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The Muscular System
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Primary Function of the Muscular System
Locomotion movement of substances through the body structure and support for organs and tissues
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Muscle Tissue: 3 Types Muscle Tissue enables the movement of body structures. Smooth, Cardiac, Skeletal
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Muscle Types: Smooth Muscle
Smooth muscle is non-striated, and acts in a number of involuntary processes in the body. Some of these processes include:
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Muscle Types: Smooth Muscle
allows the expansion and contraction of arteries and veins lines the bladder and reproductive tracts lines the entire gastrointestinal tract
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Did you know?... Tiny smooth muscle fibers in the skin called Arrector pili are responsible for “goose bumps.”
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Muscle Types: Cardiac Muscle
Cardiac muscle (heart muscle) is striated but functions involuntarily. It is solely responsible for propelling blood throughout the body.
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Muscle Types: Skeletal Muscle
Skeletal muscle is striated, and associated with voluntary movement. It also provides structure and support for organs and tissues.
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Anatomy of skeletal muscles Skeletal muscle fiber (cell)
tendon Muscle Fascicle Skeletal muscle Skeletal muscle fiber (cell)
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How Do Muscles Work? Individual muscle fibers are composed of small cylindrical structures called myofibrils. The functional component within the myofibril is called the sarcomere. Within the sacromere, protein filaments called actin and myosin allow the cell to expand and contract in a 3 step process:
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3 Steps 1) Before the muscle is stimulated, actin and myosin filaments partially overlap one another. 2) A nerve cell releases a signal which causes the actin and myosin filaments to “slide” along one another and overlap even more. 3) This contracts the myofibril and subsequently the entire muscle cell. When the nervous signal changes, the filaments relax and return to their original state.
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Actin myosin Muscle fiber myofibril sarcomere Z-line
Myosin molecule of thick myofilament Thin myofilament
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Sarcomere
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Actin and Myosin: A Closer Look
Access the website below (skip to sections 6-10) and complete the tutorial.
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Action Potentials and the Neuromuscular Junction
Impulse arrives at axon terminal Ca+ ions rush in activating synaptic vesicles Synaptic vesicles fuse with cell membrane of axon terminal ACh released ACh binds with motor end plate: deplorization occurs Impulse travels through T-tubules & SR
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Actin, Myosin, and Action Potentials Putting it all Together…
Access these online animations to help visualize these processes… ATP and Crossbridge Movement The Neuromuscular Junction Action Potential and Muscle Contraction Sarcomere Contraction
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If you check out a standard lass,
Did you Know? If you check out a standard lass, Muscles are a third of her body mass. Muscle (~35%) BODY COMPOSITION
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The Muscular System: Key Components
Muscles move body parts because they’re attached to bones by strips of dense connective tissue called tendons.
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Skeletal Muscle: Key Concepts
The place where muscle attaches to a stationary bone is called the “origin.” The place where the same muscle attaches and “pulls” is called the “insertion.” Origin Insertion
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Skeletal Muscle: Key Concepts
Skeletal muscle can be characterized as either “extensors” (causing a joint to straighten or extend), or a “flexor” (causing a joint to bend or flex).
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Challenge question How are tendons different from ligaments?
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Basic Muscle Groups You Need to Know!
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Basic Muscle Groups You Need to Know!
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Basic Muscle Groups You Need to Know!
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Naming Skeletal Muscles
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Naming Muscles: By Direction of Muscle Fibers (Relative to the Midline)
RECTUS = parallel to the midline Rectus Abdominus TRANSVERSE = perpendicular to midline Transverse Abdominus OBLIQUE = diagonal to midline External Oblique
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Naming Muscles: Location
Structure near which muscle is found FRONTALIS = near FRONTAL bone OCCIPITALIS = near OCCIPITAL bone
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Naming Muscles: Size Relative Size of Muscle MAXIMUS = largest
Gluteus Maximus MEDIUS = middle Gluteus Medius MINIMUS = smallest Gluteus Minimus LONGUS = longest Fibularis Longus BREVIS = short Fibularis Brevis TERTIUS = shortest Fibularis Tertius
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Naming Muscles: Number of Origins
Number of tendons of origin BICEPS = Two Biceps Brachii Biceps Femoris TRICEPS = Three Triceps Brachii QUADRICEPS = Four Quadriceps Femoris
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Naming Muscles: Shape Relative Shape of the Muscle
DELTOID = triangular shape Δ TRAPEZIUS = trapezoid shape SERRATUS = saw-toothed ♒ RHOMBOIDEUS = rhomboid shape TERES = round ○
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Naming Muscles: Action
NAME ACTION EXAMPLE FLEXOR Decrease angle at a joint Flexor Carpi Radialis EXTENSOR Increase angle at a joint Extensor Carpi Ulnaris ABDUCTOR Move bone away from midline Abductor Pollicis Longus ADDUCTOR Move bone toward midline Adductor Longus LEVATOR Produce upward movement Levator Scapulae DEPRESSOR Produce downward movement Depressor Labii Inferioris SUPINATOR Turn palm upward/anterior Supinator PRONATOR Turn palm downward/posterior Pronator Teres
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Cateorigizing muscles by the Actions they Facilitate
Examples __________ Prime mover– muscle with the major responsibility for a certain movement Antagonist – muscle that opposes or reverses a prime mover Synergist – muscle that aids a prime mover in a movement and helps prevent rotation Fixator – stabilizes the origin of a prime mover
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Head & Neck Muscles
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Head & Neck Muscles Frontalis: elevate eyebrows
Orbicularis Oculi: close eyelid Zygomaticus: draw angle of lip upward Buccinator: draws cheeks against teeth Orbicularis Oris: closes mouth Platysma: draws lower lip down & back Cranial Aponeurosis: connects frontalis to occipitalis Temporalis: elevates mandible Occipitalis: draws scalp back Masseter: elevates mandible Sternocleidomastoid: Flexes head Draws head toward shoulder
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Key Muscles of Facial Expression
Smiling Muscles Orbicularis Oculi Nasalis Levator Labii Superioris Levator Anguli Superioris Zygomaticus Risorius Frowning Muscles Frontalis Orbicularis Oris Depressor Anguli Oris Depressor Labii Inferioris Mentalis Platysma
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Muscles of the Axial Skeleton
Erector Spinae: maintain posture of back/extension Spinalis Longissimus Iliocostalis Oblique Muscles: rotation of the vertebrae Semispinalis Multifidus Rotatores Respiratory Muscles Diaphragm External Intercostals Internal Intercostals—deep breaths Abdominal Muscles External Obliques Internal Obliques Transverse Abdominus Rectus Abdominus
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Muscles of the Axial Skeleton
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Muscles of Scapular Stabilization
Trapezius: Retraction Elevation Depression Upward Rotation Rhomboid—retraction Levator Scapular—Elevation Pectoralis Major—Protraction Serratus Anterior—Protraction
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Anterior Muscles of Shoulder
Deltoid Flexion/Extension Abduction/Adduction Internal’External Rotation Pectoralis Major Adduction Flexion Extension Internal Rotation Biceps Brachii—Flexion
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Posterior Muscles of Shoulder
Teres Major Adduction Extension Internal Rotation Latissimus Dorsi Triceps Brachii
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Rotator Cuff Muscles (SITS)
Teres Minor External Rotation Subscapularis Internal Rotation Supraspinatus Abduction Infraspinatus External Rotation
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Muscles of the Elbow/Forearm
Triceps Brachii—Extension Bicep Brachii— Flexion Supination Brachialis—Flexion Brachioradialis— Pronation Pronator Teres Pronator Quadratus Supinator Longus
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Muscles of the Wrist & Hand
Flexor Carpi Ulnaris Flexor Carpi Radialis Flexor Digitorum Extensor Carpi Ulnaris Extensor Carpi Radialis Extensor Digitorum Anterior (Palmar) View Posterior (Dorsal) View
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Muscles of the Hip: Anterior
Medial/Adductor Muscles: Adductor Magnus Adductor Longus Adductor Brevis Gracilis Anterior Muscles Iliopsoas—Flexion Pectineus— Flexion Adduction Sartorius— Lateral Rotation
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Muscles of the Hip: Gluteal
Gluteus Maximus—Extension Gluteus Medius—Abduction Gluteus Minimus—Abduction Tensor Fasciae Latae— Flexion Abduction ** Gluteus Minimus is under the Gluteus Medius
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Muscles of Anterior Thigh
“Quadriceps” Rectus Femoris— Hip flexion Knee extension Vastus Lateralis—knee extension Vastus Medialis—knee extension Vastus Intermedius—knee extension Sartorius— Hip & Knee Flexion Lateral Hip Rotation **Vastus Intermedius is beneath Rectus Femoris
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Muscles of Posterior Thigh
“Hamstrings” Responsible for Knee Flexion & Hip Extension Semimembranosus Semitendinosus Biceps Femoris Gastrocnemius Knee Flexion
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Muscles of the Lower Leg
Anterior Compartment Tibialis Anterior — Dorsiflexion & inversion Extensor Digitorum Longus Fibularis Tertius — dorsiflexion & eversion Posterior Compartment Gastrocnemius — plantarflexion, knee flexion Soleus — plantarflexion Lateral Compartment Fibularis Longus — plantarflexion & eversion Fibularis Brevis — plantarflexion & eversion
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Can you think of different ways in which the muscular system works with other body systems to maintain homeostasis?
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Aerobic vs. Anaerobic Exercise
Muscle contraction requires ATP. When oxygen is present in sufficient amounts, the normal processes of glycolysis and cellular respiration can take place (aerobic). However, if oxygen is not present in large enough quantities to sustain vigorous muscle contraction, only a small amount of ATP is generated through glycolysis; and lactic acid forms in the absence of cellular respiration (anaerobic).
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Identify Skeletal muscle groups 1-14
Pop Quiz! Identify Skeletal muscle groups 1-14
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“That’s All Folks!” More to come…
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