pharynx + larynx + thyroid Flashcards
What does the ansa cervicalis innervate
The ansa cervicalis innervates the infrahyoid (extrinsic larynx) muscles sternohyoid, sternothyroid and omohyoid.
What is the rima glottidis
- 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
Describe the bony prominences on the neck
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
Where would an emergency airway and tracheostomy be performed?
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
Describe the anatomical location of the thyroid gland
(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
Describe the arterial supply and venous drainage of the TG
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
Describe the lymphatic drainage of the TG
(1. ) Superior + inferior deep cervical nodes
(2. ) Pre-laryngeal
(3. ) Pretracheal
(3. ) Paratracheal
What 2 complications may be associated with a thyroidectomy
(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
Why does the thyroid gland need a high blood supply
(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.
Where is the thyroid mb and cricoid mb?
Thyroid mb = between hyoid and thyroid cartilage
Cricoid mb = between thyroid cartilage and cricoid cartilage
What muscles make up the EXTRINSIC LARYNGEAL muscles?
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)
Sternocleidmastoid: origin, insertion, innervation, function
- 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
Platysma: origin, insertion, innervation
- origin = Fascia of clavicular region
- insert = Mandible + skin
- innervation = CN7
Innervations of the INTRINSIC LARYNGEAL muscles
(1. ) Recurrent laryngeal nerve
(2. ) Except for CRICOTHYROID muscle which is innervated by the external laryngeal n (that comes from the superior laryngeal nerve)
What do the intrinsic laryngeal muscles do?
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
What is the pharynx?
- Muscular tube that connects the oral and nasal cavity to the larynx and oesophagus
- It is made up of nasopharynx, oropharynx, larynogopharynx
What muscles make up the pharynx? Innervations?
(1. ) Pharyngeal constrictor muscles
(2. ) Palatopharyngeus
(3. ) Saplingopharyngeus
(4. ) Stylopharyngeus
Innervation
- CN10 pharyngeal branch + plexus (CN9,10,11)
- CN9 innervates stylopharnyngeus
Describe the origin and insertions of the three pharyngeal constrictor muscles
(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
Where is the weakest part of the pharyngeal wall?
(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.
Describe structures found within the nasopharynx, oropharynx, laryngopharynx
(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
What makes up the carotid sheath and what structures may be found surrounding it?
(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
What makes up the cervical sympathetic trunk
(1. ) Three cervical ganglions: superior, middle, inferior
(2. ) Inferior cervical ganglion can fuse with thoracic ganglion (T1) to form a stellate ganglion
Describe how BP is relayed to the brain and back to slow HR
(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
