Anatomy - The Anterior Neck and Thyroid Gland

Question 1

What is the midline connection called of the two lateral thyroid gland lobes?

Answer 1

Isthmus.

Question 2

What tracheal rings does the isthmus of the thyroid gland lie in front of?

Answer 2

2nd, 3rd and 4th.

Question 3

Where do the thyroid arteries arise from?

Answer 3

1. Superior thyroid artery - External carotid artery. 2. Inferior thyroid artery - Thyrocervical trunk, a branch of the Subclavian artery.

Question 4

What vessels are contained within the carotid sheath?

Answer 4

1. Carotid artery. 2. Jugular vein. 3. Vagus nerve.

Question 5

What is the origin of sternocleidomastoid?

Answer 5

The manubrium of the sternum and the clavicle.

Question 6

What is the insertion of sternocleidomastoid?

Answer 6

Mastoid process.

Question 7

What nerve(s) are related to the superior thyroid arteries?

Answer 7

The external laryngeal nerves.

Question 8

What nerve(s) are related to the inferior thyroid arteries?

Answer 8

The recurrent laryngeal nerve crosses the inferior thyroid artery.

Question 9

Describe the location of the thyroid gland in relation to the vertebrae?

Answer 9

C5-T1

Question 10

Why is it described as butterfly shaped?

Answer 10

• consists of two lobes, left and right
• Connected by central isthmus anteriorly

Question 11

What compartment is the thyroid gland found in? what surrounds it?

Answer 11

• Visceral compartment of the neck (Along with the trachea and oesophagus and pharynx)
• this compartment is bound by the pretracheal fascia

Question 12

What is associated on the anterior of the thyroid gland?

Answer 12

• infrahyoid muscles
  
  • Sternothyroid
  • Superior value of the omohyoid and sternohyoid

Question 13

What is associated on the lateral side of the thyroid gland?

Answer 13

• carotid sheath
  
  • Contains the common carotid artery internal jugular vein and vagus nerve

Question 14

What is associated on the medial side of the thyroid gland?

Answer 14

• organs - larynx and pharynx trachea and oesophagus
• nerves - external laryngeal and recurrent laryngeal nerves

Question 15

Why does the thyroid gland have to be highly vasculated?

Answer 15

Because it secretes hormones directly into the circulation

Question 16

Describe the 2 main arteries supplying the thyroid gland?

Answer 16

• Superior thyroid artery -
  
  • arises from the first branch of the external carotid artery
  • in close proximity to the external branch the superior laryngeal nerve
• Inferior thyroid artery
  
  • arises from the thyrocervical trunk (Subclaavian artery)
  • lies in close proximity to the recurrent laryngeal nerve

Question 17

Describe the venous drainage from the thyroid gland?

Answer 17

• venous plexus
  
  • made up from the superior middle and inferior thyroid veins
• superior and middle veins drain into the internal jugular vein
• inferior Vein drains into the brachiocephalic vein

Question 18

What is the innovation of the thyroid gland?

Answer 18

• branches derived from the sympathetic trunk
• no control of excretory functions gland ( regulated by the pituitary gland)

Question 19

Describe the lymphatic drainage of the thyroid gland?

Answer 19

drains into the paratracheal and deep cervical nodes

Question 20

What are the boundaries of the anterior triangle?

Answer 20

• superiorly - inferior border of the mandible
• Laterally - anterior border of the sternocleidomastoid
• medially - sagittal line down the midline of the neck

Question 21

What fascia covers the roof and the floor of the triangle?

Answer 21

• investing fracture covers the roof
• visceral covers the floor

Question 22

However muscles divided in relation to the hyoid bone?

Answer 22

• suprahyoid muscles are located superiorly to the hyoid bone
• Infrahyoid muscles are located inferiorly to the hyoid bone

Question 23

Describe the vasculation of the anterior triangle?

Answer 23

• Common carotid artery bifurcates into the external and internal carotid branches
• The internal jugular vein is responsible for venous drainage of the head and neck

Question 24

Name the cranial nerves found within the anterior triangle?

Answer 24

• facial VII
• loss of pharyngeal IX
• Vagus X
• accessory XI
• hypoglossal XII

Question 25

Describe the 4 infra-hyoid muscles?

Answer 25

* omohyoid * scapula to hyoid * 2 muscle bellies * Intermediate tendon, anchored to the clavicle * depresses the Hyoid bone * sternohyoid * sternum/sternoclavical joint to hyoid * depresses the hyoid bone * sternothyroid * manubrium of the sternum attaching to the thyroid cartilage * depresses the thyroid cartilage * thyrohyoid * thyroid cartilage to to the hyoid bone * depresses the hyoid, if higher bone is fixed it can elevate the larynx

Question 26

What is the plastysma?

Answer 26

* thin 'paper' like muscle * originates from the fascia of the pectorails major and deltoid * inserts into the inferior border of the mandible

Question 27

Describe the sternocleidomastoid muscle?

Answer 27

* Originates at the sternum and clavicle * inserts into the mastoid process just behind the ear

Question 28

What are the parathyroid responsible for?

Answer 28

* production of the parathyroid hormone * acts to increase the levels of serum calcium

Question 29

Describe the Anatomical location of the parathyroid glands?

Answer 29

* Located in the posterior aspect of the thyroid gland * flattened oval shaped * situated externally to the thyroid gland itself * 2 Superior parathyroid glands - middle of the posterior border of each thyroid lobe * 2 inferior parathyroid glands - usually found near the inferior pause of thyroid gland

Question 30

Describe the vasculation of the thyroid gland?

Answer 30

* Supplied by the inferior thyroid artery * Venous drainage us into the superior middle and inferior thyroid veins

Question 31

Describes the innovation of the parathyroid glands?

Answer 31

extensive supply of sympathetic nerves to rifle the thyroid branches of the cervical ganglia

Question 32

Describe the Anatomical location of the laryngeal nerves?

Answer 32

* in the groove between the trachea and oesophagus is the recurrent laryngeal nerve * on the right is the recurrent laryngeal nerve wracking behind the subclavian artery * follows the groove between the oesophagus and the trickiest passes to the larynx

Question 33

What is found within the carotid sheath?

Answer 33

* tuber fascia * carotid arteries * Jugular vein * vagus nerve X

Question 34

What occurs at the bifurcation of the common carotid artery?

Answer 34

* Bifurcates into the internal and external carotid arteries * At the bifurcation there are chemoreceptors * Measures the blood pH * feeds the control of breathing * Swelling in the internal carotid artery * carotid sinus * contains barren receptors which feeds into the blood pressure control system

Question 35

Describe how the vagus nerve gives rise to the recurrent laryngeal branch?

Answer 35

* on the right the vagus nerve runs anterior to the subclavian artery * the inferior border of the subclavian artery branches to give rise to the recurrent laryngeal branch * which passes under and behind the subclavian artery before ascending into the larynx * in the groove between the oesophagus and trachea

Question 36

What is the clinical relevance of a diseased thyroid gland?

Answer 36

* overproduce thyroxine results in low TRH and TSH * lumps in the thyroid will elevate with swallowing ( lumps in the lymph nodes will not) * As the virus around the trachea on three sides, lodgement can compress the trachea * the inferior pole of the thyroid is very close to the recurrent laryngeal nerve, therefore making the nerve at risk from thyroid pathology and surgery

Question 37

What are the functions of the extrinsic laryngeal muscles?

Answer 37

depress the larynx

Question 38

Where do you create an emergency airway?

Answer 38

an incision made through the skin and cricothyroid membrane

Question 39

What is the only complete real cartilage around the airway?

Answer 39

the cricoid cartilage - hyaline cartilage

Question 40

Why has a patient developed hypocalaemia after thyroid surgery?

Answer 40

* Low calcium levels in blood * The parathyroid glands are responsible for the release of parathyroid hormone * which controls the levels of serum calcium

Question 41

Answer 41

Question 42

Answer 42