Legend - Action: A; Innervation: I
Muscles that actively contracts during the following activities:
- Turning a door knob
Muscles involved:
- Supinator muscle - A: Supinates forearm; I: deep radial nerve
- Pronator teres - A: Pronates forearm; I: median nerve
- Pronator quadratus - A: Pronates forearm; I: median nerve via the anterior interosseous nerve
- Throwing a baseball overhead
Muscles involved:
- Subscapularis - A: assists in extension of arm, medially rotates the arm; I: upper and lower subscapular nerves (C5 & 6)
- Latissimus dorsi - A: extends and medially rotates the arm; I: C7 & 8 (thoracodorsal nerves)
- Pectoralis minor - A: draws the scapula forward, downward, and medialward; I: medial pectoral nerves (C8, T1)
3. Kicking a ball
Muscles involved:
THESE THREE ARE CALLED the hamstring group
- Biceps femoris - A: flexes the leg, extends the thigh; I: peroneal nerve (short head) and tibial nerve (long head)
- semimembranosus - A: flexes the leg, extends the thigh; I: tibial nerve
- semitendinosus - A: extends the thigh, flexes the leg; I: tibial nerve
- rectus abdominis - A: flexes the trunk *stability of the trunk is needed to deliver the full force of the legs; I: intercostal nerves 7-11 and subcostal nerve
4. Doing sit-ups
Muscles Involved:
- rectus abdominis - A: flexes the trunk *stability of the trunk is needed to deliver the full force of the legs; I: intercostal nerves 7-11 and subcostal nerve
*The following two muscles are essential in stabilizing the hips
- Iliopsoas - A: flexes the thigh, flexes, and laterally bends the lumbar vertebral column; I: Branches of the ventral primary rami of spinal nerves L2-L4 and branches of the spinal nerve
- Rectus femoris - A: Extends the leg, flexes the thigh; I: femoral nerve
5. Walking
Muscles involved:
- Tibialis anterior - A: Inverts and dorsiflexes the foot; I: deep fibular (peroneal) nerve
- vastus lateralis - A: extends the leg; I: femoral nerve
- gastrocnemius - A: flexes the leg, plantar flexes foot; I: tibial nerve
6. Breathing
Muscles involved:
- diaphragm (inspiratory) - A: Inferiorly pushes the abdominal viscera; I: phrenic nerve (C3 to C5)
- External intercostals (both expiratory and inspiratory) - A: During respiration, it keeps the intercostal space from blowing out or sucking; I: intercostal nerves (T1-T11)
- internal abdominal oblique - A: flexes and laterally bends the trunk; I: Intercostal nerves 7-11, ilioinguinal, iliohypogastric, and subcostal nerves