Chapter 11: Muscular System

(Muscular system) Chapter 11 Fasicle Arrangement: · Parallel eg. Biceps bracii, rectus abdominis · Convergent eg. Pectoralis · Pennate eg. Deltoid · Circular eg. Orbicularis oris, mouth Origin and Insertion · origin: attachment to where muscle starts; usually stationary and proximal · insertion: attachment where the muscle ends; usually movable and distal · if muscle extends from broad aponeurosis to narrow tendon ↳ aponeurosis = origin ↳ tendon = insertion · if there are multiple tendons at one end and only one tendon at the other ↳ multiple = origin ↳ single = insertion Bones are Levers · a lever is a rigid structure that moves on a fixed point (fulcrum) ↳ bones are levers, joints are fulcrums · allows for mechanical advantage · movement occurs when applied force exceeds load Muscle Action - Movements · flexion vs. extension · rotation vs. Circumduction · pronation vs. supination · elevation vs. depression · abduction vs. aduction · protraction vs. retraction · Muscle actions can be described in two ways: 1. Based on the bone impacted by the action of the muscle eg. the bicep brachii causes flexion of the forearm 2. Based on the joint impacted by the action of the muscle eg. the bicep brachii causes flexion of the elbow Muscle Action - Types · in complex movements, muscles work in groups · Four functional types: ① Agonist (prime mover) ↳ muscle most responsible for producing a movement ② Antagonist ↳ muscle that opposes the action of an agonist ③ Synergist ↳ muscle helps agonist and provides "additional pull” ④ Fixator ↳ muscle that provides stability and limits movement Naming Muscles · orientation · shape · size · origin/insertion · muscle length · muscle position Origin and insertion Orientation Shape Muscle length Size Muscle position Axial Muscles · arise from the axial skeleton · Function to position the head, ribs, and spine · includes muscles involved in movements of breathing as well as pelvic floor muscles Appendicular Muscles · For stability and movement · includes muscles that stabilize and move the pectoral girdle, pelvic girdle, and upper & lower limbs AXIAL MUSCLES 4 Groups of Axial Muscles: ① Muscles of the head and neck ② Muscles of the vertebral column ③ Oblique and rectus muscles (abdominal & respiratory muscles) ④ Muscles of the pelvic floor ① Muscles of the Head and Neck Functions: · verbal and non-verbal communication (laughing, frowning, talking, smiling, etc. ) · Eating movements (chewing, swallowing) · Eye movements Common head/neck muscles: · Zygomaticus → smiling muscle Groupings: · Orbicularis oculi → winking a. Muscles of facial expression b. Extra-ocular muscles c. Muscles of Mastication d. Tongue muscles e. Muscles of the pharynx f. Anterior neck muscles · Buccinator → sucking in your cheeks · Orbicularis oris → kissing/whistling · Masseter → chewing · Temporalis → synergistic muscle for jaw closure · Sternocleidomastoid → nodding your head a. Muscles of facial expression Note: · epicranial aponeurosis · occipitofrontalis (frontal belly): raises eyebrows, wrinkles forehead · occipitofrontalis (occipital belly): tenses & retracts scalp the origin is on the skull and insertion is the skin · orbiculis oculi: closes eye · orbiculis oris: constricts opening of mouth · buccinator: moves food across teeth, suction · platysma: tenses skin of neck, moves lower lip b. Extraocular Muscles 1. Levatator palpebrae superioris 2. Superior rectus 3. Medial rectus 4. Inferior rectus 5. Lateral rectus 6. Inferior oblique 7. Superior oblique Eye Movements: · Lateral rectus: rotates the eye laterally · Medial rectus: rotates the eye medially · Superior rectus: rotates the eye upward · Inferior rectus: rotates the eye downward · Superior oblique: rotates the eye downward and laterally · Inferior oblique: rotates the eye upward and laterally c. Muscles of Mastication · Temporalis: elevates mandible and closes jaw · Masseter: elevates mandible and closes jaw · Lateral pterygoid: opens jaw, protrudes mandible, moves mandible side -to side · Medial pterygoid: elevates mandible, closes jaw, moves mandible side-to side d. Muscles of the Tongue · Palatoglossus: elevates tongue, depresses soft palate · Styloglossus: retracts tongue, elevates side of tongue · Hyoglossus: depresses and retracts tongue · Genioglossus: depresses and protracts tongue · Hyoid bone (not a muscle but is important) Together they control the position of the tongue e. Muscles of the Pharynx · Tensor and levator reli palatini: elevate soft palate · superior constrictor · Middle constrictor · Inferior constrictor responsible for initiating the swallowing process f. Anterior Neck Muscles ↳ controls position of larynx ↳ depresses the mandible ↳ tense floor of mouth ↳ provides a stable foundation for muscles · Digastric (anterior and posterior belly) · Myohyoid · Stylohyoid · Sternocleidomastoid of tongue and pharynx ② Muscles of the Vertebral Column Muscles of the Back: · Longissimus · Spinalis · Iliocostalis · Erector spinae Muscles of the Lumbar Region: Superficial layer · Quadratus lumborum: extends vertebral column posteriorly, depresses ribs ③ Oblique and Rectus Muscles · lie between vertebral column and ventral midline · obliques compress underlying structures or rotate spinal column · rectus muscles flex the spinal column ↳ opposes erector spinal muscles · divided into cervical, thoracic, and abdominal groups Thoracic Region: · Internal intercostals · External intercostals ↳ both elevate and depress ribs Muscles of Inspiration: · scalenes · pectoralis minor · external intercostals · diaphragm · sternocleidomastoid (inspiration = inhalation) Diaphragm · dome shaped muscle · muscle fibers converged in central tendon Aorta · 3 structures go through diaphragm ↳ esophagus, inferior vena cava, thoracic aorta · When diaphragm contracts it expands the thoracic cavity and compresses the abdominopelvic cavity ↳ inhale: contracts, flattens and moves down ↳ exhale: curves upwards Muscles of Exhalation: Abdominal Region: · abdominal muscles · external oblique aponeurosis · external oblique · internal intercostals · rectus abdominis · internal oblique · transversus abdominis Abdominal Region Cross Section: · linea alba: thin band of connective tissue that divides the rectus abdominis Quiet Breathing Forced Breathing · diaphragm · accessory muscles of respiration inspiration: ↳ contraction flattens diaphragm ↳ increases vertical diameter of thoracic cavity · external intercostals ↳ lift ribs superiorly ↳ pushes sternum anteriorly expiration: · elastic recoil of lung tissue and thoracic wall inspiration: ↳ Sternocleidomastoid elevates sternum ↳ pectoralis minor elevates ribs 3-5 expiration: · internal intercostals · abdominal muscles ↳ move inferior ribs inferiorly ↳ compress viscera, move diaphragm superiorly Quiet breathing would be when your going normally in your day to day life, and forced breathing would be used when exercising of when you have asthma ④ Muscles of the Pelvic Floor 3 Main Functions: Perineum ↳ flex the joints of the sacrum and coccyx · Boundaries: ↳ support the organs of the pelvic cavity ↳ control the movement of materials through the urethra and anus Perineum/Pelvic Floor Muscles: · divided into two triangles 1. urogenital triangle ↳ Superficial urogenital triangle muscles -superficial transverse perineal -ischiocavernosus -bulbospongiosus ↳ deep urogenital triangle muscles -deep transverse perineal -external urethral Sphincter 2. anal triangle -coccygeus -levatator ani ↳ iliococcygens ↳ pubococcygeus -external anal sphincter · the two triangles are separated by: ↳ Superficial transverse perineal muscle · pelvic floor and associated structures ↳ anterior - symphysis pubis ↳ posteriorly - coccyx ↳ laterally - ischial tuberosities Underlined the urogenital triangle in blue and the anal triangle in green APPENDICULAR MUSCLES Divided into two sections ① Pectoral Girdle and upper limbs ② Pelvic Girdle and lower limbs ① Pectoral Girdle and Upper Limbs Pectoral Girdle Muscles: Muscles that position the Pectoral Girdle · Origin: from the axial skeleton · Insertion: on the clavicle and scapula · Anterior: ↳ pectoralis minor ↳ serratus anterior · Posterior: ↳ trapezius ↳ levator scapulae ↳ rhomboids Anterior: · Pectoralis minor · Serratus anterior Posterior: · Trapezius · Levator scapulae · Rhomboids Muscles of the Arm: Anterior: · pectoralis major Posterior: · deltoid · latissimus dorsi Glenohumeral (Shoulder) Joint: highly mobile and relatively weak - The more mobile a joint the more prone to injury Rotator Cuff (SITS Muscles) · Four scapulohumeral muscles reinforce the glenohumeral joint · their tendons form the rotator cuff that reinforces the joint capsule · contractions of these muscles helps to hold the head of the humerus in the shallow glenoid cavity SITS Muscles: · Supraspinatus · Infraspinatus · Teres minor · Subscapularis Muscles that Move the Arm · 9 muscles cross the shoulder joint and insert on the humerus · 2 prime movers ↳ pectoralis major Muscles of the Forearm: Flex: · biceps brachii ↳ latissimus dorsi · brachialis ↳ deltoid Extend: · 7 others originate in the scapula ↳ teres major ↳ coracobrachialis ↳ rotator cuff (SITS muscles) · brachioradialis · triceps brachii Muscles of the Wrist: Flex: · flexor retinaculum · medial epicondyle · flexor carpi radialis · palmaris longus · flexor carpi ulnaris Extend: · extensor retinaculum · extensor carpi ulnaris · extensor carpi radialis longus · extensor carpi radialis brevis Muscles of the Fingers: Flex: · flexor digitorum superficialis · flexor pollicis longus · flexor digitorum profundus Extend: · extensor digitorum Muscles of the Hand: · extrinsic and intrinsic muscles of the hand · extrinsic muscles generate power grip of the hand ↳ located in forearm · intrinsic muscles provide fine control ↳ located in hand ② Pelvic Girdle and Lower Limbs · muscles are larger and more powerful than upper limbs · divided into three groups: ↳ muscles that move the thigh ↳ muscles that move the leg ↳ muscles that move the foot and toes Lower Limb · Muscles of the Thighs: ↳ the gluteal group, lateral rotator group, adductor group, iliopsoas group · Muscles that move the leg: ↳ flexors of the knee - biceps femoris, semimembranosus, semitendinosus, sartorius, popliteus ↳ extensors of the knee - rectus femoris, vastus intermedius, vastus lateralis, vastus medialis · Muscles that move the foot: ↳ tibialis anterior, gastrocnemius Muscles that move the Thigh: · Gluteus minimus · Gluteus medius · Gluteus maximus · Iliopsoas · Adductor muscle group Flexors of the Knee: · biceps femorus · semitendinosus · semimembranosus · sartorius · popliteus Muscles that Move the Foot and Toes · Superficial group ↳ gastrocnemius ↳ soleus ↳ plantaris · Deep group ↳ tibialis posterior ↳ flexor digitorum longus ↳ flexor hallucis longus Extensors of the knee: · rectus femoris · vastus lateralis · vastus medialis