Muscles of Tongue

Muscles of the Tongue

📚 Classification of Tongue Muscles

Muscles of the Tongue are classified based on:

1. Location
2. Function

🟦 Extrinsic Muscles of Tongue

• Attach the tongue to structures outside the tongue.
• Responsible for altering the position of the tongue.

Four Extrinsic Muscles:

• Genioglossus
• Hyoglossus
• Styloglossus
• Palatoglossus

🧠 Mnemonic: "Girl Has Super Powers"
G → Genioglossus
H → Hyoglossus
S → Styloglossus
P → Palatoglossus

🟨 Intrinsic Muscles of Tongue

• Contained entirely within the tongue.
• Responsible for altering the shape of the tongue.

Four Intrinsic Muscles:

• Superior longitudinal
• Inferior longitudinal
• Transversus linguae
• Verticalis linguae

🏋️ Extrinsic Muscles of Tongue

1. Genioglossus

• Importance: Known as the "Safety Muscle of the Tongue".

• Origin: Superior Genial Tubercle of the symphysis menti (mandible).

• Insertion: Fibers spread out in a fan shape:

  • Lowest fibers: Attach to the body of the Hyoid bone.
  • Intermediate (Middle) fibers: Pass deep to the hyoglossus and continue with the middle constrictor of the pharynx.
  • Uppermost fibers: Turn forward and upward, inserting into the dorsum of the tongue from the root to the apex.

• Nerve Supply: Hypoglossal Nerve (CN XII)

• Action:

  • Protrudes the tip of the tongue (pulls anterior fibers forward).
  • Makes the dorsum concave side-to-side (when protruding).
  • Prevents backward falling of the tongue into the oropharynx, thus preventing airway obstruction (reason it's the "safety muscle").

2. Hyoglossus

• Origin: Upper surface of the Greater Cornu and part of the body of the Hyoid bone.

• Insertion: Passes upward and slightly forward (under the cover of the mylohyoid), inserting into the side of the tongue, between the styloglossus laterally and the inferior longitudinal muscle medially.

• Nerve Supply: Hypoglossal Nerve (CN XII)

• Action: Depresses the sides of the tongue; makes the dorsal surface convex.

Chondroglossus:

• Considered a detached part of the hyoglossus muscle, separated by the genioglossus.

• Origin: Lesser Cornu and part of the body of the Hyoid bone.

• Insertion: Same as hyoglossus.

• Nerve Supply: Hypoglossal Nerve (CN XII).

• Action: Same as hyoglossus (depresses tongue).

3. Styloglossus

• Origin: Tip of the Styloid Process and the Stylomandibular ligament.

• Insertion: Passes downwards and forwards, inserting into the side of the tongue:

  • Oblique fibers interdigitate with the hyoglossus muscle.
  • Longitudinal fibers continue with the inferior longitudinal muscle.

• Nerve Supply: Hypoglossal Nerve (CN XII)

• Action: Retracts the tongue backwards and upwards (antagonistic to genioglossus protrusion).

4. Palatoglossus

• Origin: Undersurface of the Palatine Aponeurosis (soft palate).

• Insertion: Passes downwards and forwards (under the palatoglossal arch), inserting into the side of the tongue in front of the Sulcus Terminalis. Most fibers are continuous with the transversus linguae muscle.

• Nerve Supply: EXCEPTION! Supplied by the cranial part of the Accessory Nerve (CN XI) via the Pharyngeal Plexus (not the Hypoglossal nerve).

• Action: Elevates the base of the tongue; helps to narrow the oropharyngeal isthmus (separating oral cavity from oropharynx).

🏋️ Intrinsic Muscles of Tongue

1. Superior Longitudinal

• Origin: Posterior part of the median fibrous septum and submucosa near the root.

• Insertion: Passes forwards and laterally, inserting into the side of the tongue (submucosa near the margin).

• Action: Shortens the tongue; makes the dorsal surface concave from side to side (e.g., creating a furrow).

2. Inferior Longitudinal

• Origin: Posterior part of the side of the tongue and root.

• Insertion: Converges forwards for insertion into the anterior part of the median fibrous septum and tip.

• Action: Shortens the tongue; makes the dorsal surface convex from side to side (e.g., rounding the tip).

3. Transversus Linguae

• Origin: Median fibrous septum.

• Insertion: Passes laterally through the genioglossus muscle, inserting into the side of the tongue (submucosa).

• Action: Reduces the width of the tongue and increases its length (elongates and narrows).

4. Verticalis Linguae

• Origin: Lamina propria of the dorsum of the tongue (submucosa).

• Insertion: Passes downwards through the fibers of genioglossus and transversus, inserting into the sides of the tongue (submucosa on the ventral surface).

• Action: Increases the width and flattens the tongue; makes the dorsal surface concave from side to side (similar to superior longitudinal, helps cup the tongue).

📊 Summary of Tongue Muscle Actions

Here's a compilation of how the muscles work together:

• Makes Dorsum Concave Side-to-Side: Genioglossus (protrusion), Superior Longitudinal, Verticalis Linguae.
• Makes Dorsum Convex Side-to-Side: Hyoglossus, Inferior Longitudinal.
• Shortens the Tongue: Superior Longitudinal, Inferior Longitudinal, Verticalis Linguae.
• Elongates (Increases Length) and Narrows the Tongue: Transversus Linguae.
• Protrudes the Tongue: Genioglossus.
• Retracts the Tongue (Back & Up): Styloglossus.
• Depresses the Tongue: Hyoglossus.
• Elevates the Base/Narrows Oropharyngeal Isthmus: Palatoglossus.