Naming Skeletal Muscles Direction of Muscle Fibers Action Location Origin & Insertion Skeletal Muscle Size Shape Number Of Origins
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
Location Structure near which muscle is found FRONTALIS = near FRONTAL bone OCCIPITALIS = near OCCIPITAL bone
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
Number of Origins Number of tendons of origin BICEPS = Two Biceps Brachii Biceps Femoris TRICEPS = Three Triceps Brachii QUADRICEPS = Four Quadriceps Femoris
Shape Relative Shape of the Muscle DELTOID = triangular shape Δ TRAPEZIUS = trapezoid shape SERRATUS = sawtoothed RHOMBOIDEUS = rhomboid shape TERES = round
Origin & Insertion Origin attachment to an immoveable bone Insertion attachment to a movable bone ILIO COSTALIS= attaches to the ilium & ribs (costal = ribs)
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 SUPINATOR Turn palm upward/anterior Supinator PRONATOR Turn palm downward/posterior Depressor Labii Inferioris Pronator Teres
Types of Muscle--Actions Prime mover (Agonist) 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
Characteristics of Muscles Muscle cells are elongated (muscle cell = muscle fiber) Contraction of muscles is due to the movement of microfilaments All muscles share some terminology Prefix myo refers to muscle Prefix mys refers to muscle Prefix sarco refers to flesh
Types of Muscle Tissue: Cardiac muscle tissue Makes up myocardium of heart Unconsciously (involuntarily) controlled Microscopically appears striated Cells are short, branching & have a single nucleus
Types of Muscle Tissue: Smooth (visceral) muscle tissue Makes up walls of organs & blood vessels Tissue is non-striated & involuntary Cells are short, spindle-shaped & have a single nucleus Tissue is extremely extensible, while still retaining ability to contract
Types of Muscle Tissue: Skeletal muscle tissue Associated with & attached to the skeleton (by tendons) Under our conscious (voluntary) control Microscopically the tissue appears striated Cells are long, cylindrical & multinucleate
Skeletal Muscle Functions of Skeletal Muscle Produce Movement Maintain posture Stabilize joints Generate Heat Sites of Muscle Attachment Bones Cartilage Connective tissue coverings Muscle Fibers blend into a connective tissue attachment Tendon cordlike structure Aponeurosis sheet-like structure Properties of Muscle Irritability ability to receive and respond to a stimulus Contractibility ability to shorten when an adequate stimulus is received Extensibility ability to lengthen when an adequate stimulus is received Elasticity ability to return to normal shape
Anatomy of skeletal muscles (pg. 131) tendon epimysium perimysium Muscle Fascicle Surrounded by perimysium Skeletal muscle Surrounded by epimysium endomysium Skeletal muscle fiber (cell) Surrounded by endomysium Play IP Anatomy of Skeletal muscles (IP p. 4-6)
Microanatomy of a Muscle Fiber
Organization of Skeletal Muscles Epimysium This is skeletal muscle The bundled muscle fascicles are surrounded by epimysium Muscle fascicle
Organization of Skeletal Muscles This is a muscle fascicle It is surrounded by perimysium and contains muscle fibers (cells) perimysium Muscle fiber
Organization of Skeletal Muscles endomysium This is a muscle fiber. Each muscle fiber is a single cell with multiple nuclei It is surrounded by endomysium and contains many myofibrils myofibril
Organization of Skeletal Muscle This is a myofibril Each myofibril is surrounded by sarcoplasmic reticulum (smooth ER) Myofibrils are made up of many sarcomeres (from Z line to Z line) Sarcoplasmic reticulum Sarcomere (unit between the Z lines)
Organization of Skeletal Muscle This is a sarcomere It is made up of thin filaments and thick filaments Thick filament Thin filament
Microanatomy of a Muscle Fiber (Cell) transverse (T) tubules sarcoplasmic reticulum terminal cisternae sarcolemma mitochondria myoglobin thick myofilament thin myofilament myofibril nuclei triad
Muscle fiber Z-line sarcomere myofibril Thin filaments Thick filaments Thin myofilament Myosin molecule of thick myofilament
Myofilaments of sarcomere Z line Z line M line Thin myofilaments Thick myofilaments
Thin Myofilament (myosin binding site)
Thick myofilament (has ATP & actin binding site) *Play IP sliding filament theory p.5-14 for overview of thin & thick filaments
Sarcomere Z line A band H zone Z line Thin myofilaments I band Zone of overlap Thick myofilaments M line Zone of overlap
How do skeletal muscles contract? 1. A signal is sent from the brain or the spinal cord to the muscle via neurons 2. An action potential is generated in the neuron, releasing Ca++ in the neuromuscular junction 3. The influx of calcium ions causes acetylcholine (AcH) to be released in the synaptic cleft 4. AcH binds to the AcH receptors present in the sarcolemma, increasing its permeability
5. Na++enter the sarcolemma, changing its polarity and creating an action potential 6. Ca++ are released by the sarcoplasmic reticulum, as the action potential travels down the T-tubules in the muscle fiber 7. Ca++ bind with troponin C, causing the myosin to bind on actin sites
8. ATP is hydrolyzed into ADP and phosphorus, releasing energy 9. Myosin head bends and actin slides over the myosin surface (contraction) 10. Myosin releases the ADP molecule 11. Actin is released and returns to original position (relaxation)
Sliding Filament Theory
Sliding Filament Theory 1. Myosin heads attach to actin molecules (at binding [active] site) 2. Myosin pulls on actin, causing thin myofilaments to slide across thick myofilaments, towards the center of the sarcomere 3. Sarcomere shortens, I bands get smaller, H zone gets smaller, & zone of overlap increases
4. As sarcomeres shorten, myofibril shortens. As myofibrils shorten, so does muscle fiber Once a muscle fiber begins to contract, it will contract maximally This is known as the all or none principle
Sliding Filament Theory
Head & Neck Muscles
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
Muscles of Mastication Masseter: elevates mandible Temporalis: elevates mandible Medial pterygoid: elevates mandible Lateral pterygoid: depresses mandible
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
Muscles of the Axial Skeleton
Muscles of the Axial Skeleton Intrinsic Muscles Erector Spinae: maintain posture of back/extension Spinalis Longissimus Iliocostalis Oblique Muscles: rotation of the vertebrae Semispinalis Multifidus Rotatores Muscles of Quiet Respiration Diaphragm External Intercostals Internal Intercostals deep breaths Abdominal Muscles External Obliques Internal Obliques Transverse Abdominus Rectus Abdominus Quadratus Lumborum
Muscles of Scapular Stabilization Trapezius: Retraction (M) Elevation (S) Depression (I) Upward Rotation (S, M) Rhomboid retraction Levator Scapular Elevation Pectoralis Major Protraction Serratus Anterior Protraction
Anterior Muscles of Shoulder Deltoid Flexion (A, M)/Extension (P, M) Abduction (M)/Adduction (A) Internal (A) /External Rotation (P) Pectoralis Major Adduction Flexion Extension Internal Rotation Biceps Brachii Flexion
Posterior Muscles of Shoulder Teres Major Adduction Extension Internal Rotation Latissimus Dorsi Adduction Extension Internal Rotation Triceps Brachii Adduction Extension
Rotator Cuff Muscles (SITS) Supraspinatus Abduction Infraspinatus External Rotation Teres Minor External Rotation Subscapularis Internal Rotation
Muscles of the Elbow/Forearm Triceps Brachii Extension Bicep Brachii Flexion Supination Brachialis Flexion Brachioradialis Flexion Pronation Pronator Teres Pronator Quadratus Supinator Longus
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
Muscles Of Hip: Anterior Muscles
Muscles of Hip: Anterior Muscles Medial/Adductor Muscles: Adductor Magnus Adductor Longus Adductor Brevis Gracilis Anterior Muscles Iliopsoas Flexion Pectineus Flexion Adduction Sartorius Flexion Lateral Rotation
Muscles of Hip: Gluteal Muscles ** Gluteus Minimus is under the Gluteus Medius Gluteus Maximus Extension Gluteus Medius Abduction Gluteus Minimus Abduction Tensor Fasciae Latae Flexion Abduction
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
Muscles of Posterior Thigh Hamstrings Responsible for Knee Flexion & Hip Extension Semimembranosus Semitendinosus Biceps Femoris Gastrocnemius Knee Flexion
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
Throwing Movement
Running & Kicking