Tongue Muscles (mostly CN XII):
• Genioglossus — protrudes tongue.
• Hyoglossus — retracts & depresses.
• Styloglossus — retracts & elevates.
• Plus intrinsic muscles for changing shape.

Pharyngeal Muscles (CN IX, X):
• Constrictors (rostral, middle, caudal) — push food caudally during swallowing.
• Stylopharyngeus — elevates pharynx.

Soft Palate Muscles (CN IX, X):
• Palatinus, Tensor + Levator Veli Palatini — close nasopharynx during swallowing.

Hyoid Muscles: Sternohyoideus, Sternothyroideus, Mylohyoideus, Geniohyoideus — move hyoid + tongue.

Laryngeal Muscles (CN X — Recurrent Laryngeal Nerve):
• Cricoarytenoideus dorsalis — ABDUCTS vocal folds (only abductor!).
• Cricoarytenoideus lateralis, Thyroarytenoideus — adduct.

Damage to recurrent laryngeal nerve → roaring/hemiplegia laryngis in horse (inspiratory whistle).

MUSCLES OF DEGLUTITION (Swallowing) & PHONATION

This complex set of muscles coordinates eating, breathing, and vocalisation. Multiple cranial nerves must work together (V, VII, IX, X, XII).

I. TONGUE MUSCLES:
Extrinsic (move the tongue) — all CN XII (Hypoglossal):
• Genioglossus — pulls tongue forward (protrusion).
• Hyoglossus — retracts and depresses.
• Styloglossus — retracts and elevates.
Intrinsic (change shape):
• Longitudinal, transverse, vertical fibres within tongue body.
Hypoglossal (CN XII) palsy: Tongue protrudes to the affected side (ipsilateral deviation).

II. PHARYNGEAL MUSCLES (CN IX, X via pharyngeal plexus):
• Rostral, Middle, Caudal Pharyngeal Constrictors — sequential contraction propels bolus.
• Stylopharyngeus — elevates pharynx during swallow.
• Palatopharyngeus — pulls pharynx upward.

III. SOFT PALATE MUSCLES:
• Tensor Veli Palatini (CN V) — tenses palate.
• Levator Veli Palatini (CN X) — elevates palate to seal nasopharynx.
• Palatinus — shortens palate.
• Palatoglossus, Palatopharyngeus — close oropharynx.

IV. HYOID MUSCLES:
• Sternohyoideus, Sternothyroideus — pull hyoid/larynx caudally during swallowing.
• Mylohyoideus — floor of mouth, raises tongue.
• Geniohyoideus — pulls hyoid forward.
• Stylohyoideus — pulls hyoid up & back.
• Digastricus (already covered) — also a hyoid mover.

V. LARYNGEAL MUSCLES (all CN X — vagus, via recurrent laryngeal nerve, except cricothyroideus = cranial laryngeal):
• Cricoarytenoideus Dorsalis (CAD): The ONLY abductor of the vocal folds. Opens the rima glottidis during inspiration.
• Cricoarytenoideus Lateralis (CAL): Adducts vocal fold.
• Thyroarytenoideus / Vocalis: Adducts and tenses vocal fold.
• Arytenoideus Transversus: Adducts.
• Cricothyroideus: Tenses vocal fold (pitch).

RECURRENT LARYNGEAL NERVE — A LONG, VULNERABLE LOOP:
The left RLN loops around the aortic arch, the right RLN around the right subclavian artery, then ascends in the trachea-oesophagus groove to the larynx. The LEFT side is longer → more vulnerable.

'ROARING' (Recurrent Laryngeal Neuropathy / Idiopathic Laryngeal Hemiplegia): Atrophy of LEFT cricoarytenoideus dorsalis → vocal fold cannot abduct → inspiratory whistle/'roar' under exercise → exercise intolerance in racehorses. Treatment = laryngoplasty ('tieback' surgery).