Neck Anatomy

Question 1

What is the action of strap muscles?

Answer 1

They are involved in the movement of the hyoid bone and larynx during swallowing and speaking.

Question 2

Name the strap muscles.

Answer 2

Deep
* Sternohyoid
* Thyrohyoid

Superficial
* Omohyoid
* Sternothyroid

Question 3

What is the nerve supply for the strap muscles?

Answer 3

All from Ansa cervicalis (C123) except thyrohyoid which is innervated by c1

Question 4

Where do you find the spinal accessory nerve

Answer 4

Beneath Sternocleidomastoid

Question 5

Where do you find greater aurocular nerve

Answer 5

Above Sternocleidomastoid

Question 6

What does spinal accessory nerve supply

Answer 6

Trapezius and sternocleidomastoid

Question 7

What does greater auricular nerve supply

Answer 7

C23
Skin over mandible, parotid, lower half of auricle

Question 8

Surface anatomy of spinal accessory nerv

Answer 8

Crosses posterior triangle from upper third of sternocleidomastoid to lower two third of trapezius

Question 9

Boundaries of anterior triangle of neck

Answer 9

Anterior - midline
Posterior - anterior border of SCM
Superior - mandible

Question 10

Sub triangles of the anterior triangle

Answer 10

Digastric (submandibular)
Muscular
Carotid

Question 11

Contents of anterior triangle

Answer 11

Digastric - submandibular gland and nodes, facial vessels and hypoglossal nerve
Muscular - strap muscles and EJV
Carotid - carotid sheath (cc, iJV, vagus) and Ansa cervicalis

Question 12

Structures at risk during submandibular gland excision

Answer 12

Marginal mandibular nerve (branch of facial) - 1-2cm inferior to mandible, damage would cause asymmetrical smile

Facial artery - runs deep to the gland and then wraps around inferior mandible anterior to massater

Lingual nerve - passes medial to the gland and wraps around the duct, damage causes loss of sensation and taste to the anterior two thirds of the tongue

Hypoglossal nerve - deep to posterior belly of digastric and stylohyoid, damage would lead to tongue weakness on the affected side

Submandibular duct (Wharton’s) - emerged from deep part of gland and opens near thebphrenulum, damage causes leak or stenosis

Question 13

Nerve supply to digastric

Answer 13

Anterior belly mylohyoid nerve (from inferior alveolar from mandicular from trigeminal)
Posterior belly facial nerve

Question 14

Boundaries of the posterior triangle

Answer 14

apex - SCM and trapezius at occipital bone

anterior - posterior SCM

posterior - anterior trapezius

base - middle 1/3 clavicle

Question 15

contents of posterior triangle

Answer 15

nerves -
- accessory nerve
- phrenic nerve
three trunks of brachial plexus
- cervical plexus: supraclavicular nerve, transverse cervical nerve, greater auricular nerve, lesser occipital nerve

vessels -
- external jugular vein
- 3rd part subclavian artery

muscles -
- inferior belly omohyoid
- scalene

lymph nodes -
- supraclavicular
-occipital

Question 16

How to identify external carotid artery?

Answer 16

branches in the neck

Question 17

Course of the ECA

Answer 17

origin: one of the 2 terminal branches of CCA, at the upper border of thyrpif cartilage (C4)

termination: behind the mandible inside the parotid gland dividing into the superficial temporal and maxillary branches

Question 18

what nerve passes anterior to the ECA?

Answer 18

hypoglossal

Question 19

branches of the ECA

Answer 19

some attendings like freaking out potential medical students

three infront
two behind
one deep

1. superficial thyroid (front)
2. asceding pharangeal (deep)
3. lingual (front)
4. facial (front)
5. occipital (behind)
6. posterior auricular (behind)
7. maxillary - inferior alveolar, middle meningeal
8. superficial temporal

Question 20

what is the carotid body

Answer 20

posterior aspect of bifucation of CCA, responds to chnages in pH

Question 21

what is the carotid sinus

Answer 21

dilated area at the bae of ICA, superior to the bifurcation. at the level of thyroid cartilage (c4). contains baroreceptors for detecting changes in BP

Question 22

nerve supply to the larynx

Answer 22

all laryngeal muscles supplied by the recurrent laryngeal nerve except for the ciricothyroid that is supplied by external laryngeal enrve (branch of superior)

Question 23

branches of superior laryngeal nerve

Answer 23

external - motor
internal - sensory

Question 24

attachments of the vocal cords

Answer 24

anterior: thyroid cartilage

posterior: arytenoid cartilage

lateral: laryngeal muscles

medial - free border

Question 25

muscles responsible for opening vocal cords

Answer 25

2 posterior cricoarytenoid muscles - externall rotate the arytenoids

Question 26

muscles responsible for closing the vocal cords during swallowing

Answer 26

lateral cricoarytenoids

Question 27

muscles responsible for tensing vocal cords

Answer 27

2 cricothyorids

Question 28

site of a cricothyroidectomy

Answer 28

cricothyroid membrane - between thyroid and cricoid cartilage

Question 29

where do the recurrent laryngeal nerves loop? Which is more vulnerable?

Answer 29

right: Right subclavian artery (T1-2) left: aortic arch - posterior to ligamentum arteriosum (T4-5) Left RLN has a longer intrathoracic course → more vulnerable to pathology like: Aortic aneurysm Left atrial enlargement (e.g., mitral stenosis) Mediastinal tumors

Question 30

where to the recurrent laryngeal nerves ascend

Answer 30

tracheooesopgaeal grooves

Question 31

what does the RLN supply

Answer 31

all laryngeal muscles except cricothyroid (- Posterior cricoarytenoid - Lateral cricoarytenoid - Transverse & oblique arytenoids - Thyroarytenoid - Vocalis) sensation to larynx below the vocal cords

Question 32

innervation of suprhyoid muscles

Answer 32

digastric - ant = mylohyoid (inf alveolar V3), post = facial mylohyoid = Nerve to mylohyoid (branch of inferior alveolar nerve, from mandibular nerve V3) geniohyoig - hypoglassal stylohyoid = facial (pierced by psterior belly digastric)

Question 33

damage to SLN

Answer 33

abnormalities in pitch pitch glide - cant sing with smooth change to higher notes

Question 34

unilateral RLN damage

Answer 34

hoarseness, diplophonia dysphagia

Question 35

bilateral RLN injury

Answer 35

partial - adducted cords - respiratory compromise full - 1/2 adducted cords - aphonia, cant speak or cough

Question 36

semon's law

Answer 36

In progressive or compressive lesions of the recurrent laryngeal nerve (RLN), the abductor muscles of the vocal cords are affected before the adductors. posterior cricoarytenoid is the only abductor s more vulnerable, and so becomes paralysed first. The adductors (which close the cords) are relatively preserved longer. his imbalance causes the vocal cords to assume a paramedian (partially closed) position. Bilateral involvement can cause airway obstruction, even though voice may be relatively preserved early on. Helps differentiate between gradual vs sudden nerve damage: Gradual lesion (e.g. tumour): follows Semon's law Sudden trauma (e.g. surgical injury): may paralyse both abductors and adductors simultaneously

Question 37

where are the preganglionic fibres for the sympathetic trunk from

Answer 37

corresponding spinal nerves T1-L2

Question 38

what connects spinal nerves and sympathetic trunk

Answer 38

ganglion, white a gray ramus communicans

Question 39

how do sympathetic nerves leave the sympathetic chain

Answer 39

through the spinal nerves forming plexuses around blood vessels cardiac and pulmonary plexuses greater splanchnic nerve lesser splanchnic nerve