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
SUB
CAROTIDMUSCULAR
MANDIBULAR
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
STERNO
HYOID
STERNOTHYRO
OMOHYOID
THYROID HOID
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.