Posterior Triangle of the Neck

Question 1

What are the boundaries of the Posterior Triangle?

Answer 1

1. Posterior border of Sternocleidomastoid
2. Anterior border of Trapezius
3. Middle third of clavicle– front of chest

Question 2

What are the boundaries of the Anterior Triangle?

Answer 2

1. Anterior Border of Sternocleidomastoid
2. Inferior Border of the Mandible
3. Midline

Further divided by Omohyoid and Digastric into:

• Carotid Triangle
• Muscular Triangle
• Submandibular Triangle
• Submental Triangle

Question 3

What divides the posterior triangle into two triangles?

Answer 3

The inferior bely of the Omohyoid

Question 4

What is the roof of the Posterior Triangle?

Answer 4

1. Skin
2. Superficial Fascia with Platsyma
3. Investing Layer of Deep Cervical Fascia

Question 5

Floor muscles in the posterior Triangle are covered by:

Answer 5

The Prevertebral layer of Deep Cervical Fascia

Question 6

Describe the muscular floor:

Answer 6

1. Semispinalis Capitis (at Apex)
2. Splenius Capitis
3. Levator Scapulae
4. Posterior Scalene
5. Middle Scalene
6. Anterior Scalene

Question 7

Describe the Semispinalis Capitis:

Answer 7

Innervated by Dorsal Rami.
Uni lateral movement: will turn head to opposite (Contralaterally)
Bilateral Movement: Extends head- Look up

Question 8

Describe the Splenius Capitis:

Answer 8

Innervated by the Dorsal Rami.
Uni lateral movement: turns head to same side
Bilateral Movement: Help extend head up

Question 9

Describe the Sternocleidomastiod:

Answer 9

Innervated by Accessory N. (CN XI)
Unilateral movement: Will our head contra laterally and tilt head to same side
Bilateral movement: Flex the head

Question 10

Describe the Levator Scapulae:

Answer 10

Innervated by the Dorsal scapular N.

Will elevate and rotate the scapula

Question 11

Describe the scalene muscles:

Answer 11

ANTERIOR SCALENE muscle lies on the lateral aspect of the neck, deep to the prominent sternocleidomastoid muscle.
Attaches to 1st rib
Function: Elevation of the first rib. Ipsilateral contraction causes ipsilateral lateral flexion of the neck, and bilateral contraction causes anterior flexion of the neck.

MIDDLE SCALENE is the largest and longest of the three scalene muscles. It has several long, thin muscles bellies arising from the cervical spine, which converge into one large belly that inserts into the first rib.
Attaches to 1st Rib:
Function: Elevation of the first rib. Ipsilateral contraction causes ipsilateral lateral flexion of the neck.

POSTERIOR SCALENE is the smallest and deepest of the scalene muscles. Unlike the anterior and middle scalene muscles, it inserts into the second rib.
Attaches to 2nd Rib
Function: Elevation of the second rib, and ipsilateral lateral flexion of the neck.

Question 12

What are the Nerves of the posterior Triangle?

Answer 12

Accessory (CN XI)
Cutaneous Branches of the Cervical Plexus:
- Lesser Occipital (C2)
- Great Auricular (C2-3)
- Transverse Cervical (C2-3)
- Supraclavicular (C3-4)
Phrenic (C3,4,5)
Venteral Rami and Trunks of the Brachial Plexus:
- Dorsal Scapular (C5)
- Long Thoracic (C5,6,7)
- Suprascapular (C5,6)

Question 13

What are the Arteries of the Posterior Triangle?

Answer 13

Subclavian (3rd Part)
Occipital (Occasionally)
Transvers Cervical
Suprascapular
Dorsal Scapular (Usually)

Question 14

What are the Veins of the Posterior Triangle?

Answer 14

External Jugular
Occipital (occasionally)
Transverse Cervical
Suprascapular

Question 15

Which parts of the Cervical Plexus are Sensory and which are Motor?

Answer 15

Cervical Plexus (C1-4)
Sensory: C2-4 (No C1 Sensory so no C1 dermatomes)
Motor: C1-3

Ansa Cervicali is (C1-3)

Question 16

Which nerves from the brachial plexus can be found in the Posterior Triangle?

Answer 16

1. Suprascapular N. (C5,6)
2. Dorsal scapular N. (C5)
3. Long thoracic N (C5,6,7)