📚 Question Bank

Cholecysto-vena caval line (Cantlie line) separates the right and left lobe of the liver.

Cantlie line is an imaginary line that divides the liver into 2 planes. It extends from the midpoint of the gallbladder fossa at the inferior margin of the liver back to the midpoint of the inferior vena cava (IVC) and contains the middle hepatic vein.

The statement that the dermis is derived from ectoderm is false.

Dermis is derived from mesoderm and epidermis is derived from ectoderm.

Linea semilunaris is derived from the aponeurosis of the internal oblique muscle.

Pectineal ligament, inguinal ligament and lacunar ligament are derived from the external oblique aponeurosis.

The median lobe of the prostate forms the uvula vesicae.

Uvula vesicae is an elevation in the mucous membrane of the urinary bladder, behind the internal urethral orifice. It is often enlarged in benign prostatic hypertrophy.

Foot drop is caused by damage to the common peroneal nerve.

The common peroneal nerve is a component of the sciatic nerve. In the posterior thigh, it supplies the short head of the biceps femoris. It curves around the neck of the fibula deep to peroneus longus and divides into superficial and deep peroneal nerves.

• The superficial peroneal nerve innervates peroneus longus and peroneus brevis which are the evertors of the foot and to the skin over the dorsal area of the foot except for the first webspace and lateral side of the little toe.
• The deep peroneal nerve innervates all muscles of the anterior compartment which are the dorsiflexors of the foot, extensor digitorum brevis, first two dorsal interossei muscles, and skin between great and second toes.

Hence, injury to the common peroneal nerve will lead to:

• Weakness of dorsiflexion of foot or foot drop
• Loss of eversion
• Loss of extension of toes
• Sensory loss
• Anterior and lateral side of the leg
• Dorsum of the foot including the medial side of the great toe

Th image given below shows the course of common peroneal nerve.

It affects APL and EPB.

De Quervain's disease is a stenosing tenosynovitis of the extensor tendons of the first dorsal compartment, namely the extensor pollicis brevis (EPB) and abductor pollicis longus (APL). It is prominent among females, especially pregnant women. Most commonly the thumb is involved. Finkelstein's test is pathognomonic. The majority of the patients are treated medically, only a few require the surgical release of the 1st dorsal compartment.

The image given shows a midsagittal section of the brain. The structure marked B is the Fornix.

Levator veli palatini is not derived from the first pharyngeal arch.

All soft palate muscles including levator veli palatini are derived from the 4th pharyngeal arch and are supplied by the vagal plexus.

The First pharyngeal arch gives rise to:

• Muscles of mastication (temporalis, masseter, lateral and medial pterygoids)
• Mylohyoid
• Anterior belly of digastric
• Tensor tympani
• Tensor veli palatini and
• Anterior 2/3 of the tongue

The lateral boundary of the anatomical snuff box is formed by extensor pollicis brevis and abductor pollicis longus.

Boundaries of the anatomical snuffbox:

• Lateral wall:
• Abductor pollicis longus (APL)
• Extensor pollicis brevis (EPB)
• Medial wall:
• Extensor pollicis longus (EPL)
• Roof:
• Cephalic vein
• Superficial branch of the radial nerve
• Floor:
• Radial styloid, scaphoid, trapezium, and 1st metacarpal
• Only content: Radial artery

The cells marked in the above histological image are Purkinje cells.

Purkinje cells are the flask-shaped cells present in the Purkinje cell layer of the cerebellum. The cells are evenly spaced and are arranged in a single layer. A dendrite arises from the neck of each flask-shaped cell, which passes upward to enter the molecular layer, which then branches extensively to form a dendritic tree. The axon of each cell passes downwards, crosses the granular cell layer to enter the white matter. Axons of Purkinje cells are the only efferents of the cerebellar cortex.

They are inhibitory and use GABA as their neurotransmitter.

The inferior belly of the omohyoid muscle is not used as an anatomical landmark for the identification of the facial nerve trunk.

There are two methods for localization of the facial nerve trunk:

1. Anterograde method: The facial nerve trunk is identified based on the anatomical landmarks after it exits from the stylomastoid foramen. This includes:

• Tragal pointer/Conley's pointer - It is the inferior portion of the cartilaginous canal. The
• facial nerve trunk lies 1 cm deep and inferior to its tip.
• Posterior belly of digastric - The facial nerve lies superior to the upper border of the muscle.
• Squamotympanic fissure - It is a fissure in the temporal bone, which runs from TMJ to the tympanic cavity. The facial nerve runs through this fissure.
• Styloid process - The facial nerve lies superficial to it.
• Mastoid process - Upon drilling it, the nerve is identified proximally.

2. Retrograde method: The main branches of the facial nerve trunk are identified and are then traced proximally until the main tunk is identified. Some branches used for tracing the facial nerve trunk include:

• Buccal branch - It lies in relation to the parotid gland.
• Marginal mandibular branch - It lies in relation to the facial vessels.

The anatomical closure of the foramen ovale takes 1 month to a year. Given below are the fetal circulatory adjustments after birth:

Ductus venosus Foramen ovale

Ductus arterios us

Functional closure

After removal of the placenta

At birth - after breathing is in itiated

10–15 hours

Anatomical closu re

7 days

Months to years 10–21 days

A tumor of the uncinate process of pancreas affects the superior mesenteric artery.

The superior mesenteric artery arises from the abdominal aorta. It lies first behind the body of the pancreas and then in front of the uncinate process.

Relations of the other parts of pancreas:

Head of pancreas:

• Anterior:
• 1st part of the duodenum
• Origin of the transverse mesocolon
• Posterior:
• Right renal vein
• Right renal artery
• Inferior vena cava
• Common bile duct (which is embedded in the head)
• Right crus of the diaphragm
• Termination of the right gonadal vein
• Neck of the pancreas:
• Anterior:
• Lesser sac
• pylorus
• The anterior superior pancreaticoduodenal branch of the gastroduodenal artery
• Posterior:
• Portal vein
• Superior mesenteric vein
• Inferior mesenteric vein (in 1/3rd individuals)

Thrombosis of the superior cerebellar artery causes cerebellar lesion which presents with ataxia and incoordination.

Blood supply of cerebellum:

• Superior cerebellar artery
• Posterior inferior cerebellar artery
• Anterior inferior cerebellar artery

Sternothyroid and sternohyoid prevent the upward extension of the thyroid swelling through its attachment to the thyroid cartilage.

Pretracheal fascia encloses the thyroid gland and is attached to the larynx. This attachment is responsible for the movement of the enlarged thyroid gland on deglutition.

The thyrohyoid membrane is a fibro-elastic ligament, which arises from the superior margin of the thyroid cartilage, and gets attached to the hyoid bone. It facilitates the upward movement of the larynx during swallowing.

The ligament of Berry, also called the suspensory ligament extends from the cricoid cartilage to the thyroid. Its attachment prevents the thyroid gland from sinking down into the mediastinum.

The lumbricals and interossei muscles are affected.

The lumbricals and interossei muscles through their attachments to the dorsal digital expansions, cause:

• Flexion of the metacarpophalangeal (MCP) joints
• Extension of the interphalangeal (IP) joints

In cases of ulnar nerve injury, these muscles may get atrophied leading to the extension of MCP joints and flexion of IP joints.

Note: The ulnar nerve innervates all the intrinsic muscles of the hand, except for

• First and second lumbrical
• Abductor pollicis brevis
• Opponens pollicis
• Part of flexor pollicis brevis

Meiosis occurs in the adult ovary.

Meiosis takes place only in germ cells and results in the formation of haploid

gametes. Meiosis requires two cell divisions, meiosis I and meiosis II, to reduce the number of chromosomes to the haploid number of 23.

Option C: Spermatogenesis begins at puberty. Primordial germ cells (PGCs) remain dormant in the testis until puberty. At puberty, PGCs differentiate into spermatogonial stem cells. These spermatogonial stem cells then give rise to spermatogonia which marks the beginning

of spermatogenesis.

Options A and D: These are somatic cells that only undergo mitosis and not meiosis.

The long left recurrent laryngeal nerve is due to the persistence of the left 6th arch artery.

During the development, the laryngeal nerves initially arise below the 6th arch artery and cross here to innervate the intrinsic muscles of the larynx. As the larynx moves cranially relative to the aortic arch arteries, the recurrent laryngeal nerves on the right and left sides are caught under the 6th arch arteries.

On the right side, the distal 6th arch artery disappears. Since there is no 5th arch artery, the right recurrent laryngeal nerve is caught under the 4th arch artery which becomes the future

right subclavian artery.

On the left side, the 6th arch artery persists, which develops into ductus arteriosus, which later forms ligamentum arteriosum. Due to the persistence of the 6th arch artery, the left recurrent laryngeal nerve is caught under it and therefore, has a relatively long course.

The muscle marked in the image is levator scapulae, which is innervated by the dorsal scapular nerve.

The dorsal scapular nerve also innervates the rhomboid major and minor. The suprascapular nerve innervates supraspinatus and infraspinatus, and the subscapular nerves supply teres major and subscapularis.

The above clinical scenario is suggestive of lateral pontine syndrome which occurs due to a lesion located at lateral pons.

Lateral pontine syndrome occurs due to the involvement of the anterior inferior cerebellar artery.

• Ipsilateral manifestations include:
• CN VII: Facial paralysis
• CN V: loss of pain and temperature sensation over the face.
• Vestibular nerve or nucleus: Horizontal and vertical nystagmus, vertigo, nausea, vomiting, oscillopsia.
• Auditory nerve or cochlear nucleus: Deafness, tinnitus.
• Middle cerebellar peduncle: Ataxia of limb and gait.
• Contralateral manifestations include:
• Spinothalamic tract: Loss of pain and temperature sensation over the body.

Medial pontine syndrome occurs due to the involvement of the paramedian branch of the basilar artery.

• Ipsilateral manifestation
• CN VI: Diplopia(lateral rectus muscle paralysis - the affected eye looks downwards and inwards)
• Vestibular nucleus: Nystagmus.
• Middle cerebellar peduncle: Ataxia of limb and gait.
• Contralateral manifestation
• Corticobulbar and corticospinal tract: Paralysis of face, arm, and leg.
• Medial lemniscus: loss of touch and proprioception from the body.

Ligation of the common hepatic artery will cause impairment in the blood supply through its branches i.e right gastric artery and right gastroepiploic artery.

Blood supply of the stomach:

The arterial supply of the stomach is contributed exclusively by the branches of the celiac trunk. They are:

• Left gastric artery - Supplies the lesser curvature of the stomach
• Splenic artery- This further divides into:
• Short gastric arteries- Supplies the fundus of the stomach
• Left gastroepiploic artery- Supplies the greater curvature of the stomach
• Common hepatic artery, which gives the following branches
• Right gastric artery- Supplies the lesser curvature of the stomach
• Gastroduodenal artery- Right gastroepiploic artery arises from this and supplies the greater curvature of the stomach.

The joint marked in the image is the costotransverse joint, which is a synovial type of joint.

The joints between the 2nd to 7th costal cartilages and the sternum are synovial joints, as are the costovertebral and costotransverse joints. The joint between the 1st costal cartilage and manubrium is a fibrocartilaginous joint (synarthrosis).

The sign shown in the image is the popeye sign, which occurs due to the rupture of the tendon of the long head of the biceps brachii.

On flexing the elbow, the characteristic deformity appears due to the bulging of the muscle belly caused by the contraction of the unrestrained muscle.

The most likely primary cause of an enlarged inguinal lymph node is anal cancer.

Lymphatics from the anal canal distal to the dentate line (anal margin) drains into the inguinal lymph nodes. Lymphatics proximal to the dentate line (anal canal) drains into internal iliac lymph nodes through superior rectal lymphatics. Testicular cancer spreads to para-aortic nodes. Prostate cancer spreads to internal and external iliac nodes.

The image shows elastic cartilage.

The elastic cartilage contains individual or small groups of chondrocytes that are surrounded by type II collagen fibrils. However, much of the interterritorial matrix consists of fine yellow elastic fibres containing elastin protein. This distinguishes it from hyaline cartilage.