Name at least three muscles that actively contracts during the following activities and name its action and innervation:
1. Turning a door knob
- Supinator
- Action: Supinates forearm at proximal and distal radioulnar joints.
- Innervation: Deep radial nerve (C5-C6)
- Pronator teres
- Action: Pronates forearm at radioulnar joints and weakly flexes forearm at elbow joint.
- Innervation: Median nerve (C6, C7)
- Pronator Quadratus
- Action: Pronates forearm at radioulnar joints.
- Innervation: Anterior interosseous branch of median nerve (C8, T1)
2. Throwing a baseball overhead
- Deltoid
- Action: At the shoulder joint, lateral fibers abduct the arm, anterior fibers flex and medially rotate the arm, and posterior fibers lengthen and laterally rotate the arm.
- Innervation: Axillary nerve.
- Pectoralis Major
- Action: As a whole, it adducts and rotates the arm medially at the shoulder joint; the clavicular head flexes the arm, and the sternocostal head extends the flexed arm to the trunk side.
- Innervation: Medial and lateral pectoral nerves.
- Latissimus Dorsi
- Action: Extends, abducts, and medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly; Elevates vertebral column and torso.
- Innervation: Thoracodorsal nerve.
3. Kicking a ball:
- Quadriceps femoris
- Action: Powerful extensor of stifle, also flexes hip, and extend leg at the hip joint
- Innervation: Femoral nerve (L2-L4)
- Hamstrings
- Action: Flexes leg at knee joint and extends thigh at hip joint.
- Innervation: Tibial nerve from sciatic nerve.
- Gluteus Maximus
- Action: Extends and laterally rotates the thigh at the hip joint; helps lock the knee in extension.
- Innervation: Inferior gluteal nerve.
4. Doing sit-ups
- Rectus abdominis
- Action: Flexes the vertebral column, particularly the lumbar region, and compresses the abdomen to facilitate feces, urination, forced exhalation, and childbirth.
- Innervation: Thoracic spinal nerves (T7-T12)
- External Obliques
- Action: Bilaterally: flexion of trunk, compression and support of abdominal viscera; Unilaterally: lateral flexion of trunk, rotation of trunk to opposite side.
- Innervation: Intercostal nerves (T8-T12); Iliohypogastric nerve (T12,L1); Ilioinguinal nerve (L1)
- Action: Bilaterally: flexion of trunk, compression and support of abdominal viscera; Unilaterally: lateral flexion of trunk, rotation of trunk to opposite side.
- Iliopsoas
- Action: Together, the psoas major and iliacus muscles flex the thigh at the hip joint, rotate the thigh laterally, and flex the trunk on the hip as in rising from a supine position.
- Innervation: Lumbar spinal nerves (L2-L3)
5. Walking
- Soleus
- Action: Plantar flexes foot at ankle joint.
- Innervation: Tibial nerve.
- Gastrocnemius
- Action: Plantar flexes foot at ankle joint and flexes leg at knee joint.
- Innervation: Tibial nerve.
- Tibialis Anterior
- Action: Dorsiflexes the foot at the ankle joint and supinates it at the intertarsal joints.
- Innervation: Deep fibular (peroneal) nerve.
6. Breathing
- Diaphragm
- Action: Contraction of the diaphragm leads it to flatten and increases the vertical dimension of the thoracic cavity; relaxation of the diaphragm causes it to migrate superiorly and decreases the vertical dimension of the thoracic cavity, resulting in exhalation.
- Innervation: Phrenic nerve, which contains axons from cervical spinal nerves (C3-C5)
- Sternocleidomastoid
- Action: Bilaterally flex cervical section of spinal column, extend head at atlanto-occipital joints; unilaterally flex neck and head to same side, rotate head to opposite side. Laterally rotate and flex head opposite contracting muscle. Posterior muscle fibers aid in head extension; raise sternum during forced inhaling.
- Innervation: Accessory (XI) nerve, C2, and C3.
- External and internal intercostals
- Action: Contraction raises the ribs and enlarges the anterior, posterior, and lateral dimensions of the thoracic cavity, resulting in inhaling. This results in exhalation; During a forced exhale, the contraction of adjacent ribs further reduces the anterior, posterior, and lateral dimensions of the thoracic cavity.
- Innervation: Thoracic spinal nerves (T2-T12)