Thyroid & Parathyroid

Question 1

What is the location of the thyroid gland ?

Answer 1

Muscular triangle of the neck deep to sternohyoid and sternothyroid.
Level of C5-T1 vertebrae.
Base usually lies at 5 & 6th tracheal rings.
Isthmus lies in front of 2, 3 & 4th tracheal rings.
Parathyroid glands are located its posterior border.

Question 2

Why does a thyroid growth would expand inferiorly ?

Answer 2

The apex of the gland is limited by the attachment of pretracheal fascia and sternothyroid muscle to oblique line of thyroid cartilage.

Question 3

What forms the false capulse that covers the thyroid gland that when thickens medially, forms the suspensory ligament of Berry?

Answer 3

Pretracheal fascia

Ligament of Berry connects the lobe to the larynx & trachea.

Question 4

The superior thyroid A. is a branch of what main artery ?

Answer 4

External carotid A.

Question 5

What nerve runs with the superior thyroid A proximally and then diverges medially as it gets closer to the gland ?

Answer 5

External laryngeal N.

Question 6

Where does the common carotid A branches into the external and internal carotid arteries ?

Answer 6

Superior border of thyroid cartilage.

Question 7

What nerve runs with the inferior thyroid artery?

Answer 7

Recurrent laryngeal N.

Question 8

What is the Thyroid Ima artery?

Answer 8

Present only in 3% of individuals. Arises from brachiocephalic trunk or directly from arch of aorta. Can be cut during tracheo and then retract to into the thorax and then become very difficult for the surgeon to get the bleeding stoped without having to open the chest cavity.

Question 9

Venous drainage of the thyroid gland.

Answer 9

Superior thyroid V. into internal jugular V.
Middle thyroid V. into internal jugular V.
Inferior thyroid V. into left brachiocephalic V.

• All 3 veins form thyroid venous plexus

Question 10

Lymphatics of the thyroid gland :

Answer 10

Prelaryngeal –> Superior deep cervical –> Brachiocephalic –>R lymphatic or thoracic duct.

Pretracheal –> paratracheal–> inferior deep cervical –>Brachiocephalic –> R lymphatic or thoracic duct.

Some nodes may open directly into thoracic duct or R lymphatic duct.

Question 11

Nerve supply

Answer 11

Recieve vasomotor sympathetic fibers via cardiac, superior and inferior periarterial plexuses that accompany the thyroid arteries.

No parasympathetic. Endocrine secretion hormonally (regulated pituitary)

Question 12

To save the external laryngeal N, the superior thyroid A should be ligated where ?

Answer 12

Closer to the gland

Question 13

To save the Reccurent laryngeal N, the inferior thyroid A should be ligated where ?

Answer 13

Away from the gland

Question 14

The Subclavian A is divided into 3 parts by the scalene muscle. What are the 3 parts?

Answer 14

1. Has 3 branches (Vertebral A, Internal thoracic A, thyrocervical trunk)
2. Costocervical trunk
3. Dorsal scapular A

Question 15

vertebral arteries ascend in the neck through the foramen trasnversarium of upper 6 thoracic vertebra. What are the 4 divisions ?

Answer 15

1. Origin to foramen transversarium of C6
2. Lie in formae transversarium of ipper 6 cervical vertebrae
3. Suboccipital triangle
4. Cranial cavity

Question 16

The inferior thyroid A is a branch of what main artery ?

Answer 16

Thyrocervical trunk.

Question 17

2 main branches of costocervical trunk ? (from second part of subclavian A)

Answer 17

Deep cervical A
Highest (supreme) intercostal A

Highest : intercost

Deep cervical A supplies the deep muscles of the neck

Question 18

What is the Carotid sinus ? Innervation ?

Answer 18

Baroreceptor located at the origin of the internal carotid A.
Nerve of Herring (branch of glossopharyngeal N.)

A rise in BP causes a slowing of HR & vasodilation of arterioles.

Question 19

What is the carotid body? Innervation ?

Answer 19

Lies posterior to the bifurcation of common carotid artery. Chemoreceptor that monitors the level of O2 in the blood.
Also innervated by Nerve of Herring.

Stimulus reflex produces rise in BP and HR and RR

Question 20

Course of the external carotid artery

Answer 20

Ends in the parotid gland by dividing into maxillary and superficial temporal arteries. At first it lies medial to the internal carotid artery, but as it ascends in the neck, it passes backward and lateral to it.

Question 21

8 branches of the external carotid A.

Answer 21

Superior thyroid A
Ascending pharyngeal A
Lingual A
Facial A
Occipital A
Posterior auricular A
Superficial temportal A
Maxillary A

Question 22

Facial artery branches in the neck (4)

Answer 22

Ascending palatine
Tonsillar
Branches to the submandibular gland
Submental

Question 23

Course and importance of middle meningeal artery ?

Answer 23

Enters skull through foramen spinosum. Runs laterally within skull and divides into ant & post branches. Ant branch is important because it lies close to motor area of cerebral cortex.

Question 24

Name 3 branches of the maxillary A.

Answer 24

Middle meningeal
Sphenopalatine
Greater&lesser palatine

Question 25

Angio of the carotid and vertebral arteries.

Answer 25

1. Brachiocephalic trunk
2. R subclavian
3. R vertebral
4. R common carotid
5. R external carotid
6. R internal carotid
7. L internal carotid
8. L subclavian A
9. Left common carotid
10. Aorta

Question 26

What is the anterior jugular vein?

Answer 26

Small vein that begins just below the chin. Descends and turns laterally deep to SCM and ends in external jugular vein.
Therefore it is a branch of the external jugual v.

Question 27

Cervical plexus

Answer 27

formed by the ventral rami of C1-C4 roots
C1 fibers runs with the hypoglossal N and supplies geniohyoid and thyrohyoid.
C2-C4 divide into upper and lower branches and form loops.