Lecture 9 Notes
Lecture 9 Notes BIOL 242 001
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This 3 page Class Notes was uploaded by Wilson on Thursday October 1, 2015. The Class Notes belongs to BIOL 242 001 at Indiana University of Pennsylvania taught by JE Duchamp in Summer 2015. Since its upload, it has received 36 views. For similar materials see Comparative Vertebrate Anatomy in Biology at Indiana University of Pennsylvania.
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Date Created: 10/01/15
Lecture 9 10 Skeletal Muscular System 1 Origin of Cranial and Vertebral Column Musicles a Somites and Somatomeres Each sclerotome splits and contributes to different vertebra Spinal nerves pass through split Developing muscle tissue naturally cross between developing vertebra Myotome Blocks of undifferentiated muscle tissue form originally from the notochord this is the subdivision of the scleretome Contributes mostly to axial muscles dermatome myotome sclerotome form together to make somite 2 Cranial Muscles a Development of cranial muscles cells from myotome migrate to other regions to contribute to muscles Muscles in the cranial region contribute to branchiomeric muscles which include branchial muscles hyoid muscles and mandibular muscles head and pharynx Hypobranchial muscles come from somites that come after the pharynx posterior come down and extend up and underneath Will be distinguish between branchiomeric muscles and hypobranchial muscles he39ll be asking where the jaw muscles originate from 3 Movements of the Jaw a b C f Protractors i Project object forward Retractors i Bring object back Depressors i Lower object Elevators i Raise object Sharkjaw i Opening jaws 1 Levator hyomandibulae elevates the hyomandibulae 2 Coracomandibularis helps to depress and retract the jaw and retract the coracohyoid meckle39s cartilage mandible 3 Epiaxial and hypaxial will want to associate muscles with the ones that open and close the jaw Not protracting ii Closing jaws 1 Adductor Mandibulae closes the mouth attaches to Meckle39s cartilage or mandible 2 Preorbitalis 3 Levator palatoquadrati will be elevated as well as retract 4 When a shark is closing its mouth it has a scissoring motion 5 lntermandibularis 6 lnterhyoideus Mammalian aws i Cat 1 Anterior diagastric muscles along with the geniohyoid muscle which helps to pull the jaw down There are no muscles in the cat that move the mouth back as is in most mammals They just open their mouths 2 Closing the Jaw a Temporalis Muscle b Masseter dentary bone to zygomatic bone c Pterygoid muscles deeper inside d Opening and closing of the jaw is much simpler in mammals 3 Homologous Muscles Group on exam a Branchiomeric muscles masseter pterygoid temporalis in mammals and homologues of Adductor Mandibulae in sharks b Are these muscles also analogues Yes They perform the same functions 4 Mammalian Carnivore vs Herbivorous jaw a Carnivores i Trying to secure an animal with its mouth usually have pretty stable jaw structures ii Deep cshaped mandibular fossa iii Transverse elongation of the mandibular condyle wider so that the lower jaw does not shift back and forth iv joint inline with tooth row ln herbivores the articulation point and the tooth row is not aligned This aligning helps to increase the direct bite force b Cat carnivore i Temporalis is large to have a fast bite closure This also resists lateral movement in the jaw ii The masseter is smaller iii Ptyerygoids smaller with little lateral movement c Alpaca Herbivore i Temporalis smaller and no resistance to lateral movement ii Master is large and powerful iii Pterygoids large and help with lateral jaw movement while chewing 4 Post cranial Skeletal Muscles a We will focus on sh amphibians and lizards today b Early Development Myotomes with the axial muscles the myotomes extend down the side of the organism Eventually it will begin to differentiate Lateral wall of the hypomere contributes to the appendicular connective tissue Will differentiate into epaxial and hypaxial muscles 1 Expaxial dorsal muscles along vertebral column 2 Hypaxial ventral muscles c Arrangement of Axial Muscle Fibers i In Fish 1 The myomere will have a complex quotWquot shape What this ends up doing is that the quotWquot shape ends up crossing vertebrae so that each myomere is not centered on one vertebrae with ribs It will cross over many When it contracts it pulls vertebrae towards each other on one side 2 Red quotSlow Fibersquot dark with lots of mitochondria and good vascular supply 3 White quotFast Fibersquot found closer to ventral and dorsal sections of myomere closer to the middle 4 When watching sh movement you will see lateral movement myomere contracts on one side to allow this to happen 5 Pectoral n muscles arrangement thin sheets of muscles extends into the n Not too much muscleture here for the bony sh There are ventral adductors and dorsal abductors a Abductors raise the ns up abducted you39re taken away b Adductors bring the ns back down adding things together 6 Fish typically have a teardrop or fusiform shape ends up reducing drag ii Tetrapods 1 Fish had basic epaxial and hypaxial muscles whereas amphibians early tetrapods have a lot more differentiation in the hypaxial muscles a External obliques b Internal obliques c transversus d rectus 2 Dorsal muscles become segmented but aren39t as distinct as in amniotes iii Amniotes 1 There is more division in the epaxial muscles Bands run through lumbar and thoracic region of the organism 2 Expaxial division a Transversospinalis group b Longissimus group c iocostais group 3 Hypaxial we will focus on this a Costal muscles ones that act primarily on the rib cage 4 Axial muscles still play a prominent role in terrestrial locomotion
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