Lecture 9 & 10: Anterior Triangle

Question 1

Answer 1

Question 2

Answer 2

Question 3

Answer 3

Question 4

Answer 4

Question 5

Answer 5

1. Superior thyroid vein
2. Middle thyroid vein

(both drain to int. jugular)

3. Inferior thyroid vein (drains to brachiocephalic)

Question 6

Answer 6

Question 7

Answer 7

Question 8

Answer 8

Question 9

Answer 9

A: Region V

B: Region III

C: Region VI

D: Region IV

E: Region II

F: Region I

Question 10

What are the four reasons for knowing the anterior triangle?

Answer 10

1. Thyroid examination
2. Central vein catheterisation
3. Penetrating trauma
4. Cricothyroidotomy / Tracheastomy

Question 11

Define the ant. triangle:

Answer 11

The region beyond the ant. border of sternocleidomastoid to the midline.

Top: Inf border of mandible

Post: Ant. border of sternocleidomastoid(s)

Imaginary midline defines left and right.

Question 12

Describe the superifical veins of the ant. triangle:

Answer 12

Many many superficial veins branch out of the anterior triangle.

Question 13

What are the infrahyoid muscles of the ant. triangle?

Answer 13

Superficial:

• Sternohyoid + Omohyoid
• Thyrohyoid + Sternothyroid

Deep??

Question 14

What provides innervation to the anterior triangle muscles?

Answer 14

Ansa cervicalis (comes off the cervical plexus), consists of:

• Superior root of ansa cervicalis (C1)
• Inferior root of ansa cervicalis (C2+C3)

These provide motor innervation to all muscles in ant. triangle EXCEPT: Thyrohyoid (C1+C12 do this)

Question 15

What provides cutaneous innervation of the cervical plexus?

Answer 15

1. Transverse cervical n.
2. Supraclavicular nerve
3. Lesser occipital n.
4. Great auricular n.

Question 16

Describe how you can examine the thyroid:

Answer 16

• Exists actually above jugular notch. People often mistake thyroid cartilage
• Sitting on 2+3rd cartilage rings
• (If short neck then they need to extend neck)
• lateral lobes might come up to thyroid cartilage

Question 17

Describe the arterial supply of the thyroid:

Answer 17

Dual supply.

• Subclavian (inf. thyroid art.)
• Ext. carotid (sup. thyroid art)

Question 18

Describe the lymphatic drainage of the thyroid and internal triangle:

Answer 18

Paratracheal nodes drain to deep cervical nodes. (posteroinf. group)

But part of thyroid drains directly into cervical lymph nodes

Question 19

Describe the innervation of the thyroid:

Answer 19

SNS: Middle cervical ganglion (runs with vertebral art)

PNS: Vagus (Recurrent laryngeal n. (sits betweem trachea and oesophagus in recurrent laryngeal groove once comes of vagus)

[Central lobe sits close to cartoid sheath]

Question 20

Whats found in the carotid sheath?

Answer 20

Int jugular, internal carotid, vagus nerve

Question 21

Whats important when it comes to the embryology of the thymus?

Answer 21

Formed in the foramen cecum and migrates through the tract of thyroglossal duct to its normal postion

It can leave behind residual tissue as it migrates. Patent duct can trap food and cause bad breath

Question 22

Describe the midline to lateral and superficial to deep suprahyoid muscles:

Answer 22

Midline ——————–> Lateral

Superficial: Ant belly digastric -> Post belly digastric

Mylohyoid muscle -> Stylohyoid muscle

Deep: Geniohyoid muscle…………………..

Question 23

Where does the mylohoid originate and insert?

Answer 23

L+R meet @ midline (Raphe // Tendinous sheath)

Attatches along mylohyoid line (mandible)

Question 24

What contributes to formation of the carotid sheath:

Answer 24

3 contributions (deep fascia)

• Investing
• Pre-vertebral
• Pre-tracheal

Question 25

Answer 25

Question 26

Answer 26

Question 27

Describe the venous structure of the face:

Answer 27

All vessels drain back to the external or internal jugular via retromandibular or facial vein.

Question 28

Describe the pathway of the vagus nerve:

Answer 28

Exits the skull : Jugular foramen

Travels through the: Carotid sheath

At the root of neck: Crosses ant. scalene close to midline (phrenic follows ant. scalene close to vagus)

Gives off branches: Carotid body branch, cardiac branch, laryngeal nerve (int and ext. branches). Pharyngeal branch.

Question 29

Describe the pathway of the CN (IX):

Answer 29

Exits the skull : Jugular foramen

Travels through: Carotid sheath (but exits after ~2cm b/c goes to post. aspect of tongue) (Sits deep to belly of digastric and stylohyoid) (Runs between int and ext. carotid)

Gives off branches: Carotid sinus branch, pharyngeal breanch

Question 30

Describe the pathway of the accessory nerve:

Answer 30

Exits the skull: Jugular foramen

Travels through: Carotid sheath ( Exits post. aspect, runs under sternocleidomastoid through the post. triangle b.c headding to trap)

Gives off branches to: Sternocleidomastid, Trapzius

Question 31

Describe the pathway of the hypoglossal nerve:

Answer 31

Exits the skull : Hypoglossal canal

Travels through;

• Sits deep to post. belly of digastric
• Stylohyoid
• Hooks AROUND occipital art.
• Superficial to int/ext carotid

Gives off:

• C1 branch (Innervates thyrohyoid m.) & sends branch to ansa cervalis (deep to carotid sheath)
• Branch to tongue

Question 32

Where does central vein cathierisation typically occur?

Answer 32

B/w clavicular and sternal heads of sternocleidomastoid

Avoids post. triangle which is filled with nerves.

Question 33

Answer 33

1. Hyoid bone
2. Thyroid cartilage
3. Thyroid

Question 34

Answer 34

Question 35

Answer 35