Posterior Triangle Flashcards
What are the borders of the posterior triangle?
the anterior border of the trapezius, the posterior border of the sternocleidomastoid (SCM), and the middle one-third of the clavicle
What is the roof of the posterior triangle?
the investing fascia
What is the floor of the posterior triangle composed of?
the anterior, middle and posterior scalene muscles,
the levator scapulae and
the splenius capitis
What are the cutaneous nerves of the nerve point of the neck (aka the punctum nervosum)?
the lesser occipital, the great auricular, the transverse cervical, and the supra scapular (the medial, intermediate, and lateral)
The path of the omohyoid demarcates a lower subdivision of the posterior triangle called what?
the omoclavicular triangle
Is the external jugular vein inside or outside of the investing fascia?
outside, BUT it penetrates this fascial layer inferiorly to join the subclavian vein directly behind the SCM near where it attaches to the manubrium and the medial clavicle
the anterior, middle and posterior scalene muscles originate from what?
cervical transverse processes
Where do the anterior and middle scalene muscles insert?
on the first rib
The borders of the anterior and middle abalone muscles form what structure?
the scalene triangle
Where does the posterior scalene muscle insert?
on the second rib
What structures pass through the scalene triangle?
the trunks of the brachial plexus and the subclavian artery
Does the subclavian vein pass through the scalene triangle?
No, it passes just anterior to the anterior scalene
What two muscles does the subclavian vein pass between in the neck?
the anterior scalene and the SCM
Does the subclavian artery pass anterior or posterior to the omohyoid (near its attachment to the scapula)?
anterior
What are the nerve roots of the phrenic nerve?
C3, C4, C5.
What muscle does the phrenic nerve descend on?
the anterior scalene
What is the sole motor innervation to the diaphragm?
the phrenic nerve
Is the phrenic nerve considered to be inside the scalene triangle?
No, it is on the anterior surface of the anterior scalene
Where does the subclavian join the internal jugular vein?
just posterior to the sternoclavicular joint
Where does the brachiocephalic trunk branch into the right common carotid artery and right subclavian artery?
just posterior to the sternoclavicular joint, sightly medial and posterior to the junction of the subclavian vein and the internal jugular vein
remember that the subclavian artery is posterior to the posterior vein and course laterally through two different spaces (artery in the scalene triangle, vein is anterior to the anterior scalene and posterior to the SCM)
What are the important branches of the common carotid artery?
There are none, other than the birfurcation to the internal and external carotid
The anterior scalene muscle divides the subclavian artery into three parts. Where are they?
The first part is medial to the anterior scalene, the second part is posterior to the anterior scalene and the third part is lateral to the anterior scalene
Where does the subclavian artery become the axillary artery?
At the lateral edge of the first rib
What are the branches of the first part of the subclavian artery?
the internal thoracic, the vertebral and the thyrocervical trunk.
Does the internal thoracic artery run anterior or posterior to the subclavian vein?
posterior. it arise from the subclavian on the inferior, anterior aspect and descends posterior to the subclavian vein and the 1st rib to enter the anterior costal cage
What nerve is descending immediately lateral to the internal thoracic artery?
the phrenic nerve
What nerve is descending immediately medial to the internal thoracic artery?
the vagus nerve
The vertebral artery enters the costotransverse foramen of which vertebrae? Then where does it go?
C6. The vertebral artery ascends through the remaining costotransverse foramina anterior to emerging cervical spinal nerves
What does the vertebral artery do at the superior end of the vertebral column?
it winds around the superior articular process of the atlas and pierces the dura mater at the foramen magnum to supply the brain
In its ascent, the vertebral artery supplies branches to the spinal cord and to deep neck muscles.
Within the cranial vault, the vertebral arteries from right and left sides join to form what?
the basilar artery, which is one of the two primary blood supplies to the brain and brainstem!
What are the main branches of the thyrocervical trunk?
inferior thyroid artery
suprascapular artery
transverse scapular artery
What does inferior thyroid artery pass directly posterior to during its course?
the carotid sheath. it arises just lateral (and deep) to it and ascends a little before turning medial at the level of the inferior pole of the thyroid gland
What is more anterior, the omohyoid or the phrenic nerve?
the omohyoid. If you were stabbed (at the precisely necessary point), you could pass (from anterior to posterior) through the SCM
Right where the inferior thyroid artery makes its 90 degree medial turn behind the carotid sheath, what does it give off?
A small ascending cervical artery. It ascends along the anterior scalene to supply muscles in the neck
Does the spending cervical artery ever cross the phrenic nerve along the anterior scalene muscle?
No, it ascend medial the entire route
What two arteries cross over the anterior scalene and phrenic nerve, essentially pinning it to the muscle?
the suprascapular and transverse cervical aa.
What muscles does the supra scapular artery pass between?
it runs anterior to the anterior scalene and then in between a space created by the omohyoid anteriorly and the posterior scalene posteriorly to reach the supra scapular notch on the scapula
Does the supra scapular a. ever cross the omohyoid anteriorly?
yes, it cross superiorly and anteriorly near the midline of the clavicle. this is because the omohyoid inserts just medial to the suprascpaular notch, which is posterior to the notch and it arises anterior to the artery
Where does the transverse cervical a. run?
branches just superior to the suprascapular a., and travels on a similar path anterior to the anterior scalene to the superior angle of the scapula
What are the branches of the second part of the subclavian artery?
the costocervical trunk. Most often it branches from the artery straight back just as it runs posterior to the anterior scalene
What are the branches of the costocervical trunk?
the highest intercostal artery and the deep cervical artery.
Where does the deep cervical artery pass posterior to the vertebral column? What does it anastomose with?
What does it supply?
it passes posteriorly below the transverse process of C7 and then descends on the edge of the vertebrae before anastomosing with the occipital artery
supplies deep neck muscles
What does the highest intercostal artery supply?
The highest intercostal artery supplies the posterior intercostal arteries to the first two intercostal spaces
What are the branches of the 3rd part of the subclavian?
The dorsal scapular artery
Where does CN XI originate?
in the upper 5 or so cervical segments of the spinal cord
Why is CN XI not considered a spinal nerve?
One reason it is not a regular spinal nerve is that although it supplies GSE fibers to SCM and trapezius, the nerve cell bodies do not emanate from exactly the same region of the spinal cord as the GSE fibers of spinal nerves. Also, nerves from 4-6 different segments collect into one nerve, and spinal nerves don’t do that
Lastly, it courses up through the foramen mangnum into the cranial vault and out of the skull through the jugular foramen
What structure do the vagus and accessory nerves surround during their route?
the jugular bulb. Both nerves originate on the lateral aspect of the medulla oblongata, with the vagus being superior to CN XI. the vagus and CN XI then cross each other in the vertical plain forming an X, and CN XI goes over the top of the jugular bulb and the vagus goes under the bottom. CN XI then turns posteriorly and courses back out of the jugular foramen to the SCM and trapezius
What innervates the SCM?
CN XI and C2-C3
What innervates the trapezius?
CN XI and C3-C4
What two spaces in the cranial cavity does CN XI pass through?
it ascends through the foramen magnum and then back down through the jugular foramen
What joint allows for nodding your head anterior and posterior?
The atlanto-occipital joint between the atlas and axis
The sympathetic trunk extends into the neck in the space posterior to what? Anterior to what?
posterior to the carotid sheath and anterior to the prevertebral muscles
Does the cervical region of the sympathetic trunk have white rami?
NOO, only grey rami. Remember that there are only 14 pairs of white rami while there are 31 pairs of grey rami
During development there are sympathetic ganglia associated with each cervical spinal nerve, but there is secondary fusion of ganglia in the neck so that usually only three (of the original 8) remain. What are they?
The superior cervical ganglion is usually the fusion of C1-4. There is usually a middle cervical ganglion as a result of the fusion of C5 and C6 ganglia. The inferior cervical ganglion (C7, 8) is frequently fused with the first thoracic to form a cervicothoracic (i.e. stellate) ganglion.
What is the final common path for most of the lymphatic drainage of head and neck?
What structure does it lie on?
the deep cervical lymphatic chain
lies along the internal jugular vein
The nodes of the deep cervical lymphatic chain are divided into what? By what?
They are arbitrarily divided into superior and inferior nodes (aka supraclavicular nodes) based on the position of the omohyoid muscle as it crosses the IJV
Nodes in the retropharyngeal space drain where?
into the superior group of nodes
Where is the the jugulodigastric node?
right anterior to the splitting of the SCM and posterior digastric belly from the mastoid process
What structures does the the jugulodigastric node drain?
drainage from the tongue and palatine tonsil, so it enlarges and becomes sore during throat or upper respiratory infections
