Human Muscle Models: Key Muscles and Their Functions

Human Muscle Models

Overview of Major Muscles

This section provides an organized overview of key human muscles, their anatomical locations, and primary functions. Understanding these muscles is essential for students studying the muscular system in anatomy and physiology (ANP) courses.

• Muscle Name: The anatomical name of the muscle.

• Location: Where the muscle is found in the body.

• Function: The primary action or role of the muscle.

Muscles of the Head and Face

• Frontalis: Located in the forehead; raises eyebrows and wrinkles forehead.

• Temporalis: Side of the head; elevates and retracts mandible (jaw).

• Orbicularis Oculi: Surrounds the eye; closes eyelids.

• Orbicularis Oris: Encircles the mouth; closes and protrudes lips.

• Zygomaticus: Cheek area; elevates corners of the mouth (smiling).

• Masseter: Jaw; elevates mandible, main muscle for chewing.

• Mentalis: Chin; protrudes lower lip.

Neck Muscles

• Sternocleidomastoid: Side of neck; flexes and rotates head.

• Trapezius: Upper back and neck; moves scapula, extends neck.

• Splenius Capitus: Posterior neck; extends and rotates head.

Muscles of the Chest and Abdomen

• Pectoralis Major: Chest; flexes, adducts, and rotates arm medially.

• Pectoralis Minor: Deep to pectoralis major; stabilizes scapula.

• Serratus Anterior: Side of chest; protracts scapula.

• External Oblique: Lateral abdomen; compresses abdomen, flexes vertebral column.

• Internal Oblique: Deep to external oblique; similar function.

• Rectus Abdominus: Front of abdomen; flexes vertebral column, compresses abdomen.

Shoulder and Upper Arm Muscles

• Deltoid: Shoulder; abducts arm.

• Biceps Brachii: Front of upper arm; flexes elbow, supinates forearm.

• Brachialis: Under biceps; flexes elbow.

• Triceps Brachii: Back of upper arm; extends elbow.

• Brachioradialis: Forearm; flexes elbow.

• Pronator Teres: Forearm; pronates forearm.

Forearm Muscles

• Palmaris Longus: Forearm; flexes wrist.

• Flexor Carpi Ulnaris: Forearm; flexes and adducts wrist.

• Flexor Carpi Radialis: Forearm; flexes and abducts wrist.

• Extensor Carpi Radialis Longus: Forearm; extends and abducts wrist.

• Flexor Digitorum Longus: Forearm; flexes fingers.

• Extensor Digitorum Longus: Forearm; extends fingers.

Back Muscles

• Latissimus Dorsi: Lower back; extends, adducts, and medially rotates arm.

• Teres Major: Shoulder; extends and medially rotates arm.

• Teres Minor: Shoulder; laterally rotates arm.

• Infraspinatus: Shoulder; laterally rotates arm.

Muscles of the Hip and Thigh

• Sartorius: Thigh; flexes, abducts, and laterally rotates thigh.

• Adductor Longus: Medial thigh; adducts thigh.

• Adductor Magnus: Medial thigh; adducts and extends thigh.

• Gracilis: Medial thigh; adducts thigh, flexes leg.

• Vastus Lateralis: Lateral thigh; extends knee.

• Vastus Medialis: Medial thigh; extends knee.

• Rectus Femoris: Front thigh; extends knee, flexes hip.

• Pectineus: Medial thigh; adducts and flexes thigh.

• Tensor Fascia Latae: Lateral thigh; abducts thigh.

• Gluteus Maximus, Medius & Minimus: Buttocks; extends, abducts, and rotates thigh.

Muscles of the Leg

• Biceps Femoris: Posterior thigh; flexes knee, extends hip.

• Semitendinosus: Posterior thigh; flexes knee, extends hip.

• Semimembranosus: Posterior thigh; flexes knee, extends hip.

• Tibialis Anterior: Front of leg; dorsiflexes and inverts foot.

• Fibularis Longus: Lateral leg; plantar flexes and everts foot.

• Gastrocnemius: Calf; plantar flexes foot, flexes knee.

• Soleus: Calf; plantar flexes foot.

• Achilles Tendon: Connects calf muscles to heel bone; enables walking, running, jumping.

Summary Table: Major Muscles and Their Functions

Muscle	Location	Primary Function
Frontalis	Forehead	Raises eyebrows
Deltoid	Shoulder	Abducts arm
Biceps Brachii	Upper arm	Flexes elbow
Rectus Femoris	Front thigh	Extends knee, flexes hip
Gastrocnemius	Calf	Plantar flexes foot
Gluteus Maximus	Buttocks	Extends thigh
Achilles Tendon	Heel	Connects calf muscles to heel bone
Masseter	Jaw	Elevates mandible
Sternocleidomastoid	Neck	Flexes and rotates head
Latissimus Dorsi	Lower back	Extends, adducts arm
Vastus Lateralis	Lateral thigh	Extends knee
Flexor Carpi Radialis	Forearm	Flexes and abducts wrist
Orbicularis Oculi	Eye	Closes eyelids

Muscle Classification and Function

• Skeletal Muscles: Voluntary muscles attached to bones; responsible for movement.

• Muscle Actions: Muscles contract to produce movement at joints; each muscle has a specific action based on its location and attachment.

• Antagonistic Pairs: Muscles often work in pairs; one contracts while the other relaxes (e.g., biceps and triceps).

Example: Biceps and Triceps Function

• Biceps Brachii: Flexes the elbow.

• Triceps Brachii: Extends the elbow.

• Application: When lifting an object, the biceps contract while the triceps relax; when lowering, the triceps contract while the biceps relax.

Additional info:

• Muscle names often reflect their location, shape, or function (e.g., rectus means straight, oblique means angled).

• Understanding muscle anatomy is crucial for fields such as medicine, physical therapy, and sports science.