Human Anatomy
Deep Structures in the Neck
Deep neck anatomy for MBBS: thyroid and parathyroid glands, trachea and oesophagus, laryngeal nerves, cervical sympathetic chain and thoracic duct, mapped to NMC codes AN35.1 to AN35.10.
MedNext Academy | 3 min read
Deep Structures in the Neck
Deep neck anatomy for MBBS: thyroid and parathyroid glands, trachea and oesophagus, laryngeal nerves, cervical sympathetic chain and thoracic duct, mapped to NMC codes AN35.1 to AN35.10.
The deep structures in the neck chapter covers the thyroid and parathyroid glands, the trachea and oesophagus, the cervical sympathetic chain and the great vessels lying on the vertebral column. It is the anatomy behind thyroid surgery, voice change and Horner's syndrome.
High-yield: Deep Structures in the Neck
- The thyroid gland has two lobes joined by an isthmus that crosses the second to fourth tracheal rings.
- The thyroid moves up on swallowing because it is enclosed in the pretracheal fascia, which binds it to the larynx.
- The superior thyroid artery lies close to the external laryngeal nerve, which is at risk during thyroid surgery.
- The inferior thyroid artery is closely related to the recurrent laryngeal nerve, which must be preserved to keep the voice.
- The recurrent laryngeal nerve supplies all the intrinsic muscles of the larynx except cricothyroid.
- The external laryngeal nerve supplies cricothyroid; its injury weakens the high notes of the voice.
- The parathyroid glands, usually four, lie behind the thyroid and control calcium through parathyroid hormone.
- The trachea begins at the lower border of the cricoid cartilage at the sixth cervical vertebra.
- The oesophagus lies behind the trachea and begins at the same level, the sixth cervical vertebra.
- The cervical sympathetic chain lies on the prevertebral fascia and has superior, middle and inferior ganglia.
- Injury to the cervical sympathetic chain produces Horner's syndrome with ptosis, miosis and anhidrosis.
- The scalenus anterior is a key landmark, with the phrenic nerve on its front and the subclavian artery behind it.
- The thoracic duct arches over the apex of the left lung to enter the junction of the left subclavian and internal jugular veins.
- The prevertebral muscles, longus colli and longus capitis, flex the neck and lie in front of the vertebral column.
Nerves at risk in thyroid surgery
- **Recurrent laryngeal nerve:** Runs with the inferior thyroid artery. Supplies all intrinsic laryngeal muscles except cricothyroid. Injury gives hoarseness.
- **External laryngeal nerve:** Runs with the superior thyroid artery. Supplies cricothyroid. Injury weakens high-pitched voice.
- **Parathyroid glands:** Four glands behind the thyroid. Accidental removal causes hypocalcaemia and tetany.
- **Cervical sympathetic chain:** Injury gives Horner's syndrome: ptosis, miosis and anhidrosis.
NMC competencies in this chapter
- **AN35.1:** Thyroid gland: parts, relations, blood supply and development
- **AN35.2:** Parathyroid glands and their clinical importance
- **AN35.3:** Trachea and oesophagus in the neck
- **AN35.4:** Recurrent and external laryngeal nerves and applied anatomy
- **AN35.6:** Prevertebral and scalene muscles and their relations
- **AN35.7:** Cervical part of the sympathetic trunk
- **AN35.9:** Subclavian artery, its parts and branches
- **AN35.10:** Thoracic duct in the neck and applied anatomy
Frequently Asked Questions
Why does the thyroid gland move on swallowing?
It is wrapped in the pretracheal fascia, which attaches it to the larynx and trachea, so when the larynx rises during swallowing the thyroid moves up with it.
Which nerve injury causes hoarseness after thyroid surgery?
Damage to the recurrent laryngeal nerve, which runs near the inferior thyroid artery and supplies most intrinsic laryngeal muscles, leaves the vocal cord paralysed and the voice hoarse.
What is Horner's syndrome?
It is the triad of ptosis, a constricted pupil and loss of sweating on one side of the face, caused by interruption of the cervical sympathetic supply.
How does this chapter help in NEET-PG?
Thyroid relations, laryngeal nerves and sympathetic anatomy are central to endocrine surgery and ENT questions, so this region is heavily tested at PG level.
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