Posterior Triangle

Question 1

Which is the only muscle that sits above the fascia of the neck?

Answer 1

Platysma muscle

Question 2

What are the superficial and deep fascial layers of the neck?

Answer 2

• Superficial: investing layer of dense connective tissue

- Deep: infrahyoid fascia, pretracheal fascia, carotid sheath, and prevertebral (deep cervical) fascia

Question 3

What are the boundaries of the posterior triangle?

Answer 3

• Anterior: sternocleidomastoid
• Posterior: trapezius
• Inferior: clavicle

Question 4

What are the two subtriangles of the posterior triangle?

Answer 4

• Occipital triangle: above omohyoid

- Omoclavicular (supraclavicular) triangle: below omohyoid, above clavicle

Question 5

What is the function of the scalene muscles?

Answer 5

Flex and laterally bend the neck to the same side; elevate 1st and 2nd ribs

Question 6

What is the function of the SCM?

Answer 6

• Unilaterally acts to TILT the head to the SAME side and ROTATE the head to the OPPOSITE site
• Bilaterally acts to extend/protract the head
• Bilaterally acts to aid in respiration when the head is fixed (but this is a minor function)

Question 7

Which muscle is part of both subtriangles?

Answer 7

anterior scalene

Question 8

What are the cutaneous branches of the cervical plexus?

Answer 8

• Lesser occipital nerve
• Greater auricular nerve
• Supraclavicular nerve
• Transverse cervical nerve

Question 9

What are the nervous and arterial contents of the occipital triangle?

Answer 9

• Cervical plexus (cutaneous and motor branches)
• CN XI
• Phrenic nerve
• Transverse cervical artery

Question 10

Do the transverse cervical artery and nerve travel in the same direction?

Answer 10

No! The transverse cervical nerve starts posterior (from ventral rami of C2-C3) and wraps anteriorly. The transverse cervical artery starts anteriorly and wraps around posteriorly to the medial side of the scapula.

Question 11

What does the motor portion of the cervical plexus consist of?

Answer 11

• Phrenic nerve
• Ansa cervicalis
• Ventral rami

Question 12

The cutaneous branches of the cervical plexus are all which type of rami?

Answer 12

Ventral rami (no dorsals)

Question 13

What are the contents of the supraclavicular triangle?

Answer 13

• Lower portion of brachial plexus
• Subclavian artery and vein
• Branches of subclavian (VIT C & D)
• Termination of external jugular vein

Question 14

Where is the phrenic nerve located in the body?

Answer 14

It lays right on top of the anterior scalene!

Question 15

Where is the thyrocervical trunk in relation to the anterior scalene muscle?

Answer 15

In front of it (thus, the transverse cervical a. and suprascapular a. run posteriorly across the anterior scalene).

Question 16

Where are the subclavian artery and vein in relation to the anterior scalene? What about in relation to the clavicle?

Answer 16

• Subclavian artery runs b/t anterior and middle scalene muscles (so, posterior to the anterior scalene)
• Subclavian vein runs in front of (anterior) to the anterior scalene
• Both are behind the clavicle!*

Question 17

Where does the dorsal scapular nerve usually run in relation to the anterior scalene?

Answer 17

Behind (deep to) it!