Muscle Physiology PDF

BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 1. Introduction 2. General muscle anatomy 3. Form & Compositio...

BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 1. Introduction 2. General muscle anatomy 3. Form & Composition 4. Function Appendix of names Sagittal extent of hip range, how quickly, changing forces thro range of movement? Lifting leg requires a force to move quickly but nothing like downforce (GR F) to move up and forward? 1 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 CONTENTS 1. Introduction -functional anatomy, movement, muscles as actuators, 2. General muscle anatomy -naming & numbers -commonality across species, quadrupeds & bipeds -layers & groups 3. Form & Composition - filaments, fibres & fascicules - straplike, fusiform (spindlelike) & pennate (feathered & multilateral) - sizes (gluteus v lumbricals) 4. Function -origin & insertion -types of action -mechanics -simple & complex movements 2 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Available online via Nusearch. 2nd & 3rd editions via Available online via Images in the presentation are largely Nusearch Nusearch. from Gray’s Anatomy, copyright is At Greenfield Med acknowledged. Library. See also https://en.wikipedia.org/wiki/List_of_skeletal_muscles_of_the_human_body#Lower_limb 3 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 1. Introduction - the functional anatomy of muscles 4 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 In a normal lean animal, the muscles make up Leg of lamb Country Food Services Ltd the bulk of the conformation. A working knowledge of the muscles of posture & movement in humans & quadrupeds is important for research, medicine & nutrition. MRI mid-thigh section of human. Grays’s Anatomy 5 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Animal behaviour is codified in action. The interaction of frameworks (skeleton) and actuators (muscles) leads to a bewildering array of movement in the animal kingdom. https://www.bwallpaperhd.com/red- kangaroos-jumping.html Kurile Lake, Kamchatka. # 6 © David Chen / 2017 National Geographic Nature Photographer of the Year BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 2. General Muscle Anatomy -naming & numbers -commonality across species, quadrupeds & bipeds -layers & groups 7 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Humans & domestic mammals have between 650-700 muscles. Muscles act in groups to maintain posture and generate actions, such as locomotion, grasping, chewing and finer movements such as rotation of the eyeball. There are 6 muscles that move the eyeball, there are ~50 that support or move each human leg, ankle & foot. 8 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 The names are not in plain English but in derivations of Latin typically from Greek. They are inconsistent and might refer to position, size, number and /or aspects of function. For example, gluteus maximus , where gluteus comes from the Greek for buttock and maximus for largest. 9 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 By comparison extensor pollicis longus tells us about function-it acts to extend some part, that it refers to the thumb (pollicis) and it is a long muscle. There is also an extensor pollicis brevis, but, where is it, where are the origin & insertion, what shape does it have, how big is it? 10 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Some names include common anatomical positioning, e.g., vastus lateralis or anterior tibialis (Latin for shin bone). Others are largely meaningless to contemporary audiences, such as sartorius, from the Latin for tailor and refers to the cross-legged position they adopted when sewing. 11 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 There are analogous muscles in humans & quadrupeds. Anatomical Chart Company 2002 12  BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Anatomical Chart Company 2002 13 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Muscles of the axial skeleton for posture are arranged in layers. 14 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 15 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 16 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Groups of muscles also act in concert to make complex movements. A very clear example is bipedal walking where numerous muscles co-ordinate for posture and movement. 17 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 3. Form & Composition - filaments, fibres & fascicules - straplike, fusiform (spindlelike) & pennate (feathered & multilateral) - sizes (gluteus v lumbricals) 18 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 The filaments form fibres that are grouped into bundles or fasciculi. The filaments are the contractile elements. The cylindrical fibres rarely run the whole length of the muscle. Bundles of fibres within fascia form the whole muscle. Muscle composition 19 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Muscles can be categorised according to their fibre orientation and overall shape. They are referred to as straplike (sartorius), spindle-like or fusiform (biceps brachii), feathered or pennate (gastrocnemius). Individually, muscles may appear triangular or like slim rods. Feathered or pennate can be uni, bi- or multi-pennate (deltoid). 20 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 The muscles of the buttock are perhaps the largest in the human body whereas the lumbricals of the hand are amongst the smallest. 21 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 4. Function -origin & insertion -types of action -mechanics -simple & complex movements 22 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 The fixed end of a muscle, attached to a part of the skeleton that does not move is called the origin. Typically, these points are those proximal (nearest) to the axial skeleton. The insertion attaches to the moving part. The gastrocnemius is a good example with each head to the rear of the widened portions of the lower femur (condyles) as the origin and the large tendon onto the calcaneus (heel bone) the insertion. 23 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Muscles may act individually or in groups where different muscles have alternate roles as agonist, antagonist, fixator or synergist. The same muscle can have different roles according to the type of action. Examples, deltoid as fixator in biceps brachii curl and contralateral pelvic & leg muscles during swing phase. Other muscles, such as the long spinal muscles support actions generated by the head & limbs. 24 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Muscles contract actively for (concentric or isotonic shortening & eccentric or isotonic lengthening) & extend passively. They also contract to provide support without shortening (isometric contraction). 25 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Muscles also stretch passively. The tendons at the attachments and the “honeycomb” of connective tissue of the fascia are under tension when the muscle is stretched during movement. Mechanically these are viewed as series and parallel springs in a model of muscle function. Stretch is limited by the physical restriction of joint movement due to bone conformation and ligaments. 26 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 The force generated by a muscle is proportional to cross section in a muscle with parallel fibres. Feathered muscles with oblique fibres generate less force from each individual fibre. However, there are more fibres, hence greater force is produced overall. The trade-off is a shorter relative contraction. 27 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Summary Muscles are the largest mass of tissue in mammals. They contract actively to work as actuators and also have passive spring-like qualities. The Latin nomenclature is inconsistent and obscure but may give some clues as to type, form, position and action. Muscles contract to generate sufficient force to counteract gravity and move the body at variable speeds to make actions. Axial muscles are arranged in layers, sets of muscles act in concert to support the prime mover of action. 28 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Appendix: muscle naming (from Gray’s Anatomy) Shape Size Deltoid (triangular) Major, minor, longus (long) Quadratus (square) Brevis (short) Rhomboid (diamond-shaped) Latissimus (broadest) Teres (round) Longissimus (longest) Gracilis (slender) Number of heads or bellies Rectus (straight) Lumbrical (worm-like) Biceps (two heads) Triceps (three heads) Quadriceps (four heads) Digastric (two bellies) Depth Superficialis (superficial) Profundus (deep) Externus/externi (external) Internus/interni (internal) Attachment Sternocleidomastoid (from sternum and clavicle to mastoid process) Coracobrachialis (from the coracoid process to the arm) 29 BIOS 3100 Musculoskeletal Physiology Muscles AHW 2024 Position Action Anterior, posterior, medial, lateral, superior, inferior, supra-, infra-, interosseus (between Extensor, flexor bones) Abductor, adductor Dorsi (of the back) Levator, depressor Abdominis (of the abdomen) Supinator, pronator Pectoralis (of the chest) Brachii (of the arm) Constrictor, dilator Femoris (of the thigh) Oris (of the mouth) Oculi (of the eye) See also https://en.wikipedia.org/wiki/List_of_skeletal_muscles_of_the_human_body#Lower_ limb 30