muscle animation

Skeletal Muscle

Skeletal muscle, also known as striated muscle, is attached to the skeleton by tendons. Skeletal muscles function in the movement of bones at joints and maintaining posture. These muscles are voluntary and contract or relax rapidly. Also, a skeletal muscle is an organ of the muscular system. It is composed of skeletal muscle tissue, nervous tissue, blood, and connective tissue.

Characteristics of Skeletal Muscles:

Skeletal Muscle Structure:
1. Bone
2. Perimysium
3. Blood Vessel
4. Muscle Fiber
5. Fascicle
6. Endomysium
7. Fascia
8. Tendon

Explore the anatomy of a skeletal muscle using your book and on-line resources. Describe how all these parts work together to produce movement.

Parts of Skeletal Muscles

Types of connective tissue coverings:

Layers of fibrous connective issue called fascia separate an individual skeletal muscle from adjacent muscles and hold it in position. This connective tissue surrounds each muscle and may project beyond the end of its muscle fibers to form a cord-like tendon. Fibers in a tendon may intertwine with those in a bone’s periosteum, attaching the muscle to the bone. In other cases, the connective tissue forms broad fibrous sheets called aponeuroses, which may attach to the coverings of adjacent muscles.

The layer of connective tissue that closely surrounds a skeletal muscle is called epimysium. Other layers of connective tissue, called perimysium, extend inward from the epimysium and separate the muscle tissue into small compartments. These compartments contain bundles of skeletal muscle fibers called fascicles. Each muscle fiber within a fascicle lies within a layer of connective tissue in the form of a thin covering called endomysium. Thus, all parts of a skeletal muscle are enclosed in layers of connective tissue, which form a network extending throughout the muscular system.

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This picture breaks down the components of a muscle. It shows a bundled section of muscle, a bundled section of muscle fiber, a section of myofibril, and lastly it depicts the thick and thin filaments. These actin and myosin are considered the basic building blocks of muscles for contraction.

1. Fibers:
  • -Skeletal muscle cells
  • -Cells run the full length of the muscle
  • -Contract when stimulated.

2. Myofibrils:

3. Motor Neuron:
  • -Skeletal muscle fibers connect to a nerve cell or a motor neuron.
  • -The brain sends electrical impulses through motor neurons to skeletal muscles.
  • -Neurons stimulate muscle fibers causing them to contract.

4. Neuromuscular junction:
  • - Connection between motor neurons and muscle fibers

5. Acetylcholine:
  • -Specialized neurotransmitters

6. Superficial fascia:
  • -Right under the skin
  • -Consists of adipose and loose connective tissue
  • -Water storage, insulation, and protection

7. Deep Fascia:
  • -Surrounds muscles
  • -Made of dense and fibrous connective tissue
  • -Holds muscles together
  • -Separate muscles into groups
  • -Forms tendons.

8. Skeletal muscle consists of skeletal muscle tissue, nervous tissue, blood, other connective tissue, and many blood vessels

  • Muscle Structure from the Outside In
  1. Epimysium- fibrous connective tissue; binds bundles of fibers together
  2. Perimysium- fibrous connective tissue; covers fascicles
  3. Fascicles- bundles of muscle fibers
  4. Endomysium- fibrous connective tissue; covers muscle fibers

1. Two types of fascia:
a. Superficial- just under the skin and is made of adipose and loose connective tissue
b. Deep Fascia- surrounds the muscles and is made of dense connective tissue
2. Structure of Skeletal:
a. Skeletal muscle tissue
b. Blood and blood vessels
c. Nervous tissue
d. Other connective tissue
3. Inside out
a. Muscle fiber- muscle cell (also known as a myofiber)
b. Endomysium- fibrous connective tissue, covers muscle fibers
c. Fascicles- Bundle of muscle fibers
d. Perimysium- separates muscles into the fasicles
e. Epimysium- closely surrounds entire muscle

Skeletal Muscle Facts!
- 605 Skeletal muscle make up 40% of your body weight.
- Skeletal muscle cells have multiple nuclei.
- Skeletal muscles are made up of 4 types of protein.
- Skeletal muscles have 3 main parts- a belly (the body of the muscle), a insertion point (where a tendon attaches a muscle to a bone across a joint and an origin (where a tendon attaches a muscle to an immovable bone.
- The origin is the strongest point of a muscle.