Phylogenetic Aspects of Human Anatomy — MCQs
Muscles taking origin from the ischial tuberosity are all except:
Appreciation of shape and size of an object placed in hand is lost in damage of-
Which of the following is the most complete statement about the appendix?
A skull was recovered from a forest. According to inquest papers, a girl had gone missing 15 days back. The skull was sent to the forensic research lab. Which of the following would identify it as a female skull? 1. Large frontal and parietal eminence 2. Heavy cheek bones 3. Smooth glabella 4. Square orbits 5. Narrow mastoid
What are the characteristics of reversible pulpitis?
Which of the following statements correctly describes the position of the primate spaces in relation to the primary canines?
Malleus and incus are derived from?
On opening the mouth, if the jaw deviates to the right side, it indicates the paralysis of:
Which of the following muscles causes the forward movement of the condyle in the mandibular fossa?
Trismus in parapharyngeal abscess is due to spasm of:
Phylogenetic Aspects of Human Anatomy Indian Medical PG Practice Questions and MCQs
Question 1: Muscles taking origin from the ischial tuberosity are all except:
- A. Adductor longus (Correct Answer)
- B. Semitendinosus
- C. Adductor magnus
- D. Semimembranosus
Explanation: ***Adductor longus*** - The **adductor longus** originates from the anterior surface of the **pubic body**, inferior to the pubic crest. - It is part of the **adductor compartment of the thigh** but does not originate from the ischial tuberosity. *Semimembranosus* - The **semimembranosus** muscle originates from the **ischial tuberosity**, specifically from its upper and outer part. - It is one of the three **hamstring muscles**. *Semitendinosus* - The **semitendinosus** originates from the **ischial tuberosity**, sharing a common origin with the long head of the biceps femoris. - It is also a **hamstring muscle**. *Adductor magnus* - The **adductor magnus** has a dual origin; its adductor (anterior) part originates from the **inferior pubic ramus** and **ischial ramus**, while its hamstring (posterior) part originates directly from the **ischial tuberosity**. - Its origin is therefore partially from the ischial tuberosity, making it an incorrect answer for the "except" question.
Question 2: Appreciation of shape and size of an object placed in hand is lost in damage of-
- A. Lateral spinothalamic tract
- B. Spinocerebellar tract
- C. Tractus gracilis
- D. Tractus cuneatus (Correct Answer)
Explanation: ***Tractus cuneatus*** - The **tractus cuneatus** transmits **fine touch, vibration, and proprioception** from the upper limbs and trunk, which is essential for appreciating the shape and size of objects (**stereognosis**). - Damage to this tract (part of the **dorsal column-medial lemniscus pathway**) would impair discriminative touch and proprioceptive inputs from the hand, leading to a loss of stereognosis. *Lateral spinothalamic tract* - This tract is responsible for transmitting **pain and temperature** sensations. - Damage to the lateral spinothalamic tract would primarily result in impaired pain and temperature perception, not the ability to recognize object shape or size. *Spinocerebellar tract* - The spinocerebellar tracts primarily convey **unconscious proprioceptive information** to the cerebellum for coordination of movement. - Damage to these tracts would cause **ataxia** and coordination problems, but not directly affect the conscious appreciation of object shape and size in the hand. *Tractus gracilis* - The **tractus gracilis** transmits **fine touch, vibration, and proprioception** from the lower limbs and lower trunk. - While part of the dorsal column system, it specifically carries information from the lower body, so damage to this tract would affect the legs, not the hands.
Question 3: Which of the following is the most complete statement about the appendix?
- A. It does not have mesentery.
- B. It has taenia coli.
- C. It develops from the midgut and is supplied by the appendicular branch of the ileocolic artery. (Correct Answer)
- D. It develops from the midgut.
Explanation: ***It develops from the midgut and is supplied by the appendicular branch of the ileocolic artery.*** - The appendix originates embryologically from the **midgut**, which also gives rise to the distal duodenum to the proximal two-thirds of the transverse colon [1]. - Its blood supply is derived from the **appendicular artery**, a branch of the **ileocolic artery**, which itself originates from the superior mesenteric artery (a major midgut vessel) [2]. - This option provides the most comprehensive information, combining both embryological origin and vascular supply. *It does not have mesentery.* - The appendix is attached to the mesentery of the ileum by a small mesentery of its own, called the **mesoappendix**, which contains the appendicular artery. - This statement is **incorrect** as the presence of a mesoappendix clearly indicates it does possess a mesentery. *It has taenia coli.* - The taenia coli are three distinct longitudinal bands of smooth muscle found on the outer surface of the **cecum** and **colon**. - The three taenia coli **converge at the base of the appendix** to form its outer longitudinal muscle layer, but the appendix itself does not have taenia coli running along its length. - This statement is **incorrect**. *It develops from the midgut.* - While this statement is factually **true**, it is incomplete compared to the correct answer. - The appendix does develop from the midgut, but this option lacks additional distinguishing information about its vascular supply, making it less complete than the best answer.
Question 4: A skull was recovered from a forest. According to inquest papers, a girl had gone missing 15 days back. The skull was sent to the forensic research lab. Which of the following would identify it as a female skull? 1. Large frontal and parietal eminence 2. Heavy cheek bones 3. Smooth glabella 4. Square orbits 5. Narrow mastoid
- A. 1,3 and 5 (Correct Answer)
- B. 2,3 and 4
- C. 1 and 4 only
- D. 3,4 and 5
Explanation: ***1,3 and 5*** - **Large frontal and parietal eminences** are characteristic features of a **female skull**, indicating a more rounded appearance. - A **smooth glabella** (the area between the eyebrows) is typical for females, as males tend to have a more prominent brow ridge. A **narrow mastoid** process is also characteristic in females. *2,3 and 4* - **Heavy cheekbones** and **square orbits** are features more commonly associated with a **male skull**. - While a **smooth glabella** is a female characteristic, its combination with male features makes this option incorrect. *1 and 4 only* - **Large frontal eminences** are indicative of a female skull, but **square orbits** are a feature of a **male skull**. - This combination presents conflicting information regarding gender identification. *3,4 and 5* - A **smooth glabella** and **narrow mastoid** are features of a **female skull**. - However, **square orbits** are typically found in **male skulls**, rendering this option incorrect.
Question 5: What are the characteristics of reversible pulpitis?
- A. Aggravated by heat and may be relieved by cold
- B. Aggravated by cold and may be relieved by heat
- C. No reaction to hot and cold, indicating necrosis
- D. Reacts to electric pulp tester (Correct Answer)
Explanation: ***Reacts to electric pulp tester*** - In **reversible pulpitis**, the pulp is still vital and responsive, thus it will react to an **electric pulp tester** (EPT) with a sharp, transient pain at a lower current. - The sensation elicited by EPT indicates the presence of nerve fibers and a viable pulp, consistent with a reversible condition. *Aggravated by heat and may be relieved by cold* - This symptom profile, where pain is **aggravated by heat** and **relieved by cold**, is characteristic of **irreversible pulpitis**, not reversible pulpitis. - The relief with cold often indicates a build-up of pressure within the pulp that is temporarily alleviated by the vasoconstrictive effect of cold. *Aggravated by cold and may be relieved by heat* - While some mild, transient cold sensitivity can occur in **reversible pulpitis**, severe or prolonged cold sensitivity is more indicative of irreversible pulpitis. Relief with heat is not a typical characteristic of reversible pulpitis and would be very unusual for any pulpitis. - This pattern of discomfort is not a direct characteristic of reversible pulpitis; reversible pulpitis typically presents with **sharp, transient pain to cold** that resolves quickly. *No reaction to hot and cold, indicating necrosis* - A lack of reaction to thermal stimuli (hot and cold) is indicative of a **necrotic pulp**, meaning the pulp tissue has died. - In **reversible pulpitis**, the pulp is inflamed but still vital, and therefore will react to thermal stimuli, usually with a sharp, transient pain to cold.
Question 6: Which of the following statements correctly describes the position of the primate spaces in relation to the primary canines?
- A. Distal to the maxillary primary canines and mesial to the mandibular primary canines.
- B. Mesial to the maxillary primary canines and distal to the mandibular primary canines. (Correct Answer)
- C. Distal to both the maxillary and mandibular primary canines.
- D. Mesial to both maxillary and mandibular primary canines.
Explanation: ***Mesial to the maxillary primary canines and distal to the mandibular primary canines.*** - The primate spaces serve as essential developmental spaces in the primary dentition for the correct alignment of permanent teeth. - The **maxillary primate space** is located **mesial to the primary canine**, between the primary lateral incisor and the primary canine. *Distal to the maxillary primary canines and mesial to the mandibular primary canines.* - This statement incorrectly identifies the position for both the maxillary and mandibular primate spaces. - The **mandibular primate space** is actually located **distal to the primary canine**, between the primary canine and the primary first molar. *Distal to both the maxillary and mandibular primary canines.* - This statement is incorrect as the **maxillary primate space** is located **mesial** to the maxillary primary canines. - While the mandibular primate space is distal to the mandibular primary canine, the generalized statement for both is false. *Mesial to both maxillary and mandibular primary canines.* - This statement is incorrect as the **mandibular primate space** is located **distal** to the mandibular primary canines. - The maxillary primate space is indeed mesial to the maxillary primary canine, but the statement for both is incorrect.
Question 7: Malleus and incus are derived from?
- A. 3rd Arch
- B. 4th Arch
- C. 1st Arch (Correct Answer)
- D. 2nd Arch
Explanation: ***1st Arch*** - The **malleus** and **incus** are ossicles of the middle ear that develop from the **cartilage of the first pharyngeal arch** (Meckel's cartilage). - This arch also contributes to the development of the **mandible** and muscles of mastication. *2nd Arch* - The **second pharyngeal arch** (Reichert's cartilage) gives rise to the **stapes**, a different ossicle of the middle ear. - It also forms the **styloid process**, **lesser cornu of the hyoid**, and muscles of facial expression. *3rd Arch* - The **third pharyngeal arch** contributes to the development of the **greater cornu of the hyoid bone** and the **stylopharyngeus muscle**. - It plays no direct role in the formation of the malleus or incus. *4th Arch* - The **fourth pharyngeal arch** contributes to the formation of the **thyroid cartilage**, **cricoid cartilage**, and muscles of the pharynx and larynx. - It is not involved in the development of the ear ossicles.
Question 8: On opening the mouth, if the jaw deviates to the right side, it indicates the paralysis of:
- A. Right lateral pterygoid (Correct Answer)
- B. Left medial pterygoid
- C. Left lateral pterygoid
- D. Right medial pterygoid
Explanation: Right lateral pterygoid - The **lateral pterygoid muscle** is primarily responsible for **protrusion** of the mandible and **depressing** the jaw during mouth opening. - When the right lateral pterygoid is paralyzed, the **intact left lateral pterygoid** pulls the mandible forward and toward the **opposite side** (the paralyzed right side), causing the jaw to **deviate to the right** upon opening. - This follows the principle: **"The jaw deviates toward the side of the paralyzed lateral pterygoid."** *Left medial pterygoid* - The **medial pterygoid muscle** primarily helps in **elevation** (closing) and **protrusion** of the mandible, as well as side-to-side movements, but is not a primary opener. - Paralysis of the left medial pterygoid would primarily affect jaw closing or specific side-to-side movements, not cause significant deviation to the right during opening. *Left lateral pterygoid* - If the **left lateral pterygoid** were paralyzed, the intact right lateral pterygoid would pull the jaw toward the paralyzed left side, causing deviation to the **left side** upon opening. - The jaw always deviates toward the side of the weakened or paralyzed lateral pterygoid muscle. *Right medial pterygoid* - Paralysis of the **right medial pterygoid** would mainly impair the **elevation** and **protrusion** of the right side of the mandible. - It would not cause the observed deviation to the right upon opening the mouth, as medial pterygoids are primarily jaw closers, not openers.
Question 9: Which of the following muscles causes the forward movement of the condyle in the mandibular fossa?
- A. Masseter
- B. Lateral pterygoid (Correct Answer)
- C. Medial pterygoid
- D. Temporalis
Explanation: ***Lateral pterygoid*** - The **lateral pterygoid muscle** (especially its inferior head) is primarily responsible for **protrusion (forward movement)** of the mandible, causing the condyle to slide anteriorly along the articular eminence in the temporomandibular joint. - Its superior head stabilizes the **articular disc** during jaw movements, while the inferior head produces the forward translation. *Masseter* - The **masseter muscle** is a powerful muscle of mastication primarily involved in **elevation (closing)** of the mandible. - While it can assist slightly in protrusion when both sides contract, it does not produce the forward gliding movement of the condyle. *Medial pterygoid* - The **medial pterygoid muscle** primarily functions in **elevating** the mandible and assists in **protrusion** and grinding movements. - While it contributes to protrusion, the **lateral pterygoid** is the primary muscle responsible for the forward movement of the condyle. *Temporalis* - The **temporalis muscle** is a strong elevator of the mandible and its posterior fibers act as a **retractor**, pulling the mandible backward. - It opposes forward movement and is responsible for retrusion, not protrusion of the condyle.
Question 10: Trismus in parapharyngeal abscess is due to spasm of:
- A. Medial pterygoid (Correct Answer)
- B. Temporalis
- C. Masseter muscle
- D. Lateral pterygoid
Explanation: ***Medial pterygoid*** - The **medial pterygoid muscle** is intimately associated with the parapharyngeal space, and inflammation or infection (abscess) in this region directly irritates it. - **Spasm** of the medial pterygoid muscle, a primary muscle of mastication involved in jaw closure, is the direct cause of **trismus** (difficulty opening the mouth) in parapharyngeal abscess. *Masseter muscle* - While the **masseter** is a strong muscle of mastication and contributes to jaw closure, it is located more superficially and is less directly affected by an abscess in the parapharyngeal space. - Its involvement in trismus due to parapharyngeal abscess is typically secondary, arising from generalized muscle guarding rather than direct irritation. *Lateral pterygoid* - The **lateral pterygoid muscle** is primarily involved in jaw opening (depression) and protrusion. - Spasm of this muscle would typically lead to difficulty closing the jaw or deviations, rather than the profound difficulty in opening characteristic of trismus. *Temporalis* - The **temporalis muscle** is a major muscle for jaw elevation and retraction, contributing significantly to biting force. - While temporalis spasm can cause trismus, it is less directly impacted by a parapharyngeal abscess compared to the medial pterygoid muscle.
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