Carotid triangle

4- Carotid triangle
Objectives
By the end of this lab students are expected to be able to
1. Describe the boundaries, roof, floor and content of the triangle
2. Discuss the carotid sheath regarding its formation, extension, and content
3. Compare the different courses of internal & external carotid arteries
4. List the branches of external carotid artery
5. Describe the site, vertebral level, function of carotid sinus
6. Identify the three cranial nerves found in the triangle
7. Identify the roots, loop and branches of ansa cervicalis

? Boundaries
• Superiorly: Posterior belly of digastric supplemented by stylohyoid.
• Antero-inferiorly: Superior belly of omohyoid.
• Posteriorly: Anterior border of sternocleidomastoid.

? Contents
1. Carotid sheath containing
I. Carotid arteries
(a) Common carotid artery (Carotid sinus and body)
(b) Internal carotid artery
(c) External carotid artery (ECA).
II. Internal jugular vein.
III. three cranial nerves
(a) Vagus (X)
(b) Spinal accessory (XI)
(c) Hypoglossal (XII)
2. Ansa cervicalis.
3. Cervical part of the sympathetic chain.
4. Deep cervical lymph nodes (along the internal jugular vein)

Note: Common carotid artery, divides into external and internal carotid arteries at the level of the upper border of the thyroid cartilage (C4).

Note: The common carotid artery can be compressed against the prominent anterior tubercle of transverse process of the 6th cervical vertebra called carotid tubercle.








Home work:

Q1: A working man started to suffer from sudden attacks of syncope on rotation of head especially when wearing a shirt with tight collar or a tie with tight knot. The doctor suspects a diseased Carotid sinus.

1- Where the sinus is located?
2- At which vertebral level it lie?
3- It seems that applying pressure on this sinus causes syncope, how?