Name at least three muscles that actively contracts during the following activities and name its action and innervation:
Turning a doorknob
Supinator
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Action: Supinates forearm at radioulnar joints
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Innervation: Deep radial nerve
Brachioradialis
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Action: Flexes forearm at elbow joint; supinates and pronates forearm at radioulnar joints to neutral position
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Innervation: Radial nerve
Pronator teres and quadratus
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Action: Pronates forearm at radioulnar joints and weakly flexes forearm at elbow joint
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Innervation: Median nerve
Throwing a baseball overhead
Teres major
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Action: Extends arm at shoulder joint and assists in adduction and medial rotation of arm at shoulder joint
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Innervation: Lower subscapular nerve
Deltoid
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Action: Lateral fibers abduct arm at shoulder joint; anterior fibers flex and medially rotate arm at shoulder joint; posterior fibers extend and laterally rotate arm at shoulder joint
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Innervation: Axillary nerve
Pectoralis major
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Action: Adducts and medially rotates arm at shoulder joint; clavicular head flexes arm, and sternocostal head extends flexed arm to side of trunk
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Innervation: Medial and lateral pectoral nerves
Kicking a ball
Rectus femoris
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Action: Extends leg at knee joint; flexes thigh at hip joint.
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Innervation: Femoral nerve
Psoas major
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Action: Acts together with iliacus muscles to flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip as in sitting up from supine position
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Innervation: Lumbar spinal nerves L2–L3.
Iliacus
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Action: Acts together with psoas major to flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip as in sitting up from supine position
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Innervation: Femoral nerve
Doing sit-ups
External oblique
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Action: Acting together (bilaterally), compress abdomen and flex vertebral column; acting singly (unilaterally), laterally flex vertebral column, especially lumbar portion, and rotate vertebral column
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Innervation: Thoracic spinal nerves T7–T12 and the iliohypogastric nerve
Rectus abdominis
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Action: Flexes vertebral column, especially lumbar portion, and compresses abdomen to aid in defecation, urination, forced exhalation, and childbirth
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Innervation: Thoracic spinal nerves T7–T12
Transversus abdominis
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Action: Compresses abdomen
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Innervation: Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve
Walking
Soleus
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Action: Plantar flexes foot at ankle joint
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Innervation: Tibial nerve
Gastrocnemius
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Action: Plantar flexes foot at ankle joint and flexes leg at knee joint
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Innervation: Tibial nerve
Tibialis posterior
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Action: Plantar flexes foot at ankle joint and inverts (supinates) foot at intertarsal joints
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Innervation: Tibial nerve
Breathing
Diaphragm
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Action: Its contraction causes it to flatten and increases vertical dimension of thoracic cavity, resulting in inhalation; its relaxation causes it to move superiorly and decreases vertical dimension of thoracic cavity, resulting in exhalation
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Innervation: Phrenic nerve, which contains axons from cervical spinal nerves (C3–C5)
External intercostals
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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
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Innervation: Thoracic spinal nerves T2–T12
Internal intercostals
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Action: Contraction draws adjacent ribs together to further decrease anteroposterior and lateral dimensions of thoracic cavity during forced exhalation
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Innervation: Thoracic spinal nerves T2–T12
References
Tortora, G. J., & Derrickson, B. (2014). Principles of Anatomy and Physiology (14th ed.). Wiley.