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The neck contains several vital structures arranged in layers and compartments, including:
Visceral structures: thyroid, parathyroid glands, trachea, and oesophagus
Vascular structures: carotid arteries and jugular veins
Neural structures: cervical sympathetic trunk and cranial nerves IX–XII
Muscular and fascial planes that divide and protect these components.
The thyroid is an endocrine gland shaped like a butterfly, located in the lower part of the anterior neck.
Function:
Regulates basal metabolic rate (BMR)
Promotes growth and development
Plays a key role in calcium metabolism
It is the only gland in the body that uses iodine to synthesize hormones (T₃ and T₄).
Right and left lobes connected by a thin isthmus
Occasionally a pyramidal lobe extends upwards from the isthmus
A fibrous/muscular band called levator glandulae thyroideae may connect the isthmus or pyramidal lobe to the hyoid bone
Lies anterior to C5–T1 vertebrae, embracing the upper trachea
Isthmus:
Lies opposite 2nd–4th tracheal rings
Lobes:
Extend from middle of thyroid cartilage to 6th tracheal ring
True capsule: condensation of gland’s connective tissue
False capsule: derived from pretracheal fascia
Posterior surface related to:
Carotid sheath and its contents
Parathyroid glands
Recurrent laryngeal nerve
Arteries:
Superior thyroid artery – from external carotid
Inferior thyroid artery – from thyrocervical trunk
Thyroid ima artery (inconstant) – from brachiocephalic trunk
Veins:
Superior and middle thyroid veins → internal jugular vein
Inferior thyroid vein → left brachiocephalic vein
Sympathetic: from middle and inferior cervical ganglia
Parasympathetic: via vagus nerve
Recurrent laryngeal nerve lies in the tracheoesophageal groove near the gland — at surgical risk.
Reflect sternocleidomastoid laterally and cut sternothyroid muscle to expose thyroid.
Identify:
Isthmus over 2nd–4th tracheal rings
Lateral lobes on either side
Superior and inferior thyroid arteries
Recurrent laryngeal nerves posteriorly
Parathyroid glands near posterior border
Non-inflammatory enlargement of thyroid gland.
May compress:
Trachea → Dyspnoea
Oesophagus → Dysphagia
Recurrent laryngeal nerve → Hoarseness
During surgical removal, care to:
Ligate superior thyroid artery close to gland (avoid external laryngeal nerve injury)
Avoid ligation of inferior thyroid artery (to preserve recurrent laryngeal nerve)
Preserve parathyroid glands
Present in about 50% of people; represents remnant of the thyroglossal duct.
Midline cyst due to persistence of thyroglossal duct; moves with tongue protrusion.
May be found anywhere along thyroglossal duct pathway, even at the base of tongue (lingual thyroid).
The thyroid gland is composed of numerous follicles, separated by thin connective tissue septa.
Each follicle is roughly spherical and filled with colloid material.
Follicular cells (principal cells):
Lined by simple cuboidal epithelium.
Synthesize and secrete thyroglobulin, precursor of thyroid hormones (T₃, T₄).
Epithelium becomes columnar when active and squamous when inactive.
Parafollicular cells (C cells):
Found between follicles or in follicular basement membrane.
Secrete calcitonin, which lowers blood calcium by inhibiting osteoclastic activity.
Stroma:
Rich in capillaries, elastic fibers, and connective tissue.
Highly vascular to facilitate hormone transport.
Origin: Endodermal thickening in the floor of the primitive pharynx (between tuberculum impar and copula).
It descends through the thyroglossal duct to its final position in the neck.
The foramen caecum of the tongue marks the site of origin.
The pyramidal lobe represents the persistent upper part of thyroglossal duct.
Occasionally, thyroid tissue remains along the path (lingual, suprahyoid, or substernal thyroid).
Time of development: Begins in 4th week of intrauterine life.
Four small, oval, yellowish-brown glands on posterior surface of the thyroid gland.
Arranged as:
Two superior parathyroids
Two inferior parathyroids
Shape: Ovoid
Size: About 6 × 3 × 2 mm
Weight: 30–50 mg each
Each lies within the capsule of thyroid, on its posterior aspect.
The recurrent laryngeal nerve runs near the inferior parathyroids.
Artery: Inferior thyroid artery
Vein: Parathyroid veins → thyroid venous plexus
Nerve Supply: Sympathetic from middle and inferior cervical ganglia
Cells:
Chief (principal) cells: Small, pale-staining cells producing parathormone (PTH).
Oxyphil cells: Larger, acidophilic cells; increase in number with age; function uncertain.
Stroma: Delicate connective tissue with rich vascular network.
Function: PTH increases blood calcium by stimulating bone resorption and renal calcium reabsorption.
Hypoparathyroidism:
Occurs accidentally after thyroidectomy if parathyroids are removed.
Causes hypocalcaemia, leading to tetany (muscle spasms).
Hyperparathyroidism:
Caused by adenoma or hyperplasia.
Leads to hypercalcaemia and bone resorption (osteitis fibrosa cystica).
A bilobed lymphoepithelial organ in the superior and anterior mediastinum, extending into the neck in children.
Functions in T-lymphocyte (T-cell) maturation and immune development.
Involution: After puberty, it gradually shrinks and is replaced by fatty tissue.
Right and left lobes, separated by connective tissue septa into lobules.
Each lobule has:
Cortex: Densely packed with lymphocytes.
Medulla: Paler, with fewer lymphocytes and Hassall’s corpuscles (epithelial reticular cells).
Capsule: Thin connective tissue layer enclosing each lobe.
Cortex: Densely packed with small lymphocytes and epithelial reticular cells.
Medulla: Contains fewer lymphocytes and numerous Hassall’s corpuscles—concentric, eosinophilic, keratinized epithelial structures.
Function:
Site of T-lymphocyte differentiation and maturation.
Secretes thymosin and thymopoietin, promoting immune cell development.
Thymus:
Develops from endoderm of the ventral wing of the third pharyngeal pouch (during 6th week).
The two thymic primordia fuse in the midline to form the bilobed gland.
Parathyroid glands:
Superior parathyroids – from fourth pharyngeal pouch.
Inferior parathyroids – from third pharyngeal pouch (descend with thymus).
Final positions: posterior surface of thyroid gland.
Migration: Failure of descent leads to ectopic parathyroids, sometimes within thymus or carotid sheath.
Origin:
Right side → from brachiocephalic trunk.
Left side → directly from arch of aorta.
Extent: From its origin to the outer border of the first rib where it continues as the axillary artery.
Parts (3 by scalenus anterior):
First part – from origin to medial border of scalenus anterior.
Second part – posterior to scalenus anterior.
Third part – from lateral border of scalenus to outer border of first rib.
Branches:
First part → vertebral a., internal thoracic a., thyrocervical trunk.
Second part → costocervical trunk.
Third part → no branch (occasionally suprascapular or dorsal scapular a.).
Relations (anterior–posterior–superior–inferior):
Anteriorly → internal jugular & subclavian veins, vagus nerve.
Posteriorly → pleura, apex of lung.
Superiorly → brachial plexus trunks.
Inferiorly → first rib and pleura.
Clinical Notes – aneurysm compresses brachial plexus → pain & paresthesia in upper limb.
Origin: Right from brachiocephalic trunk; left from arch of aorta.
Extent: From sternoclavicular joint to upper border of thyroid cartilage (C4) → divides into internal and external carotid arteries.
Relations: Enclosed in carotid sheath with internal jugular vein (lateral) and vagus nerve (posterior between them).
Pulsation: Felt between trachea and sternocleidomastoid at C6 level.
Clinical Notes – carotid sinus (baroreceptor) and carotid body (chemoreceptor) at bifurcation; sensitive to pressure → bradycardia or syncope on massage.
Course: Ascends deep to posterior belly of digastric & stylohyoid, enters carotid canal → cranial cavity.
No branches in neck.
Supplies: brain, eye (through ophthalmic a.).
Continuation of axillary vein at outer border of first rib.
Passes in front of scalenus anterior to join internal jugular vein forming the brachiocephalic vein.
Has a valve near its termination.
Clinical Note: Often used for central venous catheterization; injury can cause pneumothorax due to close pleural relation.
Continuation of sigmoid sinus in jugular foramen.
Descends within carotid sheath → joins subclavian vein behind sternoclavicular joint forming brachiocephalic vein.
Tributaries: inferior petrosal sinus, common facial, lingual, pharyngeal, superior and middle thyroid veins.
Clinical Note: Used for central venous pressure (CVP) monitoring; pulsation visible in right heart failure.
Formed by: union of subclavian and internal jugular veins behind sternoclavicular joint.
Right vein – short & vertical; Left – long & oblique across superior mediastinum → join to form superior vena cava.
Clinical Note: Enlarged thyroid or retrosternal goitre may compress left brachiocephalic vein → neck vein distension.
Descends between internal and external carotid arteries.
Lies deep to the styloid process and associated muscles (styloglossus, stylopharyngeus).
Runs with stylopharyngeus muscle, giving branches to it.
Tympanic branch (Jacobson’s nerve): to middle ear.
Carotid branch: to carotid sinus and carotid body (baroreceptor and chemoreceptor).
Pharyngeal branches: form pharyngeal plexus with vagus and sympathetic fibers.
Tonsillar branches: to palatine tonsil.
Lingual branches: to posterior one-third of tongue (taste + general sensation).
Sensory: pharynx, tonsil, posterior tongue, middle ear.
Motor: stylopharyngeus muscle.
Parasympathetic: parotid gland (via otic ganglion).
Clinical Note:
Lesion causes loss of gag reflex (afferent limb), dysphagia, and loss of taste in posterior 1/3 of tongue.
Descends within carotid sheath between internal jugular vein (lateral) and carotid arteries (medial).
Gives off pharyngeal, superior laryngeal, and recurrent laryngeal branches.
Pharyngeal branches: motor to pharyngeal constrictors and soft palate (except tensor palati).
Superior laryngeal nerve:
External branch → cricothyroid muscle.
Internal branch → mucosa above vocal cords.
Recurrent laryngeal nerve: supplies all intrinsic laryngeal muscles except cricothyroid.
Cardiac branches: to cardiac plexus.
Clinical Note:
Injury to recurrent laryngeal nerve → hoarseness or loss of voice.
Vagus lesion → dysphagia, loss of cough reflex (afferent limb), and deviation of uvula to opposite side.
Cranial part: joins vagus → supplies pharynx, palate, larynx.
Spinal part: main functional part.
Emerges from spinal cord (C1–C5) → enters skull via foramen magnum → exits through jugular foramen.
Passes obliquely down and backward, entering sternocleidomastoid then trapezius.
Function: Motor to sternocleidomastoid and trapezius.
Clinical Note:
Lesion → drooping of shoulder, difficulty in turning head to opposite side.
Continuation of thoracic sympathetic chain.
Lies behind carotid sheath, on prevertebral fascia.
Has three ganglia:
Superior cervical ganglion (C1–C4)
Middle cervical ganglion (C5–C6)
Inferior cervical ganglion (C7–C8) – often fuses with first thoracic → stellate ganglion.
Gray rami communicantes: to cervical spinal nerves.
Cardiac branches: superior, middle, and inferior cardiac nerves → cardiac plexus.
Pharyngeal branches: to pharyngeal plexus.
Vascular branches: form periarterial plexuses around carotid arteries.
Vasomotor, pilomotor, and secretomotor (sweat glands of head and neck).
Dilates pupil (via internal carotid plexus → long ciliary nerves).
Due to lesion of cervical sympathetic chain.
Features:
Ptosis (drooping eyelid)
Miosis (constricted pupil)
Anhidrosis (loss of sweating)
Enophthalmos (sunken eyeball)
Done for relief of pain or vascular spasm in upper limb and head (e.g., Raynaud’s disease).
During dissection, identify lymph nodes in:
Submental, submandibular, parotid, mastoid, and occipital regions.
Include deep cervical nodes and jugular lymph trunk at the root of the neck.
Occipital Nodes – at the apex of posterior triangle, drain posterior scalp.
→ Efferents → supraclavicular deep cervical nodes.
Mastoid (Posterior Auricular) Nodes – behind the ear, drain scalp above and behind auricle.
→ Efferents → upper deep cervical nodes.
Parotid Nodes – on and within parotid gland, drain eyelids, external ear, and scalp anterior to ear.
→ Efferents → upper deep cervical nodes.
Submandibular Nodes – beneath mandible, over submandibular gland.
→ Drain:
Forehead (center)
Nose and paranasal sinuses (frontal, maxillary, ethmoidal)
Inner canthus of eye
Upper lip, anterior cheek, gums, and teeth
Outer part of lower lip and teeth
Anterior two-thirds of tongue (except tip)
Receive efferents from submental nodes
→ Efferents → jugulo-omohyoid and jugulodigastric nodes.
Submental Nodes – below chin; drain tip of tongue, central lower lip, and anterior floor of mouth.
→ Efferents → deep cervical nodes (both sides).
Anterior Cervical Nodes – along anterior jugular vein; drain skin below hyoid.
Lateral Superficial Cervical Nodes – along external jugular vein, over sternocleidomastoid; drain lower parotid region and skin near jaw angle.
Upper Lateral (Jugulodigastric Node)
Below posterior belly of digastric.
Main drainage: palatine tonsil, pharynx, and posterior tongue.
Middle Lateral Nodes
Around internal jugular vein.
Drain thyroid and parathyroid glands and larynx via prelaryngeal, pretracheal, and paratracheal nodes.
Lower Lateral (Jugulo-omohyoid Node)
Above omohyoid tendon; main node of tongue drainage.
Posterior Triangle Nodes
Around spinal accessory nerve.
Drain posterior scalp and neck.
Retropharyngeal Nodes
Behind buccopharyngeal fascia, in front of prevertebral fascia.
Drain pharynx, nasal cavity, palate, auditory tube.
Efferents → upper deep cervical nodes.
Prelaryngeal and Pretracheal Nodes
Over cricothyroid membrane and in front of trachea.
Drain larynx, trachea, and thyroid isthmus.
Paratracheal Nodes
Along sides of trachea and oesophagus with recurrent laryngeal nerves.
Drain trachea, larynx, thyroid, and oesophagus.
Jugular Lymph Trunks (Right and Left):
Formed by efferents of deep cervical nodes.
Right trunk: opens into right lymphatic duct or directly into right venous angle.
Left trunk: opens into thoracic duct.
Thoracic Duct:
Largest lymphatic channel.
Terminates at left jugulosubclavian angle (junction of left internal jugular and subclavian veins).
Arch lies ~3–4 cm above clavicle, in front of C7 transverse process.
Relations:
Anterior – left common carotid artery, vagus, internal jugular vein.
Posterior – vertebral vessels, sympathetic trunk, thyrocervical trunk.
Enlarged in tonsillitis or pharyngitis (“tonsillar node”).
Enlarged in carcinoma of the tongue (“main node of tongue”).
Enlarged in infections of face, lips, or oral cavity.
Metastatic spread in laryngeal, thyroid, or tongue cancers.
Enlargement indicates abdominal malignancy, often gastric carcinoma.
The styloid apparatus is a set of four structures connected to the styloid process of the temporal bone:
Styloglossus muscle
Stylohyoid muscle
Stylopharyngeus muscle
Stylohyoid ligament
Origin: Styloid process of temporal bone.
Insertion: Side of tongue blending with intrinsic muscles.
Nerve supply: Hypoglossal nerve (XII).
Action: Retracts and elevates the tongue during swallowing.
Origin: Styloid process.
Insertion: Hyoid bone; splits around the intermediate tendon of digastric.
Nerve supply: Facial nerve (VII).
Action: Elevates and retracts hyoid bone, elongating the floor of the mouth.
Origin: Styloid process.
Insertion: Posterior border of thyroid cartilage and pharyngeal wall.
Nerve supply: Glossopharyngeal nerve (IX).
Action: Elevates pharynx during swallowing and speech.
Fibrous band extending from styloid process to lesser cornu of hyoid bone.
Occasionally ossified → called the epihyal bone (in some mammals).
The three muscles diverge downward and forward, forming a fan-shaped arrangement.
Between them lie key neurovascular structures:
Glossopharyngeal nerve (IX) between stylopharyngeus and styloglossus.
External carotid artery and facial artery pass near stylohyoid.
Coordinates swallowing movements — tongue elevation, pharyngeal elevation, and hyoid retraction occur sequentially.
Collectively, the styloid apparatus acts as a “suspensory framework” between skull and hyoid.
Eagle’s Syndrome:
Elongated styloid process or calcified stylohyoid ligament causes neck and facial pain, dysphagia, or earache due to pressure on glossopharyngeal nerve.
Diagnosed by palpation in the tonsillar fossa or radiographs.
Major arteries of the head and neck arise from aortic arches associated with the pharyngeal arches in the embryo.
There are six pairs of arches, though not all persist.
| Arch | Derivative Artery/Structure |
|---|---|
| 1st arch | Part of maxillary artery |
| 2nd arch | Stapedial artery (mostly disappears) |
| 3rd arch | Common carotid artery and proximal part of internal carotid artery |
| 4th arch (right) | Right subclavian artery (proximal part) |
| 4th arch (left) | Arch of aorta |
| 5th arch | Rudimentary / disappears |
| 6th arch | Pulmonary arteries and (on left side) ductus arteriosus |
External carotid artery: sprouts from 3rd arch.
Subclavian artery: distal parts from 7th intersegmental artery.
Vertebral artery: formed by longitudinal anastomosis of 1st–6th intersegmental arteries.
Double aortic arch – persistence of both 4th arches → tracheal or oesophageal compression.
Right aortic arch – left 4th arch regresses; associated with situs inversus.
Coarctation of aorta – narrowing near ductus arteriosus.
Aberrant right subclavian artery – arises distal to left subclavian, passes behind oesophagus → dysphagia lusoria.
Mnemonic: “Stylo Gave High Praise”
Stylo → Styloglossus
Gave → Glossopharyngeal nerve (nerve to stylopharyngeus)
High → Hypoglossal nerve (nerve to styloglossus)
Praise → Facial nerve (nerve to stylohyoid)
This helps recall all three styloid muscles and their different cranial nerve supplies:
Styloglossus → Hypoglossal (XII)
Stylohyoid → Facial (VII)
Stylopharyngeus → Glossopharyngeal (IX)
Mnemonic: “Max Stays Calm, Often Silent, Patiently”
Max → 1st arch → Maxillary artery
Stays → 2nd arch → Stapedial artery
Calm → 3rd arch → Common & Internal carotid arteries
Often → 4th arch → Aortic arch (left), Right subclavian (right)
Silent → 5th arch → Disappears (no derivative)
Patiently → 6th arch → Pulmonary arteries + Ductus arteriosus
The styloid process develops from the Reichert’s cartilage of the 2nd pharyngeal arch.
Eagle’s syndrome results from elongation of styloid process or ossification of stylohyoid ligament, compressing cranial nerves IX or X.
The styloid apparatus is closely related to the parapharyngeal space, which contains vital neurovascular structures.
The 3rd aortic arch is responsible for forming both the common and proximal internal carotid arteries.
The external carotid artery arises as a sprout from the 3rd aortic arch.
The right subclavian artery is derived from 4th arch (proximal) + right dorsal aorta (middle) + 7th intersegmental artery (distal).
The left 4th arch forms the arch of aorta between left common carotid and left subclavian origins.
The 6th aortic arches give rise to pulmonary arteries; the left one retains its distal connection as the ductus arteriosus.
Ductus arteriosus becomes ligamentum arteriosum after birth.
Vertebral artery develops from longitudinal anastomosis between first six intersegmental arteries.
Answer:
Eagle’s Syndrome (Elongated Styloid Process Syndrome)
Explanation:
Caused by elongation or ossification of the styloid process or stylohyoid ligament.
The elongated process irritates nearby structures such as:
Glossopharyngeal nerve (IX) → throat and ear pain
Internal carotid artery → headache or neck pain
Pain increases during swallowing, yawning, or tongue movement.
Diagnosis: palpation in the tonsillar fossa reproduces the pain.
Treatment: surgical shortening of styloid process (styloidectomy).
Answer:
Ossified Stylohyoid Ligament
Explanation:
The stylohyoid ligament connects the styloid process to the lesser cornu of hyoid bone.
Ossification makes it rigid and may compress adjacent nerves (IX, X, XII).
Can produce symptoms similar to Eagle’s syndrome.
Answer:
Aberrant Right Subclavian Artery (Arteria Lusoria)
Explanation:
Caused by persistence of right 7th intersegmental artery and distal right dorsal aorta, with regression of right 4th arch and proximal dorsal aorta.
The artery arises distal to the left subclavian from the descending aorta, and passes behind oesophagus.
Leads to dysphagia lusoria (difficulty in swallowing due to vascular compression).
Answer:
Left 6th Aortic Arch
Explanation:
The ductus arteriosus, derived from the distal part of the left 6th aortic arch, connects the pulmonary artery to the aorta in the fetus.
After birth, it normally closes to form the ligamentum arteriosum.
Failure to close results in PDA, causing left-to-right shunt and cyanosis.
Answer:
Retrosternal (Substernal) Goitre
Explanation:
The left brachiocephalic vein lies behind the manubrium sterni and in front of large arteries.
An enlarged thyroid gland extending into the thorax can compress it → venous congestion and neck swelling.
The styloid apparatus consists of:
Three muscles — Styloglossus, Stylohyoid, Stylopharyngeus
One ligament — Stylohyoid ligament
Styloglossus → Hypoglossal nerve (XII)
Stylohyoid → Facial nerve (VII)
Stylopharyngeus → Glossopharyngeal nerve (IX)
Acts as a coordinated functional unit during swallowing and speech, elevating the tongue, pharynx, and hyoid bone in sequence.
Helps stabilize the upper neck by suspending the hyoid from the skull.
A condition caused by elongation of the styloid process or calcification of the stylohyoid ligament.
Produces throat or ear pain, dysphagia, and facial discomfort, especially during swallowing or tongue movement.
Pain radiates along glossopharyngeal or vagus nerve distribution.
Develops from Reichert’s cartilage of the second pharyngeal (hyoid) arch.
Forms the common carotid artery and proximal internal carotid artery.
External carotid develops as a sprout from it.
Right side: proximal part → right pulmonary artery; distal part disappears.
Left side: proximal part → left pulmonary artery; distal part → ductus arteriosus (later ligamentum arteriosum).
Regression of the right 4th arch and proximal dorsal aorta, with persistence of right 7th intersegmental artery.
The artery arises from the aortic arch and passes behind the oesophagus.
1st arch → part of maxillary artery.
2nd arch → stapedial and hyoid arteries (mostly disappear).
Becomes the ligamentum arteriosum, a fibrous band connecting the pulmonary artery to the aorta.
Persistence of both right and left 4th aortic arches, forming a vascular ring that compresses trachea and oesophagus.
1. Which of the following structures does not form part of the styloid apparatus?
A. Styloglossus
B. Stylohyoid
C. Stylopharyngeus
D. Stylomastoid ligament
✅ Answer: D. Stylomastoid ligament
Explanation: Only the stylohyoid ligament is part of the apparatus; no stylomastoid ligament exists.
2. The stylohyoid ligament connects which two structures?
A. Styloid process and body of hyoid bone
B. Styloid process and lesser cornu of hyoid bone
C. Styloid process and greater cornu of hyoid bone
D. Mastoid process and hyoid bone
✅ Answer: B. Styloid process and lesser cornu of hyoid bone
3. The styloid process develops from which embryological structure?
A. Meckel’s cartilage
B. Reichert’s cartilage
C. Mandibular arch
D. Fourth pharyngeal arch cartilage
✅ Answer: B. Reichert’s cartilage
Explanation: Reichert’s cartilage belongs to the second pharyngeal arch and gives rise to the styloid process and part of the hyoid apparatus.
4. The nerve supply of stylopharyngeus muscle is —
A. Hypoglossal nerve
B. Glossopharyngeal nerve
C. Facial nerve
D. Mandibular nerve
✅ Answer: B. Glossopharyngeal nerve
5. Eagle’s syndrome is due to —
A. Elongation of styloid process
B. Ossification of stylohyoid ligament
C. Compression of glossopharyngeal nerve
D. All of the above
✅ Answer: D. All of the above
Explanation: The elongated or ossified styloid process compresses nearby nerves (especially IX and X), causing pain during swallowing or head movement.
6. The 3rd aortic arch gives rise to —
A. External carotid artery
B. Internal carotid artery (proximal part)
C. Common carotid artery
D. Both B and C
✅ Answer: D. Both B and C
7. The 4th aortic arch on the right side forms —
A. Right subclavian artery (proximal part)
B. Arch of aorta
C. Pulmonary artery
D. Vertebral artery
✅ Answer: A. Right subclavian artery (proximal part)
8. The 4th aortic arch on the left side forms —
A. Right subclavian artery
B. Arch of aorta
C. Pulmonary artery
D. Common carotid artery
✅ Answer: B. Arch of aorta
9. The 6th aortic arch gives rise to —
A. Pulmonary arteries and ductus arteriosus
B. Vertebral artery
C. Subclavian artery
D. Maxillary artery
✅ Answer: A. Pulmonary arteries and ductus arteriosus
10. The external carotid artery develops as a sprout from —
A. 1st aortic arch
B. 2nd aortic arch
C. 3rd aortic arch
D. 4th aortic arch
✅ Answer: C. 3rd aortic arch
11. Persistence of both right and left 4th arches results in —
A. Double aortic arch
B. Coarctation of aorta
C. Patent ductus arteriosus
D. Aberrant subclavian artery
✅ Answer: A. Double aortic arch
12. The ductus arteriosus connects —
A. Aorta to pulmonary veins
B. Aorta to left pulmonary artery
C. Pulmonary artery to aorta
D. Left atrium to pulmonary artery
✅ Answer: C. Pulmonary artery to aorta
13. The ductus arteriosus becomes which adult structure after birth?
A. Ligamentum teres
B. Ligamentum venosum
C. Ligamentum arteriosum
D. Median umbilical ligament
✅ Answer: C. Ligamentum arteriosum
14. Aberrant right subclavian artery passes behind oesophagus because of —
A. Persistence of right 4th arch
B. Regression of right 4th arch
C. Persistence of left 4th arch
D. Regression of left 6th arch
✅ Answer: B. Regression of right 4th arch
15. The first aortic arch forms —
A. Maxillary artery
B. Stapedial artery
C. Common carotid artery
D. Internal thoracic artery
✅ Answer: A. Maxillary artery
Q1. What is the styloid apparatus?
It is a group of structures derived from the second pharyngeal arch, consisting of:
Three muscles: Styloglossus, Stylohyoid, Stylopharyngeus
One ligament: Stylohyoid ligament
All are connected to the styloid process of the temporal bone.
Q2. Name the nerves supplying the muscles of the styloid apparatus.
Styloglossus → Hypoglossal nerve (XII)
Stylohyoid → Facial nerve (VII)
Stylopharyngeus → Glossopharyngeal nerve (IX)
Q3. From which pharyngeal arch does the styloid process develop?
From the second pharyngeal (hyoid) arch, specifically from Reichert’s cartilage.
Q4. What is the function of the styloid apparatus?
To coordinate movements of the tongue, pharynx, and hyoid bone during swallowing and speech.
Q5. What is Eagle’s syndrome?
A condition caused by elongation of the styloid process or ossification of the stylohyoid ligament, producing throat and ear pain, especially during swallowing or tongue movement.
Q6. What embryological anomaly causes an aberrant right subclavian artery?
Due to regression of the right 4th aortic arch and persistence of the right dorsal aorta, which makes the artery arise from the aortic arch and pass behind the oesophagus.
Q7. What does the 3rd aortic arch form?
The common carotid artery and proximal part of the internal carotid artery.
Q8. What are the derivatives of the 4th aortic arch?
Right side: proximal part of right subclavian artery
Left side: part of the arch of aorta
Q9. What does the 6th aortic arch form?
The pulmonary arteries, and on the left side, its distal part becomes the ductus arteriosus.
Q10. What is the fate of the ductus arteriosus after birth?
It closes to form the ligamentum arteriosum.
Q11. What does the external carotid artery develop from?
It develops as a sprout from the 3rd aortic arch.
Q12. What are the derivatives of the 1st and 2nd aortic arches?
1st arch: part of maxillary artery
2nd arch: stapedial and hyoid arteries (which mostly disappear)
Q13. What is the developmental basis of double aortic arch?
Persistence of both right and left 4th aortic arches, forming a vascular ring around the trachea and oesophagus.
Q14. Which aortic arch contributes to the ductus arteriosus?
The left 6th aortic arch.
Q15. Which nerve is at risk in Eagle’s syndrome?
The glossopharyngeal nerve (IX), due to proximity to the styloid process.
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