Head And Neck – 2016

Cleft lip repair (cheiloplasty) is usually performed at 3 months of age following the “Rule of 10s” to ensure the infant is healthy enough for surgery.

“Rule of 10s” for Cleft Lip Surgery:

A baby should have:

✅ At least 10 weeks of age (≈ 3 months)

✅ At least 10 pounds in weight

✅ Hemoglobin of at least 10 g/dL

This ensures safe anesthesia and better healing outcomes.

Why the Other Options Are Incorrect:

1.“10th month”  ❌ Incorrect

•Cleft lip is typically repaired earlier (around 3 months) to aid in feeding, speech development, and social integration.

2.“9th month” ❌ Incorrect

•Too late; by this time, cleft lip repair should already have been done.

3.“6th month ❌ Incorrect

•Although some variations exist, the standard practice is around 3 months, not 6 months.

4.“12th month”  ❌ Incorrect

•Cleft palate repair (palatoplasty) is usually done around 9–12 months, but cleft lip is corrected much earlier (≈ 3 months).

Personality is shaped by a combination of biological, psychological, and social factors. Among the options given, temperament has the strongest and most direct influence on personality development.

•Temperament refers to the inborn traits that influence how a person reacts to their environment, such as emotional reactivity, adaptability, and activity levels.

•It forms the foundation of personality and remains relatively stable throughout life, shaping behaviors, attitudes, and interactions with others.

Thus, temperament plays a key role in personality formation, making option 4 the correct answer.

Why the Other Options Are Incorrect:

“Gender”  ❌Incorrect

•While gender influences societal roles and expectations, it does not directly determine personality.

•Personality is shaped more by temperament and environment than by gender alone.

“Health” ❌ Incorrect

•Health conditions can impact behavior and mood, but they do not fundamentally shape personality.

•Chronic illness may influence personality over time, but it is not the primary factor.

“Physical capabilities” ❌ Incorrect

•Physical abilities can affect confidence and lifestyle, but they do not define core personality traits.

•For example, two individuals with the same physical abilities can have completely different personalities.

“Skin color”  ❌ Incorrect

•Skin color may influence social experiences, but it does not biologically determine personality.

•Personality is shaped by genetics, temperament, and life experiences, not physical appearance.

Lateralization in hearing tests is commonly assessed using Weber’s test, which helps differentiate between sensorineural and conductive hearing loss.

Weber’s test principle:

•A tuning fork (512 Hz) is placed at the midline of the forehead.

•The patient is asked which ear hears the sound louder.

•The sound will lateralize to either:

•The better ear in sensorineural hearing loss (SNHL).

•The worse ear in conductive hearing loss (CHL).

Interpretation of Lateralization to the Left Ear:

•If the patient hears the sound louder in the left ear, it means one of the following:

•Right-sided sensorineural hearing loss (SNHL) → Sound lateralizes to the better (left) ear. ✅ (Correct Answer)

•Left-sided conductive hearing loss (CHL) → Sound lateralizes to the affected (left) ear ❌ (This option is missing, but if present, would also be correct).

Thus, option  (sensorineural hearing loss in the right ear) is correct because in SNHL, sound lateralizes to the better ear.

Why the Other Options Are Incorrect:

“Sensorineural hearing loss in left ear” ❌ Incorrect

•In left SNHL, sound would lateralize to the right ear, NOT the left.

“None of these”  ❌ Incorrect

•Since right SNHL  is correct, this option is wrong.

“Conductive hearing loss in right ear”  ❌ Incorrect

•In right CHL, sound lateralizes to the right ear, NOT the left.

“Combined hearing loss in left ear”  ❌ Incorrect

•If left ear had both SNHL & CHL, sound wouldn’t lateralize to it, because SNHL would make it hear worse.

Principle of Rinne’s Test:

•Rinne’s test is a tuning fork test used to differentiate between conductive hearing loss and sensorineural hearing loss.

•It is based on the principle that air conduction (AC) is normally better than bone conduction (BC).

Normal Hearing (Positive Rinne Test)

•Air conduction (AC) > Bone conduction (BC)

•This means that sound is heard louder when the tuning fork is placed near the ear (AC) than when placed on the mastoid process (BC).

Conductive Hearing Loss (Negative Rinne Test)

•Bone conduction (BC) > Air conduction (AC)

•This occurs in conditions like otosclerosis, tympanic membrane perforation, or middle ear effusion, where sound is better transmitted through bone than through the damaged conductive pathway.

Sensorineural Hearing Loss (Positive Rinne Test but Reduced Perception)

•Air conduction (AC) > Bone conduction (BC), but both are reduced

•This occurs in cochlear or auditory nerve damage, where both AC and BC are impaired, but AC still remains better than BC.

Since normal hearing follows the principle that air conduction is better than bone conduction, option 4 is the correct answer.

Why the Other Options Are Incorrect:

1.“Bone conduction is better than air conduction” (Option 1) ❌ Incorrect

•This is seen only in conductive hearing loss, not in normal individuals.

2.“Air conduction is the same as bone conduction” (Option 2) ❌ Incorrect

•This is not the normal condition; if AC = BC, it suggests sensorineural hearing loss in both ears or a non-functioning ear.

3.“None of these” (Option 3) ❌ Incorrect

•Since option 4 is correct, this option is wrong.

4.“All of these” (Option 5) ❌ Incorrect

•Since option 1 and 2 are incorrect, this option is also incorrect.

Mouth opening (jaw depression) is primarily performed by the lateral pterygoid muscle, assisted by gravity and the suprahyoid muscles.

Key Actions of the Muscles of Mastication:

1.Lateral pterygoid → ✅ Opens the mouth (jaw depression) & protrudes the mandible.

2.Medial pterygoid → ❌ Closes the mouth (jaw elevation).

3.Masseter → ❌ Closes the mouth (jaw elevation).

4.Temporalis → ❌ Closes the mouth (jaw elevation) & retracts the mandible.

Thus, only the lateral pterygoid is responsible for mouth opening, making option 1 the correct answer.

Why the Other Options Are Incorrect:

2.Temporalis (Option 2) ❌ Incorrect

•Elevates and retracts the mandible (helps in closing the mouth), NOT opening it.

3.Masseter (Option 3) ❌ Incorrect

•Elevates the mandible, helping in jaw closure, NOT opening.

4.Medial pterygoid (Option 4) ❌ Incorrect

•Also elevates the mandible (like masseter), helping in jaw closure.

5.None of these (Option 5) ❌ Incorrect

•Since lateral pterygoid opens the mouth, this option is incorrect.

Homonymous hemianopia is a condition where a person loses vision in the same visual field of both eyes (e.g., right or left visual field in both eyes).

•This occurs due to damage after the optic chiasm, which means the optic tract, lateral geniculate nucleus (LGN), optic radiations, or visual cortex are affected.

•The primary visual cortex (occipital lobe), supplied mainly by the posterior cerebral artery (PCA), is a key structure responsible for processing visual information.

An infarct in the PCA can lead to contralateral homonymous hemianopia because:

•The left PCA infarct → causes right homonymous hemianopia.

•The right PCA infarct → causes left homonymous hemianopia.

•If the macular cortex is spared (due to dual blood supply from MCA), it results in homonymous hemianopia with macular sparing.

Thus, the PCA infarct is the most common cause of homonymous hemianopia, making option 5 the correct answer.

Why the Other Options Are Incorrect:

Anterior cerebral artery  ❌ Incorrect

•The ACA supplies the medial frontal and parietal lobes, affecting motor and sensory function of the lower limbs, NOT vision.

All of these  ❌ Incorrect

•Only PCA infarcts cause homonymous hemianopia, so this option is incorrect.

3.Middle cerebral artery (Option 3) ❌ Partially Correct but Not the Best Answer

•The MCA supplies the optic radiations (especially Baum’s loop in the parietal lobe and Meyer’s loop in the temporal lobe), so an infarct could cause quadrantanopia, but not a full homonymous hemianopia in most cases.

•However, if a large MCA infarct affects both optic radiations, it can cause homonymous hemianopia, but this is less common than PCA infarcts.

None of these  ❌ Incorrect

•Since PCA infarcts do cause homonymous hemianopia, this option is incorrect.

Right homonymous hemianopia refers to loss of vision in the right visual fields of both eyes. This condition occurs due to damage to the visual pathway after the optic chiasm, meaning it must affect structures like the optic tract, optic radiations, or visual cortex on the left side.

Key visual pathway components:

1.Optic nerve (before the chiasm) → Damage causes monocular blindness.

2.Optic chiasm → Damage causes bitemporal hemianopia (loss of outer visual fields).

3.Optic tract (after the chiasm) → Damage causes contralateral homonymous hemianopia.

4.Optic radiation (Meyer’s & Baum’s loops) → Damage causes quadrantanopia or homonymous hemianopia.

5.Visual cortex → Damage causes homonymous hemianopia, often macular-sparing if caused by PCA infarction.

Since homonymous hemianopia occurs only with lesions after the optic chiasm, a lesion of the optic chiasm cannot produce right homonymous hemianopia, making option 2 (Optic chiasm) the correct answer.

Why the Other Options Are Incorrect:

Visual cortex  ❌ Incorrect

•Damage to the left occipital lobe (visual cortex) causes right homonymous hemianopia, often with macular sparing if PCA infarction is the cause.

Optic tract ❌ Incorrect

•A lesion of the left optic tract causes right homonymous hemianopia because it disrupts signals from the right visual field of both eyes.

Optic radiation ❌ Incorrect

•Damage to left optic radiations leads to right homonymous hemianopia (partial or complete).

•Meyer’s loop (temporal lobe lesion) → Right superior quadrantanopia (“pie in the sky”).

•Baum’s loop (parietal lobe lesion) → Right inferior quadrantanopia (“pie on the floor”).

None of these ❌ Incorrect

•Since optic chiasm lesions do NOT cause homonymous hemianopia, “None of these” is incorrect.

Cephalohematoma is a subperiosteal hemorrhage that occurs between the skull bone and the periosteum. It is caused by trauma during birth, often due to pressure on the infant’s head during delivery (e.g., forceps or vacuum-assisted delivery).

Key Features of Cephalohematoma:

•Location: Blood collects between the skull and periosteum, meaning it is confined to a single bone (usually the parietal bone).

•Does NOT cross suture lines, as the periosteum is tightly attached at the sutures.

•Resolves over weeks to months as the blood is gradually reabsorbed.

•No discoloration of skin (unlike caput succedaneum, which is more superficial).

Since the fluid (blood) is present between the skull and periosteum, option 4 is the correct answer.

Why the Other Options Are Incorrect:

1.“Dura and arachnoid”  ❌ Incorrect

•Bleeding between the dura and arachnoid results in a subdural hematoma, which is a different condition (often due to tearing of bridging veins).

2.“None of these” ❌ Incorrect

•Cephalohematoma does exist, and option 4 correctly describes it.

3.“Dural folds” ❌ Incorrect

•The dural folds (e.g., falx cerebri, tentorium cerebelli) are intracranial structures, unrelated to cephalohematoma.

4.“Arachnoid and pia” ❌ Incorrect

•Bleeding between the arachnoid and pia leads to a subarachnoid hemorrhage, typically due to ruptured aneurysms or trauma, NOT birth injury.

Stenson’s duct is the excretory duct of the parotid gland. It plays a crucial role in delivering saliva to the oral cavity.

Key Features of Stenson’s Duct:

•It originates from the anterior border of the parotid gland (NOT the posterior surface).

•It travels anteriorly across the masseter muscle.

•Then, it pierces the buccinator muscle before opening into the oral cavity at the level of the second upper molar tooth.

Since the duct pierces the buccinator muscle, option 4 is the correct answer.

Why the Other Options Are Incorrect:

1.“It is a duct of the submandibular gland” (Option 1) ❌ Incorrect

•The submandibular gland has Wharton’s duct, NOT Stenson’s duct.

2.“None of these” (Option 2) ❌ Incorrect

•One statement (option 4) is correct, so “None of these” is wrong.

3.“It is a duct of the sublingual gland” (Option 3) ❌ Incorrect

•The sublingual gland has multiple small ducts (ducts of Rivinus and Bartholin’s duct), NOT Stenson’s duct.

4.“It arises from the posterior surface of the parotid gland” (Option 5) ❌ Incorrect

•Stenson’s duct arises from the anterior border of the parotid gland, NOT the posterior surface.

The sternocleidomastoid (SCM) muscle is responsible for contralateral rotation of the head. This means:

•The right SCM turns the head to the left.

•The left SCM turns the head to the right.

If the SCM is damaged, the person will be unable to rotate their chin to the opposite side of the affected muscle.

The SCM is innervated by the accessory nerve (CN XI), and its actions include:

•Unilateral contraction → Rotates the head to the opposite side and slightly tilts it upward.

•Bilateral contraction → Flexes the neck.

Thus, damage to the SCM prevents contralateral head rotation, making it the correct answer.

Why the Other Options Are Incorrect:

1.Masseter:

•A muscle of mastication responsible for jaw elevation (closing the mouth), NOT for head rotation.

2.Buccinator:

•A muscle of facial expression, involved in chewing and blowing, NOT in moving the chin.

3.Levator scapulae:

•A neck muscle that elevates the scapula and helps with lateral flexion of the neck, but does not rotate the head.

4.Temporalis:

•Another muscle of mastication, mainly responsible for jaw closure and retraction, NOT for head movement.

The stomodeum is the primitive oral cavity in the early embryo, which later develops into the mouth. It is initially a depression lined by ectoderm and is bounded by different facial prominences derived from the first pharyngeal arch.

The boundaries of the stomodeum are:

1.Rostral (Superior) Boundary: Formed by the frontonasal prominence (NOT the maxillary prominence).

2.Lateral Boundaries: Formed by the maxillary prominences (part of the first pharyngeal arch).

3.Caudal (Inferior) Boundary: Formed by the mandibular prominences (also from the first pharyngeal arch).

Since the maxillary prominences form the lateral boundaries, option 3 (Lateral) is correct.

Why the Other Options Are Incorrect:

1.Rostral (Superior) Boundary (Option 1):

•Formed by the frontonasal prominence, NOT the maxillary prominences.

2.All of these (Option 2):

•Incorrect because maxillary prominences form only the lateral boundaries, not all of them.

3.None of these (Option 4):

•Incorrect because maxillary prominences do contribute to the boundaries of the stomodeum (laterally).

4.Caudal (Inferior) Boundary (Option 5):

•Formed by the mandibular prominences, NOT the maxillary prominences.

During the fifth week of embryonic development, six auricular hillocks (small mesenchymal swellings) appear on the first and second pharyngeal arches. These hillocks give rise to the external ear (auricle or pinna).

•Three hillocks develop from the first pharyngeal arch (Mandibular arch)

•Three hillocks develop from the second pharyngeal arch (Hyoid arch)

These hillocks gradually fuse and reshape to form the final structure of the auricle (external ear) by the third month of development.

Why the Other Options Are Incorrect:

1.Eyes:

•The eyes develop from optic vesicles, which arise from the forebrain (diencephalon) and surface ectoderm, not from auricular hillocks.

2.Internal ear:

•The internal ear (cochlea, semicircular canals, vestibule) originates from the otic placode, an ectodermal thickening, and not from auricular hillocks.

3.Tongue:

•The tongue develops from lingual swellings of the first, second, third, and fourth pharyngeal arches, not from auricular hillocks.

4.Nose:

•The nose forms from nasal placodes, which develop into nasal pits and later into the nasal cavity and external nose, separate from auricular hillocks.

Hair cells in the cochlea and vestibular system are responsible for converting mechanical stimuli into electrical signals. This process occurs in the organ of Corti (for hearing) and the semicircular canals, utricle, and saccule (for balance).

1.The stereocilia of hair cells are bathed in endolymph, a unique extracellular fluid found in the cochlear duct.

2.Endolymph has an unusually high concentration of K⁺ (potassium) and a low concentration of Na⁺ (opposite to most extracellular fluids).

3.When the stereocilia bend toward the tallest stereocilium, mechanically gated K⁺ channels open.

4.K⁺ ions enter the hair cell from the endolymph, leading to depolarization.

5.This depolarization opens voltage-gated Ca²⁺ channels, allowing Ca²⁺ influx, which triggers neurotransmitter release and signal transmission to the auditory nerve (CN VIII).

Why the Other Options Are Incorrect:

1.Na⁺ (Sodium ion):

•Unlike most extracellular fluids, endolymph is K⁺-rich and Na⁺-poor, so Na⁺ does not play a major role in depolarization.

2.Mg²⁺ (Magnesium ion):

•Magnesium is important for enzymatic processes but is not involved in hair cell depolarization.

3.Ca²⁺ (Calcium ion):

•While Ca²⁺ enters the hair cell after K⁺ depolarizes it, the initial depolarization is caused by K⁺ influx, not Ca²⁺.

4.Cl⁻ (Chloride ion):

•Chloride does not play a major role in hair cell depolarization.

The tongue has four types of papillae, but not all of them contain taste buds. Here’s a breakdown:

1.Fungiform papillae – Found on the anterior part of the tongue, they contain some taste buds, but not the most.

2.Circumvallate papillae – Located at the back of the tongue, these large, dome-shaped papillae are the least numerous but contain the most taste buds (~250 per papilla).

3.Filiform papillae – The most numerous papillae, but they lack taste buds and are primarily for texture and friction.

4.Foliate papillae – Found on the lateral edges of the tongue, they contain moderate numbers of taste buds but fewer than circumvallate papillae.

Since circumvallate papillae contain the highest number of taste buds per papilla, they are the correct answer.

Why the Other Options Are Incorrect:

1.Fungiform papillae – Do contain taste buds but not as many as circumvallate papillae.

2.Filiform papillae – Do not contain any taste buds, making this option incorrect.

3.Foliate papillae – Contain some taste buds but fewer than circumvallate papillae.

4.All of these – Incorrect because filiform papillae do not contain taste buds.

The tongue has dual innervation, with different nerves supplying general sensation (touch, pain, temperature) and special sensation (taste).

•Tip of the tongue (Anterior 2/3):

•General sensation (touch, pain, temperature):Lingual nerve (branch of Mandibular nerve, V3 of the Trigeminal nerve, CN V).

•Taste sensation:Chorda tympani (branch of Facial nerve, CN VII).

•Posterior 1/3 of the tongue:

•Both general and taste sensation are carried by the Glossopharyngeal nerve (CN IX).

Since the question asks which nerve innervates the tip of the tongue, we focus on general sensation, which is provided by the lingual nerve (branch of the mandibular nerve, V3).

Why the Other Options Are Incorrect:

1.Abducens nerve (CN VI):

•This nerve controls the lateral rectus muscle of the eye and has no role in tongue innervation.

2.Glossopharyngeal nerve (CN IX):

•It supplies both general and taste sensation to the posterior 1/3 of the tongue, not the tip.

3.Facial nerve (CN VII):

•While the chorda tympani branch of CN VII carries taste sensation from the anterior 2/3, it does not provide general sensation.

4.Vagus nerve (CN X):

•The internal branch of the superior laryngeal nerve of the vagus innervates a small area near the epiglottis, but not the tip of the tongue.

The parotid gland, a major salivary gland, primarily secretes secretory IgA (sIgA), which plays a crucial role in mucosal immunity. sIgA is transported across the epithelial cells into the saliva, where it helps neutralize pathogens, preventing their adherence and invasion in the oral cavity.

sIgA is the most abundant immunoglobulin in external secretions, including saliva, tears, mucus, and breast milk.

Why the Other Options Are Incorrect:

1.IgM: While IgM is the first antibody produced during an immune response, it is primarily found in blood and lymphatic fluid, not in saliva.

2.None of these: This is incorrect because the parotid gland does release IgA.

3.IgD: This antibody is primarily involved in B cell activation and is not significantly present in secretions like saliva.

4.IgE: This antibody is mainly involved in allergic reactions and parasitic infections, binding to mast cells and basophils rather than being secreted in saliva.

The scalp consists of five layers, remembered by the mnemonic SCALP:

1.S – Skin: The outermost layer containing hair follicles, sebaceous glands, and sweat glands.

2.C – Connective Tissue: A dense layer rich in blood vessels and nerves.

3.A – Aponeurosis (Galea Aponeurotica): A tough, fibrous sheet connecting the frontalis and occipitalis muscles.

4.L – Loose Areolar Tissue: A potential space allowing movement of the upper layers over the pericranium. This is the “danger layer” of the scalp because infections can easily spread here.

5.P – Pericranium: The deepest layer, which is the periosteum of the skull bones and provides nutrition to the bones and a base for their repair.

The scalp terminates at the pericranium, beyond which is the skull bone.

Why the Other Options Are Incorrect:

1.Skin: The skin is the outermost layer, but the scalp has multiple layers beneath it before reaching the skull.

2.Aponeurosis: While the aponeurosis is an important fibrous layer that connects muscles, the scalp does not terminate here; it has deeper layers.

3.Epicranium: This term is sometimes used interchangeably with the aponeurosis, referring to the fibrous covering of the cranium, but it does not represent the deepest layer.

4.Connective Tissue: The connective tissue layer is rich in vasculature but lies above the aponeurosis, meaning the scalp does not terminate here.

A lesion of the trochlear nerve (CN IV) causes upward deviation (hypertropia) but not lateral rotation (extorsion). Instead, it actually results in medial rotation (intorsion) impairment, leading to relative extorsion of the affected eye.

•The superior oblique muscle is responsible for depression, abduction, and intorsion of the eye.

•When the trochlear nerve is damaged, the inferior oblique muscle acts unopposed, leading to:

•Upward deviation (hypertropia) of the affected eye

•Extorsion (outward rotation) due to the lack of superior oblique function

•Diplopia (double vision), especially when looking downward (e.g., while reading or going downstairs)

•Head tilt to the opposite side to compensate for the extorsion

Since trochlear nerve palsy does not directly cause lateral rotation, option 2 is incorrect.

Why the Other Options Are Correct:

1.“It passes through the cavernous sinus” → TRUE

•The trochlear nerve (CN IV) travels in the lateral wall of the cavernous sinus before entering the superior orbital fissure.

2.“It supplies superior oblique” → TRUE

•The trochlear nerve innervates only the superior oblique muscle.

3.“It supplies extraocular muscles” → TRUE (but vague)

•It supplies only one extraocular muscle (superior oblique), but the statement itself is technically correct.

4.“It is the only nerve arising from the back of the brainstem” → TRUE

•The trochlear nerve is the only cranial nerve that exits from the dorsal (posterior) aspect of the brainstem.

The muscles of mastication (masseter, temporalis, medial pterygoid, and lateral pterygoid) are supplied by the mandibular nerve (V3), which is a branch of the trigeminal nerve (cranial nerve V).

•The mandibular nerve (V3) exits the skull through the foramen ovale in the greater wing of the sphenoid bone.

•After exiting, it gives off motor branches to the muscles of mastication and sensory branches to the lower face, jaw, and anterior two-thirds of the tongue (via the lingual nerve).

Why the Other Options Are Wrong:

2.Mental foramen:

•The mental nerve, a branch of the inferior alveolar nerve (from V3), exits through the mental foramen to provide sensory innervation to the chin and lower lip.

•However, this foramen does not transmit the motor fibers that supply the muscles of mastication.

3.Foramen spinosum:

•This foramen transmits the middle meningeal artery and vein along with the meningeal branch of the mandibular nerve (nervus spinosus).

•It does not carry motor fibers to the muscles of mastication.

4.Foramen rotundum:

•This foramen allows passage of the maxillary nerve (V2), which provides sensory innervation to the midface but has no role in mastication.

5.Foramen lacerum:

•This is largely a closed structure in a living person, filled with cartilage.

•It allows passage of the internal carotid artery (which does not travel directly through it but over it).

•No branches of the trigeminal nerve pass through this foramen.

Pleomorphic adenoma is the most common benign tumor of the parotid gland, accounting for about 60–70% of all parotid tumors.

•It arises from both epithelial and myoepithelial cells, giving it a mixed histological appearance (hence the name “pleomorphic”).

•It is slow-growing, painless, and typically presents as a firm, mobile mass in the preauricular region.

•While benign, long-standing pleomorphic adenomas can undergo malignant transformation into carcinoma ex pleomorphic adenoma.

Why the Other Options Are Wrong:

1.Acinic cell carcinoma:

•This is a malignant tumor, not benign.

•It arises from serous acinar cells and is relatively rare compared to pleomorphic adenoma.

2.Myoepithelioma:

•A rare benign tumor arising from myoepithelial cells.

•It is much less common than pleomorphic adenoma.

3.Canalicular adenoma:

•A benign tumor, but it occurs more commonly in the minor salivary glands (especially upper lip) rather than the parotid gland.

4.Basal cell adenoma:

•Another benign tumor, but it is less common than pleomorphic adenoma.

•It originates from basal cells of the salivary gland ducts and is usually found in older adults.

The term “ametropia” refers to all types of refractive errors in the eye. It includes:

•Myopia (nearsightedness): Light focuses in front of the retina, making distant objects blurry.

•Hyperopia (farsightedness): Light focuses behind the retina, making near objects blurry.

•Astigmatism: Irregular corneal curvature causes distorted or blurry vision at all distances.

•Presbyopia: Age-related loss of accommodation, making near vision difficult.

Why the Other Options Are Wrong:

1.Anisometropia:

•Refers to a significant difference in refractive power between the two eyes.

•It is not a general term for all refractive errors but rather a condition where each eye has a different refractive error.

2.None of these:

•Incorrect because “Ametropia” is the correct term that encompasses all refractive errors.

3.Amblyopia:

•Also called “lazy eye”, it refers to reduced vision in one or both eyes due to abnormal visual development, usually in childhood.

•It is not a refractive error itself but can result from uncorrected ametropia.

4.Astigmatism:

•Astigmatism is a specific type of refractive error, but it does not cover all types.

•Ametropia is the umbrella term that includes astigmatism along with myopia, hyperopia, and presbyopia.

The facial nerve (cranial nerve VII) is the key structure that divides the parotid gland into superficial and deep lobes.

•After exiting the stylomastoid foramen, the facial nerve enters the parotid gland and forms the parotid plexus, which gives rise to its terminal branches.

•This nerve runs between the superficial and deep parts of the gland, effectively acting as a landmark for their division.

•Surgical significance: During parotidectomy, surgeons must be careful to preserve the facial nerve to prevent facial muscle paralysis.

Why the Other Options Are Wrong:

1.Retromandibular vein:

•This vein is formed within the parotid gland but does not divide it.

•It is a tributary of the external jugular vein.

2.Facial vein:

•The facial vein runs superficially and does not pass through the parotid gland.

•It drains blood from the face into the internal jugular vein.

3.Facial artery:

•The facial artery arises from the external carotid artery and passes over the mandible to supply the face.

•It does not enter or divide the parotid gland.

4.External carotid artery:

•The external carotid artery runs through the deep part of the parotid gland and gives off branches like the superficial temporal and maxillary arteries.

•However, it does not serve as the dividing structure between the superficial and deep parts.

The upper lip and palate develop during the 6th to 9th weeks of gestation through the fusion of different embryonic structures:

•The upper lip forms from the fusion of the maxillary prominences (from the first pharyngeal arch) and the medial nasal prominences around the 6th week.

•The primary palate begins forming around the 6th week as part of the intermaxillary segment.

•The secondary palate develops between weeks 7-9, when the palatal shelves (outgrowths of the maxillary prominences) elevate and fuse along the midline.

Failure of these processes can lead to cleft lip and/or cleft palate.

Why the Other Options Are Wrong:

1.3rd-4th weeks of pregnancy:

•At this stage, the primitive face is just beginning to form.

•The pharyngeal arches start developing, but the upper lip and palate have not yet formed.

2.21st-23rd weeks of pregnancy:

•By this time, the lip and palate formation is already complete.

•This period is more related to lung development (canalicular stage) and brain growth rather than craniofacial development.

3.4th-5th weeks of pregnancy:

•The facial prominences begin to appear, but they have not yet fused to form the lip and palate.

•The maxillary and mandibular prominences are still growing.

4.13th-18th weeks of pregnancy:

•The palate and lip have already formed by this stage.

•This period is associated more with bone ossification and fetal movements rather than craniofacial development.

The facial nerve (cranial nerve VII) passes through the parotid gland, but it does not innervate it. After emerging from the stylomastoid foramen, it enters the gland and divides into its terminal branches forming the parotid plexus, which supplies the muscles of facial expression.

Mnemonic: “FEAR” (Facial nerve, External carotid artery, Retromandibular vein)

• F – Facial nerve (most superficial)

• E – External carotid artery (deepest)

• A – Auriculotemporal nerve (related, but not strictly within)

• R – Retromandibular vein (in between)

Why the Other Options Are Wrong:

None of these:

•This is incorrect because the facial nerve does pass through the parotid gland.

Internal carotid artery:

•The internal carotid artery is a deep structure that ascends within the carotid sheath and does not pass through the parotid gland.

•The external carotid artery, however, does pass through the gland and gives off the posterior auricular, superficial temporal, and maxillary arteries.

Internal jugular vein:

•The internal jugular vein lies deep to the parotid gland, within the carotid sheath, and does not traverse the gland.

Facial vein:

•The facial vein runs superficially along the face and does not pass through the parotid gland.

•However, the retromandibular vein, formed by the union of the superficial temporal and maxillary veins, does pass through the gland.

The transverse facial artery is not a branch of the facial artery; it is actually a branch of the superficial temporal artery, which arises from the external carotid artery. This artery runs superior to the parotid duct, supplying blood to the lateral face.

Why the Other Options Are Correct (Branches of Facial Artery):

1.Superior labial artery:

•Supplies blood to the upper lip, nasal septum, and surrounding structures.

2.Submental artery:

•The largest branch of the facial artery in the neck, supplying the chin and submental region.

3.Inferior labial artery:

•Supplies the lower lip, anastomosing with its counterpart on the opposite side.

4.Lateral nasal artery:

•Supplies the ala (wing) of the nose and anastomoses with branches of the ophthalmic artery.

The external jugular vein (EJV) is formed by the union of the retromandibular vein (posterior division) and the posterior auricular vein. It runs superficially over the sternocleidomastoid (SCM) muscle and drains into the subclavian vein.

Why the Other Options Are Wrong:

2.Superficial temporal vein:

•The superficial temporal vein is a tributary of the retromandibular vein, not the external jugular vein.

•It joins with the maxillary vein to form the retromandibular vein.

3.Subclavian vein:

•The external jugular vein drains into the subclavian vein, but it is not formed by the retromandibular and posterior auricular veins.

4.Common facial vein:

•The common facial vein is formed by the facial vein and the anterior division of the retromandibular vein.

•It drains into the internal jugular vein (IJV), not the external jugular vein.

5.Maxillary vein:

•The maxillary vein is a deep vein that combines with the superficial temporal vein to form the retromandibular vein.

•It does not directly contribute to the formation of the external jugular vein.

The pterygoid venous plexus is a network of interconnected veins located around the lateral pterygoid muscle in the infratemporal fossa. It has multiple drainage pathways, but its primary drainage is into the maxillary vein, which eventually contributes to the formation of the retromandibular vein.

Why the Other Options Are Wrong:

2.External Jugular Vein:

•The external jugular vein primarily drains the posterior scalp and superficial structures of the head.

•It does not receive direct drainage from the pterygoid venous plexus.

3.Middle Meningeal Vein:

•The middle meningeal vein drains blood from the dura mater and connects with the pterygoid venous plexus.

•However, it is not a major drainage route for the plexus itself.

4.Facial Vein:

•The pterygoid venous plexus is connected to the facial vein via the deep facial vein, but the primary drainage is still into the maxillary vein.

5.Cavernous Sinus:

•The pterygoid venous plexus communicates with the cavernous sinus via small veins (e.g., the emissary veins), but this is not its main drainage route.

•This connection is clinically important because infections from the face (danger triangle) can spread to the cavernous sinus, leading to cavernous sinus thrombosis.

The posterior one-third of the tongue is supplied by the glossopharyngeal nerve (cranial nerve IX) for both general sensation (touch, pain, temperature) and special sensation (taste). This nerve arises from the medulla oblongata and provides sensory innervation to the posterior tongue, pharynx, and part of the soft palate.

Why the Other Options Are Wrong:

1.Olfactory nerve (Cranial Nerve I):

•This nerve is responsible for the sense of smell, not tongue sensation or taste.

•It innervates the olfactory epithelium in the nasal cavity, making it irrelevant to tongue innervation.

2.Facial nerve (Cranial Nerve VII):

•The chorda tympani branch of the facial nerve supplies taste sensation to the anterior two-thirds of the tongue, not the posterior one-third.

•It does not provide general sensation (touch/pain).

3.Vagus nerve (Cranial Nerve X):

•The vagus nerve provides some minor taste sensation from the epiglottis and pharynx, but it does not primarily supply the tongue.

•It is more involved in autonomic control of the heart, lungs, and digestive tract.

4.Trigeminal nerve (Cranial Nerve V):

•The mandibular division (V3) supplies general sensation to the anterior two-thirds of the tongue, not the posterior one-third.

•It does not carry taste sensation.

The buccinator muscle is not a derivative of the second pharyngeal arch. It is actually a derivative of the first pharyngeal arch.

Let’s break down the derivatives of the second pharyngeal arch:

• Stylohyoid: The stylohyoid muscle is derived from the second pharyngeal arch and is innervated by the facial nerve (CN VII).
• Stapedius: The stapedius muscle, which helps control the movement of the stapes bone in the middle ear, is derived from the second pharyngeal arch and is innervated by the facial nerve (CN VII).
• Levator veli palatini: The levator veli palatini muscle, which helps elevate the soft palate, is also derived from the second pharyngeal arch and is innervated by the vagus nerve (CN X) (via the pharyngeal plexus).
• Buccinator: This muscle, which is involved in the movement of the cheek, is actually a derivative of the first pharyngeal arch. It is innervated by the mandibular branch of the trigeminal nerve (CN V3).

Why the other options are correct:

• Stylohyoid, Stapedius, and Levator veli palatini are all derived from the second pharyngeal arch.

The nasolacrimal duct carries tears from the eye (specifically from the lacrimal sac) into the nasal cavity. It opens into the inferior meatus, which is located beneath the inferior nasal concha in the nasal cavity.

Why the other options are incorrect:

1. Middle meatus: The middle meatus is the site where the frontal sinus, maxillary sinus, and anterior ethmoidal cells drain into the nasal cavity. It is not where the nasolacrimal duct opens.
2. Superior meatus: The superior meatus is the site for drainage from the posterior ethmoidal cells. It does not receive drainage from the nasolacrimal duct.
3. Infraorbital foramen: The infraorbital foramen is a hole in the maxilla (below the orbit) through which the infraorbital nerve and vessels pass. It does not have any connection to the nasolacrimal duct.
4. None of these: This is not the correct answer because the nasolacrimal duct does open into the inferior meatus.

The third-order neurons of the olfactory bulb are responsible for transmitting the olfactory signals to the olfactory cortex, which is located in the temporal lobe of the brain. This area includes structures like the piriform cortex, amygdala, and entorhinal cortex. These regions are essential for processing smell and associating odors with emotions and memories.

Why the other options are incorrect:

1. Hypothalamus: While the hypothalamus is involved in regulating autonomic functions and emotions, it is not the primary site where third-order neurons of the olfactory bulb terminate.
2. Frontal lobe: The frontal lobe is involved in higher cognitive functions, but the olfactory signals don’t terminate there. The olfactory cortex, located in the temporal lobe, is the main area for smell processing.
3. Basal ganglia: The basal ganglia are involved in motor control and coordination, not the processing of olfactory signals.
4. Thalamus: Unlike most sensory systems, the olfactory system does not pass through the thalamus before reaching the cortex. Instead, it directly projects to the olfactory cortex in the temporal lobe.

When a girl develops an infection from wearing earrings (“tops”), the body’s lymphatic drainage system responds by directing immune cells to the nearest lymph nodes draining the infected area. Understanding lymphatic drainage of the ear helps us identify the specific nodes involved.

🧠 Lymphatic drainage of the external ear:

• The external ear (auricle) drains into multiple lymph node groups:

  • Preauricular (parotid) nodes – anterior to the ear.

  • Mastoid (postauricular) nodes – posterior to the ear.

  • Superficial cervical lymph nodes – along the external jugular vein, they receive drainage from parts of the auricle, lower scalp, and skin behind the ear.

  • These nodes ultimately drain into deep cervical lymph nodes.

In the case of an earlobe or helix piercing infection, the superficial cervical lymph nodes are commonly involved, particularly when the infection affects the lower external ear or the skin around the ear. These nodes are part of the first-line lymphatic defense in this region.

❌ Why the Other Options Are Incorrect:

• Maxillary nodes:

• Drain the cheeks, upper lip, and lower eyelids, not the ear.

• Deep cervical nodes:

• These are secondary drainage nodes. Involved later if the infection spreads deeper.

• Axillary nodes:

• Drain the upper limb, breast, and lateral chest wall—unrelated to ear infections.

• Mastoid nodes:

• These do drain parts of the external ear, especially the posterior auricle, but are more associated with infections behind the ear, not necessarily the earlobe or anterior pinna.

The nasopharynx is the upper part of the pharynx that connects with the nasal cavity. The sensory innervation of the nasopharynx is primarily supplied by the maxillary nerve, specifically through its branch, the pharyngeal branch(which is a branch of the V2 division of the trigeminal nerve). This nerve provides the sensation to the mucous membranes of the nasopharynx.

Why the other options are wrong:

1. Glossopharyngeal nerve: While this nerve provides sensory innervation to the oropharynx and part of the laryngopharynx, it does not supply the nasopharynx. It does, however, innervate the tonsils, uvula, and part of the soft palate.
2. Ophthalmic nerve: This nerve (V1) provides sensory innervation to the forehead, eyes, and parts of the nose but not the nasopharynx.
3. Facial nerve: The facial nerve primarily controls motor functions, such as facial expression, and provides taste sensation to the anterior two-thirds of the tongue. It does not supply sensory innervation to the nasopharynx.
4. All of them: Since the maxillary nerve is the main sensory nerve for the nasopharynx, the other options being incorrect means that “all of them” cannot be the right answer.

• The auditory (Eustachian) tube connects the middle ear cavity to the nasopharynx and helps in equalizing air pressure on both sides of the tympanic membrane.
• It opens into the anterior wall of the middle ear, ensuring proper ventilation and drainage of the middle ear.

Why the Other Options Are Wrong:

1. Roof:
   • The roof of the middle ear cavity (tegmen tympani) separates it from the cranial cavity but does not contain the auditory tube.
2. Floor:
   • The floor (jugular wall) is related to the jugular vein but does not house the auditory tube.
3. Lateral Wall:
   • The lateral wall contains the tympanic membrane (eardrum) but does not include the auditory tube.
4. Medial Wall:
   • The medial wall separates the middle ear from the inner ear and contains structures like the oval window and round window, but not the auditory tube.

• Rods are photoreceptor cells responsible for vision in dim light (scotopic vision). They are highly sensitive to light but do not detect color.
• The fovea is the central region of the retina, rich in cones and responsible for sharp central vision. However, rods are absent in the fovea and are instead concentrated in the parafoveal region, which surrounds the fovea and extends outward. This area allows for better night vision and peripheral vision.

Why the Other Options Are Wrong:

1. Nissl’s Granules:
   • These are found in the neuronal cell body (soma) and are involved in protein synthesis. They have no relation to photoreceptors in the retina.
2. Synaptic Bulb:
   • The synaptic bulb is the terminal part of a neuron where neurotransmitters are released. It plays a role in neural communication but does not house rods or cones.
3. Maculae:
   • The macula (macula lutea) is a small, central region of the retina rich in cones, not rods. It is responsible for high-acuity vision and color perception.
4. All of These:
   • Since rods are not present in all the listed structures, this option is incorrect.