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Topic

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Genioglossus muscle

The genioglossus muscle is the largest and most powerful of the extrinsic tongue muscles, forming the bulk of the tongue's inferior portion. It arises from the superior mental spine (genial tubercle) of the mandible and fans posteriorly and superiorly to insert throughout the substance of the tongue and into the hyoid bone.

It plays key roles in tongue protrusion, airway maintenance, swallowing, articulation, and stabilization of the upper airway during sleep. Its bilateral contraction moves the tongue forward, preventing airway collapse, while unilateral contraction deviates the tongue to the opposite side.

Synonyms

  • Genioglossus

  • Genial muscle of the tongue

  • Musculus genioglossus

Origin

  • Superior mental spine (genial tubercle) on the inner surface of the mandible, near the symphysis menti

Course

  • Fibers fan posteriorly and superiorly from the mandibular midline

  • Inferior fibers extend to the hyoid bone

  • Middle fibers pass into the entire dorsum of the tongue

  • Superior fibers ascend to the tip of the tongue

Insertion

  • Tongue substance: from tip to base

  • Hyoid bone: especially the upper portion of the body

Relations

  • Superiorly: Intrinsic muscles of the tongue

  • Inferiorly: Mylohyoid and geniohyoid muscles

  • Laterally: Hyoglossus and intrinsic tongue musculature

  • Anteriorly: Mandibular symphysis

  • Posteriorly: Oropharyngeal airway

Attachments

  • Bony attachment to the superior mental spine

  • Fibrous insertion throughout the dorsum and root of the tongue

  • Connection to the body of the hyoid bone

Nerve Supply

  • Hypoglossal nerve (CN XII)

Arterial Supply

  • Lingual artery (branch of external carotid artery)

  • Small contributions from sublingual and facial arteries

Venous Drainage

  • Lingual veins draining into the internal jugular vein

Function

  • Protrudes the tongue: Primary muscle for forward tongue movement

  • Depresses central portion of tongue: Creating concavity for bolus manipulation

  • Maintains airway patency: Especially during sleep and anesthesia

  • Assists with speech articulation

  • Aids swallowing: Helps position bolus and initiate posterior movement

MRI Appearance

T1-weighted images:

  • Muscle shows intermediate signal intensity

  • Fatty tissue in floor of mouth appears bright, outlining the muscle

  • Tongue musculature displays clear fascicular architecture on high-resolution scans

T2-weighted images:

  • Muscle displays intermediate-to-dark signal intensity, slightly darker than on T1

  • Surrounding mucosa and glands appear relatively brighter

  • Tongue intrinsic and extrinsic muscle boundaries remain well-defined

STIR:

  • Muscle exhibits intermediate-to-dark signal due to uniform suppression of fat

  • Provides high contrast between musculature and adjacent fat planes

T1 Fat-Saturated Post-Contrast:

  • Muscle shows mild, uniform enhancement typical of vascular skeletal muscle

  • Enhancing mucosa and vascular structures appear brighter, improving visualization of muscular contours

CT Appearance

Non-Contrast CT:

  • Muscle appears as a soft-tissue density structure in the floor of the mouth

  • Clear visualization of genioglossus fan-shaped configuration from mandible to tongue

  • Mandibular symphysis and genial tubercles well shown as bony landmarks

Post-Contrast CT:

  • Muscle demonstrates mild, homogeneous enhancement consistent with normal muscle perfusion

  • Floor-of-mouth structures and airway margins become more distinct

  • Helps define genioglossus boundaries relative to sublingual space and intrinsic tongue musculature

MRI image

genioglossus muscle MRI axial image