Which of the following statements about articular cartilage is true?
A person is not able to extend his metacarpophalangeal joint. Injury to which of the following nerve result in this?
Downward and outward movement of eye is affected in injury of?
What is the distance of the medial rectus from the limbus?
Upper Lid Retractors include
Which nerve is not involved in superior orbital fissure syndrome?
Site of glomus jugulare tumor?
Which nerve does NOT carry referred ear pain?
Which of the following does not contribute to the formation of the nasal septum?
Which of the following statements is true regarding the anatomy of the external nose?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 81: Which of the following statements about articular cartilage is true?
- A. Very vascular structure
- B. Surrounded by thick perichondrium
- C. Has no nerve supply (Correct Answer)
- D. Fibrocartilage
Explanation: ***Has no nerve supply*** - Articular cartilage is **aneural**, meaning it lacks nerve endings, which is why damage to it doesn't immediately cause pain until underlying bone or surrounding tissues are affected [1]. - Its aneural nature contributes to its low metabolic activity and limited capacity for repair. *Very vascular structure* - Articular cartilage is **avascular**, meaning it lacks a direct blood supply [1]. - It receives nutrients primarily through diffusion from the synovial fluid [1]. *Surrounded by thick perichondrium* - Articular cartilage is typically **not covered by a perichondrium**, unlike most other types of cartilage. - The absence of perichondrium prevents potential ossification of the articular surface. *Fibrocartilage* - Articular cartilage is primarily composed of **hyaline cartilage**, not fibrocartilage [1]. - **Hyaline cartilage** provides a smooth, low-friction surface for joint movement and acts as a shock absorber [1].
Question 82: A person is not able to extend his metacarpophalangeal joint. Injury to which of the following nerve result in this?
- A. Posterior Interosseous nerve injury (Correct Answer)
- B. Radial nerve injury
- C. Ulnar nerve injury
- D. Median nerve injury
Explanation: Posterior Interosseous Nerve (PIN) injury - The Posterior Interosseous Nerve is the deep motor branch of the radial nerve that specifically innervates the extensor muscles of the fingers and thumb - These muscles include: Extensor Digitorum, Extensor Indicis, Extensor Digiti Minimi, Extensor Pollicis Longus and Brevis [1] - PIN injury causes inability to extend the MCP joints and interphalangeal joints of the fingers [1] - Wrist extension is preserved because the Extensor Carpi Radialis Longus (ECRL) and often ECRB are innervated by the radial nerve proper before it gives off the PIN [1] - This results in a characteristic finger drop without wrist drop Radial nerve injury - A high radial nerve injury (proximal, above the elbow) would cause both wrist drop AND finger extension loss - However, radial nerve injury at the spiral groove (most common site) typically spares the PIN or affects it less severely - The question asks specifically about isolated inability to extend MCP joints, which is the hallmark of PIN injury, not general radial nerve injury - Radial nerve proper gives branches to triceps, brachioradialis, and ECRL before dividing into PIN and superficial branch Ulnar nerve injury - The ulnar nerve innervates intrinsic hand muscles (interossei, lumbricals to digits 4-5, hypothenar muscles, adductor pollicis) [1] - Ulnar nerve injury causes claw hand deformity with MCP hyperextension (not loss of extension) and IP joint flexion - This is the opposite of what is described in the question Median nerve injury - The median nerve innervates the thenar muscles, lateral two lumbricals, and forearm flexors [1] - Median nerve injury causes ape hand deformity with loss of thumb opposition and flexion - It does not affect MCP joint extension, which is an extensor function
Question 83: Downward and outward movement of eye is affected in injury of?
- A. 3rd nerve (Correct Answer)
- B. 4th nerve
- C. 5th nerve
- D. 6th nerve
Explanation: 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.
Question 84: What is the distance of the medial rectus from the limbus?
- A. 4.5 mm
- B. 5.5 mm (Correct Answer)
- C. 7.0 mm
- D. 10 mm
Explanation: ***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).
Question 85: Upper Lid Retractors include
- A. Muller muscle and superior rectus
- B. Levator palpebrae superioris and superior oblique
- C. Superior oblique and superior rectus
- D. Levator palpebrae superioris & Muller muscle (Correct Answer)
Explanation: ***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.
Question 86: Which nerve is not involved in superior orbital fissure syndrome?
- A. 1st cranial nerve (Correct Answer)
- B. 3rd cranial nerve
- C. 4th cranial nerve
- D. 6th cranial nerve
Explanation: ***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].
Question 87: 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.
Question 88: 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 89: 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 90: 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.