Muscle Contractions Fatigue Names 3112021 SAP 2 b

Muscle Contractions, Fatigue & Names 3/11/2021 SAP 2 b 1

Type of Muscle Contractions • Isotonic contractions “same tone” • Myofilaments are able to slide past each other during contractions • The muscle shortens, tension rises • Walking, running, lifting an object 3/11/2021 SAP 2 b 2

Types of Muscle Contractions • Isometric contractions “same measurement” • Tension in the muscle increases • The muscle is unable to shorten –Length stays the same • Pushing against a wall with bent elbows 3/11/2021 SAP 2 b http: //www. biosolutions. info/2008/02/muscle-contraction. html 3

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Isometric vs. Isotonic https: //www. youtube. com/watch? v=T 3 Oi. OJ 6 -x 34 3/11/2021 SAP 2 b 5

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Muscle Fatigue • Muscle fatigue – the muscles inability to contract even though it is being stimulated • Occurs when: • ATP production fails to keep pace with ATP used • Lactic acid accumulates in the muscle • Ionic imbalances are present • Result of oxygen debt 3/11/2021 SAP 2 b 7

Muscle Classification • Prime Mover • agonist • Causes a desired action • Ex: elbow flexion (biceps brachii) • Antagonist • Relaxes when prime mover contracts • Ex: elbow flexion (triceps brachii) • Synergist • Helps the prime mover by reducing unnecessary movements • Fixators 3/11/2021 • Stabilize the origin of the prime mover • Can immobilize a bone SAP 2 b 8

Muscle Names • Muscles are named based on: • size • shape • location • action • number of attachments • Number of origin • direction of its fibers 3/11/2021 SAP 2 b 9

Direction • Rectus: parallel to the midline • Transverse: perpendicular to the midline • Oblique: diagonal to the midline 3/11/2021 SAP 2 b 10

Size • Maximus: largest • Magnus: large • Minimus: smallest • Major: larger • Longus: longest • Minor: smaller • Latissimus: widest • Vastus: great • Longissimus: longest 3/11/2021 SAP 2 b 11

Shape shaped • Deltoid: triangular • Trapezius: trapezoid • Platys: flat • Serratus: saw-tooth • Quadratus: square • Rhomboid: diamond- • Gracilis: slender shaped • Orbicularis: circular • Pectinate: comblike • Piriformis: pear 3/11/2021 SAP 2 b 12

Action 3/11/2021 • Flexor: decreases joint angle • Extensor: increases joint angle • Abductor: moves bone away from midline • Adductor: Moves bone closer to midline • Levator: produces superior movement • Depressor: produces interior movement • Supinator: turns palms up • Pronator: turns palms down • Sphincter: decreases size of opening • Tensor: makes body part rigid SAP 2 b 13

Number of Origins • Biceps: two origins • Triceps: three origins • Quadriceps: four origins Location: • Pectoralis: chest • Gluteus: buttock • Temporalis: temporal • Brachii: arm • Lateralis: lateral 14

Arrangement of Fascicles Circular-arranged in rings Convergent-muscle has broad origin & fascicle converge into 1 insertion

Arrangement of Fascicles Parallel- fascicle runs parallel to axis of muscle Fusiform-spindle shaped muscle with large muscle body

Arrangement of Fascicles Pennate: fascicles are short & at angle to a tendon -unipennate- fascicle insert in 1 side of tendon -bipennate-fascicles are on both sides of tendon -multipennate-from multiple directions in tendon

Basic Principles of skeletal muscles 1. skeletal muscles produce movement by pulling bones (muscle only pull, they never push) 2. Bones act as levers and joints act as fulcrums for muscles to bring about movement 3. They contract only when stimulated 4. They contract according o the graded strength principle 5. A muscle fiber will follow the all or none principle 6. Muscles that move parts usually do not lie over that part 7. Muscles act in groups rather than singly.

Lever Systems A partnership between muscle and bone • Levers- bone/bar that moves on a fixed point • Fulcrum-joint/fixed point • Load-weight or resistance to be moved

1 st class 2 nd class 3 rd class https: //www. youtube. com/watch? v=d 1 w. S_Ol. Jzm. I

Aging & Muscles • Muscles begin to shrink and lose mass • Size of muscle fiber decreases • Tendons become stiffer due to decreased water content

40 Superficial muscles divided into 12 regions 3/11/2021 SAP 2 b 22

27 superficial muscles divided into 7 regions 3/11/2021 SAP 2 b 23

● ● 3/11/2021 Based on what you know about naming skeletal muscles, what do you predict about the following muscles: Biceps femoris Rectus abdominis Flexor carpi ulnaris SAP 2 b 24

Sternocleidomastoideus Flexes and Rotates Head

Masseter Elevates Mandible

Temporalis Elevate & Retract Mandible

Trapezius Extend Head, Adduct, Elevate or Depress Scapula

Latissimus Dorsi Extend, Adduct & Rotate Arm Medially

Deltoid Abduct, Flex & Extend Arm

Pectoralis Major Flexes, adducts & rotates arm medially

Biceps Brachii Flexes Elbow Joint

Triceps Brachii Extends Elbow Joint

Rectus Abdominus Flexes Abdomen

External Oblique Compress Abdomen

External Intercostals Elevates ribs

Internal Intercostals Depress ribs

Diaphragm Inspiration

Forearm Muscles • Flexor carpi—Flexes wrist • Extensor carpi—Extends wrist • Flexor digitorum—Flexes fingers • Extensor digitorum—Extends fingers • Pronator—Pronates • Supinator—Supinates