Muscle Notes

Muscle Cell Structure

• Sarcolemma: The plasma membrane of a muscle cell.
• Nuclei: Muscle cells contain multiple nuclei.
• Organelles: Muscle cells contain typical organelles, with the exception of centrioles, lysosomes, and Golgi apparatus.

Microscopic Anatomy

• Analogy: Muscle structure can be visualized like an electrical cable composed of tiny, colored wires wrapped in a black rubber skin.

Muscle Types

• Smooth muscles are not striated.

Facial Muscles

• Name, action, and code for each muscle must be known. The code is available on the lab list.

Occipitofrontalis

• Action: Raise eyebrows.
• Location: on the head

Orbicularis Oculi

• Action: Close eye.
• Innervation: Facial nerve
• Labeled with the same color tape as other facial expression muscles.

Nasalis

• Action: Flare nostril.

Triangularis

• Origin and Insertion: The insertion is where the muscle pulls; if the lips were cut off, the insertion would be there. The origin is the bone where the other end of the muscle is connected.

Rectus Muscles

• Rectus
  • Major rectus
  • Inferior Rectus

Oblique Muscles

• Second group of muscle