Anterior & Posterior Trianlges
The neck can be divided into Anterior and Posterior Triangles.
The anterior triangle can be further divided into:
- Carotid Triangle
- Submental Triangle
- Submandibular (Digastric) Triangle
The posterior triangle can be further divided into:
- Occipital Triangle
- Subclavicular Triangle
Superficial Neck Muscles
Three muscles form the most superficial muscular layer of the neck. The Playsma is actually a muscle of facial expression, thus it is innervated by Facial N. (CN VII).
Hyoid Muscles
We can divide the hyoid neck muscles into groups, relative to their location to the hyoid bone. Of note, the hyoid bone is located at the level of C3.
There are 5 suprahyoid muscles. In general, they assist in elevating the hyoid and larynx during swallowing and phonation.
The infrahyoid muscles, better known as the strap muscles, depress the hyoid and larynx during swallowing and phonation.
All strap muscles are innervated by the ansa cervicalis from the cervical plexus (C1- C3), with the EXCEPTION of Thyrohyoid, which is innervated by C1 only (its fibers travel alongside CN XII).
⚠️ Mneumonic: C1 = GT (G= genioglossus , T= Thyrohyoid).
Vascular
Arteries of the head and neck are branches of the subclavian and common carotid arteries.
The right and left subclavian arteries enter the neck and pass laterally between the anterior & middle scalene muscles. Medial to the anterior scalene, two branches arise: Vertebral A. & Thyrocervical Trunk
Vertebral A.
- Passes posteriorly to ascend through the transverse foramina of C1-C6
- Enters skull through foramen magnum
- Supplies the posterior circulation of the brain
Thyrocervical Trunk
- Short arterial trunk that gives off 4 branches
- Inferior Thyroid A.
- Suprascapular A
- Transverse Cervical A.
- Ascending Cervical A.
The common carotid artery enters the neck as a branch of the bracheocephalic a. on the right and as a branch of the aorta on the left. It ascends w/ the internal jugular vein & vagus n. within the carotid sheath. It biFOURcates at the level of C4 into the internal and external carotid arteries.
External Carotid Artery
Supplies most of the face, with the exception of the orbits and brain. The ECA gives off 6 branches before terminating as the maxillary and superficial temporal branches.
⚠️ Mneumonic: “Some Angy Lady Figured Out PMS”
- S - Superior Thyroid A.
- Gives off a branch, superior laryngeal a., which travels w/ the internal laryngeal n.
- A - Ascending Pharyngeal A.
- L - Lingual A.
- F - Facial A.
- O - Occipital A.
- P - Posterior Auricular A.
- M - Maxillary A.
- S - Superficial Temporal A.
