NSB 5. Posterior Triangle of the Neck Flashcards
Which part of the spine is more easily damaged than others?
CERVICAL spine more easily damaged than lumbar or thoracic
What are the triangles of the neck?
[1] Anterior Triangle
[2] Posterior Triangles (2x)
What are the boundaries of the posterior triangle of the neck?
ANTERIOR:
- posterior edge of the sternocleidomastoid muscle
POSTERIOR:
- anterior edge of trapezius
INFERIOR:
- middle 1/3 of clavicle
SUPERIOR/APICALLY:
- occipital bone just posterior to mastoid process
What is the mastoid process?
a pyramidal bony projection from the posterior section of the temporal bone
What makes up the floor of the posterior triangle? (from superior to inferior)
[1] Splenius Capitis
[2] Levator Scapulae
[3] Posterior, Middle and Anterior Scalene Muscles
- they are covered by prevertebral layer of cervical fascia
What makes up the roof of the posterior triangle?
Cervical Fascia:
- prevertebral layer
- investing layer
How can infection spread from the neck to the mediastinum?
through the Retropharyngeal Space
- or spaces that are created around the fascia layers
What is the retropharyngeal space?
space of the head and neck, bounded by the buccopharyngeal fascia anteriorly and the alar fascia posteriorly
- it contains lymph nodes
What are the layers of the cervical fascia from outside to in?
[1] Superficial Cervical Fascia
[2] Deep Cervical Fascia
(a) Investing Fascia
— goes around sternocleidomastoid, trapezius + “strap” muscle
(b) Pretracheal Fascia
- – around the trachea, oesophagus and thyroid gland
(c) Prevertebral Fascia
- – surrounds cervical vertebrae + surrounding muscles
(d) Carotid Sheath
- – around internal jugular vein, carotid arteries (common, internal + external) and vagus nerves
What are the attachments of the sternocleidomastoid muscle? Where does it originate from? Where does it end up?
- it originates from the mastoid
- there are 2 heads of the sternocleidomastoid
- the first part attaches to the sternum
- the second part attaches to the clavicle
What is the nerve supply of the sternocleidomastoid?
the accessory nerve (XI)
If a sternocleidomastoid muscle was to act on its own/individually (only one side working) what movement will occur?
it will turn the chin towards the opposite shoulder
If the sternocleidomastoid muscles were to act together, what movement will occur?
when the 2 sides are working together, it will draw the head forward
What path does the accessory nerve (XI) take?
- it starts from the upper 1/3 of the posterior border of the sternocleidomastoid
- passes deep to the investing layer of deep cervical fascia
- descends and enters the posterior triangle
- enters lower 1/3 of anterior border of trapezius
What is the nerve supply of the trapezius?
accessory nerve (XI)
What is the action of the trapezius?
- assist in rotating the scapula during abduction of the humerus above the horizontal (raise your hand)
- shrug the shoulders
How do you test the XI nerve?
[1] Sternocleidomastoid
- make the person turn their head to the opposite side – the examiner needs to resist their movements
[2] Trapezius
- shrug shoulders
- examiners tries to push person’s shoulder down
What are the roots of the cervical plexus?
C1 to C4
What are the cutaneous branches of the cervical plexus?
- accessory nerve [XI]
- lesser occipital nerve
- great auricular nerve
- transverse cervical nerve
- supraclavicular nerves
What are the nerve roots of the brachial plexus?
C5, C6, C7, C8 and T1
- the nerve roots are located in the posterior triangle
What are the branches of the aorta?
[1] Braciocephalic
(a) Right Subclavian
(b) Right Common Carotid
[2] Left Common Carotid
[3] Left Subclavian Artery
What are the arteries in the posterior triangle of the neck?
- 1st Part of Subclavian Artery
- 3rd Part of Subclavian Artery
- Suprascapular Artery
- Transverse Cervical Artery
What are the main veins of the posterior triangle?
[1] External Jugular Vein
- it is at the angle of the mandible to 3cm above middle 1/3 of the clavicle where it pierces the investing fascia to join the subclavian vein
[2] Subclavian Vein
- crosses the base of the posterior triangle
[3] Internal Jugular Vein
- found between the 2 heads of the SCM
- from he temperomandibular joint to the sternoclavicular joint
Where is the internal jugular vein located?
between the 2 heads of the sternocleidomastoid
What is the path that the internal jugular vein takes?
it goes from the temperomandibular joint to the sternoclavicular joint
What are the lymph nodes in the posterior triangle of the neck?
[1] Occipital Nodes
[2] Supraclavicular Nodes
What are the 2 structures within the chest cavity which extends up into the posterior triangle of the neck?
[1] Apex of the Lung
[2] Cervical Pleura
they extend 2cm above the middle 1/3 of the clavicle
To summarize, what are the major contents of the posterior triangle?
[1] Accessory Nerve (XI)
[2] Cervical Plexus - Cutaneous Branches
[3] Subclavian Artery (3rd part) + Suprascapular + Transverse Cervical (from 1st part)
[4] Subclavian Vein
[5] Upper Trunk of Brachial Plexus
[6] Apex of Lung
[7] Occipital and Supraclavicular Lymph Nodes
If there is injury to the cervical pleura, what can this lead to?
pneumothorax
If there is injury to the subclavian vessels, what can this lead to?
it can lead to potentially catastrophic bleeding
If the accessory nerve is injured what happens?
Dropped Shoulder
- since it gives action to the trapezius and sternocleidomastoid
What is Erb Duchenne Palsy?
- upper brachial plexus injury (C5 + C6)
- leads to over extension of the neck
outcomes:
- internal rotation of shoulder
- wasting of the arm
- “waiter’s tip”
What is the path that the external jugular vein takes?
it is at the angle of the mandible to 3cm above middle 1/3 of the clavicle where it pierces the investing fascia to join the subclavian vein
