The posterior triangle of the neck is bounded by the sternocleidomastoid muscle anteriorly and the trapezius muscle posteriorly. It is subdivided into the occipital and subclavian triangles by the omohyoid muscle. The posterior triangle contains nerves like the accessory nerve and branches of the brachial plexus, blood vessels like the external jugular vein and subclavian artery, and lymph nodes. Knowledge of the anatomy of the posterior triangle is important for procedures like brachial plexus blocks and catheterization of the external jugular vein.

1. Posterior Triangle of Neck
Lecture By
Dr.N.Mugunthan.MBBS,MS,DNB,MNAMS,
Associate professor in Anatomy
MGMC&RI

2. OBJECTIVES
Posterior triangle of Neck:
Boundaries
Subdivisions
Contents
Applied anatomy
©Dr.N.Mugunthan

3. ©Dr.N.Mugunthan

4. BOUNDARIES
Anteromedially:
• Posterior border of
sternomastoid muscle
Posterolaterally:
• Anterior border of
trapezius
Base:
• Middle third of clavicle
Apex:
• Meeting point of
sternomastoid & trapezius
on superior nuchal line
©Dr.N.Mugunthan

5. Roof :
• Skin
• Superficial fascia with
platysma
• Investing layer of deep
cervical fascia
Structures piercing the roof:
1. External jugular vein
2. Supraclavicular nerves
3. Small cutaneous arteries
4. Lymph vessels
BOUNDARIES cont…
©Dr.N.Mugunthan

6. Floor:
(From above downwards)
1. Splenius capitis
2. Levator scapulae
3. Scalenus medius
* Semispinalis capitis
* Scalenus posterior
BOUNDARIES cont…
©Dr.N.Mugunthan

7. Inferior belly of
omohyoid divides the
triangle into 2 parts
1. Upper larger part –
occipital triangle
2. Lower smaller part –
subclavian or
supraclavicular triangle
SUBDIVISIONS OF POSTERIOR TRIANGLE
©Dr.N.Mugunthan

8. CONTENTS
1. Nerves
2. Blood vessels
3. Lymph nodes
©Dr.N.Mugunthan

9. I. NERVES
Arranged in three groups:
 All the nerves are emerging
from middle of posterior
border of sternomastoid
muscle
A. Superficial group:
(Lies superficial to roof
fascia)
1. Supraclavicular nerves
( C3&C4)
2. Transverse cervical nerve
( C2&C3)
3. Great auricular nerve
(C2&C3)
4. Lesser occipital nerve (C2)
©Dr.N.Mugunthan

10. B. Middle group: (situated
between roof fascia &
floor fascia)
1. Accessory nerve
C. Deep Group:
(Situated deep to the floor
fascia)
1. Branches from C3& C4
to trapezius
2. Nerve to levator
scapulae ( C3&C4)
3. Upper & middle trunks
of brachial plexus
I. NERVES cont…
©Dr.N.Mugunthan

11. C. Deep Group (cont….)
Branches of brachial plexus:
4. Nerve to subclavius*
( C5 &C6)
5. Suprascapular nerve*
(C5&C6)
* Erb’s Point
6. Nerve to rhomboids
(dorsal scapular nerve) (C5)
7. Nerve to Serratus anterior
(long thoracic nerve of bell)
(C5,C6&C7)
I. NERVES cont…
©Dr.N.Mugunthan

12. II. BLOOD VESSELS
• Suprascapular artery *
• Transverse cervical artery*
( Superficial branch –
accompanies accessory nerve
& deep branch accompanies
nerve to rhomboids)
*Branch from thyrocervical
trunk of 1st part of subclavian
artery
• 3rd part of subclavian artery
(emerging between scalenus
anterior & medius) – axillary
sheath (scalene fascia)
©Dr.N.Mugunthan

13. • External jugular vein – just
above clavicle pierce the
deep fascia & drain into
subclavian vein
• Subclavian vein (infront of
scalenus anterior )
• Terminal part of transverse
cervical vein, suprascapular
vein,anterior jugular vein &
external jugular vein.(drain
into subclavian vein)
II. BLOOD VESSELS (CONT….)
©Dr.N.Mugunthan

14. III. LYMPH NODES
• Chain of lymph nodes lie
along posterior border of
sternomastoid
• Chain of lymph nodes lie
along accessory nerve
©Dr.N.Mugunthan

15. Surface anatomy
External jugular vein:
• A point on sternomastoid
at the level of angle of
mandible
• Midpoint of clavicle
©Dr.N.Mugunthan

16. Surface anatomy
Accessory nerve:
• A point midway between
mastoid & head of
mandible
• Midpoint of
sternomastoid
• A point 5cm above
clavicle on anterior
border of trapezius.
©Dr.N.Mugunthan

17. APPLIED ANATOMY
External jugular vein:
Air embolism
Catheterization
Measuring the right atrial
pressure
©Dr.N.Mugunthan

18. APPLIED ANATOMY
All nerves are emerging
from middle of posterior
border of sternomastoid
Brachial plexus block
©Dr.N.Mugunthan

19. SUMMARY
Posterior triangle of Neck:
Boundaries
Subdivisions
Contents
Applied anatomy
©Dr.N.Mugunthan

20. ©Dr.N.Mugunthan