Muscle and Bone Anatomy Overview

Muscle Attachments

• Origin is the fixed, less mobile attachment point of a muscle, typically located proximal to the insertion.
• Insertion is the less fixed, more mobile attachment point of a muscle, typically located distal to the origin.

Muscle Forms

• Fleshy Part: This is the main, thick, fleshy component of the muscle.
• Non-Fleshy Part: This part connects the muscle to a bone. It can be:
  • Tendon: A fibrous cord that attaches the muscle to the bone.
  • Aponeurosis: A broad, sheet-like structure that attaches the muscle to the bone.

Types of Muscles

• Skeletal (Voluntary) Muscles: Striped, under conscious control, responsible for movement of limbs.
• Cardiac Muscle: Involuntary, partially stripped, found in the heart.
• Smooth (Involuntary) Muscles: Not under conscious control, non-stripped, found in the walls of internal organs like the intestine.

Types of Bones

• Long Bone: Long and has two enlarged ends. Example: Femur
• Short Bone: Small with limited movement. Example: Tarsal bones
• Flat Bone: Protects certain areas or provides attachment points. Example: Scapula
• Irregular Bone: Has an unusual shape. Example: Hip bone
• Pneumatic Bone: Contains air spaces or sinuses. Example: Paranasal sinuses

The Function of Muscles

• Contraction and Relaxation: Skeletal muscles contract and relax to move bones across joints.
• Skeletal Muscle Attachment: Muscle contraction brings the attachment points closer together.
• Cardiac and Smooth Muscle: Form the walls of cavities and tubes (e.g. heart, digestive tract).

Functions of Bones

• Bodily Support: Bones form the framework of the body, providing structural support.
• Motion: Bones provide attachment points for muscles, enabling movement and locomotion.
• Leverage: Bones act as levers, amplifying the forces generated by muscles.
• Protection: Bones protect delicate internal organs.
• Formation of Blood Cells: Red blood cells are formed in the red bone marrow, found within flat bones.
• Storage for Salts: Bones store minerals, such as calcium and phosphorus.

Muscle Types

• Fusiform: Spindle-shaped, with a thicker middle. Example: Biceps.
• Strap or Parallel: Long and thin, with parallel fibers. Example: Sartorius.
• Pennate: Fibers are arranged at an oblique angle to the tendon.
  • Unipennate: Fibers converge on one side of the tendon.
  • Bipennate: Fibers converge on both sides of the tendon. Example: Rectus femoris.
  • Multipennate: Several tendons with fibers converging from multiple directions. Example: Deltoid muscle.
  • Circumpennate: Fibers arranged in a circumradial manner around the central tendon.