Muscle Tissue

Types of Tissue

Four Types of Tissue:

  1. Connective Tissue: Provides support and structure to the body, connecting different tissues and organs. Includes various subtypes such as bone, adipose (fat), blood, and cartilage.

  2. Epithelial Tissue: Covers body surfaces, lines hollow organs and cavities, and forms glands. This tissue is classified based on cell shape (squamous, cuboidal, columnar) and the number of cell layers (simple or stratified).

  3. Muscle Tissue: Responsible for the movement of the body and its parts. Comprised of three types:

    • Cardiac Muscle

    • Skeletal Muscle

    • Smooth Muscle

  4. Nervous Tissue: Composed of neurons and glial cells, it processes and transmits information throughout the body.

Muscle Tissue Overview

Types of Muscle Tissue:

  1. Cardiac Muscle

    • Characteristics: Contains intercalated discs that facilitate synchronized contraction, possesses one nucleus per cell, and is classified as involuntary striated muscle.

    • Function: Responsible for the pumping of blood throughout the heart and into the circulatory system.

    • Reference: (p. 305)

    2. Skeletal Muscle

    • Characteristics: Composed of fibrous structures called sarcolemma, features anisotropic and isotropic substances for muscle contraction, houses an intermediate line, and myofibrils. Each cell contains one nucleus and is classified as voluntary striated muscle.

    • Function: Facilitates movements of the skeleton and overall body motion, allowing for a range of voluntary actions.

    • Reference: (p. 298)

  2. Smooth Muscle

    • Characteristics: Lacks visible striations, possesses one nucleus per cell, and is often associated with blood vessels (specifically, blood capillaries). It is classified as involuntary visceral muscle.

    • Function: Controls involuntary movements such as the contraction of blood vessels, digestion in the gastrointestinal tract, and contractions in other hollow organs.

    • Reference: (p. 305)

Neuromuscular Junction

  • Reference: (p. 299)

  • Description: The neuromuscular junction is the synapse between a motor neuron and a skeletal muscle fiber, facilitating muscle contraction through neurotransmitter release.

Skeletal Muscle Physiology

  • Overview: Comprises nearly 40% of total body mass and is essential for voluntary movement.

  • Components: Each muscle is made up of numerous muscle fibers/cells, surrounded by a protective sarcolemma. Contains thousands of myofibrils composed of interlocking actin and myosin myofilaments, crucial for contraction.

  • Muscle Proteins: Four major proteins involved in muscle contraction are actin, myosin, tropomyosin, and troponin.

  • Reference: (p. 296)

Structure and Function of Sarcomeres

  • Sarcomere Structure: The basic contractile unit of muscle, divided by the Z Line.

  • Filament Types Within Sarcomere:

    • Thin filament (actin)

    • Thick filament (myosin)

  • Key Features:

    • I and A bands alternate in visibility.

    • A band represents the entire length of thick/myosin filament.

    • H Zone is a lighter zone in the center due to the non-overlapping actin and myosin. Upon muscle contraction, the H-zone disappears due to the overlapping of actin with myosin.

Muscles of the Head and Neck

  • Key Muscles:

    • Frontalis

    • Buccinator

    • Platysma

    • Risorius

    • Mentalis

    • Depressor anguli oris

    • Occipitalis

    • Depressor labii inferioris

    • Orbicularis oculi

    • Temporalis

    • Orbicularis oris

    • Sternocleidomastoid

    • Levator labii superioris

    • Zygomaticus (minor & major)

    • Sternohyoid

    • Omohyoid

    • Masseter

    • Sternothyroid

Detailed Facial Muscles

  • Includes Muscles Such As:

    • Temporal fascia

    • Epicranial aponeurosis

    • Procerus muscle

    • Auricularis anterior, superior, and posterior

    • Zygomaticus minor and major

    • Buccinator

    • Risorius

    • Mentalis

    • Depressor labii inferioris

    • Depressor anguli oris

    • Platysma

Nerves and Muscles of the Head and Neck

  • Key Components:

    • Nerves:

      • Supraorbital nerve

      • Supratrochlear nerve

      • Great auricular nerve

      • Lesser occipital nerve

      • Transverse cervical nerve

      • Spinal accessory nerve

    • Blood Vessels:

      • Superficial temporal vessels and nerves

      • Facial artery

      • External jugular vein

    • Muscle Details:

      • Includes Sternocleidomastoid, Omohyoid, Trapezius, and Levator scapulae, among others.

Miscellaneous Information

  • Mention of muscles related to scapula and sternum, highlighting their relevance in upper body movements and stabilization.