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Table 2 Main subdivisions of facial musculature in Actinopterygii

From: Evolution of the facial musculature in basal ray-finned fishes

Muscle Subdivision Additional features
1. Constrictor mandibularis dorsalis 1. Dorsomedial Origin on lateral region of otic-sphenoidal portion of neurocranium; insertion on lateral face of palatoquadrate, hyomandibula, and opercle (except acipenseriforms)
1.1. Levator arcus palatini 1.1. Anterior Insertion on lateral face of suspensorium, usually on hyomandibula and metapterygoid
1.2. Dilatator operculi 1.2. Middle Insertion on anterodorsal region of opercle
1.3. Spiracularis 1.3. Posterior Insertion on spiracular canal or ossicles; lost or undifferentiated from dilatator operculi in neopterygians
2. Adductor mandibulae 2. Ventrolateral Origin on lateral region of palatoquadrate and, often, hyomandibula and neurocranium; insertion on lower jaw; additional attachments to maxilla in Amia and several teleosts
2.1. Segmentum facialis 2.1. Dorsolateral Larger and most superficial division on cheek
2.1.1. Pars rictalis 2.1.1. Ventrolateral Origin on ventroposterior region of suspensorium, usually involving quadrate
2.1.2. Pars malaris 2.1.2. Dorsolateral Origin on dorsoposterior region of suspensorium, usually involving hyomandibula
2.1.3. Pars stegalis 2.1.3. Medial Shorter fibers with origin on anterior region of suspensorium, usually involving metapterygoid
2.2. Segmentum buccalis 2.2. Dorsomedial Deeper division on cheek; lost in teleosts
2.2.1. Pars orbitalis 2.2.1. Anterior Located just posterior or anteroventral to eyeball
2.2.2. Pars sphenoidalis 2.2.2. Posterior Origin medial to levator arcus palatini
2.3. Segmentum mandibularis 2.3. Ventral Fully or mostly concealed laterally by lower jaw
3. Constrictor hyoideus dorsalis 3. Dorsal Origin on lateral region of otic-temporal region of neurocranium; insertion on medial faces of palatoquadrate, hyomandibula, and opercle
3.1. Adductor hyomandibulae 3.1. Anterior Insertion on hyomandibula and, often, metapterygoid and endopterygoid
3.2. Adductor operculi 3.2. Middle Insertion on the anterior region of opercle, near its articulation with hyomandibula; associated with medial crest of opercle in teleosts.
3.3. Levator operculi 3.3. Posterior Narrow origin via elongate tendon/aponeurosis; broader insertion on posterior portion of opercle