Flat, quadrilateral (rectangular) muscle of the tongue. Key landmark muscle of the submandibular/suprahyoid region — its relations define the layout of all neighbouring surgical structures.

Origin

• Upper surface of entire length of the greater cornu + adjacent part of body of hyoid bone

A part from the lesser cornu may form a separate slip = chondroglossus

Insertion

• Side of tongue, between styloglossus (laterally) and inferior longitudinal muscle (medially)
• Fibres run upward + slightly forward; decussate with styloglossus fibres

Nerve Supply

• Hypoglossal nerve (CN XII)

Develops from occipital myotomes (like all tongue muscles) → supplied by CN XII (nerve of occipital myotomes), not by pharyngeal arch nerves

Actions

1. Depresses the side of the tongue (makes dorsal surface convex)
2. Assists retraction of protruded tongue

Suprahyoid Muscular Planes (Superficial → Deep)

1. Digastric + Stylohyoid
2. Mylohyoid
3. Geniohyoid + Hyoglossus
4. Genioglossus

Relations — THE Critical Section

Superficial Relations (outer/lateral face of hyoglossus)

Deep Relations (inner/medial face of hyoglossus)

• Inferior longitudinal muscle of tongue
• Genioglossus (anteriorly)
• Middle constrictor of pharynx (posteriorly)
• Glossopharyngeal nerve
• Stylohyoid ligament
• Lingual artery — lies deep to hyoglossus; to expose it surgically, hyoglossus must be divided

Structures Passing Deep to Posterior Border (above → below)

1. Glossopharyngeal nerve (CN IX)
2. Stylohyoid ligament
3. Lingual artery

Mnemonic: GSL — Glossopharyngeal, Stylohyoid ligament, Lingual artery

Summary Table

Applied Anatomy

• Lingual artery ligation — artery lies deep to hyoglossus; must identify + divide hyoglossus to access it; Pirogoff’s triangle defines access (bounded by hypoglossal nerve below, posterior border of mylohyoid anteriorly, intermediate tendon of digastric below)
• Submandibular gland surgery — deep part of gland lies on hyoglossus; hypoglossal + lingual nerves on hyoglossus surface must be preserved (tongue movement + sensation)
• Ranula — mucus retention cyst from sublingual gland; dissects along mylohyoid; presents in relation to deep submandibular region, close to hyoglossus

The hyoglossus is a flat, quadrilateral (rectangular) muscle of the tongue. It is the key muscle of the submandibular/suprahyoid region — it acts as a landmark for all neighbouring structures, making its relations critically important in surgery.

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Origin

From the upper surface of the entire length of the greater cornu and the adjacent part of the body of the hyoid bone.

A part of hyoglossus arising from the lesser cornu may form a separate slip called the chondroglossus.

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Insertion

Into the side of the tongue, between:

• Styloglossus — laterally
• Inferior longitudinal muscle — medially

The fibres run upwards and slightly forwards, and decussate with the fibres of styloglossus.

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Nerve Supply

Hypoglossal nerve (CN XII)

Developmental basis: Hyoglossus develops from occipital myotomes (like all tongue muscles) — hence supplied by CN XII (which is the nerve of the occipital myotomes), NOT by the pharyngeal arch nerves.

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Actions

1. Depresses the side of the tongue — making the dorsal surface of the tongue convex
2. Assists in retraction of the protruded tongue

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Relations — The Core of the Topic

The hyoglossus lies in the 3rd muscular plane of the submandibular region (superficial to genioglossus, deep to mylohyoid and geniohyoid).

Suprahyoid muscular planes (superficial to deep):

1. Digastric + Stylohyoid
2. Mylohyoid
3. Geniohyoid + Hyoglossus
4. Genioglossus

Superficial Relations (structures on the outer/lateral face of hyoglossus)

Mnemonic for superficial relations: “My Lingual Hypoglossal Duct Submandibular Ganglion Styloglossus” — Mylohyoid, Lingual nerve, Hypoglossal nerve, submandibular Duct, Submandibular gland (deep part), Ganglion (submandibular), Styloglossus

Deep Relations (structures on the inner/medial face of hyoglossus)

The lingual artery lies deep to the hyoglossus — protected by it. To expose the lingual artery surgically, the hyoglossus must be divided.

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Structures Passing Deep to the Posterior Border of Hyoglossus

Three structures pass from superficial to deep position by curling around the posterior border of hyoglossus — from above downwards:

1. Glossopharyngeal nerve (CN IX)
2. Stylohyoid ligament
3. Lingual artery

Mnemonic: “Go Straight in (GSL)” — Glossopharyngeal nerve, Stylohyoid ligament, Lingual artery

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Hyoglossus as a Surgical Landmark — Summary Table

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Clinical Correlations

Lingual artery ligation: The lingual artery lies deep to the hyoglossus. To ligate it (e.g., in tongue cancer surgery or to control haemorrhage), the hyoglossus muscle must be identified and divided. The Pirogoff’s triangle defines where the lingual artery can be accessed — bounded by the hypoglossal nerve (below), the posterior border of the mylohyoid (anterior), and the intermediate tendon of digastric (below).

Submandibular gland surgery: In excision of the submandibular gland, the deep part of the gland lies on the hyoglossus. The hypoglossal and lingual nerves on the surface of hyoglossus must be carefully preserved to avoid loss of tongue movement and sensation.

Ranula: Mucus retention cyst from the sublingual gland — may dissect along the mylohyoid and present in relation to the deep surface of the submandibular region, close to hyoglossus.

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