1. Organization of Skeletal Muscle

2. Skeletal Muscle Organization
Connective Tissue Coverings
Skeletal muscles are attached to tendons which attach the muscle to bone
Belly: Thicker part of muscle
Epimysium: connective tissue layer that covers the muscle
Separates muscles from other structures/organs
Perimysium: Layer underneath the epimysium
Separates muscles into individual bundles
Endomysium: Layer underneath the perimysium
Surrounds each individual muscle fiber

3. Skeletal Muscle Organization

5. 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

6. Structure of a Skeletal Muscle Fiber
Individual Muscle Fiber consists of: (outside to inside)
Outside of muscle fiber
Sarcolemma: cell membrane of muscle fiber
Sarcoplasm: cytoplasm of muscle fiber
Transverse Tubules or T-Tubules: connections from the sarcolemma to interior of muscle fiber for connection
Inside muscle fiber
Myofibrils: proteins that run the length of each fiber, surrounded by Sarcoplasmic Reticulum
S. R. stores Ca2+ ions which dictates muscle contraction

7. 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

8. 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

9. Rigor Mortis
After death, ion pumps stop functioning  calcium builds up in the sarcoplasm causing a fixed muscular contraction

10. Muscle Pain Soreness after a workout
Stretching the muscle tissue farther than usual
Small microscopic tears to an individual muscle fiber
Skeletal muscle tissue is multinucleated + many neuromuscular junctions  you mind sends signals when you are injured

11. Skeletal muscle identification
Muscular system can be divided into 2 groups:
Axial Muscles (60 %)
Appendicular Muscles (40%)

12. 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

13. Axial Muscles
Muscles that position the head, spinal column, and move the rib cage.
Divided into 4 groups based on location and function:
Muscles of the head and neck
Muscles of the vertebral column
Oblique and rectus muscles
Muscles of the pelvic

14. Axial Muscles Muscles of the Skull Orbicularis oris Orbicularis Oculi
Nasalis
Zygomaticus Major
Zygomaticus Minor
Frontalis

15. Axial Muscles Muscles of the Skull continued… Platysma Buccinator
Temporalis
Occipitalis
Masseter*
Sternocleidomastoid*
Sternomastoid on cats

16. Axial Muscles Trapezius* Latissimus Dorsi* Muscles of the Back
Clavotrapezius on cats
Latissimus Dorsi*

17. Axial Muscles Pectoralis major* Serratus Anterior* Rectus Abdominis*
Muscles of the Oblique
Pectoralis major*
Serratus Anterior*
Serratus ventralis on cats
Rectus Abdominis*
External abdominal oblique*

18. Day 2

19. Appendicular Muscles
Muscles that support the pectoral and pelvic girdles, and the limbs.
Separated into 2 major groups:
Muscles of shoulders and upper limbs
Muscles of pelvis and lower limbs

20. Muscles of Pectoral girdle:
Appendicular Muscles
Muscles of Pectoral girdle:
Pectoralis major*
Deltoid*
Clavodeltoid on cat
Latissimus Dorsi

21. Appendicular Muscles Deltoid* Supraspinatus* Subscapularis
Muscles that move the arm:
Deltoid*
Clavodeltoid on cat
Supraspinatus*
Subscapularis
Infraspinatus*
Pectoralis major*
Latissimus dorsi*

22. Appendicular Muscles Biceps brachii* Triceps brachii* Brachialis*
Muscles of the arm:
Biceps brachii*
Triceps brachii*
Brachialis*
Brachioradialis*

23. Appendicular Muscles Flexor carpi ulnaris* Flexor carpii radialis*
Muscles of the arm:
Flexor carpi ulnaris*
Flexor carpii radialis*
Palmaris longus*
Extensor carpi radialis*
Extensor carpi ulnaris*

24. Appendicular Muscles Muscles of the Pelvic Girdle: Gluteus maximus*
Gluteus medius*

25. Appendicular Muscles The “Quad”: Sartorius* Biceps femoris
Muscles that move the lower limb:
The “Quad”:
Rectus femoris*
Vastus Medialis *
Vastus Lateralis*
Sartorius*
Biceps femoris
Semitendinosus*

26. Appendicular Muscles Gastrocnemius* Soleus* Tibialis posterior*
Muscles of the lower limb:
Gastrocnemius*
Soleus*
Tibialis posterior*
Tibialis anterior
Calcaneal tendon

27. Appendicular Muscles Muscles of the lower limb: Gastrocnemius* Soleus*
Tibialis posterior*
Tibialis anterior
Calcaneal tendon*