Through which meatus is a nasal puncture typically performed?
Which structure prevents spread of infection from middle ear to brain?
All are parts of anterior segment of eye except?
Which of the following statements is true regarding the anatomy of the external nose?
The junction between Retina & Ciliary body is?
Which are the second order neurons in the optic pathway?
What is the thinnest portion of the sclera?
Which of the following does not contribute to the formation of the nasal septum?
Which nerve does NOT carry referred ear pain?
Site of glomus jugulare tumor?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 81: Through which meatus is a nasal puncture typically performed?
- A. Superior meatus
- B. Middle meatus
- C. Inferior meatus (Correct Answer)
- D. Sphenoethmoidal recess
Explanation: ---Inferior meatus--- - A nasal puncture for **maxillary sinus irrigation** is typically performed through the **inferior meatus** because it provides direct access to the floor of the nasal cavity and the passage to the maxillary sinus. - The floor of the **inferior meatus** is the thinnest part of the lateral nasal wall, making it an ideal entry point for procedures into the maxillary sinus. *Superior meatus* - The **superior meatus** is associated with the drainage of the **posterior ethmoid cells** and the **sphenoid sinus**. - Puncturing here would not provide access for maxillary sinus irrigation and could risk damage to the **cribriform plate**. *Middle meatus* - The **middle meatus** is where the **maxillary**, **frontal**, and **anterior ethmoid sinuses** primarily drain. - While related to the maxillary sinus, it is not the preferred site for a puncture for irrigation, as it is more complex and less direct than the inferior meatus. *Sphenoethmoidal recess* - The **sphenoethmoidal recess** is located superior to the superior concha and is the drainage site for the **sphenoid sinus**. - This area is too high and posterior to be relevant for a puncture aimed at the **maxillary sinus**.
Question 82: Which structure prevents spread of infection from middle ear to brain?
- A. Tegmen tympani (Correct Answer)
- B. Cribriform plate
- C. Fundus tympani
- D. Petrous apex
Explanation: ***Tegmen tympani*** - The **tegmen tympani** is a thin plate of bone forming the roof of the middle ear cavity, separating it from the **middle cranial fossa** and the brain. - Its primary function is to act as a **bony barrier**, preventing upward spread of infection from the middle ear space into the intracranial cavity. *Cribriform plate* - The **cribriform plate** is part of the ethmoid bone, located in the anterior cranial fossa, and is perforated by the **olfactory nerves**. - It does not form a boundary to the middle ear cavity and is not involved in preventing infection spread from the middle ear. *Fundus tympani* - This term is not a standard anatomical landmark. The **floor of the tympanic cavity**, or **fundus tympani**, separates the middle ear from the **internal jugular vein**. - It does not prevent the spread of infection to the brain but rather to structures below the middle ear. *Petrous apex* - The **petrous apex** is the very tip of the petrous part of the temporal bone, which houses the cochlea and vestibule. - While part of the temporal bone, it is not the direct barrier between the middle ear cavity and the brain; its involvement in infection spread is typically due to **petrous apexitis**, a distinct complication.
Question 83: All are parts of anterior segment of eye except?
- A. Lens
- B. Cornea
- C. Aqueous humor
- D. Vitreous (Correct Answer)
Explanation: ***Vitreous*** - The **vitreous humor**, or simply vitreous, is a transparent, gel-like substance that fills the space posterior to the lens and anterior to the retina, making it part of the **posterior segment** of the eye [3]. - Its main function is to maintain the shape of the eye and keep the retina in place. *Lens* - The **lens** is a transparent, biconvex structure located behind the iris and in front of the vitreous, making it a key component of the **anterior segment** [2]. - It works to focus light onto the retina, changing shape to alter the focal length of the eye. *Cornea* - The **cornea** is the transparent, outermost layer of the eye that covers the iris, pupil, and anterior chamber, clearly positioning it within the **anterior segment** [2]. - It plays a crucial role in focusing light into the eye. *Aqueous humor* - The **aqueous humor** is a clear, watery fluid located in the space between the cornea and the lens (the anterior and posterior chambers), which is definitively part of the **anterior segment** [1]. - It nourishes the cornea and lens and maintains intraocular pressure.
Question 84: Which of the following statements is true regarding the anatomy of the external nose?
- A. The lower one-third is primarily cartilaginous. (Correct Answer)
- B. The upper two-thirds is entirely bony.
- C. The lateral aspect has only a single cartilage.
- D. The external nose is supported by two nasal bones.
Explanation: ***The lower one-third is primarily cartilaginous.*** - The **lower one-third** of the external nose, including the nasal tip and alae, is predominantly supported by **alar cartilages** (lower lateral cartilages) and other minor cartilages, giving it flexibility. - This cartilaginous structure allows for movement and shaping of the nostrils. - This statement is **anatomically accurate and complete**. *The upper two-thirds is entirely bony.* - This is **incorrect**. - The **upper one-third** is bony (nasal bones and frontal process of maxilla). - The **middle one-third** is primarily **cartilaginous** (upper lateral cartilages). - Therefore, the upper two-thirds consists of **both bone and cartilage**, not entirely bone. *The lateral aspect has only a single cartilage.* - This is **incorrect**. - The lateral aspect contains **multiple cartilages**: upper lateral cartilages, lower lateral (alar) cartilages, and accessory cartilages. - The presence of multiple cartilages provides structural support and flexibility. *The external nose is supported by two nasal bones.* - This is **incomplete and misleading**. - While two **nasal bones** do form the superior bony bridge (upper one-third), the external nose is also supported by: - Frontal process of the maxilla - Upper and lower lateral cartilages - Septal cartilage - Stating only the nasal bones ignores the majority of nasal support structures.
Question 85: The junction between Retina & Ciliary body is?
- A. Equator
- B. Pars plicata
- C. Pars plana
- D. Ora serrata (Correct Answer)
Explanation: ***Ora serrata*** - The **ora serrata** represents the **anterior-most jagged edge** of the retina where the sensory retina terminates. [1] - It marks the transition point where the neural retina becomes the **non-photoreceptive ciliary body epithelium**. *Equator* - The **equator** is the imaginary line circling the globe of the eye, approximately equidistant from the anterior and posterior poles. - It is a landmark on the retina itself, indicating the approximate middle of the retina, and not its junction with the ciliary body. *Pars plicata* - The **pars plicata** is the anterior, folded portion of the **ciliary body** that produces aqueous humor. - While part of the ciliary body, it is anterior to the junction with the retina and not the junction itself. *Pars plana* - The **pars plana** is the posterior, relatively flat portion of the **ciliary body**, located between the ora serrata and the pars plicata. - It is a part of the ciliary body immediately adjacent to the ora serrata, but the ora serrata itself is the definitive junction.
Question 86: Which are the second order neurons in the optic pathway?
- A. Bipolar cells (Correct Answer)
- B. Ganglionic cells
- C. Cells of lateral geniculate body
- D. Astrocytes
Explanation: ***Bipolar cells*** - **Photoreceptors** (rods and cones) are first-order neurons, sensing light. [1] - **Bipolar cells** receive input from photoreceptors and transmit signals to retinal ganglion cells, acting as second-order neurons. [1] *Ganglionic cells* - **Ganglion cells** are third-order neurons in the visual pathway. [1] - Their axons form the **optic nerve**, which carries visual information to the brain. [2] *Cells of lateral geniculate body* - The **lateral geniculate nucleus (LGN)** of the thalamus contains fourth-order neurons. [1] - These cells project to the primary visual cortex. [2] *Astrocytes* - **Astrocytes** are a type of glial cell that provides support and protection to neurons in the central nervous system. - They are **not directly involved** in the transmission of visual information in the optic pathway.
Question 87: What is the thinnest portion of the sclera?
- A. Anterior to the rectus muscle insertion
- B. At the posterior pole
- C. At the limbus
- D. Posterior to the rectus muscle insertion (Correct Answer)
Explanation: ***Posterior to the rectus muscle insertion*** - The sclera is thinnest immediately **posterior to the insertion of the rectus muscles**, where it is about 0.3 mm thick. - This area is clinically relevant as it is a common site for globe rupture during trauma. *Anterior to the rectus muscle insertion* - The sclera is relatively thick in this region, measuring around **0.6 mm thick**. - It provides robust support and attachment for the rectus muscles. *At the posterior pole* - At the posterior pole, the sclera is the **thickest**, reaching about 1.0 mm, especially around the optic nerve. - This thickness is necessary to protect the delicate neural structures exiting the eye. *At the limbus* - The sclera-corneal junction, or **limbus**, has an intermediate thickness, around **0.8 mm**. - This area is critical for surgical procedures but is not the thinnest point.
Question 88: Which of the following does not contribute to the formation of the nasal septum?
- A. Nasal bone (Correct Answer)
- B. Vomer
- C. Ethmoid
- D. Septal cartilage
Explanation: ***Nasal bone*** - The **nasal bones** form the bridge of the nose and are part of the external nasal skeleton, not the internal nasal septum. - They articulate with the frontal bone superiorly and the maxilla laterally, forming the **roof of the nasal cavity** anteriorly. *Septal cartilage* - The **septal cartilage**, or quadrangular cartilage, forms the anterior and inferior parts of the cartilaginous nasal septum. - It provides flexibility and support to the anterior nasal cavity. *Vomer* - The **vomer** is a thin, plowshare-shaped bone that forms the posteroinferior part of the bony nasal septum. - It articulates with the sphenoid, ethmoid, palatine, and maxillary bones. *Ethmoid* - The **perpendicular plate of the ethmoid bone** forms the superior part of the bony nasal septum. - It extends downward from the cribriform plate to meet the vomer and septal cartilage.
Question 89: Which nerve does NOT carry referred ear pain?
- A. Glossopharyngeal nerve
- B. Vagus nerve
- C. Trigeminal nerve
- D. Abducens nerve (Correct Answer)
Explanation: ***Abducens nerve*** - The **abducens nerve (CN VI)** primarily controls the **lateral rectus muscle** of the eye, responsible for **abduction of the eyeball**. - It has **no sensory function** and, therefore, cannot carry referred pain from any region, including the ear. *Trigeminal nerve* - The **trigeminal nerve (CN V)**, particularly its **auriculotemporal branch**, provides sensory innervation to part of the external ear and temporomandibular joint, making it a common pathway for **referred otalgia** from dental or TMJ issues. - Pain from conditions like **trigeminal neuralgia**, **TMJ disorders**, or **dental caries** can be referred to the ear via this nerve. *Glossopharyngeal nerve* - The **glossopharyngeal nerve (CN IX)** supplies sensory innervation to the **middle ear**, pharynx, and posterior tongue. - Conditions affecting these areas, such as **glossopharyngeal neuralgia**, **tonsillitis**, or **pharyngitis**, can cause **referred ear pain**. *Vagus nerve* - The **vagus nerve (CN X)**, specifically the **auricular branch (Arnold's nerve)**, provides sensory innervation to a portion of the external auditory canal and concha. - Irritation of this nerve from conditions in the **larynx**, **pharynx**, **esophagus**, or **heart** can lead to referred ear pain.
Question 90: Site of glomus jugulare tumor?
- A. Hypotympanum (Correct Answer)
- B. Epitympanum
- C. Mesotympanum
- D. Internal ear
Explanation: ***Hypotympanum*** - **Glomus jugulare tumor** is a paraganglioma arising from the **paraganglia** (chemoreceptor cells) located in the **adventitia of the jugular bulb** in the **jugular foramen**. - This anatomical location places the tumor in the **hypotympanum** (inferior compartment of the middle ear cavity), which lies directly above the jugular bulb [1]. - These tumors typically present with **pulsatile tinnitus**, **hearing loss**, and a **reddish-blue mass** behind the tympanic membrane (rising sun sign). - The hypotympanum extends from the floor of the middle ear to the level of the inferior margin of the tympanic membrane [1]. *Epitympanum* - The **epitympanum** (attic) is the **superior compartment** of the middle ear, located above the tympanic membrane [1]. - It contains the head of the **malleus** and body of the **incus** [1]. - **Glomus tympanicum tumors** (arising from paraganglia along the tympanic plexus on the promontory) may present here, but glomus jugulare tumors originate inferiorly in the hypotympanum. *Mesotympanum* - The **mesotympanum** is the **middle compartment** of the middle ear, at the level of the tympanic membrane. - It contains the **manubrium of malleus** and **long process of incus**. - While glomus jugulare tumors may extend into this region as they grow, their primary site of origin is the hypotympanum. *Internal ear* - The **internal ear** (inner ear) is located medial to the middle ear and contains the **cochlea**, **vestibule**, and **semicircular canals** [1]. - Advanced glomus jugulare tumors may erode into the inner ear causing **sensorineural hearing loss** and **vertigo**, but this is not their site of origin.