical trunk, external jugular vein, lymph nodes Nerves: accessory nerve (CN XI), the trunks of the brachial plexus, fibers of the cervical plexus Of the muscles listed in the options, only the anterior scalene is situated within the posterior triangle of the neck.

Motor innervation to all other muscles of the larynx and sensory innervation to the subglottis is by the recurrent laryngeal nerve.

Congenital neck masses are developmental anomalies typically seen in infants or children. Common conditions include thyroglossal duct cysts, branchial cleft cysts, and cystic hygromas. These malformations present as painless neck masses, which can cause dysphagia, respiratory distress, and neck pain due to compression of surrounding structures. The location of the mass depends on the embryological structure the cysts arise from. Diagnosis is made based on clinical findings and imaging results (ultrasound, CT, MRI), which also help in surgical planning. Treatment consists of complete surgical resection to prevent recurrence and complications such as infection or abscess formation. The thyroglossal cyst is present from birth and usually detected during early childhood. It presents as a painless, firm midline neck mass, usually near the hyoid bone, which elevates with swallowing and tongue protrusion. May cause dysphagia or neck/throat pain if the cyst enlarges.

Diphtheria is an infection caused by the bacterium Corynebacterium diphtheriae. Signs and symptoms may vary from mild to severe. They usually start two to five days after exposure. Symptoms often come on fairly gradually, beginning with a sore throat and fever. In severe cases, a grey or white patch develops in the throat. This can block the airway and create a barking cough as in croup. The neck may swell in part due to enlarged lymph nodes.The disease may remain manageable, but in more severe cases, lymph nodes in the neck may swell, and breathing and swallowing are more difficult. People in this stage should seek immediate medical attention, as obstruction in the throat may require intubation or a tracheotomy. Abnormal cardiac rhythms can occur early in the course of the illness or weeks later, and can lead to heart failure. Diphtheria can also cause paralysis in the eye, neck, throat, or respiratory muscles. Patients with severe cases are put in a hospital intensive care unit and given a diphtheria antitoxin (consisting of antibodies isolated from the serum of horses that have been challenged with diphtheria toxin). Since antitoxin does not neutralize toxin that is already bound to tissues, delaying its administration increases risk of death. Therefore, the decision to administer diphtheria antitoxin is based on clinical diagnosis, and should not await laboratory confirmation.Antibiotics are used in patients or carriers to eradicate C. diphtheriae and prevent its transmission to others. The Centres for Disease Control and Prevention recommends either:MetronidazoleErythromycin is given (orally or by injection) for 14 days (40 mg/kg per day with a maximum of 2 g/d), orProcaine penicillin G is given intramuscularly for 14 days (300,000 U/d for patients weighing 10 kg); patients with allergies to penicillin G or erythromycin can use Rifampicin or clindamycin.

The preauricular sinus is a benign congenital malformation of the preauricular soft tissues. Mostly it is noted during routine ear, nose and throat examination, though can present as an infected and discharging sinus. Preauricular sinus is more often unilateral, only occasionally are bilateral forms inherited. The right side is more often involved and females more than males. Most sinuses are clinically silent, eventual, however not rare, appearance of symptoms is related to an infectious process. Erythema, swelling, pain and discharge are familiar signs and symptoms of infection. The most common pathogens causing infection are Staphylococcal species and, less frequently Proteus, Streptococcus and Peptococcus species.Courses of treatment typically include the following:- Draining the pus occasionally as it can build up a strong odour- Antibiotics when infection occurs.- Surgical excision is indicated with recurrent fistula infections, preferably after significant healing of the infection. In case of a persistent infection, infection drainage is performed during the excision operation. The operation is generally performed by an appropriately trained specialist surgeon e.g. a otolaryngologist or a specialist General Surgeon.The fistula can be excised as a cosmetic operation even though no infection appeared. The procedure is considered an elective operation in the absence of any associated complications.

Foramen ovale, ductus arteriosus (DA) and ductus venosus (DV) are the three important cardiac shunts in-utero. At birth the umbilical vessels constrict in response to stretch as they are clamped. Blood flow through the ductus venosus (DV) decreases but the DV closes passively in 3-10 days. As the pulmonary circulation is established, there is a drastic fall in pulmonary vascular resistance and an increased pulmonary blood flow. This increases flow and pressure in the Left Atrium that exceeds that of the right atrium. The difference in pressure usually leads to the IMMEDIATE closure of the foramen ovale. The DA is functionally closed within the first 36-hours of birth in a healthy full-term newborn. Subsequent endothelial and fibroblast proliferation leads to permanent anatomical closure within 2 – 3 weeks. Oxygenated blood from the placenta passes via the umbilical vein to the liver. Blood also bypasses the liver via the ductus venosus into the inferior vena cava (IVC). The Crista dividens is a tissue flap situated at the junction of the IVC and the right atrium (RA). This flap directs the oxygen-rich blood, along the posterior aspect of the IVC, through the foramen ovale into the left atrium (LA). The Eustachian valve also known as the valve of The IVC is a remnant of the crista dividens.

Answer: Kiesselbach’s plexusEpistaxis is defined as acute haemorrhage from the nostril, nasal cavity, or nasopharynx. The source of 90% of anterior nosebleeds within the Kiesselbach’s plexus (also known as Little’s area) on the anterior nasal septum. Kiesselbach’s plexus (Kiesselbach’s area or Little’s area) is a vascular region of the anteroinferior nasal septum that comprises four arterial anastomoses:1)anterior ethmoidal artery – a branch of the ophthalmic artery2)sphenopalatine artery

The carotid triangle is a portion of the anterior triangle of the neck. It is bounded superiorly by the posterior belly of the digastric muscle, antero-inferiorly by the superior belly of omohyoid and posteriorly by the sternocleidomastoid. The floor is formed by the thyrohyoid, hyoglossus, middle and inferior pharyngeal constrictors and the roof is formed by the skin, superficial fascia, platysma and deep fascia.

Parotidectomy is basically an anatomical dissection. Identification of the facial nerve trunk is essential during parotid gland surgery because facial nerve injury is the most daunting potential complication of parotid gland surgery owing to the close relation between the gland and the extratemporal course of the facial nerve. After exiting the stylomastoid foramen, the facial nerve enters the substance of the parotid gland and then gives off five terminal branches: From superior to inferior, these are the: – Temporal branch supplying the extrinsic ear muscles, occipitofrontalis and orbicularis oculi – Zygomatic branch supplying orbicularis oculi – Buccal branch supplying buccinator and the lip muscles – Mandibular branch supplying the muscles of the lower lip and chin – Cervical branch supplying platysma. There are two approaches to identify the facial nerve trunk during parotidectomy—conventional antegrade dissection of the facial nerve, and retrograde dissection. Numerous soft tissue and bony landmarks have been proposed to assist the surgeon in the early identification of this nerve. Most commonly used anatomical landmarks to identify facial nerve trunk are stylomastoid foramen, tympanomastoid suture (TMS), posterior belly of digastric (PBD), tragal pointer (TP), mastoid process and peripheral branches of the facial nerve.

Buccinator is a muscle of facial expression and is therefore innervated by the facial nerve. The lateral pterygoid, masseter, anterior belly of digastric and temporalis are all muscles of mastication and therefore innervated by the mandibular division of the trigeminal nerve.

The following structures arise from each branchial pouch: 1st pouch – eustachian tube, middle ear, mastoid, and inner layer of the tympanic membrane2nd pouch – middle ear, palatine tonsils3rd pouch – inferior parathyroid glands, thymus 4th pouch – superior parathyroid glands, ultimobranchial body which forms the parafollicular C-cells of the thyroid gland, musculature and cartilage of larynx (along with the sixth pharyngeal pouch)5th pouch – rudimentary structure6th pouch – along with the fourth pouch, contributes to the formation of the musculature and cartilage of the larynx.