Muscles of Dogfish (Hyman notes)

Topics: Muscle, Nerve, Mandible Pages: 4 (684 words) Published: November 22, 2013
VEA, Jairah Mae R. | 3BIO7
----------------------------------------------------------------------------------------------------------------------------- --GENERALIZED VERTEBRATE MUSCULATURE AS EXEMPLFIED BY THE DOGFISH The musculature of the dogfish is considered under the heads of somatic, fin, branchial and hypocranchial musculature.

I.PARIETAL or SOMATIC MUSCLES
The Parietal muscles which completely covers the whole body of dogfish consists of: 1. Myotomes - zigzag series which is separated from one another by: 2. Myosepta - white connective partitions
3. Lateral septum - white longitudinal line in the middle part of the side of the body, outer edge of of horizontal skeletongenous septum that divides into:
a. Dorsal or Epaxial portions
i. Dorsal longitudinal bundles - usually 2 seen in x.s.
b. Ventral or Hypaxial portions
i. Lateral longitudinal bundle - below the lateral septum, darker color ii. Ventral longitudinal bundle - subdivided into 2 bundles seen in x.s.  Therefore in most elasmobranchs the fibers of myotomes are arranged into 5 longitudinal bundles.



Linea alba - white partition in midventral line, separates myotomes to 2 sides

II. FIN MUSCUALTURE
 Dorsal side of the fin are mass of muscles that act as abductor, levator or extensor  Fin muscles are outgrowths of the myotomes

 Ventral side of pelvic fin has muscle mass which acts as depressor, adductor or flexor which is divided into 2 parts: 1)extending from linea alba and puboishac bar to metapterygium 2)metapterygium to fin

III. BRANCHIAL MUSCULATURE
 Epaxial part of myotomes continues unaltered above gill region and attaches to rear of chondrocranium while Lateral longitudinal bundle terminates at the scapular process  Branchial muscles front of pectoral fin, operate the gill arches and jaws, supplied by motor nerves

VEA, Jairah Mae R. | 3BIO7...
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