Anatomy of the Thyroid Gland (and ovaries)

Question 1

what makes up the thyroid gland

Answer 1

2 lateral lobes (right and left) and an isthmus (a narrow connecting band)

Question 2

what do the lobes of the thyroid attach to

Answer 2

lateral aspects of the thyroid and cricoid cartilages and to the trachea

Question 3

where is the isthmus

Answer 3

lies anterior to the 2nd and 3rd cartilages of the trachea

Question 4

what is a goitre

Answer 4

an enlarged gland

Question 5

what happens to a lump in the thyroid when you swallow

Answer 5

will move superiorly and then inferior with the larynx

Question 6

what is the adams apple

Answer 6

laryngeal prominence of the thyroid cartilage

Question 7

where are the parathyroid glands

Answer 7

on the posterior surface of the thyroid gland’s lateral lobes

Question 8

what glands make up the parathyroid glands

Answer 8

4 glands- superior and inferior on both sides

Question 9

what is the pyramidal lobe

Answer 9

extension of the thyroid glandular tissue- can extend as far superiorly as the hyoid bone but most attach superiorly to the thyroid cartilage

Question 10

where does the thyroid gland begin its development

Answer 10

as a midline epithelial proliferation at the tongue (foramen caecum in adults)

(at junction between anterior 2/3rds and posterior 1/3rd)

Question 11

what is the migratory path of the thyroid gland

Answer 11

inferiorly whilst remaining attached to the tongue via the thyroglossal duct

Question 12

when does the thyroid reach its final position

Answer 12

7th week of development

Question 13

where can thyroglossal duct cysts or ectopic thyroid tissue be found

Answer 13

anywhere in thyroid or along migratory path

Question 14

what is a platysma

Answer 14

a skeletal muscle in the superficial fascia

is a muscle of facial expression

Question 15

what is the cranial nerve supply of the platysma muscles

Answer 15

cranial nerve VII

Question 16

what does paravertebral deep fascia contain

Answer 16

postural neck muscles

cervical vertebrae

Question 17

what does the investing fascia contain

Answer 17

encloses all other neck fascia
compartments enclose:
-trapezius
-sternocleidomastoid

Question 18

where are the carotid sheaths and what do they contain

Answer 18

located anterolaterally either side of the thyroid gland
contain:
-vagus nerves
-deep cervical lymph nodes 
-carotid arteries
-internal jugular vein

Question 19

where is the pretracheal fascia and what does it contain

Answer 19

located anteriorly 
contains:
-oesophagus
-trachea
-thyroid gland
-strap muscles 
-recurrent laryngeal nerve

Question 20

what is the danger zone

Answer 20

area behind retopharyngeal space that extends down to the diaphragm- can allow infection to spread

Question 21

what nerve supplies the SCM and trapezius

Answer 21

spinal accessory nerve

Question 22

where does the trapezius attach inferiorly

Answer 22

spine of the scapula and the lateral end of the clavicle

Question 23

what does the external jugular vein run within

Answer 23

the superficial fascia

Question 24

what does the external jugular vein drain into

Answer 24

subclavian vein then into the brachiocephalic vein

Question 25

what does the anterior jugular vein run within

Answer 25

superficial fascia

Question 26

what does the anterior jugular vein drain into

Answer 26

external jugular vein

Question 27

where does the sternal head of the SCM attach to

Answer 27

manubrium of the sternum

Question 28

where does the clavicular head of the SCM attach to

Answer 28

medial end of the clavicle

Question 29

where do both heads of the SCM attach to proximally

Answer 29

mastoid process of the temporal bone

Question 30

what are the carotid sheath made of

Answer 30

deep fascia

Question 31

where do the carotid sheath attach to

Answer 31

superiorly- base of the skull (around jugular foramen and the entrance to carotid canal) inferiorly- mediastinal fascia

Question 32

what is the blood supply of the thyroid and parathyroid glands

Answer 32

superior thyroid artery from external carotid artery from common carotid artery inferior thyroid artery from right subclavian artery thyroid ima artery from brachocephalic artery

Question 33

what is the venous drainage of the thyroid and parathyroid glands

Answer 33

superior and middle thyroid vein- go into internal jugular veins inferior thyroid veins- go into brachiocephalic veins

Question 34

what is the lymphatic drainage of the thyroid and parathyroid glands

Answer 34

superior deep cervical lymph nodes inferior deep cervical lymph nodes on right- right lymphatic duct to right venous angle on left- thoracic duct to the left venous angle tracheal lymph nodes- comprised of pretracheal (front) and paratracheal (side) nodes

Question 35

how does the vagus nerve travel in the neck

Answer 35

branches from the medulla oblongata exit the skull via the jugular foramen descend through in the carotid sheath

Question 36

how does the vagus nerve travel in the thorax

Answer 36

descends through the chest: right side- lateral to trachea left- left side of aortic arch both- posterior to the lung hilum and on the oesophagus

Question 37

how does the vagus nerve travel in the abdomen

Answer 37

both vagus nerves pass through the diaphragm with the oesophagus then divide into their terminal branches on the surface of the stomach supply the abdominal organs with parasympathetic axons to the distal midgut

Question 38

what is the paths of the recurrent laryngeal nerves

Answer 38

left- recurs under the arch of the aorta right- recurs under the subclavian artery

Question 39

where are the recurrent laryngeal nerves in the neck

Answer 39

between trachea and oesophagus

Question 40

what are the strap muscles

Answer 40

infrahyoid muscles - sternohyoid - sternothyroid - thyrohyoid - omohyoid

Question 41

what do the infrahyoid muscles do

Answer 41

position hyoid bone, swallowing, movement of the larynx, depressing the hyoid

Question 42

what does the fascial sling of the omohyoid do

Answer 42

attaches the intermediate tendon of the omohyoid to the clavicle

Question 43

what are the surgical approaches to the thyroid gland

Answer 43

- classical thyroidectomy - endoscopy assisted thyroidectomy - endoscopy trans-axillary approach - endoscopy trans-breast approach

Question 44

describe a classical thyroidectomy incision

Answer 44

a collar incision is made with natural skin crease/ within langers lines incision superior to clavicles and jugular notch incision is made through skin and platysema

Question 45

what might be at risk in a thyroidectomy incision

Answer 45

``` anterior jugular veins right sternohyoid pretracheal fascia inferior thyroid veins vagus nerve right subclavian artery right recurrent laryngeal nerve ```

Question 46

describe the process of a classical thyroidectomy

Answer 46

right carotid sheath structures retracted laterally mobilise the thyroid lobes anteriorly to dissect the parathyroid glands and their blood supplies free from the posterior surface of the thyroid gland thyroid isthmus sectioned and retracted laterally

Question 47

what does the right recurrent laryngeal nerve supply

Answer 47

provides motor supply to most of the skeletal muscles that move the right vocal chord (intrinsic muscle of the larynx)

Question 48

what does recurrent nerve injury result in

Answer 48

paralysis of the vocal chord

Question 49

what does unilateral recurrent nerve injury result in

Answer 49

hoarseness or weakness of the voice and a weak cough

Question 50

what does bilateral recurrent nerve injury cause

Answer 50

aphonia (inability to produce sound) inability close the rima glottidis and prevent aspiration inability to produce good cough (requires closure of rima glottidis)

Question 51

what is the rima glottidis

Answer 51

opening between vocal chords

Question 52

what nerve crosses the posterior triangle of the neck

Answer 52

accessory nerve

Question 53

what do the ovaries secrete

Answer 53

oestrogen and progesterone

Question 54

what is the blood supply to the ovaries

Answer 54

vascular anastomosis= ovarian artery (from aorta) + unterine atery (from internal iliac)