ORGANIZATION OF SKELETAL MUSCLE

SKELETAL MUSCLE ORGANIZATION Connective Tissue Coverings

Skeletal muscles are attached to tendons which attach the muscle to bone

Belly: Thicker part of muscleEpimysium: connective tissue layer that

covers the muscleSeparates muscles from other structures/organs

Perimysium: Layer underneath the epimysiumSeparates muscles into individual bundles

Endomysium: Layer underneath the perimysium Surrounds each individual muscle fiber

SKELETAL MUSCLE ORGANIZATION

MICRO-ANATOMY OF MUSCLE TISSUE

SKELETAL MUSCLE BUNDLE (COVERED BY EPIMYSIUM) MANY MUSCLE FASCICLES (COVERED BY PERIMYSIUM) MANY MUSCLE FIBERS (COVERED BY ENDOMYSIUM) MANY MYOFIBRILS MANY SARCOMERES MANY ACTIN AND MYOSIN FILAMENTS

STRUCTURE OF A SKELETAL MUSCLE FIBER

Individual Muscle Fiber consists of: (outside to inside) Outside of muscle fiber

1. Sarcolemma: cell membrane of muscle fiber2. Sarcoplasm: cytoplasm of muscle fiber3. Transverse Tubules or T-Tubules:

connections from the sarcolemma to interior of muscle fiber for connection

Inside muscle fiber

1. Myofibrils: proteins that run the length of each fiber, surrounded by Sarcoplasmic Reticulum

1. S. R. stores Ca2+ ions which dictates muscle contraction

STRUCTURE OF A SKELETAL MUSCLE FIBER

Myofibril Components: Several Sarcomeres

made up of:Actin: Thin Filaments, bundles with globular sections that fit into the binding sites on actin

Myosin: Thick Filaments, has binding sites to which actin attaches to during contraction

MUSCLE CONTRACTION

T-tubules are stimulated from the nervous system

T-tubules release Ca2+ ions The thin filaments/actin then are pulled

along the thick filaments/myosin in place of where the Ca2+ ions were

http://www.youtube.com/watch?v=Ae0UYxqj3cM

RIGOR MORTIS

After death, ion pumps stop functioning calcium builds up in the sarcoplasm causing a fixed muscular contraction

MUSCLE PAIN

Soreness after a workout Stretching the muscle tissue farther

than usualSmall microscopic tears to an individual

muscle fiberSkeletal muscle tissue is multinucleated + many neuromuscular junctions you mind sends signals when you are injured

SKELETAL MUSCLE IDENTIFICATION Muscular system can be divided into 2

groups:1. Axial Muscles (60 %)2. Appendicular Muscles (40%)

NEUROMUSCULAR JUNCTION

Each skeletal muscle is controlled by a nerve cell called a motor neuron Where the motor neuron and muscle fiber

meet = Neuromuscular Junction

AXIAL MUSCLES

Muscles that position the head, spinal column, and move the rib cage.

Divided into 4 groups based on location and function:1. Muscles of the head and neck2. Muscles of the vertebral column3. Oblique and rectus muscles4. Muscles of the pelvic

AXIAL MUSCLES

Muscles of the SkullOrbicularis orisOrbicularis OculiNasalisZygomaticus

MajorZygomaticus

MinorFrontalis

AXIAL MUSCLES Muscles of the Skull continued…

PlatysmaBuccinatorTemporalisOccipitalisMasseter*Sternocleidomastoid*

Sternomastoid on cats

AXIAL MUSCLES Muscles of the Back

Trapezius*Clavotrapezius on cats

Latissimus Dorsi*

AXIAL MUSCLES Muscles of the Oblique

Pectoralis major*Serratus Anterior*

Serratus ventralis on cats

Rectus Abdominis*External abdominal

oblique*

Day 2

APPENDICULAR MUSCLES

Muscles that support the pectoral and pelvic girdles, and the limbs.

Separated into 2 major groups:1. Muscles of shoulders and upper

limbs2. Muscles of pelvis and lower limbs

APPENDICULAR MUSCLES

Muscles of Pectoral girdle:Pectoralis major*Deltoid*

Clavodeltoid on catLatissimus Dorsi

APPENDICULAR MUSCLES

Muscles that move the arm:Deltoid*

Clavodeltoid on catSupraspinatus*SubscapularisInfraspinatus*Pectoralis major*Latissimus dorsi*

APPENDICULAR MUSCLES Muscles of the arm:

Biceps brachii*Triceps brachii*Brachialis*Brachioradialis*

APPENDICULAR MUSCLES Muscles of the arm:

Flexor carpi ulnaris*Flexor carpii

radialis*Palmaris longus*Extensor carpi

radialis*Extensor carpi

ulnaris*

APPENDICULAR MUSCLES

Muscles of the Pelvic Girdle: Gluteus maximus* Gluteus medius*

APPENDICULAR MUSCLES Muscles that move the lower limb:

The “Quad”:Rectus femoris*Vastus Medialis *Vastus Lateralis*

Sartorius*Biceps femorisSemitendinosus*

APPENDICULAR MUSCLES

Muscles of the lower limb:Gastrocnemius*Soleus*Tibialis posterior*Tibialis anteriorCalcaneal tendon

APPENDICULAR MUSCLES Muscles of the lower limb:

Gastrocnemius*Soleus*Tibialis posterior*Tibialis anteriorCalcaneal tendon*