Muscles of the Face and Neck PDF

Muscles of the Face and Neck: 1. Frontalis ○ Location: Forehead region ○ Action: Raises the eyebrows, wrinkles the forehead. 2. Occipitalis ○ Location: Back of the skull ○ Action: Pulls the scalp backward. 3. Corrugator Supercilii ○ Location: Near...

Muscles of the Face and Neck: 1. Frontalis ○ Location: Forehead region ○ Action: Raises the eyebrows, wrinkles the forehead. 2. Occipitalis ○ Location: Back of the skull ○ Action: Pulls the scalp backward. 3. Corrugator Supercilii ○ Location: Near the eyebrow (above the eyes) ○ Action: Draws eyebrows downward and medially (as in frowning). 4. Galea Aponeurotica ○ Location: Connective tissue covering the scalp, between the frontalis and occipitalis ○ Action: Serves as a tendon that connects the frontalis and occipitalis muscles. 5. Nasalis ○ Location: Across the nose ○ Action: Compresses the nasal cartilages (flaring the nostrils). 6. Procerus ○ Location: Between the eyebrows (on the bridge of the nose) ○ Action: Lowers the eyebrows and wrinkles the skin of the nose (expression of anger or frowning). 7. Orbicularis Oculi ○ Location: Around the eyes ○ Action: Closes the eyelids, squints, and helps with blinking. 8. Levator Palpebrae ○ Location: Above the eye, in the upper eyelid ○ Action: Raises the upper eyelid. 9. Orbicularis Oris ○ Location: Around the mouth ○ Action: Closes and protrudes the lips (e.g., for kissing). 10. Levator Labii Alaeque Nasi ○ Location: Side of the nose to the upper lip ○ Action: Elevates the upper lip and dilates the nostrils. 11. Levator Labii Superioris ○ Location: Above the upper lip ○ Action: Elevates the upper lip (as in expressing disgust). 12. Levator Labii Angularis ○ Location: Near the angle of the mouth ○ Action: Elevates the angle of the mouth (smiling). 13. Zygomaticus Major ○ Location: From the cheekbone to the corners of the mouth ○ Action: Pulls the corners of the mouth upward (smiling).  14. Zygomaticus Minor ○ Location: Above the zygomaticus major ○ Action: Elevates the upper lip. 15. Risorius ○ Location: Along the sides of the mouth ○ Action: Draws the corners of the mouth laterally (involved in smiling). 16. Depressor Labii Angularis ○ Location: Below the mouth, near the chin ○ Action: Pulls the corners of the mouth downward (frowning). 17. Depressor Labii Inferioris ○ Location: Chin to the lower lip ○ Action: Depresses the lower lip (sad expression). 18. Mentalis ○ Location: Chin ○ Action: Raises and protrudes the lower lip (pouting). 19. Buccinator ○ Location: Cheeks ○ Action: Compresses the cheek against the teeth (used in blowing, sucking). 20. Platysma ○ Location: Neck and lower face ○ Action: Depresses the mandible (lowers the jaw), tenses the neck skin. 21. Masseter ○ Location: Side of the jaw ○ Action: Elevates the mandible (used in chewing). 22. Temporalis ○ Location: Side of the head, above the ears ○ Action: Elevates and retracts the mandible (used in chewing). 23. Digastric ○ Location: Under the jaw ○ Action: Lowers the mandible (opens the mouth), elevates the hyoid bone. Other Key Terms (Related to Muscle Contraction): 1. Myosin ○ Protein filaments in muscle fibers that interact with actin to produce muscle contraction. 2. Actin ○ Protein filaments in muscle fibers that interact with myosin to produce muscle contraction. 3. Crossbridges ○ Connections formed between myosin heads and actin filaments during muscle contraction. 4. ATP (Adenosine Triphosphate) ○ Energy molecule used by muscles for contraction. 5. Calcium Ions (Ca²⁺) ○ Released from the sarcoplasmic reticulum to initiate muscle contraction by binding to troponin on actin filaments. 6. Sodium/Potassium Ions (Na⁺/K⁺) ○ Essential for maintaining the action potential during muscle contraction (important in the process of muscle excitability). 7. Synergist ○ A muscle that assists the primary muscle (agonist) in a particular movement. 8. Antagonist ○ A muscle that opposes the action of another muscle (e.g., triceps is antagonist to biceps). 9. Origin ○ The fixed attachment point of a muscle where it begins (usually proximal to the center of the body). 10. Insertion ○ The movable attachment point of a muscle where it ends (usually distal from the body’s center). 11. Action ○ The specific movement that a muscle produces when it contracts. Muscles of the Back, Chest, and Upper Limbs: Trapezius Location: Upper back and neck Action: Elevates, retracts, and rotates the scapula (shoulder blade). Involved in shrugging. Latissimus Dorsi Location: Lower back Action: Extends, adducts, and medially rotates the arm. Important for actions like pulling. Supraspinatus Location: Above the spine of the scapula Action: Abducts the arm, stabilizes the shoulder joint. Infraspinatus Location: Below the spine of the scapula Action: Laterally (externally) rotates the arm, stabilizes the shoulder joint. Subscapularis Location: Front of the scapula (on the ribcage side) Action: Medially (internally) rotates the arm. Teres Major Location: Below the infraspinatus Action: Adducts and medially rotates the arm. Teres Minor Location: Below the infraspinatus Action: Laterally (externally) rotates the arm, stabilizes the shoulder joint. Rhomboids Location: Between the spine and scapula (upper back) Action: Retracts and elevates the scapula, helps to square the shoulders. Levator Scapulae Location: Neck, from cervical vertebrae to the scapula Action: Elevates the scapula and tilts it downward. Coracobrachialis Location: Upper arm (from scapula to humerus) Action: Flexes and adducts the arm at the shoulder. Pectoralis Minor Location: Chest (underneath the pectoralis major) Action: Depresses and protracts the scapula, elevates the ribs during deep inhalation. Deltoid Location: Shoulder Action: Abducts, flexes, extends, and rotates the arm (responsible for the rounded shape of the shoulder). Serratus Anterior Location: Side of the chest, near the ribs Action: Protracts the scapula and helps with upward rotation (important for reaching and pushing movements). Biceps Brachii Location: Upper arm (front) Action: Flexes the elbow and supinates the forearm. Brachialis Location: Under the biceps brachii Action: Flexes the elbow. Brachioradialis Location: Forearm Action: Flexes the elbow, especially when the forearm is in a neutral position. Triceps Brachii Location: Upper arm (back) Action: Extends the elbow. Flexor/Extensor Carpi Location: Forearm Action: Flexes (flexor) or extends (extensor) the wrist. Flexor/Extensor Digitorum Location: Forearm Action: Flexes (flexor) or extends (extensor) the fingers. Flexor/Extensor Pollicis Location: Forearm, thumb muscles Action: Flexes (flexor) or extends (extensor) the thumb. Pronator Quadratus/Teres Location: Forearm Action: Pronates the forearm (turns the palm down). Respiratory and Abdominal Muscles: Diaphragm Location: Below the lungs, separates the thoracic and abdominal cavities Action: Contracts to allow inhalation and relaxes to allow exhalation (primary muscle in breathing). Intercostal Muscles Location: Between the ribs Action: Assist in breathing by expanding and contracting the thoracic cavity (external intercostals for inhalation, internal for exhalation). Pectoralis Major Location: Chest (over the ribcage) Action: Flexes, adducts, and medially rotates the arm. Pectoralis Minor Location: Under the pectoralis major Action: Depresses the scapula, assists in deep breathing. Rectus Abdominis Location: Abdomen (front) Action: Flexes the spine, compresses the abdominal contents, important for posture and breathing. Obliques Location: Sides of the abdomen (external and internal) Action: Rotates and laterally flexes the trunk, compresses abdominal contents. Muscle Types and Fiber Arrangements: Pennate Muscle Description: A muscle whose fibers are arranged at an angle to the tendon. There are three types: Unipennate: Fibers are on one side of the tendon (e.g., extensor digitorum longus). Bipennate: Fibers are on both sides of the tendon (e.g., rectus femoris). Multipennate: Fibers are arranged around a central tendon (e.g., deltoid). General Muscle Terminology: Synergist: A muscle that assists the prime mover in producing a movement. Antagonist: A muscle that opposes the action of the prime mover. Origin: The fixed attachment point of a muscle. Insertion: The movable attachment point of a muscle. Action: The specific movement produced when a muscle contracts.