ACTIVITY 2
Name at least three muscles that actively contracts during the following activities and name its action and innervation:
1. Turning a doorknob
- SUPINATOR
- Action: Supinates forearm at radioulnar joints.
- Innervation: Deep radial Nerve
- TRICEPS BRACHII
- Action: Extends forearm at elbow joint and extends arm at shoulder joint.
- Innervation: Radial nerve
- EXTENSOR CARPI RADIALIS LONGUS
- Action: Extends and abducts hand at wrist joint
- Innervation: Radial Nerve
2. Throwing a baseball overhead
- DELTOID
- Action: abducts arm at shoulder joint; flexes and medially rotates arm at shoulder joint; extends and laterally rotate arm at shoulder joint.
- Innervation: Axillary nerve
- TERES MAJOR
- Action: Extends arm at shoulder joint and assists in adduction and medial rotation of arm at shoulder joint.
- Innervation: Lower subscapular nerve
- SUPRASPINATUS
- Action: Assists deltoid muscle in abducting arm at shoulder joint
- Innervation: Suprascapular nerve.
3. Kicking a ball
- SEMITENDINOSUS
- Action: Flexes leg at knee joint and extends thigh at hip joint
- Innervation: Tibial nerve and sciatic nerve
- GASTROCNEMIUS
- Action: Plantar flexes foot at ankle joint and flexes leg at knee joint.
- Innervation: Tibial nerve
- TIBIALIS POSTERIOR
- Action: Plantar flexes foot at ankle joint and inverts (supinates) foot at intertarsal joints
- Innervation: Tibial nerve
4. Doing sit-ups
- TRANSVERSUS ABDOMINIS
- Action: Compresses abdomen
- Innervation: Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve.
- EXTERNAL OBLIQUE
- Action: Acting together (bilaterally), compress abdomen and flex vertebral column
- Innervation: Thoracic spinal nerves T7–T12 and the iliohypogastric nerve.
- INTERNAL OBLIQUE
- Action: Acting together, compress abdomen
- Innervation: Thoracic spinal nerves T8–T12, the iliohypogastric nerve, and ilioinguinal nerve.
5. Walking
- GRACILIS
- Action: Adducts thigh at hip joint, and flexes leg at knee joint
- Innervation: Obturator nerve
- BICEPS FEMORIS
- Action: Flexes leg at knee joint and extends thigh at hip joint.
- Innervation: Tibial and fibular nerves from sciatic nerve
- SARTORIUS
- Action: Weakly flexes leg at knee joint; weakly flexes and abducts thigh at hip joint
- Innervation: Femoral nerve
6. Breathing
- DIAPHRAGM
- Action: Contraction of diaphragm (inhalation); relaxation of diaphragm (exhalation)
- Innervation: Phrenic nerve, which contains axons from cervical spinal nerves (C3-C50)
- EXTERNAL INTERCOSTALS
- Action: Elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity and depresses ribs and decreases anteroposterior and lateral dimensions of thoracic cavity.
- Innervation: Thoracic spinal nerves T2–T12.
- INTERNAL INTERCOSTALS
- Action: Contraction draws adjacent ribs together during forced exhalation.
- Innervation: Thoracic spinal nerves T2–T12.