cardiac notch
(noun)
A concave impression molded into the left lung to accommodate the shape of the heart.
Examples of cardiac notch in the following topics:
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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.
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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.
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Ulna and Radius (The Forearm)
- The cornoid process is a similar project which together with the olecranon forms the trochlear notch in which articulates with the trochlea of the humerus.
- Laterally to the trochlear notch lies the radial notch which articulates with the head of the radius forming the proximal radioulnar joint.
- Proximally the radius terminates with a disk shaped head which 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 forming part of the wrist.
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Cardiac Cycle
- The cardiac cycle describes the phases of contraction and relaxation of the heart that drive blood flow throughout the body.
- The cardiac cycle is the term used to describe the relaxation and contraction that occur as a heart works to pump blood through the body.
- Heart rate is a term used to describe the frequency of the cardiac cycle.
- Every single "beat" of the heart includes three major stages: Atrial systole, ventricular systole and complete cardiac diastole.
- Blood pressure is a regulated variable that is directly related to blood volume, based on cardiac output during the cardiac cycle.
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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.
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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.
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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.
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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
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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.
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Anatomy of the Heart
- The heart is a muscular 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 nervousĀ impulses to cardiac tissue.
- The middle layer of the heart is called 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.