W4: Major Skeletal Muscle Groups Flashcards
Categories of regional musculature
Head and neck, abdominal wall, pelvic floor, upper and lower limbs
Categories by defining movements
Abduction (movement away from midline) Adduction (movement towards the midline) Flexion (movement forwards) Extension (movement backwards) Circumduction, inversion, eversion, supination, pronation, protrusion, retraction
Size relating to name of muscle
Vastus (huge), maximus (large), longus (long) minimus (short), brevis (short)
Shape relating to name of muscle
Deltoid (triangular), latissimus (wide), teres (round)
Direction of fibre linked to name
Rectus (straight), transverse (across), oblique (diagonally), orbicularis (circular)
Location relating to name
Pectoralis (chest), gluteus (buttock), brachii (arm)
Muscular agonist and antagonism
Agonists = prime movers. E.g., extensors as antagonists and flexors as agonists.
What does muscle tone mean?
Muscles are in a constant state of partial contraction. Only part of skeletal muscle activity that is under involuntary control.
What does a loss of muscle tone mean?
E.g., by paralysis (loss of innervation). Means the muscles become flaccid.
What is the origin of a muscle?
The attachment site that does not move during contraction
What is the insertion of a muscle?
The attachment site that does move when the muscle contracts.
What can muscles be inserted into?
Tendons and aponeurosis (flattened tendon)
What is fascia?
Sheet of fibrous tissue allowing the attachment of muscle.
How do skeletal muscles produce movements?
By contracting - shortening of muscle fibres
Categorisation of muscles by function
Flexors, extensors, abductors, adductors, sphincters, dilators, levator (to lift or elevate a structure), masseter (a chewer)
Categorisation of muscles: pennate structure
Pennate muscles have long parallel tendons with short muscle fibres arranged between them at an angle (Image at min15). Unipennate, bipennate, multipennate (image at 16:50)
What do multipennate muscles allow for?
Multipennate muscles allow packing of more muscle fibres, makes for powerful muscles. The more pennate the muscle, the more powerful it is.
What can happen when tendons are prone to compression?
When tendons are prone to compression, sesamoid bones may develop, e.g., patella. A bone not attached to any other bone in the body.
How do wrinkles appear in the skin?
The face has no distinct deep fascia. As skin ages, it becomes less elastic. Wrinkles in the skin appear at right angles to the muscle fibres in muscles of facial expression.
