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Brachialis & Anconeus
MUSCLE: Brachialis
ACTION: Flexes forearm at elbow joint
INNERVATION: Musculocutaneous and radial nerves
MUSCLE: Anconeus
ACTION: Extends forearm at elbow joint
INNERVATION: Radial nerve
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Semitendinosus & Semimembranosus
MUSCLE: Semitendinosus
ACTION: Flexes at knee joint and extends thigh at hip joint
INNERVATION: Tibial nerve from sciatic nerve
MUSCLE: Semimembranosus
ACTION: Flexes at knee joint and extends thigh at hip joint
INNERVATION: Tibial nerve from sciatic nerve
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External oblique & Internal oblique
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
MUSCLE: Internal oblique
ACTION: Acting together, compress abdomen and flex vertebral column; acting single, laterally flex vertebral column, especially lumbar portion, and rotate vertebral column
INNERVATION: Thoracic spinal nerves T8-T12, the iliohypogastric nerve, and the ilioinguinal nerve
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Diaphragm & External intercostals
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: 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