The document describes the anatomy of six suprahyoid muscles - the digastric, stylohyoid, mylohyoid, geniohyoid, hyoglossus, and genioglossus muscles. It details the origin, insertion, nerve supply, and actions of each muscle. The superficial and deep relations of some muscles are also outlined.

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Submandibular Region
Suprahyoid Muscles
Attachments:
1.DigastricMuscle
2.StylohyoidMuscle
3.Mylohyoid Muscle
4.GeniohyoidMuscle
5.Hyoglossus Muscle
6.GenioglossusMuscle
1.DigastricMuscle
Origin: arises by two bellies
1. Anterior belly: from the digastric fossa on the lower
border of the mandible close to the symphysis menti.
2. Posterior belly: from the mastoid notch on the medial side
of the mastoid process
Insertion: into the intermediate tendon which is attached to the
hyoid bone by a fibrous bully.
Nerve supply:
1. Anterior belly: by nerve to mylohyoid (from the mandibular)
because it develops from the first branchial arch.
2. Posterior belly: from the facial nerve because it develops
from the second branchial arch.
Actions:
1. Depresses the mandible.
2. Elevates the hyoid bone

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Superficial relations of posterior belly of digastric muscle
 Mastoid process with sternomastoid.
 Parotid gland: between the mastoid process and the angle
of the mandible.
 Angle of the mandible.
 Submandibularsalivary gland.

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Deep relations of posterior belly of digastric muscle
1.Three big vessels:
a.Internal carotid artery
b.External carotid artery
c. Internal jugular vein
2.Three cranial nerves:
a.Vagus: lies between the internal jugular vein and the
inter carotid artery (posteriorly).
b.Hypoglossal: between the internal jugular vein and the
into carotid artery.
c. Accessory nerve: between the muscle and the internal
jugular vein
3.Along its upper border:
a.Posterior auricularartery
b.Stylohyoid muscle
4.Along its lower border
a.Occipital artery
b.Hypoglossal nerve

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2.StylohyoidMuscle
Site: lies along the upper borderof the posterior belly of
digastric
Origin: posterior surface of styloid process.
Insertion: body of the hyoid boneat its junction with and
the greater cornu.
Nerve supply: facial nerve
Actions: pullsthe hyoid boneupwards and backwards.
Note: its tendonis perforated by the intermediate tendon of
the digastric muscle.

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3.Mylohyoid Muscle
The two mylohyoids form the floor the floor of the mouth
(oral diaphragm).
Origin: mylohyoid line of the mandible.
Insertion:
1.Posteriorone-fourthof fibers: into the body of the
hyoid bone.
2.Anterior three-fourths of fibers: into the median
raphe which extends
3.From the symphysis menti to the hyoid bone
Nerve supply: mylohyoid nerve.

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Actions:
1.Elevation of floor of the mouth in the first stage of
deglutition
2.Depression of the mandible.
3.Elevation of the hyoid bone
Superficial
relations of
mylohyoid
muscle
 Anterior
belly of
digastric

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 Superficial part of the submandibular salivary
gland
 Mylohyoid nerve and vessels
 Submental vessels and lymph nodes
Deep relations of mylohyoid muscle
1.Hyoglossus muscle: with the following structures
intervening between it and the mylohyoid:
a. Styloglossus muscle
b.Lingual nerve and submandibularganglion.
c. Submandibular ganglion
d.Deep part of submandibulargland and its duct

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e. Hypoglossal nerve
2.Genioglossusmuscle: anterior to the hyoglossus.
3.Sublingual salivarygland: on the lateral surface of the
genioglossus
4.GeniohyoidMuscle
Origin: inferior genial tubercle
Insertion: anterior surface of the body of the hyoid bone
Nerve supply: C1 through the hypoglossal nerve.
Actions:
a.Elevates the hyoid bone
b.Depresses the mandible when the hyoid bone is fixed

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5.Hyoglossus Muscle
Origin: body and greater cornu of the hyoid bone.
Insertion: posterior half of the side of the tongue.
Nerve supply: hypoglossal nerve
Actions: depression of the tongue.

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Superficial relations of hyoglossus muscle
a. Overlapped by the mylohyoid muscles
b.Structuresintervening between the mylohyoid and
hyoglossus are as follows from above downwards
1.Styloglossus muscle
2.Lingual nerve
3.Submandibularganglion: suspended from the lingual
nerve by two roots.
4.Deep part of submandibulargland and its duct.
5.Hypoglossal nerve and vena comitans hyoglossi.
6.Suprahyoid branch of the first part of lingual artery.

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Deep relations of hyoglossus muscle
1.Genioglossus
2.Middle constrictorof pharynx
3.Glossopharyngeal nerve
4.Stylohyoid ligament
5.Lingual artery. (C)
Structures passingdeep to the posteriorborder of hyoglossus
from above down are:
1.Glossopharyngeal nerve
2.Stylohyoid ligament
3.Lingual artery.

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6.GenioglossusMuscle
Shape: fan – shaped; forms the main bulk of the tongue.
Origin: from the superior genial tubercleof the mandible
Insertion: into the tongue.
Nerve supply: hypoglossal nerve.
Actions:
a.Acting alone: pullsthe tongue forwards to the opposite
side.
b.With its fellow of the opposite:protrudethe tongue