Muscle types, muscles and terminology Flashcards
Three types of muscle
Smooth muscle, skeletal muscle, cardiac muscle
Smooth muscle
Found in visceral structures - blood vessels, gastrointestinal tract, uterus, bladder. Cells overlap onto each other. Movement is involuntary, controlled by the autonomous nervous system or hormones.
Skeletal muscle
Associated with the skeleton and individual muscles for movement. Consists of individual muscle cells (fibres) grouped together into bundles.
Cardiac muscle
Found in the heart and made up of branched muscle cells grouped by discs. Structure is similar to skeletal muscle.
Purpose of skeletal muscle
Movement, maintaining posture, prevents excess movement of bones and joints. Found at opening of internal tract to allow voluntary control over movement (swallowing, urination, defecation). Supports internal organs where there is no skeletal support. Barrier to external pressure and trauma. Maintains homeoastasis by generating heat through involuntary movement (shivering).
Origin of a muscle
Starting point of a muscle, contracts the least, contains the tendon of the origin.
Muscle belly
Thick, fleshy, central part of the muscle. Tapers at each end, muscle can have more than one belly that inserts at one point. The muscle then has number of heads.
Muscle insertion
Insertion point of a muscle is the muscle attachment point to the bone that moves. Opposite of the origin and contains the tendon of insertion.
Tendons connect
muscle to bone
Ligaments connect
bone to bone
Tendons and ligaments are made up of
Fibrous connective tissue bundles rich in collagen fibres. They are a strong extension of a muscle but rigid compared to elastic muscle fibres.
How do tendons attach to the bone
Collagen in the three layers of the muscle (mysia) bind with collagen of a tendon which connects to the periosteum of a bone.
Aponeuroses
Flattened sheets of connective tissue.
Skeletal muscle fibres
Long, striated, multinucleated. Each muscle fibre contains myofibrils. Myofibrils divide into sarcomere units which contain actin and myosin proteins. Myofibrils contain thousands of sarcomeres within one muscle fibre.
How skeletal muscle moves
Voluntarily by contraction, as the the bundles of prottein filaments within the muscle fibres shorten.
How muscle contraction occurs
When a nerve impulse triggers the release of calcium. It alters the environment within sarcomere to allow the attraction between myosin and actin.
Isotonic contraction
Muscle contracts when it’s working. If contraction results in movement it is isotonic contraction.
Isometric contraction
When there is resistance with muscle tension, but without movement. Occur to maintain posture, bone, joint stability, moving an unmovable object.
Muscle atrophy
If a muscle is not used, it becomes weak, looses muscle fibres and the muscle itself.
Muscle hypertrophy
A muscle that is constantly and vigorously used will become larger in mass and generate more muscle fibres.
Hypotonia
Absence of low-level muscle contractions that maintain muscle tone. Results in flaccid, soft appearance and absent reflexes. Can be caused by nerve damage.
Hypertonia
Excessive muscle tone presenting with muscle rigidity, spasmodic tension and relaxation. May result from damage to motor neurons/ stroke or other disease.
Flexion/flexor muscles
Angle of a joint is reduced/ muscle found on the side to which the joint bends.
Extension/extensor muscles
Angle of a joint is increased/ muscles lie to the opposite side of the joint to the flexor muscles.
Abduction/abductor muscles
Limb is moved away from the midline of the body (dog cocking his leg). Abductor muscles lie on the lateral part of the limb.
Adduction/adductor muscles
Limb moved towards the midline of the body (dog putting his leg down after urinating). Adductor muscles lie between the limb and the midline.
Pronation
When dorsal surface of the paw is turned upper/outermost. Involves the long axis of the radius rotating around the ulna at the elbow, while the carpus is twisted.
Supination
Palmar surface of the paw being turned uppermost. (Cat licks its paws to clean them).
Protraction
Limb is moved forwards
Retraction
Limb is moved backwards
Circumduction
Entire limb is rotated through a complete circle involving the hip or shoulder joint.
Agonist muscle
Muscle that causes the primary movement of the joint. (Biceps)
Antagonist muscle
Muscle that causes opposing action to the agonist muscle. (Triceps)
Synergists
Muscles that contract at the same time as the prime mover and help to rotate the joint.
Fixators
Are muscles that act to stabilise a joint.
Muscles of mastication
Group of muscles associated with the movement of the jaw.
Trapezius muscle
Inserts on the spine of the scapula. Abducts the forelimb.
Epaxial muscles
Lie dorsal to the transverse processes of the vertebrae and extend the vertebral column.
Biceps brachii
The biceps muscle group contains two muscles which flex the elbow and extend the shoulder.
Triceps brachii
Triceps muscle consists of three muscles which run from the caudal border of the scapula. Flex the shoulder and extend the elbow.
Intercostal muscles
Line the rib cage, categorised into external and internal. Assist with breathing in and out.
Rectus abdominus
Lie either side of the linea alba, forms the floor of the abdomen. (6pack)
Gluteals
Gluteals relate to the buttock area and act to extend the hip and abduct the limb.
Quadriceps
Group of four muscle bellies that work to extend the stifle.
