Small Muscles
Closes the eyes.
Orbicularis Oculi
Flexes the forearm at the elbow.
Biceps Brachii
Raises the mandible (closes the jaw).
Masseter
Extends the forearm at the elbow.
Triceps brachii
Compresses the cheek when chewing or blowing.
Buccinator
Pulls the corners of the mouth upward when smiling.
Zygomaticus
Lowers during inspiration to increase the size of the thoracic cavity.
Diaphragm
Closes the lips.
Orbicularis Oris
Flexes the head toward the chest when both muscles contract.
Sternocleidomastoid
Extends the head when both muscles contract.
Splenius capitis
Raises the ribs during inspiration.
External Intercostals
Extends the arm and pulls it toward the body.
Latissimus Dorsi
Flexes the vertebral column ("six-pack" muscle).
Rectus Abdominus
Abducts the arm at the shoulder.
Deltoid
Pulls the ribs downward during expiration.
Internal intercostals
Flexes, abducts, and medially rotates the thigh
Tensor fasciae latae
Plantar flexes the foot and helps you stand on your toes.
Gastrocnemius
This is the longest muscle in the human body. It flexes, abducts, and laterally rotates the thigh while also flexing the knee
Sartorius
Extends the knee
Quadriceps femoris
Rotates the arm outward and helps keep the shoulder joint stable
Infraspinatus
Stabilizes the scapula by pulling it upward.
Levator Scapulae
Compresses the abdominal contents and tightens the abdominal wall.
Transversus Abdominus
Flexes the knee
Biceps Femoris
Dorsiflexes the foot so your toes point upward.
Tibialis anterior
Retracts (pulls back) the scapula.
Rhomboids