SKELETAL MUSCLES OF BODYI. Introduction: > 600 Skeletal muscles in human bodyAge 30 starts to be replaced by fatA. 4 Functional Groups1. Prime Movers (agonists)- causes a specific movement of body2. Antagonists- opposes, reverses, or steadies a movement3. Synergists- assist prime movers by adding extra force & preventing unwanted movement4. Fixators- immobilizers of bone or muscle's origin (e.g. scapula - shoulder)B. Muscle Terminology1. Origin - point of attachment that stays “fixed” during contraction (anchor)2. Insertion - moveable attachment of a muscle3. Actions - what muscle does (ex. flexion, extension, protractio, retraction, pronation, suppination, etc.)SKELETAL MUSCLESC. Skeletal Muscle to Know:HEAD MUSCLESMuscles Action 1. Frontalis/Epicranius raises eyebrows2. Occipitalis retracts scalp*galea aponeurotica – aponeurosis of scalp connecting frontalis to occipitalis3. Temporalis elevates/retracts jaw4. Orbicularis oculi closes eye5. Zygomaticus pulls lips superiorly/posteriorly (smile)6. Orbicularis oris puckers lips7. Masseter clenches jaw8. Mentalis pouts (lower lip)9. Buccinator compresses cheek (whistle, suck)10. Corrugator frownNECK MUSCLES Muscles Action 1. Platysema tenses skin of neck 2. Sternocleidomastoid flexes/laterally rotates head3. Splenius capitis prime mover of head(cervical vert to skull) up & side to side*antagonists to sternocleidomastoidCorrugatorMentalisSplenius capitisErector spinaeSKELETAL MUSCLESTORSO (CHEST / ABS / BACK) Anterior Muscles Action chest:1. Pectoralis major push/throw/climb rib muscles: respiration2. Serratus protracts scapula(boxer’s muscle – throw punch, brings scapula forward) 3. Internal intercostals inhalation *forced exhalation 4. External intercostals inhalation 5. diaphragm inhalation abs: torso flexion6. Rectus abdominis sit ups/curls 7. Transverse abdominis presses abd contents 8. External obliques trunk rotation/lat flex9. Internal obliques trunk rotation/lat flexIn general:Ab muscles are FLEXORSBack muscles are EXTENSORS = antagonists!Posterior Muscles Actionback: torso extension1. Trapezius shrugging/slumping2. Latissimus dorsi prime arm extension3. Erector spinae prime back ext./lateral flexionshoulder:4. Supraspinatus slightly abducts humerus5. Infraspinatus stabilizes shoulder6. Teres major arm swing7. Rhomboid major retracts scapula (stand at
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