The Muscular System Chapter 10

Understanding Muscles Pull never push Attach to skeleton via tendons or muscles via aponeurosis Attachment points Origin: end attaches to a stationary bone; doesn’t move Insertion: end attaches to a moving bone; moves Contractions shorten muscles

Functional Groups Agonist (prime movers) Antagonist Synergist Fixators Prime responsibility for causing a movement Antagonist Oppose/reverse movement Regulate agonist by adding resistance Synergist Assist prime mover Add extra force or reduce undesirable movement Fixators Immobilize bone or muscle origin Not mutually exclusive

Naming Muscles Location Shape Size Direction of fibers & fasicles Bone or region associated w/ Brachii and femoris Shape Deltoid and trapezius Size Maximus, minimus, longus Direction of fibers & fasicles Rectus, oblique, transversus Number of origins Biceps and triceps Location of attachment Points of origin & insertion Sternocleidomastoid Action Flexor , extensor, supinator

Fasicle Arrangement Determines range of mov’t & power Types Parallel Parallel to long axis Pennate Short & attach obliquely to an insertion tendon Uni-, bi-, or multi Convergent Broad origin converges to an insertion Circular Concentric rings around external openings Contractions close

Lever Systems A lever is a rigid bar moving on a fixed point (fulcrum) when force is applied (effort) to move resistance (load) Bones = levers, joints = fulcrums, muscle contract = effort at insertion, load = bone and everything else Mechanical advantage (power lever) Effort farther from load then fulcrum Little effort needed Force gained for speed and stability E.g. car jack Mechanical disadvantage (speed lever) Effort nearer load then fulcrum Force lost for speed and range E.g. shovel

Classes of Levers First Second Third Uncommon in body Always advantage Most skeletal muscles Always disadvantage

Learning Muscles Need to know Studying Names of major muscles Functions/actions of muscles Table 10.1 Location Studying Learn names Look for clues in names from existing knowledge Draw and or act out Identify on models or self

Muscles to Know Facial expression Scapula Humerus Mastication Frontalis Orbicularis oculi & oris Zygomaticus major Buccinator Platysma Extrinsic eye Superior, inferior, medial, lateral rectus Superior & inferior oblique Mastication Masseter Temporalis Pterygoid Moving head & deep to back Sternocleidomastoid Capitis group Erector spinae group Abdominal wall Rectus abdominis External & internal oblique Transverse abdominis Scapula Trapezius Serratus anterior Pectoralis minor Levator scapula Rhomboids major & minor Humerus Pectoralis major Latissimus dorsi Deltoid Supraspinatus Infraspinatus Subscapularis Teres major Forearm Brachialis Brachioradialis Biceps & triceps brachii Supinator Pronator teres

Muscles to Know (cont.) Wrist Fingers Thumb Breathing Pelvic floor Flexor carpi radialis & ulnaris Extensor carpi radialis & ulnaris Fingers Flexor digitorum superficialis & profundus Extensor digitorum Thumb Extensor pollicis longus & brevis Abductor pollicis longus & brevis Breathing Diphragm External & internal intercostals Pelvic floor Coccygeus group Levator ani External anal sphincter Femur at hip Illiacus & psoas major (Iliopsoas) Gluteus maximus, medius, & minimus Adductor group Thigh Gracilis Sartorius Leg at knee Quadriceps femoris Rectus femoris Vastus intermedius, lateralis, and medialis Hamstrings Semitendinosus Semimembranosus Biceps femoris

Muscles to Know (cont.) Foot at ankle Toes Gastrocnemius Soleus Tibialis anterior & posterior Fibularus group (peroneus muscles) Toes Flexor & extensor digitorum longus Flexor & extensor hallucis longus