Anterior triangle of the neck

A. Boundaries

The anterior triangle is bounded by the anterior median line of the neck, the inferior border of mandible, and the anterior border of sternocleidomastoid muscle.

B: subdivisions

1. The submandibular triangle

between the inferior border of mandible and the anterior and posterior bellies of the digastric muscle.

Submandibular gland is located in it and hypoglossal nerve passes into

2. The carotid traiangle:

bounded by superior belly of the omohyoid, the posterior belly of the digastric, and the anterior border of the sternocleidomastoid muscle.

Common carotid divides into internal and external carotid arteries. Carotid sinus and carotid body are located in this region.

3. The muscular triangle:

bounded by the superior belly of the omohyoid muscle, the anterior boredr of the sternocleidomastoid muscle, and the median plane of the neck

It contains infrahyoid muscles

4. The submental triangle:

Unpaired area is bounded by inferiorly by the body of hyoid bone and laterally by the right and left anterior belly of digastric muscles

B. Arteries

Common carotid artery

Right common carotid artery:

starts at bifurcation of the brachiocephalic trunk

Left common carotid artery:

arises from aorta

At the level of superior border of thyroid cartilage, it splits into internal and external carotid artery.

Internal carotid artery provides blood to internal structure of the brain. External carotid artery terminates into two branches, maxillary and superficial temporal artery.

External carotid artery gives off six branches before it terminates:

internal jugular vein

E. Muscles:

Hyoid muscles:

several muscles that are attached to mandible, skull, thyroid cartilage, manubrium of the sternum, and the medial end of scapula. The major functions of these muscles are concerned with steadying or moving the hyoid bone and larynx.

Two groups of muscles: suprahyloid and infrahyloid muscles. Suprahyoid group includes mylohyoid, geniohyoid, stylohoid, and digastric muscles.

Mylohoid

O: mylohoid line of mandible

I: body of hyoid & median raphe

F: elevates hyoid & togue, depress mandible

N: trigeminal (V)

Geniohyoid

O: median ridge of the mandible

I: body of huoid

F: elevates hyoid & togue, depress mandible

N: ansa cervicalis, C1, 2

Stylohoid:

O: styloid process of temoral bone

I: body of huoid

F: elevates hyoid & togue, depress mandible

N: facial (VII)

Digastric (anterior belly)

O: inferior border of mandible near symphysis

I: intermediate tendon to body and cornu of hyoid

F: assist in depressing the mandible

N: trigeminal (V)

Digastric posterior belly

O: mastoid process

I: intermediate tendon to body and cornu of hyoid

F: elevates and pulls hyoid posteriorly

N: facial (VII)

Infrahyoid muscles: include sternohyoid, sternothyroid, thyrohoid and omohyoid mscles.

Sternohyoid:

O: manubrium sterni: medial end of the clavicle

I: body of hyoid inferior border

F: depress yoid

N: ansa cervicalis

Sternothyroid:

O: manubrium sterni, costal cartilage of 1st rib

I: oblique line of thyroid cartilage

F: depresses thyroid cartilage

N: ansa cervicalis

Omohyoid muscle

O: superior border of scapula near scapular notch (inferior belly)

I: body of htoid, inferior border (superior belly)

F: depresses the hyoid

N: ansa cervicalis

Thyrohyoid:

O: oblique line of thyroid cartilage

I: greater horn of hyoid

F: elevates the thyroid cartilage, depresses the hyoid

N: ansa cervicals, C1, 2