Facial Muscles and Mastication

Muscles of Facial Expression

• Corrugator supercilli: pulls eyebrows medially and inferiorly, causing frowning
• Orbicularis oculi: closes eyelids, helps protect the eyes
• Depressor anguli oris: pulls corner of the mouth inferiorly and laterally, frowning
• Orbicularis oris: encircles the mouth, closes the lips, helps with speech and eating
• Frontalis: raises eyebrows and wrinkles the forehead, expressing surprise or concentration
• Galea aponeurotica: a broad aponeurosis (fibrous sheet) that connects the frontal and occipital muscles, helps with muscle action
• Buccinator: compresses cheeks against teeth, helps with chewing and blowing
• Risorius: pulls corner of the mouth laterally, producing a smile
• Mentalis: elevates and protrudes the lower lip, expressing doubt or sulking
• Zygomaticus major: elevates and retracts the corner of the mouth, producing a smile

Muscles of Mastication

• Masseter: elevates the mandible, closes the jaw for chewing
• Temporalis: elevates and retracts the mandible, closes the jaw for chewing
• Medial pterygoid: elevates and protracts the mandible, helps with chewing
• Lateral pterygoid: protracts and depresses the mandible, helps with chewing
• Digastric: depresses the mandible and elevates the hyoid bone, helps with opening the mouth and swallowing

Muscles That Move The Head

• Sternocleidomastoid: rotates and flexes the head, bilateral contraction flexes the neck
• Splenius capitis: extends and rotates the head

Muscles That Move The Shoulder (Scapula)

• Levator scapulae: elevates the scapula, helps with shrugging
• Rhomboid major: retracts and elevates the scapula, helps with pulling shoulders back
• Rhomboid minor: retracts and elevates the scapula, helps with pulling shoulders back
• Trapezius: elevates, depresses, retracts, rotates, and stabilizes the scapula, helps with shrugging, pulling shoulders back, and rotating the scapula
• Pectoralis minor: depresses and protracts the scapula, helps with pushing a door open or pulling a drawer open
• Serratus anterior: protracts and rotates the scapula upwards, helps with pushing and throwing motions

Muscles That Move The Arm (Humerus)

• Rotator Cuff Muscles:
  • Teres minor: externally rotates the arm, helps stabilize the shoulder joint
  • Subscapularis: internally rotates the arm, helps stabilize the shoulder joint
  • Supraspinatus: abducts the arm, helps stabilize the shoulder joint
  • Infraspinatus: externally rotates the arm, helps stabilize the shoulder joint
• Deltoid: abducts, flexes, and extends the arm, helps with lifting objects and reaching overhead
• Latissimus dorsi: extends, adducts, and internally rotates the arm, helps with pulling motions
• Pectoralis major: flexes, adducts, and internally rotates the arm, helps with pushing motions
• Teres major: extends, adducts, and internally rotates the arm, helps with pulling motions

Muscles That Move The Forearm (Radius and/or Ulna)

• Brachialis: flexes the forearm at the elbow
• Brachioradialis: flexes the forearm at the elbow
• Biceps brachii: flexes the forearm at the elbow and supinates the forearm (turns palm upward)
• Triceps brachii: extends the forearm at the elbow
• Coracobrachialis: adducts and flexes the arm at the shoulder

Mufcles Acting On Abdominal Wall

• Rectus abdominis: flexes the vertebral column, helps with compressing the abdomen
• Internal oblique: rotates the vertebral column, helps with compressing the abdomen
• Transversus abdominis: compresses the abdominal cavity, helps with breathing and defecation
• External oblique: rotates the vertebral column, helps with compressing the abdomen
• Linea alba: a fibrous band that runs along the midline of the abdomen, helps with stabilizing the abdominal muscles
• Abdominal aponeurosis: a fibrous sheet that connects the abdominal muscles, helps with stabilizing the abdominal muscles
• Thoracolumbar fascia: a fibrous sheet that connects the abdominal muscles to the back muscles, helps with stabilizing the abdominal muscles

Muscles Moving Wrist, Hand, and Fingers

• Extensor carpi radialis longus: extends and abducts the wrist
• Extensor digitorum: extends the fingers
• Flexor carpi ulnaris: flexes and adducts the wrist
• Palmaris longus: flexes the wrist, helps with gripping
• Flexor digitorum superficialis: flexes the middle phalanges of the fingers
• Extensor carpi ulnaris: extends and adducts the wrist
• Extensor retinaculum: holds tendons of wrist extensor muscles in place, helps with wrist extension and finger extension
• Flexor carpi radialis: flexes and abducts the wrist
• Flexor retinaculum: holds tendons of wrist flexor muscles in place, helps with wrist flexion and finger flexioin
• Palmar aponeurosis: a dense fibrous sheath on the palm of the hand, helps with grip and hand function
• Pronator teres: pronates the forearm (turns palm downward)

Muscles That Move Thigh (Femur) and/or Leg (Tibia, Fibula)

• Quadriceps femoris muscles :
  • Rectus femoris: extends the leg at the knee, flexes the thigh at the hip
  • Vastus medialis: extends the leg at the knee
  • Vastus lateralis: extends the leg at the knee
  • Vastus intermedius: extends the leg at the knee
• Gluteus medius: abducts and rotates the thigh, helps with walking and running
• Adductor longus: adducts and flexes the thigh, helps with walking and running
• Adductor magnus: adducts and extends the thigh, helps with walking and running
• Gracilis: adducts the thigh, helps with walking and running
• Sartorius: flexes, abducts, and rotates the thigh, helps with crossing legs and sitting
• Tensor fasciae latae (TFL): abducts and flexes the thigh, helps with walking and running
• Illiotibial tract (IT Band): a thick band of connective tissue that runs along the lateral thigh, helps with stability and motion of the hip and knee
• Hamstring muscles:
  • Semimembranosus: extends the thigh and flexes the leg
  • Semitendinosus: extends the thigh and flexes the leg
  • Biceps femoris: extends the thigh and flexes the leg
• Illiopsoas: flexes and rotates the hip
• Psoas major: flexes the thigh at the hip
• Iliacus: flexes the thigh at the hip
• Gluteus maximus: extends the thigh and externally rotates the thigh, helps with walking and running

Muscles That Move The Foot And Toes

• Tibialis anterior: dorsiflexes (points toes up) and inverts the foot
• Extensor digitorum longus extends the toes and dorsiflexes the foot, helps with walking and running
• Gastrocnemius: plantar flexes (points toes down) the foot, flexes the leg at the knee
• Soleus: plantar flexes the foot
• Fibularis longus: everts (points toes out) the foot
• Extensor hallucis longus: extends the big toe and dorsiflexes the foot, helps with walking and running
• Achilles/Calcaneal Tendon: connects the gastrocnemius and soleus muscles to the calcaneus (heel bone), helps with plantarflexion
• Extensor retinaculum: holds tendons of foot extensor muscles in place, helps with foot extension and toe extension
• Plantar aponeurosis: a thick band of connective tissue on the sole of the foot, helps with supporting the arches of the foot and with running on the balls of your feet

This quiz explores the key muscles of facial expression and mastication. Learn about their functions, locations, and how they enable us to express emotions and perform essential tasks like chewing. Test your knowledge on the anatomy involved in our daily facial movements.