Head And Neck

Question 1

Different parts and blood supply of thyroid gland

Answer 1

Thymus right and left lobe
Superior thyroid artery branch of external carotid artery
Inferior thyroid artery branch of thyrocervical trunk
Thyroid ima artery branch of brachiocephalic or aortic arch

Venous
Superior and middle thyroid vein drain to internal jugular
Inferior thyroid vein to brachiocephalic vein

Question 2

Embryonic development of thyroid

Answer 2

The thyroid gland develops from the foramen caecum (⅔ along the length of tongue from the tip) to pass forward and loop around beneath the hyoid bone.
Incomplete descent → lingual or pyramidal thyroid
Incomplete closure of the pathway of descent → thyroglossal cyst

Question 3

Nerves at risk during thryoidectomy and consequences

Answer 3

Recurrent Laryngeal Nerve (RLN)

Function:
• Motor: All intrinsic laryngeal muscles (except cricothyroid)
• Sensory: Below vocal cords, upper trachea

Course:
• In tracheoesophageal groove
• Close to inferior thyroid artery

Injury Causes:
• Over-dissection near Berry’s ligament
• Ligating inferior thyroid artery too close to gland

Clinical Picture:
• Unilateral: Hoarseness, weak voice
• Bilateral: Stridor, airway obstruction (emergency!)

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2. External Branch of Superior Laryngeal Nerve (EBSLN)

Function:
• Motor: Cricothyroid muscle (tenses vocal cords → pitch control)

Course:
• Close to superior thyroid artery, often deep and not visible

Injury Causes:
• During ligation of superior thyroid vessels

Clinical Picture:
• Voice fatigue
• Loss of high pitch (especially noticed in singers/public speakers)
• Normal speech preserved

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3. Cervical Sympathetic Chain

Function:
• Autonomic (sympathetic supply to head and neck structures)

Course:
• Posterior to carotid sheath, along prevertebral fascia

Injury Causes:
• Deep or lateral dissection
• Retraction or trauma during large goiter or malignancy surgery

Clinical Picture (Horner’s Syndrome):
• Ptosis
• Miosis
• Anhidrosis
• Enophthalmos (less common)

Question 4

What is the supply of the recurrent laryngeal nerve (RLN)?

Answer 4

• Motor: All intrinsic muscles of larynx except cricothyroid
• Sensory: Below vocal cords and upper trachea
• Branch of vagus nerve (CN X)
• Loops around:
• Right RLN: Subclavian artery
• Left RLN: Aortic arch