Posterior Triangle Flashcards
What forms the apex, anterior, posterior, and inferior borders of the posterior ∆?
Apex:
Occipital Bone
Anterior:
SCM
Posterior:
Trapezius
Inferior:
Clavicle (Middle 1/3)
What forms the roof of the posterior ∆?
Roof:
Investing Fascia
What fascial layers form the floor of the posterior ∆?
- Underlying muscles from superior to inferior
Floor Fascia:
- Prevertebral Fascia
Floor Muscles:
- Splenius Capitis
- Levator Scapulae
- Posterior, middle, and Anterior Scalene muscles
T or F: the scalene muscles are secondary muscles of respiration.
True
What is the origin and insertion of Splenius Capitis?
Origin:
- Lower half of ligamentum nuchae
- Spinous processes of vertebrae C7-T4
Insertion:
- Mastoid Process
- Skull below lateral one-third of superior nuchal line
What is the innervation and action of splenius capitis?
Innervation:
Posterior Rami of Middle Cervical Nerves
Action:
- Together: draw head backward
- Indiviual: Rotate head to one side (turn face to same side)
What is the origin and insertion of anterior scalene?
Origin:
Transverse processes of Cervical Vertebrae (like all the scalenes)
Insertion:
1st Rib
What is the action and innervation of the anterior scalene?
Innervation:
- Ventral Rami of the Cervical Plexus (like all of the scalenes)
Action:
- Laterally Bends the Neck
- Elevates the 1st Rib
What is origin and insertion of the middle scalene?
Origin:
Transverse Processes of Cervical Vertebrae (like all of the scalenes)
Insertion:
1st Rib
What is the action and innervation of the middle scalene?
Innervation:
- Ventral Rami of the cervical plexus (like all of the scales)
Action:
- Laterally Bends the Neck
- Elevates the 1st Rib
What is the origin and insertion of the posterior scalene?
Origin:
- Transverse Processes of the Cervical Vertebrae (like all of the scalenes)
Insertion:
- 2nd Rib
What is the action and innervation of the posterior scalene?
Innervation:
- Ventral Rami of the cervical plexus (like all of the scales)
Action:
- Laterally bends the Neck
- Elevates the 2nd rib
What is the origin and insertion of levator Scapulae?
Origin:
-C1-C4 transverse Processes
Insertion:
- Medial Border of the Scapula (above the spine)
Innervation and action of levator scapulae?
Innervation:
Dorsal Scapular n.
Action:
Moves the shoulder girdle
What is the common innervation of all scalene muscles?
- Ventral Rami of the Cervical Plexus
What muscle crosses the inferior border of the posterior ∆ crossing anterior to middle scalene?
- Inferior Belly of Omohyoid
What are the borders of the scalene ∆?
Anterior:
Anterior Scalene
Posterior:
Middle Scalene
Inferior:
Rib 1
What structures pass through the scalene ∆?
- Subclavian Artery
2. ROOTS and TRUNKS of the Brachial Plexus pass to upper limb
T or F: the Phenic nerve and Subclavian Vein pass though the scalene ∆.
FALSE, these DO NOT
What nerve roots give rise to the phrenic Nerve?
C3, C4, C5
C4 being the biggest contributor
What muscles does the phenic nerve emerge from behind then subsequently travel along?
Anterior Scalene
T or F: the subclavian artery provides an important source of oxygenated blood to the thyroid and brain.
True
What defines the 3 parts of the subclavian a?
- How many branches off of each part?
Anterior Scalene Parts: 1. Medial to Scalene (3) 2. Posterior to Scalene (1) 3. Lateral to Scalene (1)
What artery arises from the 3rd part of the subclavian?
Dorsal Scapular a. (to the rhomboids)
What major trunk does the 1st part of the subclavian give rise to?
- branches of this trunk?
Thryocervical Trunk
Gives rise to:
- Inferior Thyroid
- Transverse Cervical
- Suprascapular aa.
What are the 3 branches off of the First Part of the Subclavian artery?
- Vertebral a.
- Thyrocervical trunk
- Internal Thoracic a.
What branch comes off of the 2nd part of the subclavian BEHIND anterior scalene?
- describe additional branching from this structure
Costocervical Trunk
2 Branches:
- Deep Cervical
- Supreme Intercostal aa.
You notice is a patient that the Dorsal Scapular artery is not coming from the 3rd part of the Subclavian as you usually expect, but you see it coming off another structure. What is it?
- Branching off of Transverse Cervical Artery from the 1st Branch
**This happens about 30% of the time
Where can you find the cervical part of the SYMPATHETIC CHAIN?
- Deep to the part of the PREVERTEBRAL fascia that is deep to the CAROTID SHEATH
What 6 nerves exit directly being SCM and almost immediately exits the posterior ∆ (except for 2)?
- Lesser Occipital
- Greater Auricular
- Transverse Cervical
- Medial Supraclavicular
^ All immediately exit - Lateral Supraclavicular
- Intermediate Clavicular
^ remain inside the ∆ before exiting
T or F: strucutures that are deep to SCM are TECHNICALLY OUT of the posterior ∆.
True
What is the punctum nerosum?
Same thing as Nerve point its where the 6 nerves exit midway down the SCM
What issue might you run into when trying to adminster anesthetics to the nerve point?
- The Phrenic Nervis is nearby
What is the omoclavicular ∆?
- Lower Subdivision of the posterior ∆ formed by posterior belly of omohyoid
Describe how a ventral ramus exits the vertebral area in the cervical region.
- Passes POSTERIOR to the Vertebral a. (traveling through transverse foramen)
- ANTERIOR to the superior facet
THEN
- Anterior to middle scalene and Posterior to Anterior Scalene
What structures pass THROUGH the scalene ∆?
-which pass OVER?
THROUGH:
- Superior, Middle, and Inferior trunks of the Brachial Plexus
- Subclavian Artery
OVER (but still IN it)
- Phenic N. (C3-5)
What passes anterior to the anterior scalene and thus is NOT in the scalene ∆?
subclavian VEIN
What 2 vein join just posterior to the sternoclavicular joint?
- Subclavian joins the internal jugular to form the brachiocephalic trunk
What the bifurcation of what artery happens at the sternoclavicular joint?
Brachiocephalic Truck bifurcates to RIGHT Subclavian and RIGHT common carotid
***NOTE THIS ONLY HAPPENS ON THE RIGHT SIDE