1. VERTEBRATE MUSCULAR SYSTEM Mrs. Ofelia Solano Saludar Department of Natural Sciences University of St. La Salle Bacolod City

2. HISTOLOGY: striated, cardiac, smooth FUNCTION: contraction  locomotion: result of muscle action  posture determinant  orientation of body in the environment  heat production

4. GROSS FEATURES OF SKELETAL MUSCLE Origin & insertion; Tendon; Aponeurosis; Fascia, Action GROSS FEATURES OF SKELETAL MUSCLE Origin & insertion; Tendon; Aponeurosis; Fascia, Action

5. Various wrappings of connective tissues extend beyond the ends of the muscle fibers to connect with the periosteum of the bone:  Tendon - cordlike attachment consisting of extensions of a muscle's tough connective tissue sheath that anchor a muscle to its origin & insertion  Aponeurosis - thin flat sheet o Fascia - thin flat sheets of connective tissues that wrap and bind adjacent muscle groups o Raphe - junction of two muscles at a band of connective tissue to form a line of fusion, such as the linea alba

7. 1.Agonists- primary action 2.Antagonistic - oppose or resist the action of another muscle 3.Synergistic - work together to produce a common effect

8. Names of skeletal muscles are based on:  action (e.g., levator scapulae)  direction of fibers (e.g., oblique)  location or position (e.g., superficial)  number of divisions (e.g., triceps)  shape (e.g., deltoid)  origin and/or insertion (e.g., iliocostalis)  size (e.g., major) … or some combination of these

9. STRIATED MUSCLE  Skeletal, voluntary muscles: axial, body wall & tail, hypobranchial & tongue, extrinsic eyeball, appendicular, branchiomeric or branchial muscles  Myofibrils are striated cylinders within syncytial myofibers

12. SOMATIC MUSCLESVISCERAL MUSCLES Histo logy Striated, skeletal, voluntarySmooth, involuntary, includes cardiac muscle Seg men tation Primitively segmented (*partially unsegmented: somitomeres) Unsegmented Origin Myotomal/somiticLateral mesoderm Loca tion Body wall & appendages (*branchial region) Splanchnopleure Func tion Primarily for orientation in external environment Regulate internal environment Inner vation Spinal nerves & cranial nerves III, IV, VI & XII (except tongue) Postganglionic fibers of ANS

13. TWITCH (RED)TONIC (WHITE) ContractionFast to slow contraction Slow contraction SlowMammalian postural muscles Amphibian & reptilian postural muscles FastMost locomotor muscles Extraocular & ear muscles of mammals InnervationSingle axonMultiple axons Action potential All-or-noneA temporal summation with a graded contraction Onset of fatigue Variably fatiguesCan maintain tension efficiently

14. SLOW TWITCH Type I of mammals FAST OXIDATIVE Type IIA of mammals FAST GLYCOLYTIC Type IIB of mammals Posture or slow repetitive movements FastPowerful & fast Fatigues slowly Fatigues quickly Large # of mitochondria Few mitochondria High oxygen storage proteins (myoglobin): “red muscle” ATP formed by oxidative phosphorylation ATP formed by glycolysis- with possible oxygen debt “Dark meat” of fish & fowl Bird flight muscles“White breast” of domestic fowl

15. SMOOTH MUSCLE TISSUE  Fusiform, uninucleate cells with myofibrils but without striations; occur in sheets  Two general types: 1.Unitary- has myogenic contraction to aid in sustaining the rhythmic movement of the organ 2.Multiunit- has neurogenic contraction, which requires action potentials sent by neurons

16.  Lateral plate mesoderm in origin  Involuntary- innervated by ANS  Muscles of tubes, vessels, & hollow organs; intrinsic eyeball muscles; erectors of feathers & hair  Regulates internal body temperature

17. CARDIAC MUSCLE TISSUE  Heart muscle  Uninucleate, striated cells separated by intercalated disks  Lateral plate mesoderm in origin  Involuntary, self depolarizes (myogenic); ANS nerves modify its rhythmicity

18.  Include the skeletal muscles of the trunk & tail  Are segmental because of their embryonic origin; arise from segmental mesodermal somites  Metamerism is most evident in fishes and aquatic amphibians where the axial muscles are used in locomotion  Metamerism is obscured in tetrapods due to presence of paired appendages responsible for locomotion on land  Myotomes are separated by myosepta which serve as muscle origins & insertions  Myoseptum becomes indistinct in amniotes

19.  Myotomes become divided by the horizontal skeletogenous septa into: 1.EPAXIALS- above the septum, dorsoflex spine 2.HYPAXIALS- below the septum, ventroflex spine o present in orbits as extrinsic eyeball muscles o extend forward beneath the pharynx as hypobranchial muscles & muscles of the tongue

20. Epaxial Muscles:  Innervated by dorsal rami of spinal nerves  Extend spine & some lateral bending  Extrinsic eye muscles (innervated by cranial nerves)

21. Hypaxial Muscles:  Innervated by ventral rami of spinal nerves  Ventroflex and lateral bending  Hypobranchial muscles: hypaxial muscles that migrated forward & come to lie on floor of pharynx, pectoral girdle to jaw; function in respiration & feeding, e.g. coracomandibularis

22. Epaxials are elongated bundles that extend through many body segments located below the expanded appendicular muscles; required to operate the limbs lie along vertebral column

23. Urodeles & some lizards - epaxials (DORSALIS TRUNCI) are still obviously metameric Anterior lateral musculature of a urodele (Ambystoma or tiger salamander)

24.  Beginning with fishes, epaxial bundles split into longitudinal systems: long, short & segmented  Short & long bundles both arch & support the vertebral column  Extend from base of the skull to tip of the tail SHORT BUNDLES:  Extend from the 1 st vertebrae to the skull (occipitals)  Short segmental muscles (intervertebrals) include several systems between various parts of the vertebrae & ribs, with each member extending only over one body segment  Connect processes of adjacent vertebrae  Tetrapod bundles perform same function as in fishes (side-to-side movements of vertebral column)

25. LONG BUNDLES:  Longissimus group- lies on transverse processes of vertebrae; includes the longest epaxial bundles: longissimus dorsi, longissimus cervicis, longissimus capitis  Iliocostalis group- lateral to longissimus & spinalis; arises on ilium & inserts on dorsal ends of ribs or uncinate processes  Spinalis group- lies close to neural arches; connects spinous processes or transverse processes with those several vertebrae anteriorly

26. Hypaxials :  Muscles of lateral body wall: oblique (external & internal), transverse, & rectus muscles  Muscles that form longitudinal bands in roof of body cavity: subvertebral muscles  Hypaxials of the abdomen have no myosepta & form broad sheets of muscle

27. oes, obliquus externus superficialis oep, obliquus externus profundus oi, obliquus internus ta, transversus abdominis

28.  Modern amniotes: myosepta & ribs are restricted to the thorax, hence abdominal muscles are not obviously segmented  Hypaxials are reduced in volume compared to fishes; support contents of abdomen & assist in respiration

29.  Weakly developed in most fishes but stronger in tetrapods  Support ventral body wall, compresses abdomen, assist epaxials in bending vertebral column  Consists of: rectus abdominis, cervicis, and geniohyoid in front of hyoid apparatus  Diaphragm – unique to mammals for breathing

32. EPAXIALHYPAXIAL Intervertebrals: Intertransversarii, Interspinalis, Interarcuales, Interarticularis Longissimus: L. capitis, L. cervicis, L. dorsi, Extensor caudae lateralis Spinalis: S. dorsi, S. cervicis, S. capitis, Transversospinalis Iliocostales Subvertebralis: Longus colli, Quadratus lumborum, Psoas minor Oblique group (parietals): Internal & External intercostals, Internal & External oblique of abdomen, Cremaster, Supracostals (Scalenus, Serratus dorsalis, Levatores costarum, Transversus costarum) Diaphragm Transverse group (parietals): Transversus costalis (subcostal), Transversus abdominis Rectus muscles: Rectus abdominis, Pyramidialis

33. Muscles of the back: Longissimus dorsi - extends vertebral column Iliocostalis - draws ribs together Multifidus spinae - extends vertebral column Spinalis dorsi - extends vertebral column Abdominal muscles: Rectus abdominis - compresses abdomen Internal oblique - compresses abdomen External oblique - constricts abdomen Internal oblique - constricts abdomen Respiratory muscles: Serratus - draw ribs cranially Scalenus - flexes the neck Diaphragm - separates the thoracic/abdominal cavities, functions in breathing Intercostals - protract/retract ribs

34.  Arise from preotic somitomeres  6 voluntary muscles  Obliques rotate eye along its transverse axis; rectus move eyes up, down, left, right; retractor in some  Retractor bulbi pulls the eyeball further into the orbit to allow for coverage by the nictitating membrane (lacking in humans)  Innervated by the oculomotor nerve

35.  Develop from somitomeres & the myotomes caudal to those that produce the ocular muscles  Closely associated with the visceral skeleton so they are used in both breathing and feeding.  Perform the function of operating the jaw, opening and closing the spiracle  Primitively had a levator & a constrictor muscle series; in present vertebrates coracobranchials, subarcuals and ventral transversals are added  May be subdivided based on what visceral arch they are associated with

38.  Hypobranchial- ventral muscles of the head and trunk region that perform functions associated with jaw and tongue movement  Extend forward from pectoral girdle & insert on mandible, hyoid, & gill cartilages  Strengthen floor of pharynx  Assist branchiomeric muscles in elevating floor of mouth, lowering jaw, & extending gill pouches

39. Fishes- associated with feeding and breathing:  Coracoarcuals - opens mouth  Coracomandibular - opens mouth  Coracohyoid - helps in feeding  Coracobranchial - helps in swallowing Tetrapods- associated with the hyoid apparatus & tongue  Tongue muscles: hyoglossus, styloglossus, genioglossus (also speech & sound production)  Geniohyoid: draws hyoid cranially  Sternohyoid: draws hyoid posteriorly  Sternothyroid: draws larynx caudally Tongue of amniotes is a 'sac' anchored to hyoid skeleton & filled with hypobranchial muscle

40. Hypobranchials ending in "hyoid" stabilize hyoid and larynx; e.g. geniohyoid, sternohyoid, sternothyroid, thyrohyoid  Those beginning or ending with "thyro" are attached to the larynx; e.g. thyrohyoid  Those ending with “glossus” or start with “lingu” are tongue muscles, e.g. lingualis, styloglossus

42. EYEBALLHYPO BRANCHIAL (tongue) BRANCHIOME RIC (pharynx) Superior & inferior oblique Medial & lateral rectus Superior & inferior rectus Genioglossus Hyoglossus Styloglossus Lingualis Mandibular muscles Hyoid muscles Other branchial muscles

43.  Muscles of girdles and appendages  Move fins or limbs  Innervated by ventral ramus of spinal nerves  Two types based on origin: o Extrinsic - originate on axial skeleton or fascia or trunk & insert on girdles or limbs o Intrinsic - originate on girdle or proximal skeletal elements of appendage & insert on more distal elements

44. FISHES  Appendicular muscles serve mostly as stabilizers  Intrinsic muscles are limited in number and undifferentiated  Originated as extensions of hypaxials of body wall  Paired fins are appendicular (from myotome)

45.  Median dorsal & ventral fins are NOT appendicular, from myotome of epaxials & hypaxials respectively  Dorsal mass on paired fins are extensors or abductors  Ventral mass on paired fins are flexors or adductors

46. TETRAPODS  Appendicular muscles are much more complicated than in fish  Greater leverage required for locomotion on land  Jointed appendages (as opposed to fins) require complex muscles

49. BIRDS  Intrinsic musculature is reduced  Pectoralis (humerus adductor), is the largest flight muscle that lowers wing  Supracoracoideus elevates wing

50.  Dorsal group of the forelimbs (e.g., trapezius and latissimus dorsi) arise on: o fascia of trunk in lower tetrapods o skull, vertebral column, & ribs to a point well behind the scapula in higher tetrapods & converge on the girdle & limb  Ventral group (e.g., pectoralis) arises on sternum & coracoid, & converge on limb  RESULT = pectoral girdle & limb are joined to trunk by extrinsic appendicular muscles

51. The 'muscular sling' of tetrapods: Appendicular muscles of the forelimbs suspend the anterior body of tetrapods from the shoulders: axial muscles (rhomboideus & serratus ventralis) branchial muscles (trapezius) forelimb musculature (pectoralis)

52.  The pelvic girdle requires no such muscular anchoring because it is attached directly to the vertebral column, resulting to relatively lesser volume of extrinsic muscle in posterior limbs.  Referred to as 2 0 appendicular muscles because:  they arise from embryonic body wall & spread to the girdles and limb buds  it was not their original function to operate appendages

53. MAMMALSREPTILES EXTRINSIC: Forelimb onlySecondary appendicular: Levator scapulae, Rhomboideus, Serratus ventralis Primary appendicular: Latissimus dorsi, Pectorales Secondary appendicular: Levator scapulae, Rhomboideus, Serratus ventralis Primary appendicular: Latissimus dorsi, Pectorales INTRINSIC: GIRDLE (girdle to humerus, proximally) Deltoideus Subscapularis Teres minor Supraspinatus Infraspinatus Coracobrachialis Teres major Deltoideus clavicularis Dorsalis scapulae Subcoracoscapularis Scapulohumeralis anterior Supracortacoideus Coracobrachialis Slip of Latissimus dorsi UPPER ARM (girdle of humerus to proximal end of radius or ulna) Triceps brachii Biceps brachii Brachialis Epitrochleoanconeus Anconeus Triceps brachii Biceps brachii Brachialis Epitrochleoanconeus Anconeus FOREARM (humerus & proximal end of radius & ulna to hand) Extensors & flexors of carpus & digits Supinators & pronators of hand Extensors & flexors of carpus & digits Supinators & pronators of hand HANDExtensors, flexors, abductors, adductors of digits

54. Region of BodySharkSalamander Mammal Hypobranchial (pharyngeal) muscles Coracoarcuales Coracomandibularis Coracohyoid Tongue Geniohyoid Recus cervicis Tongue Geniohyoid Sternohyoid, Sternothyroid Pectoral Appendages Dorsal extensors Ventral flexors Latissimus dorsi Shoulder muscles Arm extensors Pectoralis Supracoracoid Arm flexors Latissimus dorsi, cutaneous maximus Deltoids, subscapularis, teres major Triceps, supinator (turn hand up), extensors of manus and digits Pectoralis Suprasinatus, infraspinatus Biceps,pronator, flexors of manus and digits Branchial muscles First Arch Adductor mandibulae Intermandibularis Adductor mandibulae Intermandibularis Masseter, temporalis, pterygoids mylohyoid Second Arch Ventral constrictors Levator Subarcual rectus, interhyoid, constrictor colli platysma Other arches Trapezius (cucullaris) TrapeziusTrapezius (and its smaller units), sternomastoid, cleidomastoid

57.  Move skin of amniotes  Extrinsic, striated muscle (e.g., platysma)  Originate on the skeleton & insert on the underside of the dermis  Intrinsic integumentary muscles (arrector pili muscles) lie entirely within the dermis; found in birds & mammals; mostly smooth muscles

58.  Consist of electric discs (up to 20,000) which are modified muscle cell with associated nerves & mitochondria  Each disc (electroplax) produces electric signals that propagate through the water.  Specialized skin receptors can sense disturbances which are sent up to specialized regions of the brain that compute a "picture" of the fish's environment.

59.  Salt water eel can emit up to 50V  Fresh water eel can emit up to 500V  Functions: communication, orientation with objects in environment, detection of prey, offense & defense, locating prey (electrolocation)