cardiac notch

Examples of cardiac notch in the following topics:

• Lobes, Fissures, and Lobules

  • The left lung has a depression on the medial side of its surface called the cardiac notch, a concave impression molded to accommodate the shape of the heart.
  • Above and behind the cardiac impression is a triangular depression named the hilum.
  • The hilium is thinner in the left lung compared to the right lung because it lies between the cardiac notch and the groove for the aorta.
  • This has a concave depression that accommodates the shape of the heart, called the cardiac notch.

• Lungs

  • The right lung is larger than the left lung, and the left lung contains the cardiac notch, a concave impression that the heart lies against.

• Ulna and Radius (The Forearm)

  • The cornoid process, together with the olecranon, forms the trochlear notch where it articulates with the trochlea of the humerus.
  • Laterally to the trochlear notch lies the radial notch, which articulates with the head of the radius to form the proximal radioulnar joint.
  • Proximally, the radius terminates with a disk-shaped head that articulates with the capitulum of the humerus and the radial notch of the ulna.
  • Distally the radius expands, medially the ulnar notch articulates with the head of the ulnar.
  • Immediately adjacent to the ulnar notch, the radius articulates with the scaphoid and lunate carpal bones to form part of the wrist.

• Cardiac Cycle

  • The cardiac cycle describes the heart's phases of contraction and relaxation that drive blood flow throughout the body.
  • Heart rate is a term used to describe the frequency of the cardiac cycle.
  • Every single heartbeat includes three major stages: atrial systole, ventricular systole, and complete cardiac diastole.
  • Complete cardiac diastole occurs after systole.
  • Blood pressure is a regulated variable that is directly related to blood volume, based on cardiac output during the cardiac cycle.

• Types of Muscle Tissue

  • The function of muscles is movement, but the types of movement elicited differ between skeletal, cardiac, and smooth muscle.
  • There are three kinds of muscle tissue: skeletal, smooth, and cardiac.
  • Cardiac muscle is found in the walls of the heart.
  • Although cardiac muscle is involuntary in nature, it is structurally different from smooth muscle.
  • Cardiac muscle is striated, similar to skeletal muscle, but beats involuntarily.

• Ischium

  • Two indentations run parallel to the spine—superiorly ,the greater sciatic notch and, inferiorly, the lesser sciatic notch, through which key nervous and vascular vessels pass.

• Characteristics of Muscle Tissue

  • The three types of muscle tissue are skeletal, smooth, and cardiac.
  • Cardiac muscle tissue is found only in the heart where cardiac contractions pump blood throughout the body and maintain blood pressure.
  • Cardiac muscle can be further differentiated from skeletal muscle by the presence of intercalated discs which control the synchronized contraction of cardiac tissues.
  • Both cardiac and smooth muscle are involuntary while skeletal muscle is voluntary.
  • Differentiate among the structure and location of skeletal, smooth, and cardiac muscles

• Microscopic Anatomy

  • Cardiac muscle appears striated due to the presence of sarcomeres, the highly-organized basic functional unit of muscle tissue.
  • Cardiac muscle, like skeletal muscle, appears striated due to the organization of muscle tissue into sarcomeres.
  • While similar to skeletal muscle, cardiac muscle is different in a few ways.
  • Cardiac muscles are composed of tubular cardiomyocytes, or cardiac muscle cells.
  • A sarcomere is the basic unit of muscle tissue in both cardiac and skeletal muscle.

• Mechanism and Contraction Events of Cardiac Muscle Fibers

  • Cardiac muscle fibers undergo coordinated contraction via calcium-induced calcium release conducted through the intercalated discs.
  • In cardiac, skeletal, and some smooth muscle tissue, contraction occurs through a phenomenon known as excitation contraction coupling (ECC).
  • Similarly to skeletal muscle, the influx of sodium ions causes an initial depolarization; however, in cardiac muscle, the influx of calcium ions sustains the depolarization so that it lasts longer.
  • The actual mechanical contraction response in cardiac muscle occurs via the sliding filament model of contraction.
  • Calcium in the cytoplasm then binds to cardiac troponin-C, which moves the troponin complex away from the actin binding site.

• Anatomy of the Heart

  • The heart is an organ responsible for pumping blood through the blood vessels using rhythmic contractions of cardiac muscle.
  • The heart has its own self-sustaining conduction system that sends nervous  impulses to cardiac tissue.
  • The middle layer of the heart, the myocardium, and contains specialized cardiac muscle tissue responsible for contraction.
  • Cardiac tissue is permanent tissue that does not heal or regenerate when damaged.
  • The position of valves ensures proper directional flow of blood through the cardiac interior.