Posterior Triangle Flashcards
A muscular patient who regularly lifts weights presents with pain and weakness in his right upper limb that has been slowly developing over time. His limb is cool and there is an obvious vascular insufficiency in his upper extremity. Subsequent tests show that a large vessel passing between the anterior and middle scalene muscles is being occluded by hypertrophy (enlargement) of the muscles due to the excercise. The artery involved is the:
The** subclavian artery **runs between the anterior and middle scalene muscles. Since this is the major artery supplying blood to the upper limb, occluding this artery might cause the symptoms of pain and weakness.
In repairing a damaged right subclavian artery, the surgeon notices and protects a large nerve passing around to the posterior surface of the artery. This nerve, which does not encircle the subclavian on the left side, is the:
The recurrent laryngeal nerves have different relationships to structures on the right and left sides of the body. On the right side, the recurrent laryngeal nerve loops around the right subclavian artery at approximately the T1/T2 vertebral level. On the left side, the recurrent laryngeal nerve loops around the arch of the aorta, behind the ligamentum arteriosum, at approximately the T4/T5 level.
A stab wound just above the left clavicle, lateral to the sternocleidomastoid muscle, may be life-threatening because of the possibility of injury to the:
The subclavian artery crosses between the anterior and middle scalene muscles, which means that it is also posterior to the sternocleidomastoid muscle. Lateral to the sternocleidomastoid muscle, the subclavian artery runs just above the clavicle.
A 27-year-old man who is a professional weight lifter comes to his physician complaining of recent weakness in his left arm and frequent tingling in his hand and fingers during exercise sessions which subsides with rest. He is diagnosed as having vasuclar insufficiency due to scalenus anticus syndrome and as a remedy it is decided to transect the anterior scalene muscle where it inserts on the first rib. During surgery, which structure in contact with the anterior surface of the muscle must the surgeon be careful of sparing?
The phrenic nerve is formed from contributions from the C3, 4, and 5 ventral primary rami. It lies on the anterior scalene muscle, which means that the surgeon would need to watch for this nerve while transecting the anterior scalene.
A 60-year-old man with a previous history of right carotid endarterectomy, comes to his physician complaining of light-headedness and dizziness whenever he uses his right hand vigorously. He is diagnosed as having subclavian steal syndrome due to an atherosclerotic plaque at the point where his subclavian artery branches from the brachiocephalic trunk. The cerebral insufficiency is the result of blood being stolen from which artery?
Vertebral
Subclavian steal syndrome occurs when there are abnormal blockages in vessels coming off of the aortic arch. Due to these blockages, there may be low blood flow to one arm through the subclavian artery. During high activity in the underperfused arm, the body needs to find a way to send blood to the arm to meet metabolic demands. It does this by shunting blood from the vertebral arteries.
A first year resident attempts to insert a central venous catheter into the heart by a subclavicular approach to the subclavian vein. Following the attempt, it is noted that the patient has difficulty breathing. What nervous structure lying immediately deep to the subclavian vein, as it crosses the anterior scalene muscle, may have been injured?
The **phrenic nerve **is formed from contributions from the C3, 4, and 5 ventral primary rami. It lies on the anterior scalene muscle, immediately deep to the subclavian vein. Since the phrenic nerve innervates the diaphragm, the patient’s symptom (difficulty breathing) fits with an injury to the phrenic nerve.
Which statement is true of the internal jugular vein?
- It drains all of the thyroid gland on that side of the body
- It drains into the external jugular vein
- It is accompanied by the deep cervical chain of lymph nodes
- It lies deep to the prevertebral fascia
- It passes superficial to the sternocleidomastoid muscle
The deep cervical chain of lymph nodes runs closely with the internal jugular vein.
Which structure lies immediately anterior to the right anterior scalene muscle at its costal attachment?
The subclavian vein lies anterior to the right and left anterior scalene muscles. It can be found coursing over the anterior scalene muscles on both the right and left sides.
A person develops a primary tumor of the thyroid gland and, among other symptoms, drooping of the eyelid and constriction of the pupil on the right side of the eye are noted. What nerve fibers have been interrupted by the tumor?
Cervical sympathetic trunk
**
A tumor of the thyroid gland could disrupt the preganglionic fibers traveling in the cervical sympathetic trunk.** The cervical sympathetic trunk lies in front of the preverterbral muscles in the preverterbral fascia–it is in the right location to be compressed by a thyroid tumor.
An abscess was surgically removed from the middle of the posterior triangle on the right side. During recovery the patient noticed that her shoulder drooped and she could no longer raise her right hand above her head to brush her hair. Which nerve has been cut?
Accessory nerve
if the tip of the shoulder is drooping, trapezius is denervated, and the accessory nerve has been damaged! The accessory nerve (CN XI) runs through the posterior triangle, so it is likely to be injured in posterior neck triangle operations. If the accessory nerve is damaged there, the trapezius will be denervated, but the sternocleidomastoid will be OK.
A surgeon doing a deep cervical lymph node dissection may encounter these structures upon the anterior surface of the anterior scalene muscle EXCEPT:
- Phrenic nerve
- Subclavian vein
- Middle trunk of the brachial plexus
- Transverse cervical artery
- Cervical part of the thoracic duct
**middle trunk of the brachial plexus
**
The roots of the brachial plexus are between the anterior and middle scalene muscles; the trunks of the brachial plexus which come from these roots travel in the posterior triangle. So, the trunks of the brachial plexus are not related to the anterior surface of the anterior scalene muscle.
The middle cervical sympathetic ganglion, recurrent laryngeal nerve, and parathyroid glands are all closely related with which blood vessel?
The** inferior thyroid artery **branches from the thyrocervical trunk to provide blood to the lower poles of the thyroid gland. This artery approaches the posterior side of the thyroid gland, crossing the recurrent laryngeal nerve and coming near the middle cervical sympathetic ganglion. This artery also supplies blood to the parathyroid glands, which are on the posterior surface of the thyroid.
During surgical procedures of the neck, structures within the carotid sheath can be retracted (pulled aside) as a unit. Which of the following structures would remain in place when the carotid sheath is retracted?
- common carotid artery
- cervical sympathetic trunk
- internal jugular vein
- internal carotid artery
- vagus nerve
The cervical sympathetic trunk lies in front of the prevertebral muscles in the prevertebral fascia. It is not part of the carotid sheath. All of the other structures listed are in the carotid sheath. The carotid sheath contains 3 vessels: internal carotid, common carotid, and internal jugular vein. It also contains 2 nerves: vagus and the superior ramus of ansa cervicalis.
Which of the following nerves is derived from the dorsal primary rami of spinal nerves?
- great auricular
- greater occipital
- lesser occipital
- phrenic
- supraclavicular
The greater occipital nerve is a branch of the dorsal primary ramus of spinal nerve C2–it provides cutaneous innervation to the posterior scalp. None of the other listed nerves are dorsal primary rami.
Which of the following hyoid muscles is an important landmark in both the anterior and posterior triangles of the neck?
- geniohyoid
- mylohyoid
- omohyoid
- sternohyoid
- stylohyoid
The omohyoid muscle is an important landmark in both the anterior and posterior triangles of the neck.
In the anterior triangle, the superior belly of the omohyoid muscle serves as the superolateral border of the muscular triangle and the anterior border of the carotid triangle.
In the posterior triangle, the inferior belly of the omohyoid muscle divides the omoclavicular triangle from the occipital triangle.
