Anterior Triangle of the Neck Flashcards
Anterior triangle borders
Lateral-anterior sternocleidomastoid
Superior-Inferior border of the mandible
Medially-midline of the neck
Muscles of anterior triangle
Suprahyoid- stylohyoid, digastric, mylohyoid and geniohyoid
Infrahyoid- sternohyoid, omohyoid, thyrohyoid, sternothyroid
Describe the loops of cervical plexus
Cervical plexus (C1-C4)
Forms loop called ansa cervicalis
Superior loop of ansa cervicalis C1
Inferior loop of ansa cervicalis C2-C3
What is the innervation of the suprahyoid muscles?
Stylohyoid-CN7
Digastric-V3
Mylohyoid-V3
Geniohyoid-C1
What is the innervation of the infrahyoid muscles?
Sternothyroid, omohyoid and sternohyoid - C2-C3 inferior loop
Thyrohyoid - C1 superior loop ansa cervicalis
What happens to the common carotid in the neck?
Bifurcates into internal and external at C3/C4 (carotid body and chemoreceptors found behind)
How do you distinguish the internal from external carotid artery?
No branches in the neck = internal
Lots of branches, 1st one is superior thyroid artery = external
Where is the internal carotid artery in the carotid sheath?
Medial to internal jugular vein and anterior to vagus nerve. Origin dilated forming carotid sinus which contains baroreceptors
Where do the internal and external jugular veins come from?
Internal= continuous from sigmoid sinus External= retromandibular vein + posterior auricular vein
Route of glossopharyngeal nerve in the neck
Leaves the skull through jugular foramen and lies deep styloid apparatus. Then runs between internal and external carotid arteries around lateral border of stylopharyngeus to the tongue
Route of vagus nerve in the neck
Jugular foramen, travels down in carotid sheath. At the bottom of the neck it travels in front of the subclavian artery and behind the subclavian vein
Route of accessory nerve in the neck
Jugular foramen, crosses the transverse process of the atlas, passes medial to the styloid process and posterior belly of digastric to reach posterior triangle
Route of hypoglossal nerve in the neck
Hypoglossal foramen, crosses occipital, external carotid and lingual arteries deep to the posterior belly of digastric to reach the tongue. Travels with a branch of cervical nerve 1
Describe the location of the thyroid gland
Two lateral lobes and isthmus which sits over the second and third tracheal cartilages
Describe the embryology of the thyroid
Thyroid grows down from the foramen caecum at the base of the tongue as the thyroglossal duct. Thyroid tissue can stop anywhere along this path as either accessory thyroid tissue or cervical thyroid. If the thyroglossal duct does not get closed off, food can get stuck leading to bad breathe
