Anatomy
9 questionsWhich intrinsic ocular muscle responsible for pupillary constriction is supplied by parasympathetic innervation?
Lips do not drain into which group of lymph nodes?
Which nerve supplies the postganglionic fibers to the parotid gland?
Secretomotor fibers to parotid gland are through?
What is the remnant of the umbilical artery?
Which is the first bone to start ossifying?
Oxyntic cells are present in -
Which of the following vessels runs through the transverse mesocolon?
Floor of Petit triangle is formed by?
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 81: Which intrinsic ocular muscle responsible for pupillary constriction is supplied by parasympathetic innervation?
- A. Constrictor pupillae (Correct Answer)
- B. Dilator pupillae
- C. Levator palpebrae superioris
- D. Ciliary muscle
Explanation: ***Constrictor pupillae*** - The **constrictor pupillae** (or **sphincter pupillae**) muscle is responsible for **miosis** (pupil constriction) and is innervated by **parasympathetic fibers** from the **oculomotor nerve (CN III)** via the **ciliary ganglion** [1]. - Stimulation of this muscle reduces the pupil size, which is a key part of the **light reflex** and **accommodation reflex** [1]. - This is the **only pupillary muscle** with parasympathetic innervation. *Ciliary muscle* - The **ciliary muscle** is involved in **accommodation**, altering the shape of the lens for focusing on near objects [1]. - While it also receives **parasympathetic innervation** from the ciliary ganglion, it does **not control pupil size**. - Its function is to change **lens curvature**, not pupillary diameter. *Levator palpebrae superioris* - This muscle is responsible for **elevating the upper eyelid**. - It is innervated by the **somatic motor fibers** of the **oculomotor nerve (CN III)**, not parasympathetic fibers. - It is **not an intrinsic ocular muscle** but rather an extraocular muscle. *Dilator pupillae* - The **dilator pupillae** muscle causes **mydriasis** (pupil dilation). - This muscle is innervated by **sympathetic fibers**, originating from the superior cervical ganglion, not parasympathetic fibers.
Question 82: Lips do not drain into which group of lymph nodes?
- A. Submandibular nodes
- B. Preauricular parotid (Correct Answer)
- C. None of the options
- D. Submental nodes
Explanation: ***Preauricular parotid*** - Lymph from the lips primarily drains into the **submental**, **submandibular**, and **deep cervical lymph nodes** [1]. - **Preauricular parotid nodes** primarily drain the lateral surface of the auricle, external auditory canal, temporoparietal scalp, and lateral parts of the eyelids and cheek. - The lips do **NOT** drain into preauricular nodes. *Submandibular nodes* - The **lateral parts of the lower lip** and the **entire upper lip** drain into the submandibular lymph nodes [1]. - These nodes are a primary drainage pathway for the oral region. *Submental nodes* - The **central part of the lower lip** drains into the submental lymph nodes [1]. - These nodes lie between the anterior bellies of the digastric muscles beneath the chin. - They receive lymph from the central lower lip, floor of mouth, and tip of tongue. *None of the options* - This option is incorrect because there is a specific group of nodes listed that the lips do *not* drain into (preauricular parotid).
Question 83: Which nerve supplies the postganglionic fibers to the parotid gland?
- A. Auriculotemporal nerve (Correct Answer)
- B. Glossopharyngeal nerve
- C. Facial nerve
- D. Greater superficial petrosal nerve
Explanation: ***Auriculotemporal nerve*** - This nerve carries the **postganglionic parasympathetic fibers** from the **otic ganglion** to the parotid gland, stimulating saliva production. - These fibers originate from the **glossopharyngeal nerve (CN IX)**, synapse in the otic ganglion, and then join the auriculotemporal nerve. *Glossopharyngeal nerve* - The glossopharyngeal nerve (CN IX) provides the **preganglionic parasympathetic fibers** that ultimately reach the parotid gland. - These preganglionic fibers synapse in the **otic ganglion**, not directly supply the gland with postganglionic fibers. *Facial nerve* - The facial nerve (CN VII) supplies the **submandibular** and **sublingual glands** with parasympathetic innervation, via the chorda tympani and submandibular ganglion. - It does not innervate the parotid gland for salivary secretion. *Greater superficial petrosal nerve* - This nerve (a branch of the facial nerve) carries **preganglionic parasympathetic fibers** to the pterygopalatine ganglion, innervating the **lacrimal gland** and glands in the nasal and oral cavities. - It is not involved in the postganglionic innervation of the parotid gland.
Question 84: Secretomotor fibers to parotid gland are through?
- A. Tympanic plexus (Correct Answer)
- B. Greater petrosal nerve
- C. Geniculate ganglion
- D. None of the options
Explanation: This is an easy question, and the expected Bloom's level is low (L1) with an expectation of just remembering the right answer. ***Tympanic plexus*** - The secretomotor fibers to the parotid gland originate from the inferior **salivatory nucleus**, travel via the **glossopharyngeal nerve (CN IX)** to the tympanic plexus. - From the tympanic plexus, these preganglionic parasympathetic fibers form the **lesser petrosal nerve**, which synapses in the otic ganglion, and postganglionic fibers then join the **auriculotemporal nerve** to reach the parotid gland. *Greater petrosal nerve* - The **greater petrosal nerve** carries preganglionic parasympathetic fibers that primarily innervate the **lacrimal gland** and glands of the nasal cavity and palate, not the parotid gland. - It is a branch of the **facial nerve (CN VII)**, whereas secretomotor innervation to the parotid is from the glossopharyngeal nerve (CN IX). *Geniculate ganglion* - The **geniculate ganglion** is a sensory ganglion of the **facial nerve (CN VII)**, containing cell bodies for taste sensation from the anterior two-thirds of the tongue. - It is not directly involved in transmitting secretomotor fibers to the parotid gland. *None of the options* - As the **tympanic plexus** is the correct conduit for the secretomotor fibers to the parotid gland, this option is incorrect. - The pathway involves a specific sequence of nerves and ganglia, which includes the tympanic plexus as a key relay point.
Question 85: What is the remnant of the umbilical artery?
- A. Ligamentum arteriosum
- B. Ligament teres
- C. Ligamentum venosum
- D. Medial umbilical ligament (Correct Answer)
Explanation: ***Medial umbilical ligament*** - The **umbilical arteries** (paired structures) carry deoxygenated blood from the fetus to the placenta during development [2]. - After birth, these arteries obliterate and persist as the **medial umbilical ligaments** (two in number, one on each side), extending from the internal iliac arteries to the umbilicus along the anterior abdominal wall. - The proximal portions of the umbilical arteries remain patent as the **superior vesical arteries**, which supply the bladder. *Ligamentum arteriosum* - This is the remnant of the **ductus arteriosus**, which shunted blood from the pulmonary artery to the aorta, bypassing the fetal lungs [2]. - It connects the arch of the aorta to the pulmonary artery. *Ligament teres* - Also known as the **round ligament of the liver**, this is the remnant of the **fetal umbilical vein** (a single midline structure) [1]. - The umbilical vein carried oxygenated blood from the placenta to the fetus [1], [2]. *Ligamentum venosum* - This is the fibrous remnant of the **ductus venosus**, a shunt in fetal circulation that bypassed the liver by connecting the umbilical vein to the inferior vena cava [1]. - It is located deep within the liver, forming a fissure.
Question 86: Which is the first bone to start ossifying?
- A. Femur
- B. Clavicle (Correct Answer)
- C. Tibia
- D. Mandible
Explanation: ***Clavicle*** - The **clavicle** is the **first bone to begin ossification** in the human body, starting around the **5th-6th week of gestation**. - It ossifies via **intramembranous ossification**, making it unique among long bones [1]. - This early ossification is a key landmark in fetal skeletal development and is consistently taught across medical curricula. *Mandible* - The **mandible** begins ossification around the **6th week of gestation**, shortly after the clavicle [1]. - While it is one of the earliest bones to ossify, it is **not the first**. - It also undergoes intramembranous ossification [1]. *Femur* - The **femur**, a long bone, begins ossification around the **7th-8th week of gestation** [1]. - It ossifies via **endochondral ossification**, which typically occurs later than intramembranous ossification [1]. *Tibia* - The **tibia** also begins ossification around the **7th-8th week of gestation**. - Like the femur, it follows the endochondral ossification pathway.
Question 87: Oxyntic cells are present in -
- A. Pylorus
- B. Cardia
- C. Body (Correct Answer)
- D. None of the options
Explanation: ***Body*** - **Oxyntic cells**, also known as **parietal cells**, are predominantly located in the **fundus and body** of the stomach [1], [2]. - These cells are responsible for secreting **hydrochloric acid (HCl)** and **intrinsic factor**, which are crucial for digestion and vitamin B12 absorption [1]. - The gastric glands in the body contain the highest concentration of parietal cells [2]. *Pylorus* - The pylorus is the distal part of the stomach that connects to the duodenum. - It primarily contains **G cells**, which secrete **gastrin**, a hormone that stimulates HCl secretion from parietal cells [3]. - Pyloric glands contain mainly mucus-secreting cells, with few or no parietal cells [2]. *Cardia* - The cardia is the region near the gastroesophageal junction (entrance of the stomach). - This area primarily contains **cardiac glands** with mucus-secreting cells that protect the esophageal lining from gastric acid reflux. - Parietal cells are sparse or absent in the cardia [2]. *None of the options* - This option is incorrect because the **body of the stomach** is the correct location for oxyntic cells.
Question 88: Which of the following vessels runs through the transverse mesocolon?
- A. Right colic artery
- B. Left colic artery
- C. Middle colic artery (Correct Answer)
- D. Iliocolic artery
Explanation: * **Middle colic artery** - The **middle colic artery** arises from the superior mesenteric artery and supplies the **transverse colon**, traversing between the two layers of the **transverse mesocolon** [1]. - Its location within the mesocolon makes it susceptible to injury during surgical procedures involving the transverse colon [2]. * *Right colic artery* - The **right colic artery** supplies the **ascending colon** and the right colic flexure, typically lying within retroperitoneal tissue and not the transverse mesocolon itself [2]. - It arises from the superior mesenteric artery but branches to supply structures primarily to the right side of the abdominal cavity. * *Left colic artery* - The **left colic artery** arises from the **inferior mesenteric artery** and supplies the descending colon and the left colic flexure [1]. - This vessel is located within the retroperitoneum and is not associated with the transverse mesocolon. * *Iliocolic artery* - The **iliocolic artery** is a terminal branch of the superior mesenteric artery, supplying the **ileum, cecum, appendix**, and beginning of the ascending colon. - It descends retroperitoneally to reach these structures and does not traverse the transverse mesocolon.
Question 89: Floor of Petit triangle is formed by?
- A. Internal oblique muscle (Correct Answer)
- B. Sacrospinalis muscle
- C. Rectus abdominis muscle
- D. Fascia Transversalis layer
Explanation: ***Internal oblique muscle*** - The **Petit triangle** (lumbar triangle) is a landmark defined by the **latissimus dorsi posteriorly**, the **external oblique anteriorly**, and the **iliac crest inferiorly**. - Its **floor** is consistently formed by the **internal oblique muscle**, which lies deep to the external oblique [1]. *Sacrospinalis muscle* - The **sacrospinalis muscle** (erector spinae) is part of the deep back muscles, located medial to the Petit triangle. - It forms part of the **vertebral column's musculature** and is not directly associated with the floor of the Petit triangle. *Rectus abdominis muscle* - The **rectus abdominis muscle** is located medially in the anterior abdominal wall [1]. - It is distinct from the lateral abdominal wall muscles that form the boundaries and floor of the Petit triangle. *Fascia Transversalis layer* - The **fascia transversalis** is a deeper fascial layer lining the abdominal wall. - While it's deep to the internal oblique, the **muscle itself** forms the immediate anatomical floor of the Petit triangle.
Physiology
1 questionsLabour pain in uterus is carried by
NEET-PG 2015 - Physiology NEET-PG Practice Questions and MCQs
Question 81: Labour pain in uterus is carried by
- A. Sympathetic nerves (Correct Answer)
- B. Pudendal nerve
- C. Parasympathetic nerves
- D. Splanchnic nerve
Explanation: ***Sympathetic nerves*** - Pain signals from the **uterus** during the first stage of labor (cervical dilation and uterine contractions) are transmitted via **visceral afferent fibers that accompany the sympathetic nerves** through the **hypogastric plexus**. - These fibers synapse in the **thoracolumbar spinal cord** at **T10-L1 segments**, leading to referred pain in these dermatomes. - The pathway is: Uterus → Uterine plexus → Superior hypogastric plexus → Sympathetic chain → T10-L1 dorsal roots. *Splanchnic nerve* - While visceral afferents do travel with splanchnic nerves in the thoracoabdominal region, for **uterine pain** specifically, the standard medical terminology refers to **sympathetic nerves** and the **hypogastric plexus** as the primary pathway. - Splanchnic nerves typically refer to thoracic sympathetic contributions (T5-T12) to upper abdominal viscera. *Pudendal nerve* - The **pudendal nerve (S2-S4)** primarily innervates the perineum, external genitalia, and pelvic floor structures. - It transmits pain during the **second stage of labor**, particularly with stretching of the perineum and vaginal distension, but **not from the uterus itself**. *Parasympathetic nerves* - **Parasympathetic innervation (S2-S4 via pelvic splanchnic nerves)** to the uterus influences motor function but does **not transmit nociceptive (pain) signals** during labor. - These nerves are involved in visceral reflexes and efferent control, not the primary afferent pain pathway.