Muscles of the Face and Neck

Muscles of the Face and Neck

• Frontalis: Located on the forehead, raises eyebrows, wrinkles forehead.
• Occipitalis: Located on the back of the skull, pulls the scalp backward.
• Corrugator Supercilii: Located near the eyebrows, draws eyebrows downwards and medially (frowning).
• Galea Aponeurotica: Connective tissue covering the scalp, between frontalis and occipitalis, serves as a tendon connecting these muscles.
• Nasalis: Located across the nose, compresses nasal cartilages (flaring nostrils).
• Procerus: Located between eyebrows, lowers eyebrows and wrinkles nose skin (expression of anger or frowning).
• Orbicularis Oculi: Around the eyes, closes eyelids, squints, and helps with blinking.
• Levator Palpebrae: Above the eye, in upper eyelid; raises upper eyelid.
• Orbicularis Oris: Around the mouth, closes and protrudes lips (kissing).
• Levator Labii Alaeque Nasi: Side of nose to upper lip, elevates upper lip and dilates nostrils.
• Levator Labii Superioris: Above upper lip, elevates upper lip (disgust).
• Levator Labii Angularis: Near angle of mouth, elevates angle of mouth (smiling).
• Zygomaticus Major: From cheekbone to mouth corners, pulls corners upward (smiling).
• Zygomaticus Minor: Above Zygomaticus major, elevates upper lip.
• Risorius: Along sides of mouth, draws corners laterally (smiling).
• Depressor Labii Angularis: Below mouth, near chin, pulls corners of mouth downward (frowning).
• Depressor Labii Inferioris: Chin to lower lip, depresses lower lip (sad).
• Mentalis: Chin, raises and protrudes lower lip (pouting).
• Buccinator: Cheeks, compresses cheek against teeth (blowing, sucking).
• Platysma: Neck and lower face, depresses mandible (lower jaw), tenses neck skin.
• Masseter: Side of jaw, elevates mandible (chewing).
• Temporalis: Side of head, above ears, elevates and retracts mandible (chewing).
• Digastric: Under jaw, lowers mandible (opens mouth), elevates hyoid bone.

Other Key Terms (Muscle Contraction)

• Myosin: Protein filaments that interact with actin to produce muscle contraction.
• Actin: Protein filaments that interact with myosin to produce muscle contraction.
• Crossbridges: Connections formed by myosin heads and actin filaments during muscle contraction.

Muscles of the Back, Chest, and Upper Limbs

• Trapezius: Upper back and neck, elevates, retracts, rotates scapula (shoulder blade).
• Latissimus Dorsi: Lower back, extends, adducts, and medially rotates the arm.
• Supraspinatus: Above spine of scapula, abducts arm, stabilizes shoulder.
• Infraspinatus: Below spine of scapula, laterally (externally) rotates arm, stabilizes shoulder.
• Subscapularis: Front of scapula, medially (internally) rotates the arm.
• Teres Major: Below infraspinatus, adducts and medially rotates arm.
• Teres Minor: Below infraspinatus, laterally (externally) rotates arm, stabilizes shoulder.
• Rhomboids: Between spine and scapula, retracts and elevates scapula, helps square shoulders.
• Levator Scapulae: Neck, elevates and tilts scapula downward.
• Coracobrachialis: Upper arm, flexes and adducts the arm.
• Pectoralis Major: Chest, flexes, adducts, and medially rotates the arm.
• Pectoralis Minor: Chest, depresses and protracts the scapula, elevates ribs during inhalation.
• Deltoid: Shoulder, abducts, flexes, extends, and rotates the arm.
• Serratus Anterior: Side of chest, protracts and elevates scapula, important for reaching/pushing.
• Biceps Brachii: Upper arm, flexes elbow and supinates the forearm.
• Brachialis: Under biceps brachii, flexes the elbow.
• Brachioradialis: Forearm, flexes elbow (especially when forearm is neutral position).
• Triceps Brachii: Upper arm, extends the elbow.
• Flexor/Extensor Carpi: Forearm, flexes or extends the wrist.
• Flexor/Extensor Digitorum: Forearm, flexes or extends the fingers.
• Flexor/Extensor Pollicis: Forearm, thumb muscles, flexes or extends the thumb.
• Pronator Quadratus/Teres: Forearm, pronates forearm (turns palm down).

Respiratory and Abdominal Muscles

• Diaphragm: Below lungs, separates thoracic and abdominal cavities; contracts for inhalation, relaxes for exhalation.
• Intercostal Muscles: Between ribs, assist in breathing by expanding/contracting thoracic cavity.
• Pectoralis Minor: Under pectoralis major, depresses scapula, assists deep breathing.
• Rectus Abdominis: Abdomen, flexes spine, compresses abdominal contents; posture/breathing.
• Obliques: Sides of abdomen, rotate and laterally flex trunk, compresses abdomen.

Other Information

• ATP: Energy molecule used by muscles for contraction.
• Calcium Ions (Ca2+): Released from sarcoplasmic reticulum to initiate muscle contraction.
• Sodium/Potassium Ions (Na+/K+): Essential for maintaining action potential during muscle contraction.
• Synergist: Muscle that assists the primary muscle (agonist).
• Antagonist: Muscle that opposes the action of another muscle.
• Origin: Fixed attachment point of a muscle.
• Insertion: Movable attachment point of a muscle.
• Action: Specific movement produced when a muscle contracts.
• Pennate Muscle: Muscle fiber arrangement at an angle to the tendon. Types: Unipennate, Bipennate, Multipennate.