pharynx + larynx + thyroid

Question 1

What does the ansa cervicalis innervate

Answer 1

The ansa cervicalis innervates the infrahyoid (extrinsic larynx) muscles sternohyoid, sternothyroid and omohyoid.

Question 2

What is the rima glottidis

Answer 2

• The rima glottidis can be defined as the opening between the true vocal cords and the arytenoid cartilages
• It varies in shape to make different speech sounds

Question 3

Describe the bony prominences on the neck

Answer 3

Ascending to descending:

(1. ) Body of hyoid
(2. ) Thyroid cartilage
- Laryngeal prominence is found here (adam’s apple)
(3. ) Cricoid cartilage
(4. ) Superfical ring of trachea

Question 4

Where would an emergency airway and tracheostomy be performed?

Answer 4

Emergency airway
- Incase of choking an emergency airway is created through the CRICOID MB

Tracheostomy
- Isthmus of TG is divided to expose the trachea and allow for direct connection between skin and trachea

Question 5

Describe the anatomical location of the thyroid gland

Answer 5

(1. ) Lies behind the sternohyoid, sternothyroid, omnohyoid
(2. ) Wraps around the cricoid cartilage and superior tracheal ring
(3. ) Inferior to thyroid cartilage

Other structures near TG

• Carotid sheath (CCA, IJV, CN10) lies postereo-lateral
• Larynx, pharynx, trachea, oesophagus, recurrent laryngeal nerve

Question 6

Describe the arterial supply and venous drainage of the TG

Answer 6

Arterial supply

(1. ) Superior thyroid artery
- comes from e.cartoid a. and supplies anterior and superior TG
(2. ) Inferior thyroid artery
- comes from thyrocervical trunk, subclavian a. and supplies posterior and inferior TG
(3. ) Thyroid IMA
- Brachiocephalic trunk and supplies isthmus

Venous Drainage

(1. ) Superior, middle thyroid veins drain into the IJV
(2. ) Inferior thyroid veins drains into the brachiocephalic vein

Question 7

Describe the lymphatic drainage of the TG

Answer 7

(1. ) Superior + inferior deep cervical nodes
(2. ) Pre-laryngeal
(3. ) Pretracheal
(3. ) Paratracheal

Question 8

What 2 complications may be associated with a thyroidectomy

Answer 8

(1. ) Hypocalcaemia as a result of hypoparathyroidism
- due to accidental removal of parathyroid glands

(2. ) Hoarsness of voice
- Recurrent laryngeal N. supplies vocal cords and intrinsic larynx muscles
- The nerve lies close to the inferior pole of the TG so is at risk of damage

Question 9

Why does the thyroid gland need a high blood supply

Answer 9

(1. ) Iodine is needed for the production of thyroid hormones
(2. ) Iodine is present in low conc in the blood
(3. ) So high delivery of blood is required for adequate delivery of iodine to the thyroid.

Question 10

Where is the thyroid mb and cricoid mb?

Answer 10

Thyroid mb = between hyoid and thyroid cartilage

Cricoid mb = between thyroid cartilage and cricoid cartilage

Question 11

What muscles make up the EXTRINSIC LARYNGEAL muscles?

Answer 11

Comprises of three groups that elevate and depress the larynx during swallowing.

(1. ) Suprahyoid (elevate) - above hyoid bone
- Stylohyoid
- Diagastric
- Genohyoid
- Mylohyoid

(2. ) Infrahyoid (depress) - below hyoid + innervated by ansa cervicalis
- Omnohyoid
- Sternohyoid
- Sternothyroid
- Thyrohyoid

(3.) Stylopharygeal (elevate)

Question 12

Sternocleidmastoid: origin, insertion, innervation, function

Answer 12

• origin = clavicle and manubrium/sternum
• insert = mastoid process + nuchal line
• innervation = CN11
• function = lateral and anterior neck flexion, head rotation, elevation of clavicle and manubrium

Question 13

Platysma: origin, insertion, innervation

Answer 13

• origin = Fascia of clavicular region
• insert = Mandible + skin
• innervation = CN7

Question 14

Innervations of the INTRINSIC LARYNGEAL muscles

Answer 14

(1. ) Recurrent laryngeal nerve
(2. ) Except for CRICOTHYROID muscle which is innervated by the external laryngeal n (that comes from the superior laryngeal nerve)

Question 15

What do the intrinsic laryngeal muscles do?

Answer 15

They act on the vocal cords - to either abduct (opens glottis) or adduct (closes glottis).

This allows for the rima glottis to vary in shape to make different speech sounds

Question 16

What is the pharynx?

Answer 16

• Muscular tube that connects the oral and nasal cavity to the larynx and oesophagus
• It is made up of nasopharynx, oropharynx, larynogopharynx

Question 17

What muscles make up the pharynx? Innervations?

Answer 17

(1. ) Pharyngeal constrictor muscles
(2. ) Palatopharyngeus
(3. ) Saplingopharyngeus
(4. ) Stylopharyngeus

Innervation

• CN10 pharyngeal branch + plexus (CN9,10,11)
• CN9 innervates stylopharnyngeus

Question 18

Describe the origin and insertions of the three pharyngeal constrictor muscles

Answer 18

(1. ) S.P.C = medial pterygoid plate, mandible -> pharyngeal tubercle
(2. ) M.P.C = hyoid bone -> pharyngeal raphe, SPC, IPC
(3. ) I.P.C = thyroid cartilage, cricoid cartilage -> pharyngeal raphe, circular oesophagus fibres

Question 19

Where is the weakest part of the pharyngeal wall?

Answer 19

(1. ) It is found within the ICP between the junction of the two different fibres
(2. ) This is called Killian’s Dehiscence - triangular shaped area of weakness
(3. ) During swallowing, the high pressures in the pharynx can cause mucosa to bulge out through the killian dehiscence
(4. ) Food enters causing swelling + difficulty swallowing + decomposes -> bad breath.

Question 20

Describe structures found within the nasopharynx, oropharynx, laryngopharynx

Answer 20

(1.) Nasopharynx = Concha, nasal septum

(2. ) Oropharynx
- soft palate + **uvula: prevents food and liquid from entering the nasal cavity by closing the nasopharynx

(3. ) Larynogopharynx
- vallecula: between tongue and epiglottis
- **epiglottis: prevents food entering larynx, protects airways
- aryepiglottic folds:
- piriform fossa: tumours can arise here and remain silents until advanced
- food/liquids may reside in the vallecula and piriform fossa after swallowing

Question 21

What makes up the carotid sheath and what structures may be found surrounding it?

Answer 21

(1. ) This is a fibrous sheath that surrounds the IJV, CCA, CNX
(2. ) Cervical sympathetic trunk lies posterior to the sheath
(3. ) CN12 can be found at angle heading toward tongue

Question 22

What makes up the cervical sympathetic trunk

Answer 22

(1. ) Three cervical ganglions: superior, middle, inferior

(2. ) Inferior cervical ganglion can fuse with thoracic ganglion (T1) to form a stellate ganglion

Question 23

Describe how BP is relayed to the brain and back to slow HR

Answer 23

(1. ) Carotid sinus (within ICA) has sensory receptors that can pick up whether the BP is too high
(2. ) Signal is sent to the brain via CNIX
(3. ) Signal returns to slow HR via CNX