POSTERIOR TRIANGLE OF NECK / BOUNDARIES / ROOF / FLOOR / FACIAL CARPET OF POSTERIOR TRAINGLE / OCCIPITAL TRIANGLE AND IT CONTENTS / SUBCLAVIAN OR SUPRASCAPULAR TRIANGLE AND IT CONTENTS / COLD ABSCESS OF POSTERIOR TRIANGLE / DAMAGE TO SPINAL ACCESSORY NERVE

 * It is a triangular space on the sides of the neck.

* It is present behind the sternocleidomastoid.

Q : What forms boundaries of posterior triangle ?

1) Anterior boundary :

* It is formed by posterior border of sternocleidomastoid.

2) Posterior boundary :

* It is formed by anterior border of trapezius.

3) Inferior boundary :

* Upper border of middle one third of clavicle.

4) Superior boundary or Apex :

* It is formed by superior nuchal line , of occipital bone where ,  sternocleidomastoid and trapezius meet.

Q : What forms roof of posterior triangle ?

* It is formed by the following structures ( superficial to deep )

1) Skin.

2) Superficial fascia

3) Platysma

4) Investing layer of deep cervical fascia

5) External jugular vein

6) Cutaneous nerves from cervical plexus

* Lesser occipital nerve

* Great auricular nerve

* Transverse cutaneous nerve of neck

* Supraclavicular nerve

Q : What structures form floor of posterior Triangle ?

* The floor is the floor of posterior triangle is muscular and is formed by following ( above downwards )

1) Semispinalis capitis

2) Splenius capitis

3) Levator scapulae

4) Scalenus posterior

5) Scalenus medius

6) Scalenus anterior ( sometimes )

Q : What forms facial carpet of posterior triangle ?

* The muscles forming the floor of posterior triangle are covered by prevertebral layer of deep cervical fascia which forms facial carpet of floor of posterior triangle.

Q : What are subdivisions of posterior triangle ?

* Posterior Triangle is subdivided into two triangles by inferior belly of omohyoid.

* Inferior belly of omohyoid divides  posterior triangle into large upper triangle called Occipital Triangle and small lower triangle called Subclavian Triangle or Supraclavicular Triangle.

Q : What are contents of Occipital  Triangle ?

1) Spinal part of accessory nerve

2) Muscular branches from C3 and C4 supplying levator scapulae and trapezius muscle

3) Dorsal scapular nerve

4) Four cutaneous branches of cervical plexus namely ,

Lesser occipital , Great auricular , Transverse cutaneous nerve of neck , Suprascapular Nerve.

5) Superior trunk of brachial plexus

6) Superficial cervical artery

7) Occipital artery

Q : What are contents of Subclavian or Supraclavicular Triangle ?

1) Third part of subclavian artery

2) Subclavian vein

3) External jugular vein ( terminal part)

4) Trunk of brachial plexus

5) Dorsal scapular nerve

6) Long thoracic nerve

7) Suprascapular nerve

8) Suprascapular artery

CLINICAL CO-RELATES OF POSTERIOR TRIANGLE :

# Cold abscess in Posterior Triangle :

* When pus gets collected deep to the facial carpet of the Posterior Triangle , it may track downwards along the axillary sheath and first appear in axilla .

# Damage to Spinal Accessory Nerve :

*  During the removal of lymph nodes in the Posterior Triangle ,  Spinal accessory nerve may get injured.

* Which leads to paralysis of trapezius muscle.

* Paralysis of trapezius leads to difficulty in combing hair.