ANTERIOR TRIANGLE

•It is in front of the Sternomastoid muscle.

BOUNDARIES•Anteriorly : midline of

the neck.•Posteriorly: anterior

border of sternomastoid.

•Superiorly: lower margin of the body of the mandible.

BOUNDARIES•Roof:

•skin, superficial fascia (containing platysma) and the Investing layer of deep cervical fascia.

SUBDIVISIONS•The anterior triangle

is subdivided by : •The Anterior and

Posterior bellies of the Digastric and

•The Superior belly of Omohyoid into (4) smaller triangles.

SUBDIVISIONS

SUBMENTAL

SUBMANDIBULARCAROTIDMUSCULAR

SUBMENTAL TRIANGLE•It lies below the chin.

•Boundaries: •Anteriorly: midline of

the neck.•Laterally: Anterior belly

of Digastric.

BOUNDARIES•Inferiorly : body

of the hyoid.•Floor:

Mylohyoid muscle.

CONTENTS•Submental

lymph nodes.•They receive

lymph from the tip of the tongue.

MYLOHYOID MUSCLE•It is a flat triangular

sheet that supports the floor of the mouth and tongue (forms the main part of the floor of the mouth).

•Origin : •Mylohyoid line of

the mandible.

MYLOHYOID•Insertion:

•The anterior fibers: Into a Fibrous Raphe .

•The posterior fibers: Into the body of hyoid bone.

MYLOHYOID•Nerve supply:

•Nerve to mylohyoid.

MYLOHYOID•Action:

•If the mandible is fixed: Elevates the floor of the mouth as in deglutition.

•If the hyoid bone is fixed: Depresses the mandible and opens the mouth.

DIGASTRIC TRIANGLE•It lies below the body

of the mandible.•Boundaries:

•Anteriorly: •Anterior belly of

Digastric.•Posteriorly:

•Posterior belly of digastric & Stylohyoid.

DIGASTRIC TRIANGLE•Superiorly:

•Lower border of the body of the mandible.

•Floor: •Mylohyoid.

Hyoglossus .

CONTENTS•A. Anterior part: •(1 )Submandibular

salivary gland.•(2 )Facial artery (deep to

gland).•(3 )Facial vein

•(4 )Submandibular lymph nodes.

•The vein and lymph nodes are superficial to the gland.

CONTENTS•(5 )Hypoglossal

nerve.•(6 )Nerve and

vessels to mylohyoid.

CONTENTS•B. posterior

part:•1 .Carotid

sheath and its contents.

•2. parotid gland (Lower part)

DIGASTRIC MUSCLE•It has two bellies :

•Anterior and Posterior .•Posterior belly :

•Arises from the mastoid process .

•Inserted into the intermediate tendon.

•Anterior belly attached to the lower border of body of mandible.

DIGASTRIC MUSCLE•Insertion : to the

•Intermediate Tendon.

•It pierces the insertion of stylohyoid.

•It binds to the hyoid bone by a loop of deep fascia.

NERVE SUPPLY•Posterior belly:

Facial Nerve •Anterior belly:

•The nerve to Mylohyoid.

ACTION

Depression of the mandible .

OR•Elevation of the

hyoid bone.

STYLOHYOID MUSCLE•Origin:

•The styloid process.•It runs along the upper

border of the posterior belly of digastric.

•Insertion: •Hyoid bone (between

body and greater horn).

STYLOHYOID MUSCLE•Nerve supply:

•Facial nerve.•Action:

•Elevation of hyoid bone.

CAROTID TRIANGLE•It is behind the hyoid

bone.•Boundaries:

•Superiorly: •Posterior belly of

Digastric.•Inferiorly:

•Superior belly of Omohyoid.

BOUNDARIES•Posteriorly:

•Anterior border of sternomastoid.

•Floor: •Thyrohyoid.

Hyoglossus.•Middle & Inferior

constrictors of the pharynx.

CONTENTS•(1 )Carotid sheath

•(2 )Hypoglossal nerve and its descending branch.

•(3 )Acessory nerve.

CONTENTS•(4 )Internal and

External laryngeal nerves.

•(5 )Deep cervical lymph nodes.

CAROTID SHEATH•It is a

condensation of deep cervical fascia.

•It is attached to the base of the skull superiorly and fuses with the pericardium inferiorly.

CONTENTS•1 .Common and

internal carotid arteries.

•2 .Internal jugular vein.

•3 .Vagus nerve.•4 .Deep cervical

lymph nodes. They form a chain along the internal jugular vein.

CAROTID SHEATH•It is crossed by•Glossopharynge

al.•Hypoglossal.•Spinal part of

acessory.

MUSCULAR TRIANGLE•It lies below the hyoid

bone.•Boundaries:

•Anteriorly: •Midline of the neck.

•Superiorly: •Superior belly of

Omohyoid.

MUSCULAR TRIANGLE•Inferiorly:

•Anterior border of Sternomastoid

•Floor: •Sternohyoid.

Sternothyroid.

FLOOR•Beneath the floor

lie:•Thyroid gland.

•Larynx.•Trachea.

•Esophagus.

INFRAHYOID MUSCLES

STERNOHYOID

STERNOTHYROID

THYROHOID OMOHYOID

ORIGIN•Sternohyoid &

Sternothyroid: •Posterior surface of

the manubrium.•Thyrohyoid:

•Oblique line of thyroid cartilage.

ORIGIN•Omohyoid:

•Inferior belly: •Suprascapular ligament

and Suprascapular notch.•Superior belly:

•Intermediate tendon.

INSERTION•Sternohyoid &

Sternothyroid: •Hyoid bone (lower

border).•Oblique line of

thyroid cartilage.•Thyrohyoid:

•Hyoid bone (lower border).

INSERTION•Omohyoid

•Hyoid bone (lower border).

NERVE SUPPLY•Ansa Cervicalis

(C1,2&3) •EXCEPT

•Thyrohyoid: •(C1) through the

hypoglossal nerve.

ACTION•(1 )stabilization of

the hyoid bone to make a base for the movements of the tongue.

•(2 )Assistance in the movements of the larynx in swallowing.