Anatomy Of Squalus - Musculature

Front 1

Pectoral fin muscles-extensor or abductor

Back 1

Origin: Scapular process and adjacent fascia
Insertion: Basal and radial pterygiophores
Action: Extends or abducts (elevates) the pectoral fin

Front 2

Pectoral fin muscles-flexor or adductor

Back 2

Origin: Coracoid portion of the scapulocoracoid bar
Insertion: Basal and radial pterygiophores
Action: Flexes or adducts (depresses) the pectoral fin

Front 3

Pelvic fin muscles-extensor or abductor

Back 3

Origin: From the trunk myomeres, iliac process of puboischiadic bar and metapterygium
Insertion: Pterygiophores; in males, slips of the muscles extend onto the surface of the clasper and insert there
Action: Extends or abducts (elevates) the pelvic fin; in males, the slips inserted on the clasper move that organ during copulation

Front 4

Pelvic fin muscles-flexor or adductor

Back 4

Origin: Proximal portion: linea alba and puboischiadic bar. Distal portion: metapterygium
Insertion: Proximal portion: metapterygium. Distal portion: pterygiophores
Action: Flexes or adducts (depresses) the pelvic fin

Front 5

Levator palatoquadrati

Back 5

Origin: Otic capsule
Insertion: Palatoquadrate
Action: Elevates the palatoquadrate (upper jaw)

Front 6

Spiracularis

Back 6

Origin: Otic capusule
Insertion: Palatoquadrate cartilage
Action: Elevates the palatoquadrate

Front 7

Adductor mandibulae

Back 7

Origin: Posterior portion of palatoquadrate
Inserton: Meckel's cartilage
Action: Elevates Meckel's cartilage (closes jaw)

Front 8

Preorbitalis

Back 8

Origin: Ventral surface of the chondrocranium
Insertion: Joins the adductor mandibulae muscle and with it inserts on Meckel's cartilage
Action: Elevates Meckel's cartilage

Front 9

Intermandibularis

Back 9

Origin: Meckel's cartilage
Insertion: Midventral connective tissue raphe
Action: Elevates the floor of the mouth, thereby reducing the volume of the oral cavity

Front 10

Interhyoideus

Back 10

Origin: Ceratohyal
Insertion: Midventral raphe
Action: Compresses gill pouches

Front 11

Cucullaris

Back 11

Origin: Fascia of the epaxial muscles
Insertion: Scapular process of the scapulocoracoid bar
Action: Elevates the scapular process

Front 12

Levator hyomandibulae

Back 12

Origin: Otic capsule
Insertion: Hyomandibular cartilage
Action: Compresses gill pouches

Front 13

Dorsal interarcual

Back 13

Origin: Pharyngobranchial cartilage
Insertion: Adjacent posterior pharyngobranchial cartilage
Action: Pulls gill arches anteriorly

Front 14

Lateral interarcual

Back 14

Origin: Pharyngobranchial cartilage
Insertion: Epibranchial cartilage of the same arch
Action: Adducts the cartilages, reducing the angle between them

Front 15

Branchial adductor

Back 15

Origin: Epibranchial cartilage
Insertion: Ceratobranchial cartilage of the same arch
Action: Adducts the cartilages reducing the angle between them

Front 16

Interbranchial

Back 16

Origin: Gill ray
Insertion: Gill ray
Action: Adducts the cartilages of the gill arch

Front 17

Superficial dorsal and ventral constrictors

Back 17

Origin: Raphe
Insertion: Raphe
Action: Compression of the gill pouches

Front 18

Coracomandibularis

Back 18

Origin: Fascia of coracoarcual muscle
Insertion: Meckel's cartilage
Action: Depresses lower jaw (opens mouth)

Front 19

Coracoarcual

Back 19

Origin: Coracoid portion of the scapulocoracoid bar
Insertion: Coracohyoid muscle
Action: Assists in depressing lower jaw (opens mouth)

Front 20

Coracohyoid

Back 20

Origin: Coracoarcual muscle
Insertion: Basihyal cartilage
Action: Assists in depressing the lower jaw (opens mouth)

Front 21

Coracobranchial

Back 21

Origin: Coracoid portion of the scapulocoracoid bar and fascia of the dorsal surface of the coracoarcual muscle
Insertion: Hypobranchial cartilages
Action: Depresses the lower jaw (opens mouth) and stabilizes the pericardial cavity