Anatomy-Anterior Cervical Triangle

Question 1

What are the boundaries of the anterior triangle?

Answer 1

Lateral: SCM. Medial: Midline Superior: Mandible

Question 2

What are the subdivisions of the anterior triangle?

Answer 2

*

Question 3

What nerves might you find during your dissection of the platysma?

Answer 3

CN VII (facial nerve motor innervation to platysma). Transversce cervical nerve (C2 & C3 nerve fibers providing neck sensation)

Question 4

What vein is responsible for drainage of the sub mental triangle?

Answer 4

Anterior jugular vein

Question 5

How does innervation of the muscle indicated below differ in its different regions?

Answer 5

Most medial muscles in the anterior triangle are innervated by the mylohyoid branch of CN V (V3). Most lateral muscles are innervated by CN VII (Facial nerve). This is the case of the digastric muscle with its anterior belly innervated by CN V3 and its posterior belly innervated by CN VII.

Question 6

What muscle straddles the tendon of the posterior belly of the digastric muscle? What nerve is it innervated by?

Answer 6

Stylohyoid muscle. Innervated by CN VII because it is located laterally.

Question 7

What nerve is mylohyoid innervated by?

Answer 7

It is located medially and is innervated by CN V3

Question 8

What muscle originates at the hyoid bone and functions to raise and lower the tongue? What nerve is it innervated by?

Answer 8

Hyoglossis muscle. It is a tongue muscle so it is innervated by CN XII

Question 9

What muscles are indicated below? What are they innervated by?

Answer 9

1) Superior belly of omohyoid (ansa cervicalis) 2) Sternohyoid (ansa cervicalis) 3) Sternothyroid (ansa cervicalis) 4) Thyrohyoid (C1: nerve to thyrohyoid)

Question 10

What are the branches of the external carotid artery?

Answer 10

“Stop Alcohol Late Friday Or Puke More Saturday”. Superior Thyroid, Ascending Pharyngeal, Lingual, Facial, Occipital, Posterior Auricular, Maxillary, Superficial Temporal.

Question 11

What structure runs in parallel and slightly deep to the superior thyroid artery?

Answer 11

External laryngeal nerve, a branch off of the vagus nerve.

Question 12

What branch comes off of the superior thyroid artery?

Answer 12

Superior laryngeal artery.

Question 13

What structure runs in parallel with the superior laryngeal artery?

Answer 13

Internal laryngeal nerve, a branch off of the vagus nerve.

Question 14

What blood vessel gets sandwiched between the hypoglossal nerve and the hyoglossis muscle?

Answer 14

Lingual artery

Question 15

What artery comes off of the external carotid opposite the facial artery and has the hypoglossal nerve sitting on top of it?

Answer 15

Occipital artery

Question 16

How do the facial vein and the facial artery compare in relation to the submandibular gland?

Answer 16

Artery is under the gland, vein is ontop of the gland

Question 17

What veins combine to form the common facial vein?

Answer 17

Facial vein + retromandibular vein

Question 18

What structures are indicated in the drawing below?

Answer 18

These are the roots of the loop that forms the ansa cervicalis. 1) Superior root (C1 only) 2) Inferior root (C2 + C3 fibers)

Question 19

In the anterior cervical triangle, what structures does the hypoglossal nerve cross anterior to and posterior to?

Answer 19

Anterior: Occipital Aa, Lingual Aa, Hyoglossus M. Posterior: Mylohyoid M.

Question 20

Where does the vagus nerve exit the skull?

Answer 20

Jugular foramen. Note that it can be found between the external jugular vein and internal carotid artery.

Question 21

What branches come off of the vagus nerve in the anterior cervical triangle?

Answer 21

Superior laryngeal nerve (further splits into internal & external laryngeal nerves) and Recurrent laryngeal nerve

Question 22

Where does the spinal accessory nerve exit the skull?

Answer 22

Jugular foramen. Note it can be found in the deep belly of the SCM.

Question 23

What arteries provide blood supply to the thyroid gland and where do they come from?

Answer 23

Superior thyroid arteries (external carotid) and inferior thyroid arteries (thyrocervical trunk off subclavian)

Question 24

Why are patients at risk for suffocation when they have their thyroid glands removed?

Answer 24

First: the recurrent laryngeal nerve intermingles with the inferior thyroid artery as it enters the thyroid. Transection of this nerve during surgery can paralyze the vocal cords. Second: the inferior thyroid artery supplies blood to the parathyroid glands that produce PTH. If these become ischemic, PTH decreases, so do Ca2+ levels, tetany occurs and can close off the airway.

Question 25

When performing a tracheotomy the patient begins bleeding profusely. What variation of thyroid blood supply may this patient have?

Answer 25

Thyroid IMA Artery

Question 26

What veins drain the thyroid gland?

Answer 26

Superior, middle and inferior thyroid veins. The Superior and middle veins drain into the internal jugular vein. The inferior thyroid vein drains into the subclavian.

Question 27

What branches come off of the medial portion of the subclavian artery?

Answer 27

Vertebral artery, Internal thoracic artery and thyrocervical trunk

Question 28

What branches come off of the thyrocervical trunk?

Answer 28

Suprascapular artery, transverse cervical artery and inferior thyroid artery.

Question 29

What branch comes off of the inferior thyroid artery?

Answer 29

Ascending cervical artery

Question 30

What branches come off of the posterior subclavian artery?

Answer 30

Costocervical trunk