Muscle. Dr. Carmen E. Rexach Anatomy 35 Mt San Antonio College

Transcription

1 Muscle Dr. Carmen E. Rexach Anatomy 35 Mt San Antonio College

2 Functions Movements of bones and soft body parts Movements of fluids through a tube (blood, digestive)

3 Functions Maintain posture Support soft organs

4 Functions Control movement through a passage or opening Control body temperature

5 Origins Macrostructure of skeletal muscle attachment of a muscle to a stationary bone Insertions attachment of a muscle to a movable bone

6 Characteristics of origins and insertions Indirect attachments (most common) tendons cordlike structures of fibrous, regular connective tissue aponeuroses a wide, thin, tendon Direct attachments the muscle surface is attached directly to the periosteum of bone

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8 Muscle fascia

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10 Fusiform Parallel Convergent Pennate Circular Fascicle orientation: 5 muscle types

11 Fusiform muscle Thick in middle Tapered at ends Moderately strong contractions Examples: Biceps brachii gastrocnemius

12 Parallel Straplike with parallel fascicles Uniform width Contract more than other muscle types Weaker than fusiform Examples: Rectus abdominis Sartorius

13 Pennate muscles Feather-shaped Fascicle inserts into tendon running through muscle Unipennate Semimembranosus Bipennate Rectus femoris Multipennate Deltoid

14 Circular and Convergent Circular Sphincters Ex) Obicularis oris Convergent Fan shaped Narrow at insertion Strong Ex) Pectoralis major

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16 Naming muscle By fiber arrangement: Rectus= fascicles (fibers) run parallel to the muscle longitudinal midline axis (LMA)

17 transverse Naming muscle By fiber arrangement: fascicles are perpendicular to the LMA oblique fascicles are at an angle different than parallel or perpendicular

18 Naming muscle: By location superficialis tibialis anterior profundus(a deep muscle) temporalis

19 Naming muscle: by size maximus minimus medius brevis longus magnus

20 Naming muscle: by the number of origins biceps triceps quadriceps

21 Naming muscle: by shape deltoideus trapezius rhomboideus

22 Naming muscle: by origin and insertion Sternocleidomastoid sternohyoid

23 Naming muscle: by action flexor pollices longus (pollux = thumb) pronator teres (teres = round) extensor digitorum

24 Functional groups of muscles 1. Prime movers (agonists) 2. Synergists 3. Antagonists 4. Fixators

25 Prime movers Muscle produces most of force during movement across a particular joint 11 types Flexor Abductor Extensor Adductor Levator Depressor Supinator Pronator Rotator Sphincter Tensor

26 Prime movers Flexor: Biceps brachii Extensor: Triceps brachii

27 Prime movers Abductors: Deltoid Adductors: Adductor brevis, longus, and magnus

28 Prime movers Levator: Levator scapulae Depressor: Latissimus dorsi

29 Prime movers Supinator & Pronator Rotator: Sartorius

30 Prime movers sphincter Open and close orifice to an open organ tensor Provides tension along a limb

31 Synergist agonists help a prime mover example Prime mover = biceps brachii Synergist = brachialis Please note: depending on the position of the joint, these muscles may have other actions, and other roles.

32 Fixators Group of muscles that keep bones stationary so that others can move with more accuracy

33 Antagonists oppose the prime mover Examples: Opposite actions of biceps and triceps brachii

34 Skeletal muscle cells

35 Skeletal muscle cells Myo-, sarcodenotes muscle Skeletal muscle cells are: Multinucleated Voluntary Striated Called fibers

36 Skeletal muscle cells Skeletal muscle cells are filled with myofibrils composed of myofilaments

37 Skeletal muscle cells Thick filaments and thin filaments Functional unit of skeletal muscle = sarcomere

38 Sarcomere

39 Motor unit

40 Summary of Sliding filament theory 1) Motor neuron triggers electrical changes in the sarcolemma 2) Changes travel down t-tubules and cause calcium ions (Ca+2) to be released from the terminal cisternae of the sarcoplasmic reticulum 3) This makes binding sites on the thin filaments available. 4) Thick filaments attach to the thin filaments and pull them over the top toward the center, shortening the muscle fiber.

41 Motor end plate Interface between the motor neuron and the muscle fiber No direct contact ACh secreted by the motor neuron binds to receptors on the surface of the muscle

42 Terminal cisternae and t-tubules T-tubules connect sarcolemma with sarcoplasm Terminal cisternae= enlargments in the sarcoplasmic reticulum, site of Ca ++ storage

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44 Cross bridge cycle

45 Additional features of muscle cells Irritability Contractility

46 Development of skeletal muscle fibers

47 Cardiac muscle Cardiac muscle cells are: Striated Involuntary Unicellular Centrally nucleated Joined by intercalated discs

48 Cardiac muscle cells

49 Smooth muscle Smooth muscle cells are: Not striated Involuntary Unicellular Found in viscera, blood vessels

50 Smooth muscle cells