Posterior triangle

Question 1

What is the superficial/investing layer of dense CT (deep cervical fascia)? What muscles does it enclose?

Answer 1

A “sleeve” binding all structures in the neck. Splits twice to enclose the SCM & trapezius.

Question 2

What does the infrahyoid fascia cover?

Answer 2

Covers supra- and infra-hyoid muscles (strap mm.)

Question 3

What does the pretracheal fascia enclose?

Answer 3

Viscera including thyroid and parathryoid glands, larynx, trachea, esophagus.

Question 4

What is enclosed in the carotid sheeth?

Answer 4

Carotid a., IJV, vagus n. (CN X)

Question 5

What does the pre-vertebral fascia (deep cervical fascia) cover?

Answer 5

Covers vertebral musculature

Question 6

What are the boundaries of the posterior triangle?

Answer 6

Anterior: SCM
Posterior: trapezius
Inferior: clavicle

Question 7

What muscle divides the posterior triangle into the occipital triangle (superior) and omoclavicular triangle (inferior)?

Answer 7

Omohyoid muscle (inferior belly)

Question 8

Sternocleidomastoid muscle: innervation and actions?

Answer 8

Innveration: accessory nerve (CN XI)
Unilateral actions: tilt head unilaterally, twist neck contralaterally.
Bilateral actions: extend the head, aid in respiration when head is fixed

Question 9

Anterior scalene: OIIA?

Answer 9

Ori: anterior tubercles of transverse processes of C3-C6
Insertion: 1st rib
Innervation: ventral rami, C5, C6
Action: Elevates 1st rib, bends neck

Question 10

Middle scalene: OIIA?

Answer 10

Ori: Posterior tubercles of transverse processes of C2-C7
Insertion: 1st rib
Innervation: ventral rami, C3-C8
Action: Elevates 1st rib, bends neck

Question 11

Posterior scalene: OIIA?

Answer 11

Ori: posterior tubercles of transverse processes of C4-C6
Insertion: 2nd rib
Innervation: anterior rami of lower 4 cervical nerves C6-C8
Action: Elevates 2nd rib, bends neck

Question 12

Where is Erb’s point? What nerves emerge from it?

Answer 12

• Located 1/2 way along the posterior border of SCM
• Cutaneous (sensory) branches of the cervical plexus:
  1. transverse cervical n.
  2. great auricular n.
  3. lesser occipital n.
  4. supraclavicular n.
  5. accessory n. (CN XI)

Question 13

Transverse cervical n.: origin and action?

Answer 13

• Ventral rami of C2-C3

- Sensory to throat

Question 14

Great auricular n.: origin and action?

Answer 14

• Ventral rami of C2-C3

- Sensory to bottom half of ear down neck

Question 15

Lesser occipital n.: origin and action?

Answer 15

• Ventral rami of C2 (sometimes C3)

- Sensory to behind ear down to neck

Question 16

Supraclavicular n.: origin and action?

Answer 16

• Ventral rami of C3-C4

- Has ant/middle/posterior branches. Sensory to area over clavicle.

Question 17

Accessory n. (CN XI): origin and action?

Answer 17

• Medulla oblongata

- Motor to SCM and trapezius mm.

Question 18

What are the roots of the phrenic nerve and what does it innervate?

Answer 18

• C3, C4, C5 (primarily C4!)

- Diaphragm (motor)

Question 19

What’s an important identifying landmark for the phrenic nerve?

Answer 19

It sits on top of the anterior scalene m.

Question 20

What are the 2 roots of the ansa cervicalis? What nerves do they originate from?

Answer 20

Superior root (comes from C1) and inferior root (comes from C2 and C3)

Question 21

What does the superior root of the ansa cirvicallis innervate?

Answer 21

Geniohyoid and thyrohyoid mm.

Question 22

What does the inferior root of the ansa cirvicallis innervate?

Answer 22

Sternohyoid, sternothyroid, omohyoid mm.

Question 23

Ventral rami of cervical plexus (C1-C4) innervates what mm.?

Answer 23

Rectus capitis lateralis, rectus capitis anterior, longus captitis, longis colli, levator scapulae, and scalene mm.

Question 24

What 4 things are within the supraclavicular triangle (below the omohyoid)?

Answer 24

1. Lower portion of the brachial plexus (C6, C7, C8)
2. Subclavian a. and branches of the subclavian a. (VIT C + sometimes D)
3. Subclavian v.
4. Termination of the EJV

Question 25

The ansa cervicalis lies on top of what structure?

Answer 25

External jugular vein

Question 26

The phrenic nerve can be found on top of what structure?

Answer 26

Anterior scalene muscle

Question 27

How many segments can the subclavian a. (near the anterior scalene) be broken into? What arteries/trunks do they contain?

Answer 27

• 2 (sometimes 3). VIT C and sometimes D
  1. Vertebral a.
  1. Internal thoracic a.
  1. Thyrocervical trunk
  2. Costocervical trunk
  3. Dorsal scapular a. (but often the suprascapular a. of the thyrocervical trunk is big enough to replace it)

Question 28

What arteries are w/in the thyrocervical trunk?

Answer 28

SITA

• Suprascapular a. (army over)
• Inferior thyroid a.
• Transverse cervical a.
• Ascending cervical a.

Question 29

What arteries are w/in the costocervical trunk? (teacher said “don’t worry about it too much”)

Answer 29

• Deep cervical a.

- Supreme intercostal a.

Question 30

Anatomically, describe where the subclavian vein runs.

Answer 30

Behind the clavicle, in front of the anterior scalene

Question 31

Anatomically, describe where the subclavian artery and brachial plexus runs.

Answer 31

Behind anterior scalene, in front of middle scalene