Posterior Triangle Flashcards
Boundries
- Anterior
- Posterior
- Below (base)
- Above (apex)
Anterior
Posterior border sternomastoid
Posterior
Anterior border trapezius
Base
Middle 1/3 clavicle
Apex
Attachment of sternomastoid and trapezius to superior nuchal line of occipital bone
Roof
- Skin
- Superficial fascia
- Deep investing fascia
Superficial fascia
Contains:
1. Platysma
2. EJV
Deep investing fascia
Pierced by:
1. EJV: 1inch above clavicle
2. Cervical plexus cutaneous: at middle of sternomastoid posterior border
3. Supraclavicular nerves: just above clavicle
Spinal root accessory nerve is embedded in it
Floor contents
- Muscles (from below):
- scalneus medius
- Levator scapulae
- splenius capitis - Deep (prevertebral) fascia: covering muscles of the floor
Contents
- Muscles
- Nerves
- Arteries
- Veins
- Lymph nodes
Muscles
Inferior belly omohyoid
Nerves
- Trunks of brachial plexus
- Cutaneous branches of cervical plexus
- Muscular branches of cervical plexuses
- Spinal root accessory nerve
Arteries
- 3rd part subclavian artery
- Suprascapular artery
- Transverse cervical artery
Veins
Lower part EJV
Lymph nodes
Along
1. Posterior border sternomastoid
2. Anterior border trapezius
3. Transverse cervical vessels
4. Spinal root of accessory nerve
Inferior belly omohyoid
- Slender muscle
- 2 1/2 cm above clavicle
- Divides triangle into:
- Above: subclavian (supraclavicular)
- Below: occipital
Trunks of brachial plexus
- Upper
- Middle
- Lower
In lower part triangle
Cutaneous branches of cervical plexus
Appear at middle of sternomastoid posterior border and pierce roof deep fascia to supply skin:
1. Lesser occipital (C2)
2. Great auricular (C2,3)
3. Transverse cutaneous nerve neck (C2,3)
4. Supraclavicular (C3,4)
Lesser occipital
C2
Ascends along sternomastoid posterior border to skin on scalp back and upper 1/3 of auricle back
Great auricular
C2,3
Runs upwards and forwards on sternomastoid to skin on:
1. Parotid
2. Mandible angle
3. Mastoid process
4. Lower 1/3 of auricle lateral surface
5. Lower 2/3 auricle medial surface
Transverse cutaneous nerve neck
C2,3
Runs transversely across sternomastoid towards midline and divides into:
1. Upper branch
2. Lower branch
To neck anterior part
Supraclavicular
C3,4
Descends as 3 branches which pierce roof deep fascia a little above clavicle then cross clavicle to skin of chest as far as sternal angle and upper 1/2 deltoid
Muscular branches of cervical plexus
To
1. Sternomastoid
2. Trapezius
3. Levator scapulae
4. Scalene muscles
5. Diaphragm (phrenic nerve)
Spinal root accessory nerve
- Appears at middle of sternomastoid posterior border
- Passes downwards and backwards over Levator scapulae (in deep fascia roof) to disappear undercover trapezius (5cm above clavicle
- Supplies:
- sternomastoid
- trapezius
3rd part subclavian artery
In lower part of triangle in front of brachial plexus lower trunk
Suprascapular artery
- Branch of thryocervical trunk (1st part subclavian artery)
- Crosses triangle very close to clavicle
Transverse cervical artery
- Branch of thyrocervical trunk (1st part of subclavian artery)
- Crosses triangle above Suprascapular artery
- End at Levator scapulae anterior border by dividing into:
- superficial branch
- deep branch
Lower part EJV
- Descends in triangle lower part in front of brachial plexus trunks
- End in subclavian vein
- Receives:
- Suprascapular vein
- transverse cervidak vein
- anterior jugular vein
