Which nerve is not involved in superior orbital fissure syndrome?
What is the thinnest portion of the sclera?
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?
Root value of the thoracodorsal nerve
What is the bispinous diameter?
In a 3 month fetus, characteristic feature seen is:
What is the anatomical relation of the upper lacrimal punctum with respect to the lower punctum?
Which muscle originates from tendon of other muscle?
Submandibular nodes are classified as
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 101: 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 102: 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 103: 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 104: 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 105: Root value of the thoracodorsal nerve
- A. C6, C7, C8 (Correct Answer)
- B. T1, T2
- C. C5, C6, C7
- D. C6, T1
Explanation: ***C6, C7, C8*** - The **thoracodorsal nerve**, also known as the middle subscapular nerve, originates from the **posterior cord of the brachial plexus**. - Its specific root values are **C6, C7, and C8**, which supply motor innervation to the **latissimus dorsi muscle** [1]. - This nerve is one of the three subscapular nerves arising from the posterior cord [1]. *C5, C6, C7* - While these roots contribute to the **posterior cord**, the thoracodorsal nerve specifically arises from **C6, C7, C8**. - **C5** primarily contributes to the **upper and middle trunk** and is more associated with nerves like the **suprascapular** and **axillary nerves**. *C6, T1* - These root values contribute to various nerves of the **brachial plexus**, but not specifically the thoracodorsal nerve. - **T1** contributes mainly to the **medial cord** and its branches like the **ulnar nerve**, not the posterior cord from which the thoracodorsal nerve arises. *T1, T2* - These are typical root values for **intercostal nerves** and contribute to the **sympathetic trunk**, not the **brachial plexus** or its branches like the thoracodorsal nerve. - The brachial plexus predominantly arises from **C5 to T1 spinal nerve roots**, and **T2** is not part of the brachial plexus.
Question 106: What is the bispinous diameter?
- A. 10.5 cm (Correct Answer)
- B. 11.5 cm
- C. 12 cm
- D. 11 cm
Explanation: ***10.5 cm*** - The **bispinous (interspinous) diameter** is the transverse diameter of the midpelvis, measured between the two ischial spines. [1] - A measurement of **10.5 cm** is the average and normal length for this diameter. [1] - This is the **narrowest diameter of the pelvis** and represents a critical measurement during labor, as it is the narrowest point through which the fetal head must pass. [1] *11.5 cm* - This measurement is typically associated with the **obstetric conjugate** at the pelvic inlet, not the midpelvis. - The bispinous diameter, being the narrowest transverse diameter of the pelvis, is normally shorter than 11.5 cm. *12 cm* - A 12 cm measurement is too wide for the **bispinous diameter**. - The **transverse diameter of the pelvic inlet** is approximately 13 cm, and the **transverse diameter of the pelvic outlet** is about 11 cm, but neither of these is the bispinous diameter. *11 cm* - While 11 cm is close, it is slightly larger than the typical average for the **bispinous diameter** of 10.5 cm. - The **transverse diameter of the outlet** is approximately 11 cm [2], but this is a different measurement at a different level of the pelvis.
Question 107: In a 3 month fetus, characteristic feature seen is:
- A. Meconium is present in the intestines.
- B. Nails are visible (Correct Answer)
- C. Anus formation begins.
- D. Limb buds are present.
Explanation: ***Nails are visible*** - By the end of the **third month** (approximately 12 weeks), the fingers and toes are fully formed, and the beginnings of fingernails and toenails usually become visible. - This marks a significant developmental milestone in fetal maturation during the first trimester. *Meconium is present in the intestines* - **Meconium** begins to form during the **second trimester**, typically around weeks 12-16, with significant accumulation in the latter part of the second and throughout the third trimester. - While some gut movements occur earlier, the presence of well-formed meconium for defecation happens later in fetal development. *Anus formation begins* - The formation of the anus is part of the development of the **cloaca**, which begins much earlier, around the **4th to 7th gestational weeks**. - By 3 months, the anorectal canal is already well-differentiated, so its formation has already been completed. *Limb buds are present* - **Limb buds** appear very early in embryonic development, around the **end of the 4th week**. [1] - By 3 months, the limbs are already well-developed with distinct fingers and toes, so these structures would have passed the "bud" stage.
Question 108: What is the anatomical relation of the upper lacrimal punctum with respect to the lower punctum?
- A. Lateral
- B. Superior (Correct Answer)
- C. No relation
- D. Apposed
Explanation: ***Superior*** - The **upper lacrimal punctum** is located slightly **superior** to the lower lacrimal punctum, which is the predominant anatomical relationship. - Additionally, the upper punctum is positioned slightly **lateral** (approximately 0.5-1mm) to the lower punctum, though the superior relationship is more clinically significant. - This arrangement facilitates efficient tear drainage into the lacrimal canaliculi and ultimately to the nasolacrimal duct. *Lateral* - While there is a slight **lateral offset** between the upper and lower puncta, this is not the primary or most significant anatomical relationship. - The **superior-inferior relationship** is the dominant spatial arrangement and is more relevant for clinical examination and cannulation procedures. *No relation* - The upper and lower lacrimal puncta have a precise anatomical relationship as paired openings into the **lacrimal canaliculi**. - They work together as part of the tear drainage system, positioned at the medial aspects of their respective eyelid margins. *Apposed* - The term **apposed** means being in direct contact or immediately adjacent, which does not describe the relationship between the puncta. - They are separated by the medial canthal area and located on different eyelid margins (upper vs. lower), not in direct apposition.
Question 109: Which muscle originates from tendon of other muscle?
- A. FCR
- B. Lumbricals (Correct Answer)
- C. Adductor pollicis
- D. Palmaris longus
Explanation: Lumbricals - The lumbrical muscles are unique in the hand because they originate from the tendons of the flexor digitorum profundus (FDP), not from bone [1]. - This attachment allows them to flex the metacarpophalangeal (MCP) joints while extending the interphalangeal (IP) joints [1]. FCR - The flexor carpi radialis (FCR) muscle originates from the medial epicondyle of the humerus, a bony origin. - Its primary function is flexion and radial deviation of the wrist. Adductor pollicis - The adductor pollicis muscle has two heads, the oblique and transverse heads, both originating from various carpal bones and the third metacarpal. - It plays a crucial role in adducting the thumb. Palmaris longus - The palmaris longus muscle originates from the medial epicondyle of the humerus, similar to the FCR. - It contributes to wrist flexion and is absent in a significant portion of the population.
Question 110: Submandibular nodes are classified as
- A. Level III neck nodes
- B. Level II neck nodes
- C. Level 1B neck nodes (Correct Answer)
- D. Level 1A neck nodes
Explanation: ***Level 1B neck nodes*** - The **submandibular nodes** are located anterior to the posterior belly of the digastric muscle and lateral to the anterior belly of the digastric muscle, placing them within **Level 1B** of the neck lymph node classification [1]. - This level primarily drains the oral cavity, face, and submandibular gland [1]. *Level III neck nodes* - **Level III** nodes are the middle jugular nodes, located between the level of the hyoid bone and the cricoid cartilage. - These nodes are typically found along the **internal jugular vein** and drain structures such as the larynx, hypopharynx, and thyroid. *Level II neck nodes* - **Level II** nodes, or upper jugular nodes, are located from the skull base to the inferior border of the hyoid bone, along the internal jugular vein. - This level is further divided into Level IIA (anterior to the spinal accessory nerve) and Level IIB (posterior to the spinal accessory nerve) and drains structures like the nasopharynx, oropharynx, and parotid gland. *Level 1 A neck nodes* - **Level 1A** nodes refer to the **submental nodes**, which are located between the anterior bellies of the digastric muscles [1]. - These nodes primarily drain the central lower lip, floor of the mouth, anterior tongue, and chin [1].