Pelvic Innervation — MCQs

10 questions

TRUE statement regarding nerve supply of adrenal gland:

"Overactivity of which of the nerves causes 'cissor gait', a condition characterized by one limb crossing in front of the other during stepping due to powerful hip adduction caused by continuous, unwanted nerve activity?"

Which of the following statements about the pudendal nerve is true?

Uterosacral ligament contains

Which of the following statements about the Levator Ani is false?

Which of the following is not a branch of the cervical plexus?

Which nerve is targeted in the nasociliary nerve block?

In a vehicle accident, the musculocutaneous nerve was completely severed, but still the person was able to weakly flex the elbow joint. All of the following muscles are responsible for this flexion, EXCEPT:

During a physical examination, a physician tests the strength of hip adduction against resistance. Which of the following nerves innervates the primary muscles responsible for this action?

Q10

Lacrimation is affected when facial nerve injury is at:

Pelvic Innervation Indian Medical PG Practice Questions and MCQs

Question 1: TRUE statement regarding nerve supply of adrenal gland:

A. Adrenal cortex has no nerve supply
B. Adrenal medulla has no nerve supply
C. Release of catecholamines is not affected by nerve supply
D. Preganglionic fibres from lower thoracic spinal segments bypass sympathetic chain (Correct Answer)

Explanation: ***Preganglionic fibres from lower thoracic & upper lumbar spinal segments bypass sympathetic chain*** - The adrenal medulla is innervated by **preganglionic sympathetic fibers** originating from the **T5-T11 spinal cord segments**, which travel through the splanchnic nerves and synapse directly on chromaffin cells, effectively bypassing the sympathetic chain ganglia [1], [2]. - This direct innervation allows for a **rapid, systemic catecholamine release** in response to stress. *Adrenal cortex has no nerve supply* - The **adrenal cortex** receives some **autonomic innervation**, primarily sympathetic, though it is less dense and its direct role in steroidogenesis is not fully understood. - While hormonal signals are primary for cortical regulation, nerve fibers are present and may modulate blood flow or cellular activity. *Adrenal medulla has no nerve supply* - The **adrenal medulla** is a modified sympathetic ganglion whose **chromaffin cells** are directly innervated by **preganglionic sympathetic fibers** [1], [2]. - This direct neural input is crucial for its rapid response in releasing **catecholamines** into the bloodstream. *Release of catecholamines is not affected by nerve supply* - The release of **catecholamines** (epinephrine and norepinephrine) from the **adrenal medulla** is directly and primarily controlled by **preganglionic sympathetic innervation** [1], [2]. - Without this nerve supply, the stress-induced release of these hormones would be severely impaired, highlighting the critical role of neural input.

Question 2: "Overactivity of which of the nerves causes 'cissor gait', a condition characterized by one limb crossing in front of the other during stepping due to powerful hip adduction caused by continuous, unwanted nerve activity?"

A. Femoral nerve
B. Inferior gluteal nerve
C. Obturator nerve (Correct Answer)
D. Tibial nerve

Explanation: ***Obturator nerve*** - The **obturator nerve** innervates the **adductor muscles of the thigh**, including the adductor longus, brevis, magnus, pectineus, and gracilis muscles. - Overactivity or spasticity of these muscles, often seen in conditions like **cerebral palsy** or **stroke**, leads to strong hip adduction, causing the legs to cross over in a **scissor gait** [1], [2]. *Femoral nerve* - The femoral nerve primarily innervates the **quadriceps femoris muscle**, responsible for **knee extension** and hip flexion. - Its overactivity would lead to excessive knee extension, not hip adduction or a scissor gait. *Inferior gluteal nerve* - The **inferior gluteal nerve** exclusively innervates the **gluteus maximus muscle**, which is responsible for **hip extension** and external rotation. - Hyperactivity of this nerve would affect hip extension, not cause excessive hip adduction. *Tibial nerve* - The **tibial nerve** innervates the **posterior compartment muscles of the leg** and the intrinsic muscles of the foot. - Its primary actions involve **plantarflexion of the foot** and flexion of the toes, and its overactivity would not directly lead to hip adduction.

Question 3: Which of the following statements about the pudendal nerve is true?

A. Enters the pelvis through the lesser sciatic foramen only.
B. Runs in a canal formed by the levator ani fascia.
C. Has a dorsal nerve branch which provides sensory innervation to the clitoris/penis. (Correct Answer)
D. Has a dorsal branch which provides motor innervation to the glans penis.

Explanation: ***Has a dorsal nerve branch which provides sensory innervation to the clitoris/penis.*** - The **dorsal nerve of the clitoris** (in females) or **dorsal nerve of the penis** (in males) is a terminal branch of the pudendal nerve that provides the **primary sensory innervation** to the clitoris or glans penis. - This nerve travels along the dorsal surface of these structures and is responsible for sexual sensation. - Understanding this anatomy is clinically important for pudendal nerve blocks and surgical procedures in the perineal region. *Enters the pelvis through the lesser sciatic foramen only.* - The pudendal nerve actually **exits** the pelvis through the **greater sciatic foramen** inferior to the piriformis muscle, then immediately curves around the **ischial spine** and **re-enters** the perineum through the **lesser sciatic foramen**. - This characteristic course around the ischial spine is crucial for understanding pudendal nerve blocks, where local anesthetic is injected near the ischial spine. *Runs in a canal formed by the levator ani fascia.* - The pudendal nerve runs within the **pudendal canal (Alcock's canal)**, which is formed by a splitting of the **obturator internus fascia**, not the levator ani fascia. - This canal is located on the lateral wall of the ischiorectal fossa and is a key anatomical landmark for understanding pudendal nerve entrapment (cyclist's syndrome). *Has a dorsal branch which provides motor innervation to the glans penis.* - The **dorsal nerve of the penis** (or clitoris in females) provides **sensory innervation** to the glans, not motor innervation. - The **motor innervation** to perineal muscles (external anal sphincter, external urethral sphincter, bulbospongiosus, ischiocavernosus) comes from the **muscular branches** and **perineal nerve** branches of the pudendal nerve, not the dorsal nerve.

Question 4: Uterosacral ligament contains

A. Mainly smooth muscle
B. Contain uterine vessels
C. Sympathetic and parasympathetic nerves (Correct Answer)
D. Ureters

Explanation: ***Sympathetic and parasympathetic nerves*** - The **uterosacral ligaments** are a component of the pelvic connective tissue that extends from the cervix to the sacrum, richly innervated [1]. - These ligaments are crucial for providing **nervous input** to the uterus and surrounding organs, including both **sympathetic** and **parasympathetic fibers**. *Mainly smooth muscle* - While ligaments are connective tissue, the **uterosacral ligaments** are primarily composed of **collagen** and **elastic fibers**, with some smooth muscle components, but not "mainly" smooth muscle [1]. - Their primary function is support, not contraction, distinguishing them from structures predominantly composed of smooth muscle. *Contain uterine vessels* - The **uterine vessels** (arteries and veins) are primarily located within the **broad ligament** (specifically, in the mesometrium) as they approach the uterus from the lateral pelvic wall. - While there might be small anastomosing vessels, the main uterine supply does not run within the uterosacral ligaments. *Ureters* - The **ureters** course through the pelvic cavity to reach the bladder, but they are not contained within the uterosacral ligaments. - They pass more laterally, close to the lateral fornix of the vagina, superior to the uterine artery, often remembered by the phrase "**water under the bridge**."

Question 5: Which of the following statements about the Levator Ani is false?

A. Converges downwards & medially
B. Attached to the pelvic brim. (Correct Answer)
C. Made up of iliococcygeus, pubococcygeus, and puborectalis.
D. Supports pelvic viscera.

Explanation: Attached to the pelvic brim - This statement is **false** because the levator ani does not attach to the pelvic brim (the inlet of the true pelvis). - The levator ani originates from: the **posterior surface of the body of pubis**, the **tendinous arch of obturator fascia** (thickening of obturator fascia on lateral pelvic wall), and the **ischial spine**. - All these attachments are on the **lateral pelvic wall below the pelvic brim**, not at the pelvic brim itself. - The muscles insert into the **perineal body**, **anococcygeal ligament**, and walls of pelvic viscera. *Converges downwards & medially* - This statement is **true** - the levator ani muscles arise from lateral attachments on the pelvic sidewalls and converge **medially and downward** toward the midline. - This creates the characteristic **funnel-shaped pelvic diaphragm** that narrows inferiorly. - The fibers run inferomedially to form a muscular sling supporting pelvic structures. *Supports pelvic viscera* - This is the **primary function** of the levator ani muscle group [1]. - It forms a muscular floor that supports the **bladder, uterus/prostate, and rectum**, preventing prolapse. - The muscle maintains the position of pelvic organs against intra-abdominal pressure. *Made up of iliococcygeus, pubococcygeus, and puborectalis* - This statement is **correct** - the levator ani consists of three main components [1]: - **Puborectalis** - forms a sling around the anorectal junction, important for fecal continence [1]. - **Pubococcygeus** - middle portion, supports pelvic viscera [1]. - **Iliococcygeus** - most posterior portion, extends from ischial spine to coccyx [1].

Question 6: Which of the following is not a branch of the cervical plexus?

A. Suprascapular nerve (Correct Answer)
B. Supraclavicular nerve
C. Lesser occipital nerve
D. Greater auricular nerve

Explanation: ***Suprascapular nerve*** - The **suprascapular nerve** originates from the **brachial plexus** (specifically the upper trunk), not the cervical plexus. - It primarily innervates the **supraspinatus** and **infraspinatus muscles**. *Lesser occipital nerve* - The **lesser occipital nerve** is a cutaneous branch of the **cervical plexus** (C2) that supplies the skin behind the ear. - It provides sensory innervation to the **scalp posterior to the auricle**. *Greater auricular nerve* - The **greater auricular nerve** is a branch of the **cervical plexus** (C2, C3) and provides sensory innervation to the skin over the parotid gland, mastoid process, and auricle. - It supplies sensation to the **external ear** and the **angle of the mandible**. *Supraclavicular nerve* - The **supraclavicular nerves** (C3, C4) are cutaneous branches of the **cervical plexus** that provide sensory innervation to the skin over the shoulder and upper chest. - They provide sensory innervation to the skin overlying the **clavicle** and the **pectoral region**.

Question 7: Which nerve is targeted in the nasociliary nerve block?

A. Greater palatine nerve
B. Sphenopalatine nerve
C. Anterior ethmoidal nerve
D. Nasociliary nerve (Correct Answer)

Explanation: ***Nasociliary nerve*** - A nasociliary nerve block specifically targets the **nasociliary nerve** itself. - This block is used to anesthetize the sensory innervation of structures supplied by the nasociliary nerve, such as parts of the **nasal cavity**, **eyeball**, and **skin of the nose**. *Greater palatine nerve* - The **greater palatine nerve** supplies sensation to the posterior hard palate and is targeted in a **greater palatine nerve block**. - This nerve is a branch of the **maxillary nerve** and is primarily involved in dental and palatal anesthesia. *Sphenopalatine nerve* - The **sphenopalatine nerve**, or pterygopalatine ganglion, contains sensory fibers for the nasal cavity, palate, and pharynx, and its block is distinct from a nasociliary block. - A **sphenopalatine ganglion block** is mainly used for conditions like cluster headaches and facial pain, not for direct eyeball sensation. *Anterior ethmoidal nerve* - The **anterior ethmoidal nerve** is a branch of the nasociliary nerve, but a nasociliary nerve block targets the main trunk, which includes all its branches. - While the anterior ethmoidal nerve supplies the anterior part of the nasal septum and lateral wall, it is a **component** of the nasociliary innervation rather than the sole target.

Question 8: In a vehicle accident, the musculocutaneous nerve was completely severed, but still the person was able to weakly flex the elbow joint. All of the following muscles are responsible for this flexion, EXCEPT:

A. Flexor carpi ulnaris
B. Flexor carpi radialis
C. Pronator quadratus (Correct Answer)
D. Brachioradialis

Explanation: ***Pronator quadratus*** - The **pronator quadratus** primarily functions in **pronation of the forearm** and has no role in elbow flexion. - It is innervated by the **anterior interosseous nerve**, a branch of the median nerve, and not involved with elbow flexion. *Flexor carpi ulnaris* - While its main actions are **wrist flexion** and **adduction**, it can contribute *weakly* to elbow flexion due to its origin partially spanning the elbow joint. - It is innervated by the **ulnar nerve**. *Flexor carpi radialis* - The **flexor carpi radialis** acts as a primary **flexor of the wrist** and also assists in **abduction of the wrist**. - It provides a *minor* contribution to elbow flexion because it crosses the elbow joint, and is innervated by the **median nerve**. *Brachioradialis* - The **brachioradialis** is a significant elbow flexor, particularly when the forearm is in a **mid-prone position**. - It is innervated by the **radial nerve**, which explains why elbow flexion is still possible despite musculocutaneous nerve damage.

Question 9: During a physical examination, a physician tests the strength of hip adduction against resistance. Which of the following nerves innervates the primary muscles responsible for this action?

A. Sciatic nerve
B. Superior gluteal nerve
C. Femoral nerve
D. Obturator nerve (Correct Answer)

Explanation: ***Obturator nerve*** - The **obturator nerve** primarily innervates the **adductor muscles** of the thigh, including the adductor longus, adductor brevis, adductor magnus (adductor part), gracilis, and pectineus (variable innervation). - These muscles are responsible for **adducting the hip**, which is the action tested when a physician checks hip adduction strength against resistance. *Sciatic nerve* - The **sciatic nerve** innervates the **hamstring muscles** (semitendinosus, semimembranosus, biceps femoris) and all muscles below the knee. - It does not significantly contribute to the innervation of the primary hip adductors. *Superior gluteal nerve* - The **superior gluteal nerve** mainly innervates the **gluteus medius**, **gluteus minimus**, and **tensor fasciae latae** muscles. - These muscles are primarily involved in **hip abduction** and medial rotation, not adduction. *Femoral nerve* - The **femoral nerve** innervates the **quadriceps femoris muscles** (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) and the sartorius. - Its primary actions are **knee extension** and hip flexion, with no direct role in hip adduction.

Question 10: Lacrimation is affected when facial nerve injury is at:

A. Mastoid segment
B. Cerebellopontine angle
C. At Stylomastoid foramen
D. Geniculate ganglion (Correct Answer)

Explanation: ***Geniculate ganglion*** - The **greater petrosal nerve** branches from the facial nerve at the **geniculate ganglion** and carries preganglionic parasympathetic fibers to the **pterygopalatine ganglion**, which supplies the **lacrimal gland**. - An injury at or just distal to the **geniculate ganglion** (affecting the greater petrosal nerve) will specifically impair **lacrimation** while potentially sparing more distal functions. - This is the **most proximal intratemporal location** where isolated lacrimal dysfunction can occur, making it the classic answer for lacrimation deficits in facial nerve injuries. *Cerebellopontine angle* - A lesion at the **cerebellopontine angle (CPA)** affects the facial nerve **before entry into the internal acoustic meatus**, which is **proximal to the geniculate ganglion**. - While CPA lesions would technically affect lacrimation (along with ALL facial nerve functions), they are **too proximal and non-specific** for this question. - CPA lesions cause global facial nerve dysfunction (motor, taste, lacrimation, hyperacusis), not isolated lacrimal problems. - The question asks for the specific anatomical landmark associated with lacrimation deficits = **geniculate ganglion/greater petrosal nerve**. *Mastoid segment* - Injury to the facial nerve in the **mastoid segment** is **distal** to the origin of the greater petrosal nerve and the nerve to stapedius. - While it affects the **chorda tympani** (taste from anterior two-thirds of tongue) and motor function distal to it, **lacrimation is preserved**. *At Stylomastoid foramen* - The **stylomastoid foramen** is the exit point of the facial nerve from the skull. - Injury here causes **facial paralysis** (motor function to muscles of facial expression) but **spares lacrimation, taste, and stapedius function** as these nerves have already branched off proximally.

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