Muscles and Their Functions

Facial Muscles

  • Orbicularis oculi: Closes the eyelids
  • Orbicularis Oris: Compression and protrusion of lips
  • Zygomaticus major: Raises the lateral corners of the mouth (smiling)
  • Masseter: Elevation/ retraction of mandible

Muscles That Move the Neck

  • Sternocleidomastoid:
    • Single: Rotates head toward opposite side
    • Pair: Flexion of cervical spine

Muscles That Move the Scapula

  • Rhomboids major: Adduct (retract) and elevate the scapula (top one)
  • Rhomboids Minor: Adduct (retract) and elevate the scapula (bottom one)
  • Trapezius:
    • Upper (orange): Elevates and upwardly rotates scapula
    • Middle (red): Adducts (retracts) scapula
    • Lower (dark red): Depresses Scapula
  • Levator Scapulae: Elevates the scapula

Muscles That Move/Stabilize the Trunk

  • Rectus abdominis: Spinal flexion
  • External Oblique:
    • Pair: Spinal flexion
    • Single: Spinal lateral flexion and rotation
  • Internal Oblique: Same as external oblique
  • Transverse abdominis: Compresses the abdomen

Muscles That Move the Scapula (Continued)

  • Pectoralis minor: Abducts (protracts) and depresses the scapula
  • Serratus Anterior: Abducts (protracts) and upwardly rotates the scapula

Muscles That Move the Shoulder Joint

  • Pectoralis major: Shoulder adduction, horizontal adduction, flexion, and internal rotation
  • Latissimus Dorsi: Shoulder adduction, extension, and internal rotation
  • Teres Major: Same as latissimus dorsi
  • Deltoid: anterior fibers

Muscles That Move the Elbow

  • Biceps Brachii: Elbow flexion
    • Long head
    • Short head
  • Brachialis: Elbow flexion
  • Brachioradialis: Elbow flexion
  • Triceps Brachii: Elbow extension
    • Lateral head
    • Long head
    • Medial head

Muscles That Move the Hip

  • Gluteus maximus: Hip extension
  • Gluteus medius: Hip abduction, stabilizes pelvis while walking
  • Tensor Fascia latae: Hip abduction, internal rotation, and flexion
  • Adductor magnus: Hip adduction
  • Adductor longus: Hip adduction
  • Sartorius: Hip flexion and lateral rotation, knee flexion
  • Piriformis: Laterally rotates and extends hip, abducts a flexed hip
  • Iliopsoas: Hip flexion

Muscles That Move the Knee

  • Quadriceps:
    • Rectus femoris: Knee extension, hip flexion
    • Vastus lateralis: Knee extension
    • Vastus Medialis: Knee extension
    • Vastus intermedius: Knee extension
  • Hamstrings:
    • Biceps femoris:
      • Long head (medial)
      • Short head (lateral)
    • Semitendinosus: Hip extension and knee flexion
    • Semimembranosus: Hip extension and knee flexion

Muscles That Move the Ankle

  • Gastrocnemius: Ankle plantar flexion and knee flexion
    • Medial head
    • Lateral head
  • Soleus: Ankle plantar flexion
  • Tibialis anterior: Ankle dorsiflexion