ANTERIOR TRIANGLE It is in front of the Sternomastoid muscle.

ANTERIOR TRIANGLEIt is in front of the Sternomastoid muscle.

BOUNDARIESAnteriorly : midline of the neck.Posteriorly: anterior border of sternomastoid.Superiorly: lower margin of the body of the mandible.

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

SUBDIVISIONSThe 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 TRIANGLEIt lies below the chin.Boundaries :Anteriorly: midline of the neck.Laterally: Anterior belly of Digastric.

BOUNDARIESInferiorly : body of the hyoid.Floor: Mylohyoid muscle.

CONTENTSSubmental lymph nodes.They receive lymph from the tip of the tongue.

MYLOHYOID MUSCLEIt 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.

MYLOHYOIDInsertion: The anterior fibers: Into a Fibrous Raphe. The posterior fibers: Into the body of hyoid bone.

MYLOHYOIDNerve supply : Nerve to mylohyoid.

MYLOHYOIDAction :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 TRIANGLEIt lies below the body of the mandible.Boundaries: Anteriorly: Anterior belly of Digastric.Posteriorly: Posterior belly of digastric & Stylohyoid.

DIGASTRIC TRIANGLESuperiorly: Lower border of the body of the mandible.Floor: Mylohyoid. Hyoglossus.

CONTENTSA. 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.

CONTENTSB. posterior part:1. Carotid sheath and its contents.2. parotid gland (Lower part)

DIGASTRIC MUSCLEIt 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 MUSCLEInsertion : to theIntermediate Tendon.It pierces the insertion of stylohyoid.It binds to the hyoid bone by a loop of deep fascia.

NERVE SUPPLYPosterior belly: Facial Nerve Anterior belly: The nerve to Mylohyoid.

ACTIONDepression of the mandible. ORElevation of the hyoid bone.

STYLOHYOID MUSCLEOrigin: The styloid process.It runs along the upper border of the posterior belly of digastric.Insertion: Hyoid bone (between body and greater horn).

STYLOHYOID MUSCLENerve supply :Facial nerve.Action :Elevation of hyoid bone.

CAROTID TRIANGLEIt is behind the hyoid bone.Boundaries :Superiorly: Posterior belly of Digastric.Inferiorly: Superior belly of Omohyoid.

BOUNDARIESPosteriorly: 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 SHEATHIt is a condensation of deep cervical fascia.It is attached to the base of the skull superiorly and fuses with the pericardium inferiorly.

CONTENTS1. 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 SHEATHIt is crossed byGlossopharyngeal.Hypoglossal.Spinal part of acessory.

MUSCULAR TRIANGLEIt lies below the hyoid bone.Boundaries: Anteriorly :Midline of the neck.Superiorly: Superior belly of Omohyoid.

MUSCULAR TRIANGLEInferiorly: Anterior border of SternomastoidFloor: Sternohyoid. Sternothyroid.

FLOORBeneath the floor lie:Thyroid gland.Larynx.Trachea.Esophagus.

INFRAHYOID MUSCLES

ORIGINSternohyoid & Sternothyroid :Posterior surface of the manubrium.Thyrohyoid: Oblique line of thyroid cartilage.

ORIGINOmohyoid :Inferior belly :Suprascapular ligament and Suprascapular notch.Superior belly:Intermediate tendon.

INSERTIONSternohyoid & Sternothyroid : Hyoid bone (lower border).Oblique line of thyroid cartilage.Thyrohyoid:Hyoid bone (lower border).

INSERTIONOmohyoidHyoid bone (lower border).

NERVE SUPPLYAnsa Cervicalis (C1,2&3) EXCEPTThyrohyoid: (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.