Anatomy, MBBS Second Year. This chapter is split into 11 topics and has
325 practice questions. The topics covered are listed below, followed by
10 free sample questions from the chapter.
Brachial plexus roots and trunks in the posterior triangle24 questions
Cervical plexus: cutaneous branches and their areas21 questions
Cervical plexus: muscular branches, ansa cervicalis and phrenic nerve20 questions
External jugular vein, subclavian vein and lymph nodes of the posterior triangle21 questions
Muscles of the floor and the omohyoid21 questions
Clinical and integrated anatomy of the posterior triangle22 questions
Sample questions: HN 07. Posterior triangle of the neck
10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.
Q1. Which statement about the boundaries of the posterior triangle is correct?
A. It has no bony boundary
B. It is bounded in front by the posterior border of sternomastoid, behind by the anterior border of trapezius and below by the middle third of the clavicle(correct answer)
C. It is bounded in front by trapezius and behind by sternomastoid
D. It is bounded above by the clavicle
Answer: B.The posterior triangle is bounded anteriorly by the posterior border of the sternomastoid, posteriorly by the anterior border of the trapezius, and inferiorly (base) by the middle third of the clavicle, meeting at the apex.
Q2. Which of the following is NOT found in the roof of the posterior triangle?
A. The cutaneous branches of the cervical plexus
B. The platysma
C. The brachial plexus roots(correct answer)
D. The external jugular vein
Answer: C.The roots and trunks of the brachial plexus are contents of the posterior triangle (deep to the roof); the roof contains skin, superficial fascia (EJV, cutaneous branches, platysma) and the investing layer of deep fascia.
Q3. Which comparison of the roof's fascia layers is correct?
A. The superficial fascia contains the prevertebral muscles
B. The superficial fascia is pierced by the brachial plexus
C. The deep fascia contains the platysma
D. The superficial fascia contains the external jugular vein, cutaneous nerves and platysma, while the deep fascia (investing layer) is pierced by the cervical plexus branches and the external jugular vein(correct answer)
Answer: D.The superficial fascia contains the external jugular vein, the 4 cutaneous branches of the cervical plexus and the platysma; the investing layer of deep fascia below it is pierced by the cervical plexus branches and the external jugular vein.
Q4. Which statement about the cervical plexus is correct?
A. It gives no cutaneous branches
B. It lies within the carotid sheath
C. It lies in front of the scalenus medius deep to the prevertebral fascia, is formed by C1-C4 ventral rami, and gives 4 cutaneous branches, 4 muscular branches and the phrenic nerve(correct answer)
D. It is formed by the dorsal rami of C1-C4
Answer: C.The cervical plexus lies in front of the scalenus medius, deep to the prevertebral fascia; it is formed by the ventral rami of C1-C4 and gives 4 cutaneous branches, 4 muscular branches and the phrenic nerve (C3, C4, C5).
Q5. Which comparison of the cervical plexus branches is correct?
A. The ansa cervicalis supplies the sternomastoid
B. The lesser occipital and great auricular nerves are cutaneous, while the branch to sternomastoid (C2, C3) is muscular(correct answer)
C. The phrenic nerve is a cutaneous branch
D. The lesser occipital nerve is muscular and the sternomastoid branch cutaneous
Answer: B.Cutaneous branches include the lesser occipital (C2), great auricular (C2,3), transverse cervical (C2,3) and supraclavicular (C3,4); muscular branches include the sternomastoid branch (C2, C3), trapezius/levator scapulae (C3, C4), scalene branches and the ansa cervicalis.
Q6. Which of the following is NOT a content of the posterior triangle?
A. The spinal accessory nerve
B. The thyroid gland(correct answer)
C. The inferior belly of omohyoid
D. The suprascapular artery
Answer: B.The thyroid gland lies in the anterior triangle (muscular triangle); the posterior triangle contains vessels (3rd part of subclavian, suprascapular, transverse cervical, occipital arteries, subclavian and external jugular veins), nerves (accessory, brachial plexus, cervical plexus, dorsal rami), the inferior belly of omohyoid and lymph nodes.
Q7. Which comparison of the sensory nerves of the posterior triangle is correct?
A. The greater occipital nerve is a ventral ramus of C2
B. All the listed nerves are ventral rami
C. The greater occipital (dorsal ramus of C2) and third occipital (dorsal ramus of C3) are dorsal rami, while the lesser occipital (C2), great auricular (C2,3), transverse cervical (C2,3) and supraclavicular (C3,4) are ventral rami(correct answer)
D. All the listed nerves are dorsal rami
Answer: C.The dorsal rami of cervical nerves (greater occipital = dorsal ramus of C2; third occipital = dorsal ramus of C3) are distinct from the ventral-ramus cutaneous branches (lesser occipital, great auricular, transverse cervical, supraclavicular).
Q8. Which statement about the sternomastoid is correct?
A. It inserts on the clavicle
B. It is supplied only by the facial nerve
C. It arises from the mastoid process
D. It arises from the manubrium and medial 1/3 of the clavicle, inserts on the mastoid process and lateral 1/3 of the superior nuchal line, and is supplied by the accessory nerve with C2-C3 sensory fibres(correct answer)
Answer: D.The sternomastoid arises from the sternal head (front of manubrium) and clavicular head (medial 1/3 of clavicle) and inserts on the lateral surface of the mastoid process and lateral 1/3 of the superior nuchal line; it is supplied by the spinal accessory nerve (motor) and C2-C3 (sensory).
Q9. Which of the following is NOT an anterior relation of the scalenus anterior?
A. The suprascapular artery
B. The subclavian vein
C. The phrenic nerve
D. The brachial plexus roots(correct answer)
Answer: D.The brachial plexus roots emerge between the scalenus anterior and scalenus medius (not anterior to scalenus anterior); its anterior relations are 2 arteries, 2 veins (subclavian, internal jugular), 2 nerves (phrenic, vagus) and 2 muscles (sternomastoid, omohyoid tendon).
Q10. Which statement summarises the posterior triangle?
A. It is bounded by the two bellies of the digastric
B. It is bounded by the mandible, hyoid and midline of the neck
C. It is bounded by sternomastoid, trapezius and the middle third of the clavicle, divided by the inferior belly of omohyoid, contains subclavian/suprascapular/transverse cervical/occipital vessels, the accessory nerve, brachial and cervical plexuses, and its floor is prevertebral muscles(correct answer)
D. It contains the thyroid gland and infrahyoid muscles
Answer: C.The posterior triangle is bounded by the posterior border of sternomastoid, the anterior border of trapezius and the middle third of the clavicle; divided by the inferior belly of omohyoid; contains the 3rd part of the subclavian, suprascapular, transverse cervical and occipital arteries, subclavian and external jugular veins, the spinal accessory nerve, roots/trunks of the brachial plexus, the cervical plexus and dorsal rami; its floor is formed by prevertebral muscles.