Posterior Triangle Wilson Flashcards
What muscles make up the boundaries of the posterior triangle?
Trapezius, Inf: Omohyoid and clavicle , and SCM
What muscles are contained int the posterior triangle? (They make up the floor)
Levator scapula, Posterior Scalene, Middle scalene, and anterior scalene.
What are the boundaries of the scalene triangle?
Omohyoid, Anterior scalene and middle scalene
What fascia covers the floor of the posterior triangle
Pre-vertebral layer of deep cervical fascia
What are the contents of the scalene triangle?
What is the huge potential of nerve injury in this area?
Trunks of the brachial plexus, Subclavian artery.
Subclavian vein and phrenic nerve are NOT in the triangle
Brachial plexus Injuries are common here.
What are the 5 things that the subcavian artery distributes to?
- Anterior thoracic wall
- Thyroid Gland
- Muscles of the dorsal scapular and superficial back
- Brain and brain stem
- Deep muscles of the anterior cervical region
What is the first branch of the subclavian artery?
Vertebral artery- Arises from the first portion of the subclavian artery ascends between the anterior scalene muscle and longus colli muscles and runs in the transverse processes of C6-C1 and enters the cranial cavity in the foramen magnum
What is the second branch of the subclavian artery?
What are the three branches?
Thyrocervical trunk
Inferior thyroid
Transverse Cervical
Suprascapular
What is the third branch that distributes into the thorax?
Internal thoracic artery- Arises from the first part of the subclavian artery and descends through the thorax behind the upper six costal cartridges and bifurcates into the superior epigastric and musculophrenic
What are the three branches of the thyrocervical trunk?
- Suprascapular artery Passes in front of the anterior scalenes muscle and brachial plexus parallel to but below the transverse cervical artery
- Transverse Cervical Artery Runs laterally across the anterior scalenes muscle, phrenic nerve, and brachial plexus passing deep to the trapezius
- Inferior Thyroid Artery- Ascends in front of the anterior scalenes muscle and turns medially behind the carotid sheeth but in front of the vertebral vessels.
What are the two branches of the costocervical trunk?
Superior Intercostal Artery- Gives rise to the first two posterior intercostal arteries.
Deep Cervical artery- Passes between the transverse process of C7 and the first rib . It anastomoses with the descending occipital artery
Where does the thoracic duct terminate?
At the union between the deep juglar vein and the subclavian vein
Where does the subclavian artery turn into the axillary artery
When it passes between the clavicle and the first rib.
If you wanted to compress the subclavian artery where could you do that?
Just medial to the clavicle you can compress the subclavian artery against the first rib
Where would be a potential place to perform a jugular vein puncture
Above the sternal notch through the SCM muscle.
Where could you perform a subclavian vein puncture?
Medial to the axillary pulse at the clavicle
What nerve courses through the posterior triangle?
Accessory Nerve
What are the causes of thoracic outlet syndrome?
- Cervical Rib
2. Pancost Tumor
What are the symptoms of Thoracic outlet syndrome?
- Numbness on the medial aspect of the forearm and hand (C8-T1)
- Weakness of ulnar innervated muscles. (Claw hand C8-T1)
- Decreases blood flow into the upper limb (weak radial pulse)
What is horners syndrome caused by?
Compression of the cervical sympathetic trunk
Compression of what nerve causes hoarseness?
Recurrent Laryngeal
What nerves pass over the subclavian artery?
Vagus, Sympathetic trunk, Recurrent Laryngeal, Phrenic
What muscles make up the boundaries of the posterior triangle?
Trapezius, Inf: Omohyoid and clavicle , and SCM
What muscles are contained int the posterior triangle? (They make up the floor)
Levator scapula, Posterior Scalene, Middle scalene, and anterior scalene.
What are the boundaries of the scalene triangle?
Omohyoid, Anterior scalene and middle scalene
What fascia covers the floor of the posterior triangle
Pre-vertebral fascia
What are the contents of the scalene triangle?
Trunks of the brachial plexus, Subclavian artery.
Subclavian vein and phrenic nerve are NOT in the triangle
What are the 5 things that the subcavian artery distributes to?
- Anterior thoracic wall
- Thyroid Gland
- Muscles of the dorsal scapular and superficial back
- Brain and brain stem
- Deep muscles of the anterior cervical region
What artery is given off of the third division of the subclavian artery
Dorsal scapular artery- Arises from the third part of the subclavian or the deep descending branch of the transverse cervical artery
What is the second branch of the subclavian artery? And what are the three branches?
Thyrocervical trunk
Inferior Thyroid Artery
Transverse Cervical Artery
Suprascapular Artery
What is the third branch that distributes into the thorax?
Internal thoracic artery.
What are the three branches of the thyrocervical trunk?
- Suprascapular artery
- Transverse Cervical Artery
- Inferior Thyroid Artery
What are the two most common nerve injuries in the scalenes triangle?
- Injury or nerve lesion to the superior cord of the brachial plexus. C5-C6 Erb Duchenne Palsy which will result in loss of fuction ot the suprascap axillary and musculocutaneous nerves
- Injury to the inferior cord of the brachial plexus which will result in a C8-T1 lesion. this will result in loss of function of the Ulnar Nerve Klumpke’s Palsy
What is the major concern if you injure the C4 transverse process?
Damage to the phrenic Nerve. C4 is the major contribution to this nerve and if injured the diaphram will not function properly.
What are the 4 cutaneous branches of the cervical plexus?
Lesses Occipital C2 Ascends along the posterior border of the SCM and innervates the skin behind the auricle
Greater Auricular C2-C3 Ascends over the SCM to innervate the skin behind the auricle and on the parotid gland.
Transverse Cervical C2-C3 Turns around the posterior border of the SCM and innervates the skin of the posterior triangle
Supraclavicular- Emerges as a common trunk from under the SCM and then divided into anterior middle and lateral branches to the skin over the clavicle and the shoulder.
What are the two motor branches of the cervical plexus
Phrenic C3-5 Keeps the diaphram alive. contains motor sensory and sympathetic fibers descends over the anterior surface of the anterior scalene muscles. Passes between the subclavian artery and vein and enters the neck.
Ansa Cervicalis- formed from the union of the superior root of C1-2 and the inferior root of C2-C3. Lies superficial to the carotid sheath in the anterior cervical triangle.
What is a grey rami?
Postganglionic sympathetic fiber that is traveling from the sympathetic chain back to the spinal nerve to be distributed to the body cavity
Describe the course of the accessory nerve
It travels superficial to the levator scapula and deep to the SCM and trapezius.
What nerve courses through the posterior triangle?
Accessory Nerve
What is a major concern of a fractured clavicle?
Laceration of the subclavian artery that passes just inferior to this structure.
Describe the danger space
The space between the anterior and posterior layers of pre vertebral fascia and because of its extension from the base of the skull to the diaphragm it is a conduit for the spread of infection
What is horners syndrome caused by?
Thyroid carcinoma Pancosts tumor or a penetrating injury to the neck can compress the cervical sympathetic chain and the disease is characterized by ptosis and mitosis.
What layer of fascia covers the scalene muscles and the deep muscles of the back?
Pre vertebral layer of deep cervical fascia.
What layer of fascia covers the SCM and trapezius muscles?
Superficial layer of deep cervical fascia.
How can you test the accessory nerve clinically?
Have the patient shrg the shoulders against resistance.
