Muscles Overview

Upper Extremity Muscles

Key Muscles and Functions

1. Biceps Brachii
   • Supinates forearm
   • Flexes elbow
   • Weakly flexes shoulder
2. Brachioradialis
   • Flexes arm at elbow
   • Brings forearm into mid-prone position (supination or pronation)
3. Deltoid
   • Abducts arm
4. Pectoralis Major
   • Flexes upper arm
   • Helps abduct it
5. Triceps Brachii
   • Extends lower arm

Additional Muscles

• Intercostal Muscles
  • Raises ribs
  • Aids in breathing
• Latissimus Dorsi
  • Extends, adducts, and medially rotates arm
  • Costal attachment aids deep inspiration and forced expiration
• Trapezius
  • Moves shoulder
  • Extends the head

Face/Neck Muscles

1. Buccinator
   • Aids mastication
   • Tenses cheeks for blowing and whistling
   • Aids closure of mouth
2. Masseater
   • Elevates mandible
   • Enables forced closure of mouth
3. Sternocleidomastoid
   • Flexes and rotates the head
4. Orbicularis Oris
   • Compresses and closes lips

Lower Extremity Muscles

Key Muscles and Functions

1. Hamstrings
   • Flex the leg
2. Quadriceps Femoris
   • Extends the leg
3. Rectus Femoris
   • Flexes hip
   • Extends leg
4. Sartorius
   • Flexes and rotates the thigh and leg
5. Gluteus Medius
   • Abducts and rotates thigh
6. Gluteus Maximus
   • Extends femur
   • Rotates it
7. Gastrocnemius
   • Points toes
   • Flexes lower leg
8. Tibialis Anterior
   • Dorsiflexion

Muscles Related to Breathing

• Diaphragm
  • Helps with breathing
• External Oblique
  • Supports abdominal wall
  • Assists forced expiration
  • Aids raising intra-abdominal pressure
  • With opposite side muscles, abducts and rotates trunk

Important Muscles for Test

1. Deltoid
2. Pectoralis Major
3. Biceps
4. Brachioradialis
5. Triceps
6. Latissimus Dorsi
7. Quadriceps
8. Hamstrings
9. Tibialis Anterior
10. Gastrocnemius