MUSCULAR SYSTEM 1

• Muscular system


  Organ system composed of specialized contractile tissue called muscle tissue
• Muscle


  Contractile tissue that makes up about 40 percent of total body weight and includes all types of muscles in the body
• Muscle cells/myocytes/muscle fibers


  Specialized contractile cells that contain protein filaments of actin and myosin
• Muscle fibers


  • Bound together into bundles or fascicles by associated connective tissue that also conveys blood vessels and nerve fibers
• Muscle tissue


  • Has four main properties: Excitability, Contractibility, Extensibility, Elasticity
• Types of muscles


  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle
• Striated muscle


  Skeletal and cardiac muscles that appear striped under a microscope
• Non-striated muscle


  Smooth muscle that does not appear striped under a microscope
• Cardiac muscle


  • Branching network of individual cells linked electrically and mechanically to work as a unit
  • Contractions are less powerful than skeletal muscle but resistant to fatigue
  • Involuntary muscle controlled by the autonomic nervous system
• Smooth muscle


  • Long, spindle-shaped cells arranged in bundles
  • Capable of slow and sustained contractions
  • Involuntary muscle controlled by the autonomic nervous system or hormones
• Skeletal muscle


  • Non-branching, organized into parallel bundles of long multi-nucleated muscle fibers wrapped in connective tissue sheaths
  • Provides voluntary movement, support, form, posture, and heat production
• There are 640 muscles in the human body
• Muscle groups


  • Muscles of facial expression
  • Masticatory muscles
  • Extraocular muscles
  • Tongue muscles
  • Pharynx muscles
  • Larynx muscles
  • Neck muscles
  • Back muscles
  • Thoracic muscles
  • Abdominal muscles
  • Pelvic floor muscles
  • Shoulder/arm muscles
  • Forearm muscles
  • Hand muscles
• Facial expression muscles


  • About 20 flat skeletal muscles that produce movements of the face such as smiling, grinning, frowning
• Masticatory muscles


  • Attach to the mandible and produce movements of the lower jaw for chewing and grinding
• Extraocular muscles


  • Control eye movement and eyelid elevation
• Tongue muscles


  • Intrinsic and extrinsic muscles that enable sensation of taste, mastication, swallowing, speech, and clearing the oral cavity
• Pharynx muscles


  • Important for the process of swallowing
• Larynx muscles


  • Enable proper air conduction, speech, movements of the epiglottis, and airway protection
• Neck muscles


  • Responsible for movement of the head and neck in all directions
• Neck muscles


  • Platysma muscle
  • Sternocleidomastoid muscle
• Back muscles


  • Provide movements of the spine, stability to the trunk, and coordination between limb and trunk movements
• Back muscle groups


  • Extrinsic/superficial back muscles
  • Intrinsic/deep back muscles
• Extrinsic back muscles


  • Trapezius muscle
  • Latissimus dorsi muscle
• Intrinsic back muscles


  • Primary function is to produce movements of the vertebral column, including the prominent erector spinae muscle group
• Thoracic muscles


  • Muscles that attach the upper limb to the thoracic wall
  • Muscles that support the thoracic wall and move the ribs during ventilation, including the intercostal muscles
• Abdominal wall


  • Provides flexible coverage and protection for the abdominal cavity, consisting of multiple muscular layers including the rectus abdominis
• Pelvic floor muscles


  • Basin-shaped muscular diaphragm that supports the pelvic organs
• Upper limb muscle regions

  • Shoulder
  • Arm
  • Forearm
  • Hand
• Scapulohumeral muscles


  • Connect the scapula to the humerus, including the deltoid muscle
• Arm muscle compartments


  • Anterior/flexor compartment
  • Posterior/extensor compartment
• Anterior arm muscles


  • Biceps brachii muscle
• Posterior arm muscles


  • Triceps brachii muscle
• Forearm muscle compartments


  • Anterior/flexor compartment
  • Posterior/extensor compartment
• Anterior forearm muscles


  • Flexor digitorum superficialis muscle
• Posterior forearm muscles


  • Brachioradialis muscle
  • Extensor digitorum muscle
• Hand muscles


  • Intrinsic hand muscles are only partially responsible for the hand's range of motion, with major contributions from forearm muscles via tendons
• Flexion of the shoulder or elbow joints


  Muscles primarily responsible
• Biceps brachii muscle


  Responsible for the anterior contour of the arm
• Posterior, or extensor compartment


  Muscles that allow the extension of the forearm at the elbow joint