1.
A person receives a shallow knife wound just behind the sternocleidomastoid muscle and about 1 1/2 inches above the clavicle. There is an immediate numbness of the skin below the wound and over the acromion and clavicle. The nerve most likely severed was the
Correct Answer
C. Supraclavicular
Explanation
The supraclavicular nerves come from C3 and C4 in the cervical plexus. These cutaneous nerves provide sensory innervation to the skin of the root of the neck, upper chest, and upper shoulder. These nerves innervate the skin right above the clavicle, so they are the correct answer. The great auricular nerve comes from C2 and C3 branches in the cervical plexus; it provides sensory innervation to the ear and the skin below the ear. The lesser occipital nerve comes from C2 in the cervical plexus - it innervates the skin behind the ear. The transverse cervical nerve is also a cutaneous branch from the cervical plexus - it is from C2 and C3 and provides sensory innervation to the skin of the neck anteriorly. The suprascapular nerve is not a cutaneous nerve - it comes from the superior trunk of the brachial plexus and provides motor innervation to supraspinatus and infraspinatus.
2.
Which muscle is innervated by a branch of the ansa cervicalis?
Correct Answer
C. Sternohyoid
Explanation
The sternohyoid muscle is one of the strap muscles which runs from the manubrium and the sternal end of the clavicle to the hyoid bone. It is innervated by the ansa cervicalis, and it depresses and stabilizes the hyoid bone. Platysma is a muscle of facial expression; it is innervated by the cervical branch of CN VII, the facial nerve. Sternocleidomastoid and trapezius are both innervated by the accessory nerve (CN XI). Sternocleidomastoid receives fibers from C2 and C3 for proprioception, while trapezius receives proprioceptive fibers from C3 and C4.
3.
The layer of encircling cervical fascia that splits to enclose sternocleidomastoid and trapezius muscles is the:
Correct Answer
B. Superficial layer of deep fascia
Explanation
The superficial layer of deep cervical fascia extends between trapezius and sternocleidomastoid in the posterior triangle and between the paired sternocleidomastoid muscles in the anterior triangle. Superficial fascia is the same as subcutaneous tissue--the tissue that you see as you remove the skin. Infrahyoid fascia is the layer of deep fascia that covers the strap muscles in a sheet. Prevertebral fascia is the deep fascia surrounding the vertebral column and the associated muscles (like the scalenes). Finally, the visceral fascia is the fascia that encloses the deep structures of the neck, including the thyroid, the larynx and trachea, and the esophagus. The anterior part of that fascia is the pretracheal fascia, and the posterior part of the visceral fascia is the buccopharyngeal fascia. To get a better picture of this, see Netter plate 30.
4.
Which of the following is a dorsal ramus of a spinal nerve?
Correct Answer
D. Greater occipital n.
Explanation
The greater occipital nerve is the cutaneous branch of the dorsal primary ramus of spinal nerve C2 - it provides cutaneous innervation to the posterior scalp. The other nerves listed are all nerves from the cervical plexus, which is formed by ventral primary rami C1-C4. The supraclavicular nerves come from C3 and C4 in the cervical plexus. These cutaneous nerves provide sensory innervation to the skin of the root of the neck, upper chest, and upper shoulder. The great auricular nerve comes from C2 and C3 branches; it provides sensory innervation to the ear and the skin below the ear. The lesser occipital nerve comes from C2 only - it innervates the skin behind the ear. The transverse cervical nerve is also a cutaneous branch from the cervical plexus--from C2 and C3, providing sensory innervation to the skin of the neck anteriorly.
5.
Which of the following is true of the inferior thyroid arteries?
Correct Answer
D. They often supply all four parathyroid glands
Explanation
The inferior thyroid arteries are branches of the thyrocervical trunk. (The superior thyroid arteries are branches of the external carotid artery.) The inferior thyroid arteries are closely associated with the middle cervical sympathetic ganglia and supply the inferior poles of the thyroid. They are found on the posterior surface of the thyroid gland, which is where the parathyroid glands are located. So, they are the primary source of blood for the four parathyroid glands.
6.
A 20 year old man was brought into the emergency room with a stab wound in the upper part of the neck. Although there was no major damage done, he lost sensation from the skin over the angle of the jaw. Which nerve has been cut?
Correct Answer
C. Great auricular n.
Explanation
The great auricular nerve comes from C2 and C3 branches of the cervical plexus; it provides sensory innervation to the ear and the skin below the ear, including the angle of the jaw. The supraclavicular nerves come from C3 and C4 in the cervical plexus. These cutaneous nerves provide sensory innervation to the skin of the root of the neck, upper chest, and upper shoulder. The transverse cervical nerves also come from the cervical plexus--they are from C2 and C3 and provide sensory innervation to the skin of the neck anteriorly. Finally, the lesser occipital nerve comes from C2--it innervates the skin behind the ear. The greater occipital nerve is not from the cervical plexus, which is the ventral rami of C1-4--it is the cutaneous branch of the DORSAL primary ramus of spinal nerve C2. It provides cutaneous innervation to the posterior scalp.
7.
The triangle in which the superior branch of the ansa cervicalis separates from the hypoglossal nerve is the:
Correct Answer
A. Carotid
Explanation
The superior branch of ansa cervicalis runs with the hypoglossal nerve until the carotid triangle. In this triangle, the superior branch of ansa cervicalis separates from the hypoglossal nerve and runs in the carotid sheath, anterior to the carotid artery. Remember--the carotid sheath is found in the carotid triangle, a space bounded laterally by the sternocleidomastoid muscle, superiorly by the posterior belly of the digastric, and anteriorly by the superior belly of omohyoid. The other triangles listed are not the spaces where ansa cervicalis separates from the hypoglossal nerve.
8.
Exploration of the tracheoesophageal groove at the level of the thyroid gland would reveal what important structure bilaterally?
Correct Answer
D. Recurrent laryngeal nerve
Explanation
The left and right recurrent laryngeal nerves can be found in the left and right tracheoesophageal grooves. This is a very characteristic relationship that you need to know! The cervical sympathetic trunk is much deeper in the neck--it lies in the prevertebral fascia, in front of the prevertebral muscles. The phrenic nerve lies on the surface of the anterior scalene muscles before it descends into the thorax to innervate the diaphragm. The pyramidal lobe of the thyroid gland is a small tract of tissue that may extend upward from the isthmus of the thyroid. This is a developmental remnant that marks the thyroid's route of migration from the foramen cecum of the tongue. The superior thyroid artery is a branch of the external carotid artery--it travels to the superior lobes of the thyroid and runs with the external branch of the superior laryngeal nerve.
9.
A 35 year old woman was diagnosed with an adenoma of the thyroid gland. This required excision of the lower pole (left lobe) of the gland and ligation of the artery supplying that region. Which of the following nerves accompanying the artery is most likely to be damaged if the surgeon is not careful?
Correct Answer
C. Recurrent laryngeal
Explanation
The inferior thyroid artery supplies the lower lobes of the thyroid. It is a branch of the thyrocervical trunk. Branches of this artery cross the recurrent laryngeal nerve, so this is the nerve that might be damaged during the surgery. The external branch of the superior laryngeal nerve runs with the superior thyroid artery--this artery and nerve might be damaged when removing the superior lobes of the thyroid. The internal branch of the superior laryngeal nerve runs with the superior laryngeal artery, piercing the thyrohyoid membrane. The vagus nerve proper runs with the common carotid artery, in the carotid sheath. It gives off the recurrent laryngeal nerve, but it does not come as close to the inferior thyroid artery. Finally, the sympathetic trunk is in the deep neck, near the vertebral bodies. It should not be damaged in thyroid surgery.
10.
One of the motor components of the cervical plexus, the ansa cervicalis, innervates all of the following muscles except the:
Correct Answer
D. Stylohyoid
Explanation
The stylohyoid muscle runs from the posterior portion of the digastric muscle to the body of the hyoid bone. It elevates and retracts the hyoid, and it is innervated by the facial nerve (CN VII). Omohyoid, sternohyoid, sternothyroid, and thyrohyoid are all strap muscles which are innervated by ansa cervicalis (although thyrohyoid receives its branch via the hypoglossal nerve).
11.
A man has metastatic carcinoma and enlarged deep cervical lymph nodes. One of his symptoms is a hoarse voice, barely heard above a whisper. Subsequently he succumbs to the disease and at autopsy it is found that one of the enlarged nodes has put pressure on a nerve in the tracheoesophageal groove. Presumably this was the reason for the hoarse voice. What nerve was involved?
Correct Answer
E. Recurrent laryngeal branch of vagus
Explanation
Damage to the recurrent laryngeal nerve is one possible cause of hoarseness. The recurrent laryngeal nerve changes its name to the inferior laryngeal nerve at the level of the inferior border of the cricoid cartilage. The inferior laryngeal nerve goes on to innervate all the intrinsic muscles of the larynx except cricothyroideus. So, if this nerve innervating all the muscles of the larynx was damaged, a patient would have a hoarse voice. A very significant piece of information that tells you that the recurrent laryngeal nerve was injured is the location of the injury-- remember, recurrent laryngeal travels in the tracheoesophageal groove.
The external and internal branches of the superior laryngeal nerve innervate cricothyroid, the inferior pharyngeal constrictor, and provide secretomotor fibers to mucosal glands of the larynx above the vocal folds. The pharyngeal branch of the glossopharyngeal nerve provides sensory innervation to the pharynx. None of these nerves are running in the tracheoesophageal groove!
12.
You are called on to do a venous catheterization to measure central venous pressure in the heart. Which muscle of the neck would provide the best area of approach to the internal jugular vein?
Correct Answer
D. Sternocleidomastoid
Explanation
The internal jugular vein is found in the carotid triangle, which is bounded medially by omohyoid, laterally by sternocleidomastoid, and superiorly by the posterior belly of digastric. Of these three muscles, sternocleidomastoid is the easiest landmark to find on the neck and the most practical muscle to find when looking for the carotid triangle and the internal jugular vein. The anterior scalene is posterior to the internal jugular vein, and is not related to the vessel. Sternohyoid is a strap muscle in the muscular triangle; it is not associated with the internal jugular vein.
13.
A patient is brought into the Emergency Room in respiratory distress. It is quickly decided to create an emergency airway to restore respiration. At what level could you rapidly create an airway below the vocal cords with a minimum danger of hemorrhage?
Correct Answer
D. Just below the thyroid cartilage
Explanation
To create an emergency airway, a midline cut can be made through the cricothyroid ligament and membrane. So, an opening is created between the thyroid cartilage and the cricoid cartilage. Since this is below the glottis and the tracheal inlet (which is the usual place where things get lodged), this is a good spot to make the cut. It is also easy to find the thyroid cartilage on a patient and make the incision right below that spot.
14.
A 47-year-old woman is diagnosed as having a thyroid tumor. Surgery to remove the cancerous growth is undertaken. In which triangle of the neck will the surgeon make an incision to gain access to the gland?
Correct Answer
B. Muscular
Explanation
The muscular triangle is found in the anterior triangle of the neck. It is bounded by the midline as its medial border, the superior belly of the omohyoid as its superolateral border, and sternocleidomastoid as its inferolateral border. The strap muscles, thyroid, and parathyroids are found in this triangle. Since the thyroid is found at the midline, deep to the strap muscles, you would need to cut into this triangle to perform surgery on the thyroid gland.
The carotid triangle is bounded laterally by the sternocleidomastoid, superiorly by the posterior belly of the digastric, and anteriorly by the superior belly of the omohyoid muscle. The carotid vessels and carotid sheath can be found in this triangle. The subclavian triangle is the same as the omoclavicular triangle. It is found in the posterior triangle of the neck. This triangle is bounded superiorly by the inferior belly of the omohyoid muscle, anteriorly by the sternocleidomasoid muscle, and inferiorly by the clavicle. The third part of the subclavian artery and the subclavian vein are located in this triangle.
The submandibular triangle is bounded anteriorly by the anterior belly of the digastric, posteriorly by the posterior belly of the digastric, and superiorly by the lower border of the mandible. It contains the superficial portion of the submandibular gland and the facial artery and vein. The submental triangle is laterally bordered by the anterior bellies of the digastric muscles. It is inferiorly bordered by the hyoid bone. Submental lymph nodes are found in this triangle.
15.
A 50-year-old woman is brought to the operating room for a biopsy of a suspicious looking nevus (mole) which is found along the anterior border of her sternocleidomastoid muscle at about its midlength. What nerve must be locally anesthetized for the operation to proceed without pain?
Correct Answer
E. Transverse cervical
Explanation
To answer this question, you want to figure out which nerves supply sensory innervation to the skin of the anterior neck. The transverse cervical nerves, which come off the C2 and C3 roots of the cervical plexus, are the nerves that supply the skin of the neck anteriorly. So, these nerves would need to be anesthetized. The great auricular and supraclavicular nerves are also cutaneous sensory nerves from the cervical plexus. The great auricular nerve innervates the skin of the ear and the area below the ear. The supraclavicular nerves innervate the skin at the root of the neck and the upper chest and upper shoulder.
Ansa cervicalis is a branch of the cervical plexus which innervates the strap muscles--it's a motor nerve, not a sensory nerve. The external branch of the superior laryngeal nerve is a motor nerve, too--it innervates the cricothyroid muscle.
16.
Following surgery on the upper pole of the right lobe of the thyroid gland, a patient complains of hoarseness and weakness of voice. What nerve may have been injured?
Correct Answer
B. External branch of the superior laryngeal
Explanation
The external branch of the superior laryngeal nerve travels with the superior thyroid artery toward the superior pole of the thyroid. So, it's in the right place to be injured by surgery on the upper pole of the gland. The external branch of the superior laryngeal nerve innervates cricothyroid, the muscle responsible for elongating the vocal cords. The patient's symptoms of horseness and a weak voice would fit with an injury to this nerve and the denervation of this muscle.
The inferior laryngeal and recurrent laryngeal nerves are one in the same--the recurrent laryngeal changes its name to the inferior laryngeal at the inferior border of cricopharyngeus. This nerve innervates all of the other muscles of the larynx, besides cricothyroid. It runs with the inferior thyroid artery to the inferior poles of the thyroid--it could be injured in any surgery involving the inferior thyroid artery or inferior aspects of the gland. The internal branch of the superior laryngeal nerve pierces the thyrohyoid membrane along with the superior laryngeal artery--it is a sensory nerve only. It supplies sensory innervation to the mucosa of the larynx, superior to the vocal folds.
Ansa cervicalis is a branch of the cervical plexus which innervates the strap muscles. It does not innervate any muscles in the larynx.
17.
These structures are all located in the superficial fascia of the neck EXCEPT
Correct Answer
D. Omohyoid muscle
Explanation
The omohyoid muscle is a muscle found in the anterior and posterior triangle of the neck. It depresses and stabilizes the hyoid bone. Like all muscles (except the muscles of facial expression), the omohyoid is not found in the superficial fascia. The external jugular vein is a small vein found in the superficial tissue on the lateral side of the neck. The platysma is a muscle of facial expression that draws down the corners of the mouth and depresses the mandible. It inserts into the skin, so it is found in the superficial fascia. The cervical branch of the facial nerve, which innervates the platysma, is also in the superficial fascia. Finally, the transverse cervical nerve is a branch of the cervical plexus that innervates the skin of the anterior neck. Because it is providing cutaneous innervation, it is found in the superficial fascia.
18.
The superior belly of the omohyoid forms the anterior border of which cervical triangle?
Correct Answer
A. Carotid
Explanation
The carotid triangle is bounded anteriorly by the superior belly of the omohyoid muscle, laterally by the sternocleidomastoid, and superiorly by the posterior belly of the digastric. The carotid vessels and carotid sheath can be found in this triangle. The muscular triangle is bounded by the midline as its medial border, the superior belly of the omohyoid as its superolateral border, and sternocleidomastoid as its inferolateral border. The strap muscles, thyroid, and parathyroids are found in this triangle. The omoclavicular triangle, in the posterior neck, is bounded superiorly by the inferior belly of the omohyoid muscle, anteriorly by the sternocleidomastoid muscle, and inferiorly by the clavicle. The third part of the subclavian artery and the subclavian vein are located in this triangle. The posterior triangle of the neck is bounded anteriorly by the sternocleidomastoid muscle, posteriorly by trapezius, and inferiorly by the clavicle. The submandibular triangle is bounded anteriorly by the anterior belly of the digastric, posteriorly by the posterior belly of the digastric, and superiorly by the lower border of the mandible. It contains the superficial portion of the submandibular gland and the facial artery and vein.
19.
The cervical plexus innervates all of the following structures EXCEPT:
Correct Answer
C. Platysma
Explanation
Platysma is a muscle of facial expression. It inserts into the skin and helps lower the angle of the mouth and depress the mandible. It is innervated by the cervical branch of the facial nerve (CN VII). All of the other muscles or areas of skin are innervated by branches of the cervical plexus, a plexus made of the ventral primary rami of the C1-C4 spinal nerves. The diaphragm is innervated by the phrenic nerve, which is made from the C3, C4 and C5 ventral primary rami. The omohyoid muscle is innervated by ansa cervicalis, a motor branch of the cervical plexus. The skin over the thyroid cartilage is innervated by the transverse cervical nerve, a cutaneous sensory nerve from C2 and C3 roots of the cervical plexus. The skin over the clavicle is innervated by other cutaneous sensory nerves from the C3 and C4 roots of the cervical plexus--the supraclavicular nerves
20.
An emergency room patient presented with considerable bleeding from a shallow stab wound in the omoclavicular triangle. Which vessel was most likely cut?
Correct Answer
C. External jugular vein
Explanation
The external jugular vein is a superficial vein on the lateral side of the neck. It is in the superficial fascia, so it could be easily injured by a superficial wound. Since this vein travels in the omoclavicular triangle, this is the structure that was injured. The axillary vein is the continuation of the subclavian vein lateral to the first rib--it is important in draining the upper limb, but it's not associated with the triangles of the neck. The common carotid artery is found in the carotid sheath and carotid triangle. The inferior thyroid vein and superior thyroid artery are both found near the thyroid gland; therefore, they are both in the muscular triangle.
21.
Which structure or area receives NO nerve fibers from the cervical plexus?
Correct Answer
C. Skin over the external occipital protuberance
Explanation
The skin over the external occipital protuberance is innervated by the greater occipital nerve, which is from the dorsal primary ramus of C2. Since the cervical plexus is made of the ventral primary rami of C1 through C4, the greater occipital nerve has no connection with the cervical plexus. The diaphragm is innervated by the phrenic nerve, which receives contributions from the ventral primary rami of C3, C4, and C5. The skin over the angle of the jaw is innervated by the great auricular nerve, which comes from C2 and C3 branches of the cervical plexus. Finally, the thyrohyoid muscle is innervated by the ansa cervicalis (specifically, C1 and C2 fibers carried by hypoglossal nerve), a motor component of the cervical plexus that innervates the strap muscles.
22.
A six-year-old child, whose medical history includes a rather difficult birth, has a permanently tilted head posture, with the right ear near the right shoulder and the face turned upward and to the left. Which of the following muscles was very likely damaged during birth?
Correct Answer
C. Sternocleidomastoid
Explanation
If the sternocleidomastoid is damaged at birth and becomes shortened, a patient may have muscular torticollis. The neck will appear twisted and the chin elevated because the sternocleidomastoid muscle will be too short on one side. This patient has an injured right sternocleidomastoid, since his head is turned down on the right side where the sternocleidomastoid is too short. Patients may also have spasmotic torticollis, where the neck is twisted and elevated due to a temporary spasm of the sternocleidomastoid muscle. None of the other muscles listed would cause similar symptoms if they were injured.
It's important to remember the association between torticollis and the sternocleidomastoid!
23.
Any irritation of the diaphragm (e.g. infection, tumor) may create referred pain that seems (to the patient) to originate in the area atop the shoulder. This is due to the fact that the phrenic nerve shares spinal segments with what cutaneous nerve in the shoulder region?
Correct Answer
D. Supraclavicular nerve
Explanation
The phrenic nerve consists of contributions from the ventral primary rami of C3, C4, and C5. The supraclavicular nerves come from the C3 and C4 roots of the cervical plexus. So, these nerves share spinal segments. This explains why pain from the diaphragm is referred to the area where the supraclavicular nerves provide cutaneous innervation. The lesser occipital nerve is another cutaneous nerve from the cervical plexus, but it is mostly made of fibers from the C2 ventral rami. The other nerves listed are all motor nerves from the brachial plexus. The dorsal scapular nerve comes from the C5 ventral primary ramus-- it innervates rhomboideus major and minor and the lower portion of levator scapulae. The long thoracic nerve comes from C5, C6, and C7 ventral primary rami--it innervates serratus anterior. The suprascapular nerve comes from the superior trunk of the brachial plexus--it innervates supraspinatus and infraspinatus.
24.
Which of the following statements about the cervical plexus is true?
Correct Answer
C. It consists solely of ventral rami of spinal nerves
Explanation
The cervical plexus consists solely of the ventral primary rami of spinal nerves C1-C4. It supplies cutaneous innervation through nerves like the lesser occipital, great auricular, supraclavicular and transverse cervical. It also supplies motor innervation to the strap muscles through the ansa cervicalis. So, it has a motor and sensory component. It does not innervate the platysma--platysma is a muscle of facial expression innervated by the cervical branch of the facial nerve (CN VII).