SCID 242 -quiz 8 - Neck (Ant. Triangle)

1. Which muscle is innervated by a branch of the ansa cervicalis?

Sternocleidomastoid

Platysma

Sternohyoid

Trapezius

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.

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.

2. A 50-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?

Carotid

Muscular

Subclavian

Submandibular

Submental

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.

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.

3. 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?

Anterior scalene

Omohyoid

Sternocleidomastoid

Trapezius

Platysma

If the sternocleidomastoid is damaged at birth and becomes shortened, a patient may have muscular torticollis.

Explanation

If the sternocleidomastoid is damaged at birth and becomes shortened, a patient may have muscular torticollis.

4. 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 _______

Greater auricular

Lesser occipital

Supraclavicular

Suprascapular

Transverse cervical

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.

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.

5. 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?

Supraclavicular n.

Transverse cervical n.

Great auricular n.

Greater occipital n.

Lesser occipital n.

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.

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.

6. 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?

Anterior scalene

Digastric

Omohyoid

Sternocleidomastoid

Sternohyoid

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.

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.

7. Exploration of the tracheoesophageal groove at the level of the thyroid gland would reveal what important structure bilaterally?

Cervical sympathetic trunk

Phrenic nerve

Pyramidal lobe

Recurrent laryngeal nerve

Superior thyroid artery

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.

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.

8. 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?

Dorsal scapular

Lesser occipital nerve

Long thoracic nerve

Supraclavicular nerve

Suprascapular nerve

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.

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.

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?

External branch of the superior laryngeal

Internal branch of the superior laryngeal

Recurrent laryngeal

Vagus

Sympathetic trunk

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.

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.

10. One of the motor components of the cervical plexus, the ansa cervicalis, innervates all of the following muscles except the: ________

Omohyoid

Sternohyoid

Sternothyroid

Stylohyoid

Thyrohyoid

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).

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).