NEET-PG 2013 - Anatomy Practice Questions

Q: Yoke muscle for the right superior rectus is:

Left Inferior Oblique. ***Left Inferior Oblique*** - Yoke muscles are pairs of synergistic muscles, one in each eye, that act together to produce conjugate eye movements in the same direction of gaze. - The **right superior rectus** and **left inferior oblique** are yoke muscles that work together during **upward and rightward gaze** (dextro-elevation) [1]. - Right SR elevates the **adducted** right eye, while left IO elevates the **abducted** left eye, producing coordinated upward-right movement [1]. - This follows **Hering's Law of Equal Innervation**, where yoke muscles receive equal and simultaneous innervation. *Left Superior rectus* - The left superior rectus is the **contralateral homologous muscle**, not a yoke muscle for the right superior rectus. - Both superior recti work together for **upward gaze in primary position**, but they are versional muscles, not yoke pairs. - Yoke muscles produce conjugate movements in oblique directions, not straight up. *Left Inferior rectus* - The left inferior rectus depresses the left eye and is an antagonist to elevation. - It would pair with the **right superior oblique** for downward-left gaze (levo-depression), not with the right superior rectus. *Left Lateral Rectus* - The left lateral rectus is responsible for **abduction** of the left eye (leftward gaze). - Its yoke muscle is the **right medial rectus** for leftward horizontal gaze (levoversion), not for upward-right gaze.

Q: Downward and outward movement of eye is affected in injury of?

3rd nerve. The 3rd cranial nerve (oculomotor nerve) controls most extraocular muscles including the superior rectus, inferior rectus, medial rectus, and inferior oblique, as well as the levator palpebrae superioris. Injury to the 3rd nerve results in paralysis of these muscles, leaving only the lateral rectus (6th nerve) and superior oblique (4th nerve) functioning. This causes the classic "down and out" position of the eye at rest due to the unopposed action of these two muscles [1]. The eye is pulled downward by the superior oblique and outward by the lateral rectus [1]. Additional features include ptosis (drooping eyelid), dilated pupil, and diplopia (double vision) [1][2]. The patient loses the ability to move the eye upward, downward (via inferior rectus), and medially. Incorrect Option: 4th nerve - The 4th cranial nerve (trochlear nerve) innervates the superior oblique muscle. The superior oblique primarily causes depression (downward), intorsion, and abduction of the eye [1]. However, its action is most effective for downward and INWARD movement when the eye is adducted. - 4th nerve palsy results in vertical diplopia (especially when looking down and inward, like reading or descending stairs), hypertropia (upward deviation), and head tilt to the opposite side. This does NOT produce a "down and out" position. Incorrect Option: 5th nerve - The 5th cranial nerve (trigeminal nerve) provides sensory innervation to the face and motor innervation to the muscles of mastication. It has no role in eye movements. Incorrect Option: 6th nerve - The 6th cranial nerve (abducens nerve) innervates the lateral rectus muscle, responsible for abduction (outward movement) of the eye [1]. 6th nerve palsy causes inability to abduct the eye, resulting in esotropia (inward deviation) and horizontal diplopia.

Q: What is the distance of the medial rectus from the limbus?

5.5 mm. ***5.5 mm*** - The **medial rectus muscle** inserts into the sclera at an average distance of **5.5 mm** from the limbus [1]. - This distance is an important anatomical landmark in **ophthalmic surgery** and ocular motility studies. - The insertion distances follow the **Spiral of Tillaux** pattern. *4.5 mm* - This distance does **not correspond** to any of the standard rectus muscle insertion points. - The closest insertion is the **medial rectus at 5.5 mm**, followed by the **inferior rectus at 6.5 mm** [1]. *7.0 mm* - This distance corresponds to the insertion point of the **lateral rectus muscle** from the limbus [1]. - It is the **second farthest insertion point** among the recti muscles. *10 mm* - This distance is incorrect for any of the **rectus muscle insertions** from the limbus. - The rectus muscles insert at varying distances following the **Spiral of Tillaux**: medial (5.5 mm), inferior (6.5 mm), lateral (7.0 mm), and superior (7.7 mm).

Q: Upper Lid Retractors include

Levator palpebrae superioris & Muller muscle. ***Levator palpebrae superioris & Muller muscle*** - The **levator palpebrae superioris (LPS)** is the primary muscle responsible for lifting the upper eyelid. It is a striated muscle innervated by the oculomotor nerve (CN III). - **Müller's muscle** (also known as the superior tarsal muscle) is a smooth muscle that provides an additional, sustained lift to the upper eyelid. It is sympathetically innervated. *Muller muscle and superior rectus* - While **Müller's muscle** is an upper lid retractor, the **superior rectus** muscle primarily acts to elevate and adduct the eyeball, not the eyelid itself [1]. - The superior rectus muscle has only a minor, indirect role in upper eyelid elevation through its connection with the LPS aponeurosis. *Levator palpabrae superioris and superior oblique* - The **levator palpebrae superioris (LPS)** is a key upper lid retractor. - However, the **superior oblique** muscle is involved in depressing and intorting the eyeball [1], and has no direct role in upper eyelid retraction. *Superior oblique and superior rectus* - Neither the **superior oblique** nor the **superior rectus** muscles are primary upper lid retractors. - The superior oblique depresses and intorts the eye, while the superior rectus elevates and adducts the eye [1]. Both are extrinsic ocular muscles.

Q: Which nerve is not involved in superior orbital fissure syndrome?

1st cranial nerve. ***1st cranial nerve*** - The **olfactory nerve (CN I)** is responsible for the sense of smell [2] and passes through the **cribriform plate** of the ethmoid bone, not the superior orbital fissure. - Due to its distinct pathway, it is not affected in **superior orbital fissure syndrome**. *3rd cranial nerve* - The **oculomotor nerve (CN III)** passes through the superior orbital fissure and is frequently involved in the syndrome. - Its involvement leads to ophthalmoplegia, ptosis, and a dilated pupil due to paralysis of most extrinsic ocular muscles [1], [3] and the parasympathetic fibers [1]. *4th cranial nerve* - The **trochlear nerve (CN IV)** also travels through the superior orbital fissure. - Damage to this nerve causes **diplopia** and impaired downward and intorsion movements of the eye due to paralysis of the **superior oblique muscle** [3]. *6th cranial nerve* - The **abducens nerve (CN VI)** enters the orbit via the superior orbital fissure. - Injury to the abducens nerve results in **lateral rectus muscle** palsy, leading to esotropia (medial deviation of the eye) and impaired abduction [3].

Q: Which nerve does NOT carry referred ear pain?

Abducens nerve. ***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.

Q: Site of glomus jugulare tumor?

Hypotympanum. ***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.

Q: Which of the following statements is true regarding the anatomy of the external nose?

The lower one-third is primarily cartilaginous.. ***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.

Q: Which of the following arteries does NOT contribute to Little's area?

Posterior Ethmoidal artery. Posterior Ethmoidal artery - The posterior ethmoidal artery primarily supplies the posterior ethmoidal cells and part of the sphenoid sinus, but it does not contribute to the vascular plexus in Little's area. - Little's area, also known as Kiesselbach's plexus, is formed by anastomoses of several arteries on the anterior nasal septum. Sphenopalatine artery - The sphenopalatine artery, a terminal branch of the maxillary artery, is a major contributor to Little's area through its septal branch. - It supplies a significant portion of the nasal septum and is frequently involved in posterior epistaxis. Greater palatine artery - The greater palatine artery, a branch of the descending palatine artery (from the maxillary artery), enters the nasal cavity through the incisive canal and contributes to Little's area on the nasal septum. - It primarily supplies the hard palate and then anastomoses with other vessels in the anterior nasal septum. Anterior Ethmoidal artery - The anterior ethmoidal artery, a branch of the ophthalmic artery, is a key contributor to Little's area. - It supplies the anterior and middle ethmoidal cells and also contributes to the blood supply of the dura mater.

Q: Posterior epistaxis occurs from:

Woodruff's plexus. ***Woodruff's plexus*** - **Woodruff's plexus** is a collection of large, often friable veins located on the **posterior aspect of the lateral wall of the nasal cavity**, making it the most common anatomical site for **posterior epistaxis**. - Bleeding from this plexus is typically more severe and difficult to control than anterior epistaxis due to the larger vessel size and posterior location. - Located in the **posterolateral nasal cavity** near the posterior end of the inferior turbinate. *Kiesselbach's plexus* - **Kiesselbach's plexus** (also known as Little's area) is located on the **anterior nasal septum** and is the most common site for **anterior epistaxis**. - This is an anastomotic network of vessels from multiple arterial sources in the anterior nasal cavity. - Bleeding from this plexus is usually less severe and often responds to local pressure or cauterization. *Sphenopalatine artery* - The **sphenopalatine artery** is the terminal branch of the maxillary artery and is the primary arterial supply to the posterior nasal cavity. - While it supplies the area where posterior epistaxis occurs, the venous **Woodruff's plexus** is the specific anatomical structure most commonly associated with posterior epistaxis. - The sphenopalatine artery may require ligation or embolization in severe posterior epistaxis cases. *Little's area* - **Little's area** is another name for **Kiesselbach's plexus** and is located on the **anterior nasal septum**, primarily responsible for anterior epistaxis. - This area is highly vascularized by anastomoses of the anterior ethmoidal, sphenopalatine, greater palatine, superior labial, and septal branches of arteries. - Prone to bleeding from minor trauma, digital manipulation, or mucosal dryness.

Question 1

Yoke muscle for the right superior rectus is:

Accepted Answer

Left Inferior Oblique

Answer

Left Lateral Rectus

Answer

Left Superior rectus

Answer

Left Inferior rectus

Question 2

Downward and outward movement of eye is affected in injury of?

Accepted Answer

3rd nerve

Answer

4th nerve

Answer

5th nerve

Answer

6th nerve

Question 3

What is the distance of the medial rectus from the limbus?

Accepted Answer

5.5 mm

Answer

4.5 mm

Answer

7.0 mm

Answer

10 mm

Question 4

Upper Lid Retractors include

Accepted Answer

Levator palpebrae superioris & Muller muscle

Answer

Muller muscle and superior rectus

Answer

Levator palpebrae superioris and superior oblique

Answer

Superior oblique and superior rectus

Question 5

Which nerve is not involved in superior orbital fissure syndrome?

Accepted Answer

1st cranial nerve

Answer

3rd cranial nerve

Answer

4th cranial nerve

Answer

6th cranial nerve

Question 6

Which nerve does NOT carry referred ear pain?

Accepted Answer

Abducens nerve

Answer

Glossopharyngeal nerve

Answer

Vagus nerve

Answer

Trigeminal nerve

Question 7

Site of glomus jugulare tumor?

Accepted Answer

Hypotympanum

Answer

Epitympanum

Answer

Mesotympanum

Answer

Internal ear

Question 8

Which of the following statements is true regarding the anatomy of the external nose?

Accepted Answer

The lower one-third is primarily cartilaginous.

Answer

The upper two-thirds is entirely bony.

Answer

The lateral aspect has only a single cartilage.

Answer

The external nose is supported by two nasal bones.

Question 9

Which of the following arteries does NOT contribute to Little's area?

Accepted Answer

Posterior Ethmoidal artery

Answer

Sphenopalatine artery

Answer

Greater palatine artery

Answer

Anterior Ethmoidal artery

Question 10

Posterior epistaxis occurs from:

Accepted Answer

Woodruff's plexus

Answer

Kiesselbach's plexus

Answer

Sphenopalatine artery

Answer

Little's area

NEET-PG 2013 — Anatomy