Anterior Triangle Of the Neck Flashcards
Boundaries of the Anterior Triangle
Anteriorly: midline of neck
Posteriorly: anterior border of sternocleidomastoid
Superiorly: inferior border of body of mandible
Muscle groups of the Anterior Triangle
Infrahyoid muscles
Suprahyoid muscles
Anterior vertebral muscles
Infrahyoid muscles
Thin, strap-like muscles
4 types:
- Sternohyoid
- Sternothyroid
- Thyrohyoid
- Omohyoid
Sternohyoid
Location, Origin, Insertion, Nerve supply, and action
L: superficially, medial to superior belly of omohyoid
O: posterior surfaces of manubrium of sternum and sternal end of clavicle
I: body of hyoid
N: ansa cervicalis (C1-C3)
A: depresses hyoid bone
Sternothyroid
Location, Origin, Insertion, Nerve supply, and action
L: deep to sternohyoid
O: posterior surface of manubrium of sternum
I: oblique line of thyroid cartilage
N: ansa cervicalis (C1-C3)
A: depresses larynx
Thyrohyoid
Location, Origin, Insertion, Nerve supply, and action
L: Upward continuation of sternothyroid
O: oblique line of thyroid cartilage
I: runs superiorly over thyrohyoid membrane, inserts into greater horn and body of hyoid
N: C1 fibers via hypoglossal nerve
A: depresses hyoid bone or elevates larynx
Nerve loop that contains fibers from ventral rami of C1 to C3 spinal nerves
Ansa Cervicalis
Lower root of ansa cervicalis is…
A direct branch of cervical plexus
- contains fibers from ventral rami of C2 to C3
- passes superficial (or deep) to internal jugular vein
- joins upper root to form ansa
Upper root of Ansa Cervicalis
Appears to originate from hypoglossal nerve, but contains no hypoglossal fibers
Consists of C1 fibers that join CN XII and travel with it for a distance
separate from CN XII and form upper root of ansa cervicalis
Joins lower root to form ansa
Ansa cervicalis gives branches that supply ___________, __________, and both bellies of __________
Sternohyoid, sternothyroid, omohyoid
Some C1 fibers continues with CN ___ (after it has given off upper root) and supply __________ and ________ muscles.
XII, thyrohyoid, geniohyoid
Suprahyoid muscles
Digastric
Stylohyoid
Mylohyoid
Geniohyoid
Digastric muscle consists of posterior and anterior bellies connected by an ….
Intermediate tendon
Posterior belly attaches to ________ _______, then becomes continuous with ___________ ________
Digastric (mastoid) notch
Intermediate tendon
Intermediate tendon pierces ___________ then becomes continuous with. ________ _____
Stylohyoid, anterior belly or digastric