Activity 2
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Turning a knob
- Muscle: Supinator
Action: supinates forearm at radioulnar joints
Innervation: deep radial nerve
- Muscle: Pronator teres
Action: Pronates forearm at radioulnar joints and weakly flexes forearm at elbow joint.
Innervation: Median nerve
- Muscle: Pronator quadratus
Action: pronates forearm at radioulnar joints
Innervation: Median nerve
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Throwing a baseball overhead
- Muscle: Subscapularis
Action: Medially rotates arm at shoulder joint.
Innervation: Upper and lower subscapular nerve.
- Muscle: Latissimus Dorsi
Action: Extends, adducts, and medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly. RMA: Elevates vertebral column and torso.
Innervation: Thoracodorsal nerve
- Muscle: Pectoralis Major
Action: As a whole, adducts and medially rotates arm at shoulder joint; clavicular head flexes arm, and sternocostal head extends flexed arm to side of trunk.
Innervation: Medial and lateral pectoral nerves
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Kicking a ball
- Muscle: Iliopsoas (psoas major)
Action: Psoas major and iliacus muscles acting together flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip as in sitting up from supine position.
Innervation: Lumbar spinal nerves L2–L3.
- Muscle: Rectus femoris
Action: muscle acting alone also flexes thigh at hip joint
Innervation: femoral nerve
- Muscle: Vastus medialis
Action: extend leg at knee joint
Innervation: femoral nerve
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Doing sit-ups
- Muscle: Transverse abdominis
Action: compresses abdomen
Innervation: Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve
- Muscle: Rectus abdominis
Action: Flexes vertebral column, especially lumbar portion, and compresses abdomen to aid in defecation, urination, forced exhalation, and childbirth. RMA: Flexes pelvis on the vertebral column.
Innervation: Thoracic spinal nerves T7–T12
- Muscle: External oblique
Action: Acting together (bilaterally), compress abdomen and flex vertebral column; acting singly (unilaterally), laterally flex vertebral column, especially lumbar portion, and rotate vertebral column
Innervation: Thoracic spinal nerves T7–T12 and the iliohypogastric nerve
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Walking
- Muscle: Tibialis anterior
Action: Dorsiflexes foot at ankle joint and inverts (supinates) foot at intertarsal joints
Innervation: Deep fibular (peroneal) nerve
- Muscle: Gluteus maximus
Action: Extends thigh at hip joint and laterally rotates thigh; helps lock knee in extension. RMA: Extends torso.
Innervation: Inferior gluteal nerve
- Muscle: Soleus
Action: Plantar flexes foot at ankle joint
Innervation: Tibial nerve
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Breathing
- Muscle: Diaphragm
Action: Contraction of diaphragm causes it to flatten and increases vertical dimension of thoracic cavity, resulting in inhalation; relaxation of diaphragm causes it to move superiorly and decreases vertical dimension of thoracic cavity, resulting in exhalation.
Innervation: Phrenic nerve, which contains axons from cervical spinal nerves (C3–C5)
- Muscle: Internal intercostal
Action: Contraction draws adjacent ribs together to further decrease anteroposterior and lateral dimensions of thoracic cavity during forced exhalation.
Innervation: Thoracic spinal nerves T2-T12
- Muscle: External intercostals
Action: Contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity, resulting in inhalation; relaxation depresses ribs and decreases anteroposterior and lateral dimensions of thoracic cavity, resulting in exhalation
Innervation: Thoracic spinal nerves T2-T12