MUSCULAR SYSTEM

TOPIC #4: Muscular System Muscle Vocabulary Introduction to Muscles Worksheet Microscopic Anatomy of Muscles Vocabulary Quiz Muscle Hodge Podge Skeletal Muscles (36 presentations) Muscle Labels Movement Lab Energy Used for Muscle Contractions Muscular System Diseases

Skeletal muscle presentations Name Bone of Origin Bone of insertion Joint crosses Why named? Action Antagonistic muscle (if any) Skeletal muscle presentations

Muscle vocabulary Threshold stimulus Motor neuron Fascicle Myosin/Actin Sarcomere Cholinterase Acetylcholine Muscle Cramp All-or-none Response Atrophy vs. Atony Muscle tone Myostatin Agonists Antagonists Synergists Fixators

BASIC TRAINING Latin word mus? Little mouse 3 types of muscles? Skeletal, cardiac, smooth Striated? Tendons? Housekeeping muscles? Functions of muscles? Key words: Skeletal: skeletal, striated, voluntary Smooth: involuntary, visceral, non-striated Cardiac: cardiac, involuntary, striated Cardiac muscle: HEART Contracting: muscle shortens

MICROSCOPIC ANATOMY

MICROSCOPIC ANATOMY Contains cells, nerve fibers, connective tissues, blood vessels Covered externally by epimysium Bundle of cells, separated by connective tissue sheath Surrounded by perimysium Elongated, multiple cells, multinucleate, has striated appearance Surrounded by endomysium

MUSCLE FIBERS ARE NOT SINGLE CELLS! They are a FUSION of many cells = myoblasts Each Muscle Fiber Contains: An array of myofibrils Mitochondria – responsible for Cellular Respiration Convert chemical energy (food) into cellular energy (ATP) Also called sarcosomes Many nuclei (multi-nucleate) Sarcolemma = cell membrane Sarcoplasmic reticulum = ER Sarcoplasm?? Sarcomere…

SARCOMERES Muscle fibers are STRIATED Myofibrils are made up parallel filaments (thick & thin) Striations are created by dark A bands and light I bands A bands are bisected by the M line I bands are bisected by the Z disk Thick filaments produce the dark A band & contain myosin Thin filaments produce the light I band & contain actin

Entire array of thick and thin filaments between Z disks video

Read pages 166 and 167 WRITE OUT QUESTIONS AND ANSWERS PLEASE! What split ATP to generate power for muscle contraction? What links the thick and thin filaments together during muscle contraction? Why does the light, H zone seem to disappear during muscle contraction? What is the major role of the SR? What provides the “go” signal for muscle contraction? Also answer #1 on page 198 and #3 on page 199

#5 Muscle Hodge Podge

Golden Rules of Muscle Activity All muscles cross at least one joint. Typically, the bulk of the muscle lies PROXIMAL to the joint crossed. All muscles have at least 2 attachments: the origin and the insertion. Muscles can only pull, they never push. During contraction, the muscle insertion moves toward the origin.

Points of muscle attachment in bone Origin = less movable bone Insertion = movable bone; moves toward origin when contracting

Body movement occurs when muscles contract across joints Flexion, Extension, Hyperextension Rotation (lateral = away vs. medial = towards) Abduction (away from midline), Adduction (toward midline) Circumduction FOOT: Dorsiflexion, Plantar Flexion, Inversion, Eversion, Supination, Pronation Opposition Elevation, Depression, Retraction, Protraction

Elevation: scapula is raised, “shrugging the shoulders” Depression: scapula pulls down to a more inferior position Protraction: scapula moves forward, “hunching the shoulders” Retraction: scapula moves backward, “squaring the shoulders”

Muscles must work in REVERSE pairs to move the bones. Muscles CANNOT push! Muscles must work in REVERSE pairs to move the bones. Immense variety of movement possible Prime mover: muscle with majority of responsibility of causing movement Antagonists: oppose/reverse a movement Synergists: help prime movers by producing same movement or lessening other movements Fixators: specialized synergists, used for stabilizing purposes

Naaaammmme That Muscle! Muscles are named, based on various characteristics. Location example: tibialis anterior is located near the front of the tibia bone. Size: example: maximus means larger & minimus means smaller. (pectoralis major & minor muscles of the chest)

Number of origins/insertions: based on the number of origins, example: quadriceps femoris (which has 4 = quad) Fiber direction: example: rectus (straight) runs parallel to midline of body. Oblique run slanted to midline of the body. Muscle shape: example: deltoid means triangular Muscle action: example: flexor, adductor, extensor

Important Skeletal Muscles Facial Muscles Neck Muscles Anterior Trunk Muscles Posterior Trunk Muscles Upper Limb Muscles Lower Limb Muscles

#6 Muscle Mania

Muscles of the Human Body Muscles of the head and neck: The muscles of the face and head can be divided into 3 main categories: (A) muscles of expression – orbicularis, buccinator, frontalis, occipitalis (B) muscles of chewing – masseter, temporalis and (C) muscles of the neck – sternocleidomastoid. Muscles of the Neck and Shoulder: Sternocleidomastoid, Trapezius, Deltoid, Rotator Cuff: is a group of 4 muscles which hold the head of the arm bone in the shoulder joint and attach the arm to the chest. Muscles of the Chest and Back: muscle of the chest includes  - Pectoralis Major, Pectoralis Minor and Intercostal Muscles. The muscles of the back include – Trapezius, Latissimus Dorsi and Serratus Posterior. Muscles of the Upper Extremity: the muscles of the upper arm include – Coracobrachialis, Biceps, Brachialis and the Triceps muscle.  The muscles of the forearm include - Pronator Teres, Extensor Digitorum Communis and the Flexor Carpi Radialis. Muscles of the hand include - Palmaris Brevis, Abductor Digiti Quinti, Abductor Pollicis Brevis and the Flexor Pollicis Brevis muscle. Muscles of the Lower Extremity: the muscles of the thigh and shin region include - Quadriceps Muscles, Hamstring Muscles, Tibialis Anterior, Calf Muscles and yhe Extensor Digitorum Longus muscle. The muscles of the foot include - Plantar Aponeurosis, Abductor Hallucis, Flexor Digitorum Brevis and the Abductor Digiti Quinti.

What’s the difference??

Aging

Muscular System Diseases Usually extremely painful, result in physical impairments (such as an inability to walk). Nerve damage Muscular Dystrophy Myasthenia Gravis ALS Cerebral palsy Torticollis