Musculature Flashcards
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Tissue types in the body
Epithelial tissue: This tissue covers the surfaces of the body, lines organs, and forms glands. Types of epithelial tissue include squamous, cuboidal, columnar, and transitional epithelium.
Connective tissue: Connective tissue provides support, structure, and metabolic support to other tissues and organs. It includes various types such as:
Loose connective tissue (areolar tissue)
Dense connective tissue (dense regular, dense irregular, elastic)
Adipose tissue (fat tissue)
Cartilage (hyaline, elastic, fibrocartilage)
Bone (compact bone, spongy bone)
Blood and lymphatic tissue
Muscle tissue: Muscle tissue is responsible for movement and includes three types:
Skeletal muscle tissue (attached to bones and responsible for voluntary movements)
Smooth muscle tissue (found in the walls of organs and blood vessels, responsible for involuntary movements)
Cardiac muscle tissue (found in the heart and responsible for involuntary rhythmic contractions)
Nervous tissue: Nervous tissue is specialized for communication and includes neurons and neuroglial cells. It forms the brain, spinal cord, and nerves, enabling coordination of activities and transmission of signals throughout the body.
Hematopoietic tissue: This tissue is responsible for the production of blood cells and is primarily found in the bone marrow.
Lymphoid tissue: Lymphoid tissue includes lymph nodes, tonsils, spleen, and thymus, and plays a vital role in the immune system by producing and maturing immune cells.
Endocrine tissue: Endocrine tissue comprises glands that secrete hormones directly into the bloodstream, regulating various physiological processes in the body.
Skeletal muscle AKA Voluntary striated muscle
Skeletal muscle, also known as voluntary striated muscle, is a specialized type of muscle tissue found in vertebrates, including humans and animals. It is characterized by its striated appearance under a microscope, which is due to the alternating pattern of dark and light bands formed by the arrangement of contractile proteins within the muscle fibers.
Skeletal muscle is called voluntary because its contraction is under conscious control, meaning it can be activated or relaxed at will. This control is mediated by the somatic nervous system, with impulses originating from the motor cortex of the brain and transmitted via motor neurons to the muscle fibers through the neuromuscular junction.
The primary function of skeletal muscle is to generate force and produce movement of the skeleton. It accomplishes this by contracting in response to nerve impulses, which causes the muscle fibers to shorten, pulling on the tendons that are attached to bones. This contraction allows for various movements, such as walking, running, jumping, and lifting objects.
The structure of skeletal muscle is highly organized, consisting of elongated, multinucleated muscle fibers bundled together by connective tissue sheaths. Each muscle fiber contains myofibrils, which are composed of repeating units called sarcomeres. Sarcomeres are the functional units of muscle contraction and contain overlapping thin (actin) and thick (myosin) filaments.
The sliding filament theory explains how skeletal muscle contracts at the molecular level. During contraction, myosin heads interact with actin filaments, forming cross-bridges that pull the actin filaments towards the center of the sarcomere. This shortens the sarcomere and, consequently, the entire muscle fiber, leading to muscle contraction.
Skeletal muscle exhibits remarkable plasticity, meaning it can adapt to changes in demand and environment. Regular exercise stimulates muscle growth (hypertrophy) and increases strength and endurance. Conversely, disuse or immobility can lead to muscle atrophy, characterized by a decrease in muscle size and function.
In veterinary medicine, understanding skeletal muscle physiology is crucial for diagnosing and managing various musculoskeletal disorders, injuries, and diseases in animals. Rehabilitation programs, therapeutic exercises, and pharmacological interventions aim to restore or optimize muscle function and improve the overall quality of life for veterinary patients.
Skeletal muscle cell
A skeletal muscle cell, also known as a muscle fiber, works through a complex process called muscle contraction. Muscle contraction involves the interaction of various cellular components and signaling pathways to generate force and produce movement.
muscles work by getting messages from your brain, letting in calcium, and then using that calcium to pull and make your muscles move. When you’re done using your muscles, everything goes back to normal until you need to use them again.
Cardiac AKA involuntary striated muscles
Cardiac muscle, also known as involuntary striated muscle, forms the myocardium of the heart and is characterized by its striated appearance and involuntary contraction regulated by the autonomic nervous system and pacemaker cells, facilitating rhythmic contractions for pumping blood throughout the body, while possessing features intermediate between skeletal and smooth muscle, including branching fibers, intercalated discs for synchronized contractions, rich mitochondria for continuous energy supply, and resistance to fatigue due to oxidative metabolism and reliance on aerobic respiration.
Smooth AKA non-striated involuntary muscle
Smooth muscle, also known as non-striated involuntary muscle, is a type of muscle tissue found in the walls of hollow organs, blood vessels, and various structures throughout the body, characterized by its lack of striations (stripes) under a microscope and involuntary contraction regulated by the autonomic nervous system and local factors, facilitating movements such as peristalsis, vasoconstriction, and organ function, with spindle-shaped cells containing a single nucleus and contractile proteins arranged in a more random pattern compared to striated muscle, exhibiting slower and sustained contractions and adaptations to stretch and stress for tasks such as maintaining blood pressure, regulating airflow, and facilitating digestion and urinary functions.
Ligaments and Tendons
Ligaments: Connect bone to bone and help stabilize joints, providing support and limiting excessive movement to prevent injury, with dense, fibrous tissue composed primarily of collagen fibers and some elastic fibers, facilitating joint stability, proprioception, and proper alignment during movement and physical activity, while also contributing to the overall integrity and strength of the musculoskeletal system.
Tendons: Connect muscle to bone and transmit the forces generated by muscle contractions to move the bones, enabling joint movement and locomotion, with tough, fibrous tissue composed primarily of collagen fibers arranged in parallel bundles, providing strength and elasticity to withstand tension and facilitate efficient transfer of muscle forces to bones, while also contributing to the structural integrity and function of the musculoskeletal system.
Tendons and Aponeuroses
Tendons: Tendons are tough, fibrous connective tissue structures that connect muscle to bone. They are composed primarily of collagen fibers arranged in parallel bundles, providing strength and elasticity to withstand tension generated by muscle contractions and transmit these forces to move the attached bones. Tendons play a crucial role in facilitating joint movement and locomotion, as well as providing stability and support to the musculoskeletal system.
Aponeuroses: Aponeuroses are broad, flat sheets of connective tissue that serve a similar function to tendons but have a different anatomical structure. Unlike tendons, which are cord-like structures, aponeuroses are thin and sheet-like, consisting of layers of collagen fibers arranged in a parallel fashion. Aponeuroses often attach muscles to other muscles or to structures such as bone or skin, providing support, distributing forces, and facilitating coordinated movement across a broader area. They are commonly found in regions where large forces need to be transmitted or where muscle attachment needs to be broad and distributed, such as the abdominal wall or the scalp.
Clinical applications of musculature
Physical Rehabilitation:
Musculature is crucial in physical therapy and rehabilitation programs aimed at restoring muscle strength, flexibility, and function following injury, surgery, or disease.
Exercises targeting specific muscle groups help improve mobility, reduce pain, and enhance overall physical performance.
Sports Medicine:
Musculature assessment is essential in sports medicine to prevent, diagnose, and treat athletic injuries.
Strength training, conditioning, and biomechanical analysis of muscle function are integral components of sports rehabilitation and performance enhancement programs.
Orthopedic Surgery:
Musculature plays a significant role in orthopedic surgery, particularly in procedures involving joint replacement, ligament reconstruction, and tendon repair.
Surgical techniques aim to restore normal musculoskeletal function, stability, and range of motion to improve patient outcomes and quality of life.
Neurology:
Evaluation of musculature function is fundamental in neurology for diagnosing and managing conditions affecting the nervous system, such as stroke, spinal cord injury, and neuromuscular disorders.
Electromyography (EMG) and nerve conduction studies assess muscle and nerve function, aiding in the diagnosis of neurological conditions and guiding treatment decisions.
Chronic Disease Management:
Musculature assessment is integral in managing chronic diseases such as muscular dystrophy, fibromyalgia, and chronic pain syndromes.
Multidisciplinary approaches incorporating physical therapy, exercise prescription, and pharmacological interventions aim to optimize musculoskeletal health, functionality, and quality of life in patients with chronic conditions.
Common locations for IM injections: Canine and Feline.
In both canines and felines, intramuscular (IM) injections are commonly administered in specific locations to ensure proper delivery of medications and minimize discomfort to the animal. Here are some common locations for IM injections in dogs and cats:
For Dogs:
Quadriceps (thigh) muscles: The lateral thigh muscles are a common site for IM injections in dogs. The injection site is typically located on the lateral aspect of the thigh, midway between the hip and the stifle (knee) joint. Epaxial muscles (dorsal lumbar muscles): The epaxial muscles, located along the dorsal aspect of the lumbar spine, can be used as an alternative site for IM injections in dogs. The injection site is typically located between the last rib and the hip.
For Cats:
Quadriceps (thigh) muscles: Similar to dogs, the lateral thigh muscles are commonly used for IM injections in cats. The injection site is typically located on the lateral aspect of the thigh, midway between the hip and the stifle (knee) joint. Epaxial muscles (dorsal lumbar muscles): As with dogs, the epaxial muscles along the dorsal aspect of the lumbar spine can be used for IM injections in cats. The injection site is typically located between the last rib and the hip.
Semimembranousus and semitendonosus
Semimembranosus:
The semimembranosus muscle is one of the hamstring muscles located in the posterior (rear) thigh of animals.
It originates from the ischial tuberosity, which is a bony prominence of the pelvis, and extends down the thigh.
The muscle attaches to the medial (inner) condyle of the tibia, one of the bones of the lower hind limb.
Its primary functions include flexing the knee joint (stifle) and extending the hip joint.
Semitendinosus:
The semitendinosus muscle is also part of the hamstring muscle group and is located in the posterior thigh.
It originates from the ischial tuberosity, along with the semimembranosus, and extends down the thigh.
The muscle tapers into a tendon as it descends and attaches to the medial surface of the tibia.
Like the semimembranosus, its primary functions include flexing the knee joint (stifle) and extending the hip joint.
Both the semimembranosus and semitendinosus play important roles in locomotion, providing stability to the hind limb and facilitating movements such as walking, running, and jumping. Additionally, they are commonly used as sites for intramuscular injections in veterinary medicine, particularly in larger animals such as horses and cattle. Proper knowledge of the anatomy and landmarks of these muscles is essential for safe and accurate administration of injections.
Muscle Condition Scoring
Muscle condition scoring is a method used to assess the amount of muscle mass or condition in animals, particularly in livestock species such as cattle, sheep, and pigs. It provides a quantitative measure of an animal’s muscle development, which can be important for evaluating overall health, productivity, and market readiness.
Muscle condition scoring often involves visually assessing specific areas of the animal’s body to evaluate muscle development. These areas may include the loin, rump, shoulders, and hindquarters.In addition to visual assessment, palpation (feeling or touching) of the muscle can provide further information about muscle tone and condition. This may involve gently pressing on the muscle to assess its firmness and consistency.Muscle condition scoring systems typically use a numerical scale or scoring system to assign a score to the animal’s muscle condition. The scale may range from low to high, with specific criteria for each score level based on visual and palpable characteristics of the muscle. Factors considered when muscle condition scoring may include muscle coverage, firmness, definition, and overall development. Animals with higher muscle condition scores generally have greater muscle mass, better muscle tone, and more pronounced muscling in key areas. Muscle condition scoring can be used in various contexts, such as evaluating livestock for breeding purposes, assessing animals for market readiness, or monitoring changes in muscle condition over time. Proper training and consistency are essential for accurate muscle condition scoring. Individuals conducting the scoring should be familiar with the scoring system and criteria, and efforts should be made to ensure consistency among different scorers. The interpretation of muscle condition scores may vary depending on the species, breed, age, and intended use of the animals. In some cases, specific muscle condition scores may be associated with certain benchmarks or standards for muscle development.
fascia
Fascia is a band or sheet of connective tissue that surrounds muscles, groups of muscles, blood vessels, and nerves, providing support and protection while also allowing for movement and flexibility, with various types including superficial fascia, deep fascia, and visceral fascia, serving as a structural framework for the body and playing a role in transmitting mechanical forces, maintaining tissue integrity, and facilitating the movement of fluids and nutrients within the body.
panniculus reflex
The panniculus reflex, also known as the cutaneous trunci reflex, is a neurological reflex observed in some mammals, particularly in dogs and cats, involving the contraction of the skin and underlying muscles in response to a specific sensory stimulus such as light pinching or tapping along the trunk or flank region, initiated by sensory receptors in the skin transmitting signals to the spinal cord where interneurons relay the information to motor neurons triggering contraction of the panniculus muscles located beneath the skin, resulting in a visible twitch or ripple in the skin, serving potential functions including defensive response, thermoregulation, and sensory feedback, and utilized as a diagnostic tool in assessing neurological function in animals.
pacemaker cells
Pacemaker cells, also known as sinoatrial (SA) node cells, are specialized cells found in the heart that generate electrical impulses to regulate the heartbeat. These cells are located in the sinoatrial node, which is a small cluster of cells located in the right atrium of the heart. Pacemaker cells have the unique ability to spontaneously depolarize and generate action potentials without external stimulation.
Action potentials
Action potentials are brief, rapid changes in the membrane potential of excitable cells, such as neurons, muscle cells (including cardiac and skeletal muscle), and some specialized cells like pacemaker cells in the heart. These changes in membrane potential occur in response to a stimulus, resulting in the propagation of an electrical signal along the cell membrane.
Loin
The loin is the area along the back of the animal, just behind the rib cage and before the rump.
In cattle and other quadrupeds, the loin typically corresponds to the area between the last rib and the pelvis (hip bone).
In pigs, the loin is often considered the portion of the back between the last rib and the start of the ham (hind leg).
Rump
The rump refers to the hindmost part of the animal’s body, including the pelvis and the muscles of the hindquarters.
It is located behind the loin and extends from the pelvis to the base of the tail.
The rump area includes the hip bones, the gluteal muscles, and other muscles of the hindquarters.
Hindquarters:
The hindquarters encompass the entire rear portion of the animal’s body, including the rump and hind legs.
This area is crucial for locomotion and contains large muscle groups responsible for movement, such as the hamstrings and gluteal muscles.
In quadrupeds like cattle, sheep, and pigs, the hindquarters are particularly important for activities such as walking, running, and jumping.
Trunk
The trunk refers to the central part of the body, excluding the head, neck, and limbs. It encompasses the chest (thorax), abdomen, and pelvis. In quadrupeds like dogs and cats, the trunk extends from the base of the neck to the tail, and it includes the ribcage, abdominal cavity, and pelvic region.
Flank
The flank region is located on the side of the body between the ribs and the hip bone (pelvis). It encompasses the area just behind the ribs and extends toward the hindquarters. The flank region includes muscles of the abdominal wall and the lateral aspect of the body.
Myofibrils
Myofibrils are long, cylindrical structures found within muscle fibers, consisting of repeating units called sarcomeres, which are the functional units of muscle contraction, composed of thin (actin) and thick (myosin) filaments arranged in a highly organized pattern, with actin filaments anchored to structures called Z-lines and myosin filaments spanning the sarcomere, interconnected by structures such as titin, nebulin, and myomesin, with regulatory proteins like tropomyosin and troponin regulating the interaction between actin and myosin during contraction, with myosin heads forming cross-bridges with actin filaments and undergoing cyclic attachment, power stroke, and detachment processes powered by ATP hydrolysis, resulting in the sliding of actin filaments over myosin filaments and sarcomere shortening, leading to muscle contraction, with myofibrils collectively responsible for generating force and producing movement in skeletal muscle fibers through the coordinated contraction of sarcomeres along their length.
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sarcomere
The sarcomere is the fundamental repeating unit of muscle fibers, delimited by Z-discs at each end, composed of overlapping thin actin and thick myosin filaments organized in a precise pattern, with actin filaments extending from the Z-disc towards the center of the sarcomere and myosin filaments occupying the central region, with additional structural proteins including titin, nebulin, and myomesin providing stability and alignment, with regulatory proteins like tropomyosin and troponin located on the actin filaments, controlling the interaction between actin and myosin during contraction, with myosin heads forming cross-bridges with actin filaments and undergoing cyclic attachment, power stroke, and detachment processes powered by ATP hydrolysis, resulting in the sliding of actin filaments towards the center of the sarcomere and sarcomere shortening, leading to muscle contraction, with the coordinated contraction of sarcomeres along the length of myofibrils generating force and producing movement in skeletal muscle fibers.
Z-discs
Z-discs are dense, protein-rich structures located at each end of the sarcomere, anchoring the thin actin filaments and serving as the boundary between adjacent sarcomeres, composed primarily of α-actinin and other structural proteins, providing structural stability and organizing the arrangement of actin filaments, with actin filaments from adjacent sarcomeres overlapping at the Z-discs, forming a lattice-like pattern, facilitating the transmission of force during muscle contraction, with additional roles in signaling and regulating muscle function, including interactions with proteins involved in mechanotransduction and muscle growth, serving as critical structural elements that contribute to the integrity and function of skeletal muscle fibers.
Actin
Actin is a globular protein that polymerizes to form thin filaments within the sarcomere.
It is one of the two main proteins involved in muscle contraction, along with myosin.
Actin filaments extend from the Z-discs towards the center of the sarcomere, overlapping with myosin filaments.
During muscle contraction, actin interacts with myosin to generate force and produce movement.
Actin is also involved in various cellular processes beyond muscle contraction, including cell shape maintenance, cell division, and intracellular transport.
filament
a slender threadlike object or fibre, especially one found in animal or plant structures
