📚 Question Bank

The otic ganglion supplies the parotid gland.

The pterygopalatine ganglion (also known as Meckel's ganglion) supplies the lacrimal glands and palatal glands

The submandibular ganglion supplies the submandibular glands and sublingual glands.

The given case scenario is suggestive of parasympathetic stimulation of the salivary glands, causing the parasympathetic secretomotor fibres to increase salivary secretion.

The parasympathetic fibres to the parotid gland are carried by the lesser petrosal nerve.

Otic ganglion is a parasympathetic ganglion which supplies secretomotor fibres to the parotid gland and is present below the foramen ovale.

• Preganglionic fibres originate in the inferior salivatory nucleus and pass through the lesser petrosal nerve which is the continuation of the tympanic branch of the glossopharyngeal nerve.
• They relay in the otic ganglion.
• Postganglionic fibres pass by the communicating branches to the auriculotemporal nerve and supply the parotid gland.

The greater petrosal nerve carries secretomotor fibres to the pterygopalatine ganglion and supplies the lacrimal, nasal, and palatine glands.

Sympathetic supply to the parotid gland is derived from the plexus around the middle meningeal artery.

Sensory supply to the parotid gland is from the auriculotemporal nerve and to the parotid capsule is from the sensory fibres of greater auricular nerve.

The structure marked X is the submandibular gland. Lobes of the submandibular gland are divided by the mylohyoid muscle.

The submandibular gland is divided into a larger superficial and smaller deep part by

the mylohyoid muscle. They are continuous with each other around the posterior border of the mylohyoid.

Relations of the submandibul ar gland

Superficial relations Facial artery

Facial vein

Deep lingual vein Submandibular ganglion

Cervical branch of the facial nerve

Glossopharyngeal nerve Lingual nerve Hypoglossal nerve

Deep relations

Deep lingual vei n

Sublingual glan d

Lingual nerve

Hypoglossal ner ve

The extent of the thyroid gland is from vertebral levels A to D in the given image. It extends from vertebral levels C5 to T1.

Levels with respect to the tra cheal rings and vertebra

Lobes of the thyroid gland Isthmus of the thyroid gland

Thyroid cartilage to 4thtrach eal ringVertebral level-C5-T1

Opposite 2ndand 3rdtracheal rings

The given case scenario is suggestive of cerebral air embolism. Intra-operative injury to the superior or middle thyroid veins causes air to get sucked into them due to the negative venous pressure. The air embolus then travels up through the internal jugular vein into the cerebral venous circulation. Head-down position during surgery prevents air embolism.

Venous drainage of the thyroid gland:

• Superior and middle thyroid veins - drain into the internal jugular vein
• Inferior thyroid vein - drains into the brachiocephalic vein

The above clinical scenario is suggestive of postoperative hypoparathyroidism due to injury to the superior branch of the inferior thyroid artery.

The parathyroid glands are small yellowish-brown structures lying between the posterior border of the thyroid gland and its capsule. There are

• Two superior parathyroid glands
• Two inferior parathyroid glands

These are supplied by the superior branch of the inferior thyroid artery. They secrete parathormone which helps in the regulation of the serum calcium, by the release of calcium from bones.

All the muscles of the tongue are derived from occipital myotomes except palatoglossus. It is derived from the fourth pharyngeal arch.

Hence all the muscles of the tongue are supplied by the hypoglossal nerve except the palatoglossus muscle which is supplied by the pharyngeal plexus.

The given image shows carcinoma of the tongue involving the marginal part of the anterior 2/3rd of the tongue. Lymphatics from this region drain to unilateral submandibular lymph nodes.

All lymphatics from the tongue ultimately drain into deep cervical nodes along the internal jugular vein. Hence jugulo-omohyoid nodes are known as the lymph nodes of the tongue.

The given image shows a cleft palate. The sensory supply to the palate is not provided by the hypoglossal nerve. It is a pure motor nerve.

General sensation from most of the soft palate is carried by:

• Lesser palatine nerve (a branch of the maxillary nerve)
• Pharyngeal branches of the glossopharyngeal nerve
• Plexus around the tonsil (formed by tonsillar branches of the glossopharyngeal and lesser palatine nerves)

Taste sensation from the oral surface of the soft palate is carried by the lesser palatine nerve. The taste fibers initially travel in the greater petrosal nerve (a branch of the facial nerve) and pass through the pterygopalatine ganglion without synapsing.

All the muscles of the soft palate are supplied by the pharyngeal plexus (CN X), except for tensor veli palatini, which is supplied by the mandibular nerve.

The hard palate is supplied by the greater palatine and nasopalatine branches of the pterygopalatine ganglion.

The lower border of the pharynx is at the level of the sixth or seventh cervical vertebrae.

The pharynx extends from the cranial base to the lower border of the cricoid cartilage (at the level of the sixth or seventh cervical vertebra). It is divided into the nasopharynx, oropharynx, and laryngopharynx.

The given case scenario is suggestive of a middle ear infection i.e., otitis media as a complication of pharyngitis. This is due to the spread of the infection via the eustachian tube. It opens approximately behind the posterior end of the inferior turbinate, in the lateral wall of

the nasopharynx.

The eustachian tube connects the nasopharynx and the tympanic cavity in the middle ear. It is usually collapsed and opens during activities such as yawning or swallowing. Its function is to maintain the pressure in the middle ear cavity and drain any secretions from the middle ear.

Valleculae will not be seen here as they are a part of the oropharynx. èypopharynx/Laryngopharynx:

• It extends from the superior border of the epiglottis to the inferior border of the cricoid cartilage.
• It is separated from the oropharynx by the lateral glossoepiglottic folds.
• The anterior wall is made by the parts of the laryngeal inlet, and posterior surfaces of the arytenoid and cricoid cartilages.

Pyriform fossae are present between the aryepiglottic folds medially and thyroid cartilage, thyrohyoid membrane laterally. They serve as channels that direct the solid and liquid food from the oral cavity into the esophagus.

Clinical significance: ‡ranches of the internal laryngeal nerve lie beneath the mucous membrane of the piriform fossa. èence this site can be used for infiltrating the local anesthetics.

The given clinical scenario with a pulsion diverticulum on the barium swallow is suggestive of Zenker's diverticulum. It originates through Killian's dehiscence, which is a site of weakness present in the inferior constrictor muscle.

The inferior constrictor muscle is made up of 2 parts:

• Upper part - thyropharyngeus, made of oblique fibres.
• Lower part - cricopharyngeus, made of transverse fibres.

Between the two muscles, there is a potential gap which is called the pharyngeal dimple or Killian's dehiscence.

Another site of weakness in the pharyngeal wall is the Laimer's triangle, which is present between the cricopharyngeus and the longitudinal muscle of the oesophagus.

The correct order of the layers of the cerebral cortex from superficial to deep are:

• Molecular layer (Plexiform layer)
• External granular layer
• External pyramidal layer
• Internal granular layer - contains the outer band of Baillarger
• Ganglionic layer (Internal Pyramidal layer) - contains the inner band of Baillarger
• Multiform layer (Layer of Polymorphic cells)

The cells producing prolactin from the pituitary gland are stained by eosin.

The pituitary gland is divided into the pars anterior, pars intermedia and pars posterior (or pars nervosa).

The pars anterior (aka pars distalis) consists of chromophil cells and chromophobe cells. The chromophil cells have brightly staining granules in their cytoplasm. They include:

• Acidophil cells - stain with acidic dyes like eosin or orange G and appear pink on H and E
• stain. They are also called alpha cells. They include:
• Somatotrophs - producing growth hormone
• Lactotrophs - producing prolactin
• Basophil cells - stain with basic dyes like hematoxylin and appear blue on H and E stain. These cells are also periodic acid Schiff (PAS) stain positive. They are also called beta cells. They
• include:
• Corticotrophs - producing ACTH
• Thyrotrophs - producing TSH
• Gonadotrophs - producing FSH and LH

The chromophobe cells do not contain granules that stain and hence appear colorless on an H and E stain.

The pars intermedia contains colloid filled vesicles, which are remnants of the pouch of Rathke.

The pars posterior consists of nerve fibers from the neurons of the hypothalamus and specialized supporting cells called pituicytes.

All the above-mentioned cells except type II alveolar cells are included under the APUD cell system.

The APUD (Amine Precursor Uptake and Decarboxylation) cell system consists of cells scattered in different parts of the body, which take up precursor substances from the circulation and process them (by decarboxylation) to form amines or peptides. The APUD cell system is also called the diffuse neuroendocrine system.

Some of the important cells included under the APUD cell system are:

• Cells of the adenohypophysis
• Neurons in the hypothalamus that synthesize the hormones of the neurohypophysis
• Chief cells of the parathyroid glands
• C- cells of the thyroid
• Cells of the adrenal medulla
• Cells of the gastro-entero-pancreatic endocrine system which includes cells of pancreatic islets
• Glomus cells of the carotid bodies
• Melanocytes of the skin
• Renin producing cells of the kidneys
• Some cells in the pineal gland, the placenta, and modified myocytes of the heart called myoendocrine cells.

The structures marked in the above histological section of the lymph node are as follows:

1 - Capsule

2 - Subcapsular sinus

3 - Germinal centre

4 - Lymphoid nodule

5 - Trabeculae

Each lymph node consists of a connective tissue framework and of numerous lymphocytes of all types which are arranged in a stroma of reticulin fibers and cells. They form 3 major regions within each lymph node:

• Cortex - It contains subcapsular sinuses, lymphoid nodules, and densely packed lymphocytes.
• It stains darkly. Each nodule has a lightly stained germinal center surrounded by a zone of densely packed lymphocytes.
• Paracortex - It lacks nodules and has fewer lymphocytes. It is, therefore, lightly stained.
• Medulla - with prominent draining sinusoids adjacent to the hilum.

Given below is a histological section of a lymph node showing the cortex, paracortex, and medulla.

The arterioles present in the spleen divide into a number of straight vessels that are called penicilli.

The splenic artery after entering the hilum of the spleen divides into about five branches that enter the organ independently. Each branch divides and subdivides as it travels through the trabecular network. Arterioles arising from this network leave the trabeculae to pass into the inter-trabecular spaces.

The spleen is histologically composed of:

• White pulp - For some distance, each arteriole is surrounded by a dense sheath of lymphocytes.
• These lymphocytes constitute the white pulp of the spleen.
• Penicilli - The arteriole then divides into a number of straight vessels that are called
• penicilli.
• Ellipsoid - Each of the penicilli shows a localised thickening of its wall that is called an
• ellipsoid.
• The ellipsoid consists of concentric lamellae formed by aggregation of fibroblasts and macrophages.
• Ampulla - Distal to the ellipsoid, the vessel dilates to form an ampulla, the walls of which become continuous with the reticular framework.
• Red pulp - As a result, blood flows into spaces lined by reticular cells, coming into direct
• contact with lymphocytes there. The part of splenic tissue, which is infiltrated with blood in this way is called the red pulp.
• Sinusoids - Blood from spaces of the red pulp is collected by wide sinusoids that drain into veins in the trabeculae.

Stave cells: The sinusoids of the spleen are lined by a somewhat modified endothelium. The endothelial cells here are elongated and are shaped like bananas. They are referred to as stave cells.

The sample is most likely to be of the thymus because of the presence of the corpuscle of Hassal as seen in the image above.

These are small rounded structures formed from eosinophilic type VI epithelial reticular cells present in the medulla of the thymus. Each corpuscle has a central core formed by

degenerated epithelial cells appearing as pink stained hyaline mass. Around this mass, there is a wall formed by concentrically arranged epithelial cells which stain bright pink in H and E staining.

The structure marked X in the above given image of a section of ileum is the MALT (Mucosal associated lymphoid tissue), also known as gut-associated lymphoid tissue. These are seen as aggregated lymphatic follicle or Peyer's patch present in the submucosa of the ileum.

The mucosal associated lymphoid tissues are present in other regions as follows:

• Tonsils - near the junction of the oral cavity with the pharynx, as collections of lymphoid
• tissue.
• The largest of these are the right and left palatine tonsils, present on either side of the oropharyngeal isthmus.
• Solitary lymphatic follicles - small collections of lymphoid tissue, similar in structure to the follicles of lymph nodes, present anywhere along the length of the gut.
• Aggregated lymphatic follicles (Peyer’s patches) - larger aggregations of lymphoid tissue, each consisting of 10 to 200 follicles present in the small intestine.

The image below of an ileal section shows Peyer's patches within the submucosa.

The above histological image is that of the trachea as identified by the presence

of pseudostratified ciliated columnar epithelium lining, the serous and mucous glands and hyaline cartilage.

The histological section of the trachea shows the following structures:

• Respiratory epithelium
• Basement membrane
• Submucosal glands (both serous and mucous parts)
• Perichondrium
• Tracheal cartilage
• Trachealis muscle (smooth muscle).

The bronchi differ from the trachea in having plates rather than rings of cartilage, and in having a layer of smooth muscle between the lamina propria and submucosa. In smaller branches, the amount of cartilage decreases, whereas the amount of smooth muscles increases. Also, the number of glands and goblet cells decreases.

The image below is a histological section of the bronchus.

The secretory cells bearing microvilli present in the epithelial lining of the alveoli are the type II pneumocytes.

The cells forming the lining epithelium of alveoli (also called pneumocytes) are mainly of the following types:

• Type I pneumocytes - large flattened cells which present a very thin diffusion barrier for gases.
• They are connected to each other by tight junctions.
• Type II pneumocytes - These are rounded secretory cells bearing microvilli on their free surfaces.
• These cells secrete the surfactant which decreases the surface tension between the thin alveolar walls, and thus prevents alveoli from collapsing during respiration.
• Type III alveolar cells (brush cells) - function is not clearly known.

The lower third of the oesophagus consists of only the smooth muscles. The oesophagus consists of the following layers:

• Mucosa - consists of a non-keratinized stratified squamous epithelium, lamina propria, and muscularis mucosae
• Submucosa - A special feature of the submucosa is the presence of compound tubuloalveolar mucous glands
• Muscularis externa - with the usual circular and longitudinal layers
• Upper 1/3rd - Only skeletal muscle fibres are present
• Middle 1/3rd - Both skeletal and smooth muscle fibres are present
• Lower 1/3rd - Only smooth muscle fibres are present
• Adventitia - Most of the oesophagus has a dense fibrous tissue covering called the adventitia.
• Only a short length of the oesophagus in the lower part has a peritoneal covering (serosa).