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Neck Triangles
By
Dr. Adel Sahib Al-Mayaly
Head & Neck Surgery
Muscular
triangle
It is one of the anterior neck
triangles that is found in the
infrahyoid region. It is bounded
by the superior belly of
omohyoid m. superiorly, SCM
inferiorly & mid line of neck
anteriorly.
It contains the infrahyoid
muscles
Muscular Triangle
 Boundaries:
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Superiorly;Inferiorly:Anteriorly:Roof:Floor:-
superior belly of omohyoid m.
anterior border of SCM
midline of neck.
investing layer.
Infrahyoid muscle.
Contents of muscular triangle
infrahyoid muscles
 Infrahyoid muscles:
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1- sternohyoid m.
2- omohyoid m.
3- sternohyoid m.
4- thyrohyoid m.
They are supplied by Ansa cervicalis n( C 1,2,3)
They depress the hyoid bone & eventually the larynx
so that they narrow the upper esophageal opening.
Infrahyoid muscles
Ansa cervicalis
is a loop of nerves that
are part of the cervical
plexus+
It lies superficial to the
internal jugular vein in
the carotid triangle.
Its name means "handle
of the neck" in Latin.
Branches from the ansa
cervicalis innervate most
of the infrahyoid
muscles
Roots of ansa cervicalis
1- Superior root:(descendens hypoglossi).
• It is derived from
anterior primary rami
of C1
• It supplies the
thyrohyoid muscle &
superior belly of
omohyoid m.
Ansa cervicalis
2-The inferior root(C2,3)
(descendens cervicalis)
gives off branches to
1- inferior belly of
omohyoid muscle
2- sternothyroid.
3- sternohyoid.
 A horseshoe-shaped bone situated in the anterior midline
of the neck between the chin and the thyroid cartilage.
 At rest, it lies at the level of the third cervical vertebra
(C3).
 Unlike other bones; is only articulated to other bones by
muscles or ligaments.

Attachments of hyoid
 Superior attachment
 1- Middle pharyngeal
constrictor muscle
 2-Hyoglossus muscle
 3-Genioglossus
 4-Intrinsic muscles of the
tongue
 5-Suprahyoid muscles
 6-Digastric muscle
 7-Stylohyoid muscle
 8-Geniohyoid muscle
 9-Mylohyoid muscle
 Inferior attachments
 Thyrohyoid muscle
 Omohyoid muscle
 Sternohyoid muscle

Submental triangle
 is a division of the anterior triangle of the neck.
 Boundaries;
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Medially: midline raphe of the neck
Laterally: anterior belly of the two digastric muscles
Posteriorly: hyoid bone
Floor :Mylohyoid muscle.
Contents:- Submental L.N, Submental veins.
Contents of Submental triangle
Submandibular triangle
 Boundaries: 1- anteriorly:- anterior belly of digastric m.
 2- posteriorly:- posterior belly of digastric muscle.
 3- superiorly:- body of mandible.
contents
 1- Arteries:- Facial & lingual.
 2- Nerves:- hypoglossal & nerve to mylohyoid.
 3- Glands:- submandibular & its duct.
 4- Submandibular L.Ns
 5- Suprahyoid muscles.
Suprahyoid muscles
Lingual Artery.
 • Is the third branch ECA .
 • Origin: external carotid artery at the level of hyoid
bone.
 • May give origin to the ascending pharyngeal artery
or the facial artery.
 • Course:
 Ascends deep to the digastric and stylohyoid muscles
against the lateral wall of the pharynx
 It Continues anteriorly until it plunges into the
hyoglossus muscle
Facial (External Maxillary) Artery
 • Is the fourth branch.
 • Origin: anteriorly at the lower border of the digastric muscle beneath the
angle of the mandible.
 • Course: ascends anterosuperiorly deep to the digastric and the stylohyoid
muscles to traverse the sub mandibular triangle in contact with the glands'
posterior surface .
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• Its cervical branches include
1-Ascending palatine
2-Tonsillar
3-Branches to the submandibular gland.
4-Submental branch to the mylohyoid muscle and adjacent tissue
5-Masticator branches
Hypoglossal Nerve (CN XII)
• Emerges from the skull through the hypoglossal
(anterior condylar) canal in the occipital bone.
• Lies medial to the internal jugular vein and the
internal carotid artery.
• Near its emergence from the skull, receives branches
from the upper cervical nerve (C-1).
• These cervical fibers leave the nerve as the superior
root of the ansa cervicalis.
• Innervates the muscles of the tongue.