Muscular System Flashcards
Actin
A protein that forms microfilaments and is found in the cytoskeleton, the myofibrils of muscle fibers, and in spindle fibers during cell division
Actin Filaments
Formed by one of the 2 contractile proteins of muscle (the other is myosin) that slide over each other to produce the shortening of the muscle cell during muscle contraction
Smooth Muscle
Mononucleated, nonstriated, involuntary muscle that is found in soft internal organs and structures
Skeletal Muscle
Multinucleated, striated, voluntary muscle that enable conscious movement and moves the bones of the skeleton
Skeletal Muscle Fiber
Skeletal muscle cell that has a long, thin, fiber-like appearance
Striated
Meaning striped
Striated Muscle
Muscle that looks striped due to alternating light and dark bands
Voluntary Muscle
Skeletal muscle
Voluntary striated muscle
Skeletal muscle
Nonstriated Involuntary Muscle
Smooth muscle
Myosin
Protein present in muscle fibers that aids in muscle contraction and makes up the majority of muscle protein
Myosin Filaments
One of two contractile proteins of muscle (the other is actin) that slide over each other to cause muscle contraction
Muscle Tissue
Collection of tissues that support the body, enable it to move, thermoregulate, and transport materials
Involuntary striated muscle
Cardiac muscle
Involuntary muscle
Smooth muscle
Fascia
Arrangement of dense regular connective tissue that lies over muscle and helps to support, separate, and connect muscle to other structures
Diaphragm
- Thin, dome-shapes sheet of muscle that forms the boundary between the thoracic and abdominal cavities and helps produce inspiration when it contracts
- It is dome-shaped at rest with the convex surface directed cranially. The dome flattens when contracted, which causes air to be drawn into the lungs by increasing the volume of the thoracic cavity
Cardiac Muscle
Striated involuntary muscle found only in the heart, that is influenced by the autonomic nervous system, and that has one centrally located nucleus and intercalated discs that form special connections between the muscle branches
Belly
Thick central portion of a muscle
Adenosine diphosphate (ADP)
‘Discharged’ form of ATP that contains 2 phosphoric acid groups.
Adenosine triphosphate (ATP)
- High-energy molecule produced in mitochondria
- A nucleotide that contains 3 phosphoric acid groups
- Energy is released when one phosphoric acid group breaks off and produces ADP
Aerobic Metabolism
- “Oxygen-consuming metabolism”
- Type of metabolism in muscle in which the supply of available O2 is sufficient to keep up with the energy needs of the muscle fibers
- Extracts the maximum amount of energy from glucose molecules
Anaerobic Metabolism
- “Non-oxygen-dependent metabolism”
- Type of metabolism in muscle that occurs when the need for energy exceeds the available O2 supply.
- Not as efficient as aerobic metabolism
- Forms lactic acid, which can cause discomfort in the muscle tissue and requires O2 for conversion back to glucose
Antagonist
Muscle or muscle group that directly opposed the action of a prime mover muscle that is directly producing a desired movement
Aponeurosis
Broad sheet of fibrous connective tissue that attaches certain muscles to bones or other muscles
Creatinine Phosphate
Molecule in muscle cells that splits to release the energy necessary to reattach the detached phosphate group to an ADP molecule to convert it back to ATP
Cross-bridges
Tiny levers on myosin filaments that ratchet back and forth to pull actin filaments toward the center of the myosin filaments
Dense Bodies
- Structure in smooth muscle cells to which small contractile units of actin and myosin attach
- Correspond to Z discs of skeletal muscle
Endomesium
Thin, delicate layer of connective tissue that surrounds each individual skeletal muscle fiber
Epimysium
Tough, connective tissue layer that covers and delineates individual muscles and surrounds groups of skeletal muscle fascicles
Expiratory Muscle
A muscle whose action is to decrease the size of the thoracic cavity to squeeze air out of the lungs
Fascicle
Group of skeletal muscle fibers bound together by the perimysium
Fixator
Muscle that stabilizes a joint so that other muscles can produce effective movements of other joints
I Band
- Large, light bands in a skeletal muscle fiber that alternate with darker A bands to give a striated appearance
- Composed of actin filaments
Inspiratory Muscle
A muscle whose action is to increase the size of the thoracic cavity and cause air to be drawn into the lungs
Intercalated Discs
- End-to-end attachment sites between cardiac muscle cells that securely fasten the cells together and transmit impulses from cell to cell
- Allows large groups of cardiac muscle cells to function as a single unit
Lactic Acid
- Waste product of anaerobic metabolism in skeletal muscle as an end product of carbohydrate metabolism
- Can cause discomfort in muscle tissue
Linea alba
Aponeurosis that connects the abdominal muscles from each side on the ventral midline
Motor Unit
One nerve fiber and all the skeletal muscle fibers it innervates
Multiunit Smooth Muscle
- Smooth muscle composed of individual smooth muscle cells or small groups of cells
- Found where small, delicate involuntary contractions are needed
- Requires nerve impulses to stimulate its contractions
Myofibrils
- Microscopic, fiber like structures that occupy most of the sarcoplasm in skeletal muscle cells
- Composed of actin and myosin packed together longitudinally in the muscle cells
Myoglobin
- A protein in muscle cells that has properties similar to hemoglobin
- Can store and release large quantities of O2 to fuel aerobic metabolism in muscle cells
Neuromuscular Junction
Synapse between the end bulb of a motor nerve fiber and a skeletal muscle cell
Perimysium
Fibrous connective tissue layer in skeletal muscle that surrounds groups of muscle fibers and binds them into fascicles
Sarcolemma
Cell membrane of a muscle cell
Sarcoplasm
Cytoplasm of a muscle cell
Sarcomere
- Basic contracting unit of skeletal muscle
- Consists of actin and myosin filaments between Z lines in a muscle cell
- Myofibrils are composed of many sarcomeres stacked end to end
Sarcoplasmic Reticulum
- Organelle in a muscle cell that’s equivalent to the endoplasmic reticulum in other cells
- Stores calcium ions (Ca2+) for muscle contraction
Sinoatrial Node
- A group of specialized cardiac muscle cells in the wall of the right atrium that acts as a “pacemaker”
- The impulse that starts each heartbeat is initiated in the SA node
T-tubules
- “Transverse tubules”
- A system of tubules that extend from the sarcolemma into the sarcoplasm of a skeletal muscle cell
- Help carry an impulse cause by a nerve stimulation of the muscle cell into its interior
Twitch Contraction
- A single skeletal muscle fiber contraction
2. Latent phase, contraction phase, & relaxation phase
Z Line
- Dark line in the center of an I band of skeletal muscle
2. Discs to which actin filaments are attached in a myofibrils
A Bands
- Large, dark bands in a skeletal muscle fiber that alternate with I bands to give a striated appearance
- Composed of myosin filaments
Cutaneous Muscles
- “Skin” muscles
- Muscles in the fascia below the skin that have little to no attachment to bones and are thin, broad, and superficial
- Only serve to twitch the skin
Masseter Muscle
- Cheek area of the skull
- Main action is to close the jaw
- Most powerful of the chewing muscles
Splenius Muscle
- Dorsal part of the neck
2. Extends and raises the head
Trapezius Muscle
- Dorsal part of the neck
2. Extends and raises the head
Brachiocephalus Muscle
- Humerus to back of head
2. Extends head and pulls thoracic limb forward
Sternocephalicus Muscle
- Sternum to back of head
2. Flexes and lowers the head and neck
External Abdominal Oblique Muscles
- Outermost abdominal muscle layer
2. Fibers run in a caudoventral (back and down) direction
Internal Abdominal Oblique Muscles
- Under the external abdominal oblique muscles
2. Fibers run in a cranioventral (forward and down) direction
Rectus Abdominus Muscle
- Under internal abdominal oblique muscles
- Form the floor/ventral portion of the muscular abdominal wall
- Consists of 2 strap like muscles on either side of the linea alba and run from the rubs and sternum to the brim of the pubis
Transverse Abdominus Muscle
- Deepest of the abdominal muscles
2. Fibers run directly ventrally (down) and insert on the linea alba
Latissimus Dorsi Muscles
- Broad and triangular shaped
- Extends from spinal column to humerus
- Flexes the shoulder to move the body forward
Pectoral Muscles
- There is one deep pectoral and one superficial pectoral
- Extends from sternum to humerus
- Adducts the front legs
Deltoid Muscles
- Triangular shaped
- Extends from scapula to humerus
- Flexes shoulder joint and abducts from legs
Biceps brachii Muscles
- Has 2 proximal attachments
- Extends from scapula to radius
- Flexes elbow joint
Triceps brachii Muscles
- Has 3 proximal attachment sites
- Extends from scapula and humerus to olecranon process
- Extends elbow joint
Extensor carpi radialis Muscles
- Located over radius
2. Extends the carpus
Deep Digital Flexor
- Beneath other digital flexors
2. Flexes the digit
Gluteal Muscles
- Extends from pelvis to femur
2. Pulls leg backward and extends the hip in conjunction with hamstring muscles
Hamstring Muscle Group Muscles
- Biceps femoris
- Semimembranosus muscle
- Semitendinosus muscle
- Mainly flex the stifle joint
Quadriceps femoris Muscles
- In cranial part of thigh
2. Main extensor of the stifle joint
Gastrocnemius Muscles
- Extends from femur to insert on calcaneal tuberosity
2. Extends the hock
Inspiratory Muscles
- Diaphragm
- External Intercostal Muscles
- Increase the size of the thoracic cavity to produce inspiration
Diaphragm Muscle
- Thin, dome-shaped sheet of muscle whose convex surface provides into the thorax that separates the thoracic and abdominal cavities
- Flattens when contracted to push abdominal organs caudally and increase size of thoracic cavity to draw air into the lungs
External Intercostal Muscles
- Located between ribs
- Fibers directed obliquely so they rotate the ribs upward & forward when contracted to increase space in thoracic cavity to draw air into lungs
Expiratory Muscles
- Internal Intercostal Muscles
- Abdominal Muscles
- Decrease the size of the thoracic cavity to push air out of lungs
Internal Intercostal Muscles
- Located between ribs
- Run at right angles to external intercostal muscles
- Rotate the ribs back when contracted to decrease the size of the thoracic cavity to push air out of lungs
Abdominal Muscles
- Push organs against diaphragm when contracted to decrease size of thoracic cavity to push air out of lungs
Head & Neck Muscle Group
- Masseter muscle
- Splenius muscle
- Trapezius muscle
- Brachiocephalicus muscle
- Sternocephalicus muscle
Abdominal Muscle Group
- External abdominal obliques
- Internal abdominal obliques
- Rectus Abdominus
- Transverse Abdominus
Thoracic Limb Muscle Group
- Latissimus dorsi
- Pectorals
- Deltoids
- Biceps brachii
- Triceps brachii
- Extensor carpi radialis
- Deep digital flexor
Pelvic Limb Muscle Group
- Gluteal muscles
- Hamstring group
a. Biceps femoris
b. Semimembranosus
c. Semitendinosus - Quadriceps femoris
- Gastrocnemius
Respiratory Muscle Group
- Inspiratory Muscles
a. Diaphragm
b. External intercostals - Expiratory Muscles
a. Internal intercostals
b. Abdominal muscles
