A&P Muscle Anatomy

Face Muscles

Orbicularis oculi

Function: Closes the eyelids; responsible for blinking and squinting.

Location: Surrounds the eye socket.

Orbicularis oris

Function: Closes and puckers the lips, as in kissing.

Location: Encircles the mouth.

Zygomaticus major

Function: Elevates the corner of the mouth, as in smiling.

Location: Extends from the zygomatic bone to the corners of the mouth.

Zygomaticus minor

Function: Elevates the upper lip.

Location: Extends from the zygomatic bone to the upper lip.

Buccinator

Function: Compresses the cheek, helping in chewing and blowing.

Location: In the cheek, between the maxilla and mandible.

Frontalis

Function: Raises the eyebrows and wrinkles the forehead.

Location: Forehead.

Occipitalis

Function: Pulls the scalp back.

Location: Back of the head, overlying the occipital bone.

Jaw Muscles

Temporalis

Function: Elevates and retracts the mandible for jaw closing.

Location: Side of the head, overlying the temporal bone.

Masseter

Function: Elevates the mandible, closing the jaw.

Location: Side of the jaw, connecting the zygomatic arch to the mandible.

Medial pterygoid

Function: Elevates and laterally moves the mandible.

Location: Deep in the jaw, inside of the mandible.

Lateral pterygoid

Function: Depresses and protrudes the mandible, assisting in opening the jaw.

Location: Inside of the jaw, near the temporomandibular joint.

Neck Muscles

Platysma

Function: Tenses the skin of the neck and depresses the lower jaw.

Location: Thin sheet covering the neck from the jaw to the collarbone.

Sternocleidomastoid (SCM)

Function: Rotates and flexes the head.

Location: Extends from the sternum and clavicle to the mastoid process of the skull.

Trapezius

Function: Elevates, retracts, and depresses the scapula; extends the neck.

Location: Covers the upper back, neck, and shoulders.

Chest and Back Muscles

Latissimus dorsi

Function: Extends, adducts, and medially rotates the arm.

Location: Lower back, connecting the spine to the humerus.

Rhomboid major

Function: Retracts the scapula.

Location: Upper back, between the spine and the scapula.

Rhomboid minor

Function: Retracts and stabilizes the scapula.

Location: Upper back, above the rhomboid major.

Serratus anterior

Function: Protracts and stabilizes the scapula.

Location: Side of the chest, covering the ribs.

Levator scapulae

Function: Elevates the scapula.

Location: Side of the neck, connecting the cervical vertebrae to the scapula.

Pectoralis major

Function: Flexes, adducts, and medially rotates the arm.

Location: Upper chest, connecting the clavicle and sternum to the humerus.

Pectoralis minor

Function: Depresses and protracts the scapula.

Location: Underneath the pectoralis major, attaching the ribs to the scapula.

Intercostals

Function: Elevate and depress the ribs during breathing.

Location: Between the ribs.

Abdominal Muscles

Rectus abdominis

Function: Flexes the trunk, as in crunches.

Location: Runs vertically along the abdomen.

Internal obliques

Function: Rotates and laterally flexes the trunk.

Location: Deep side of the abdomen, running diagonally.

External obliques

Function: Rotates and laterally flexes the trunk.

Location: Outer layer of the abdomen, running diagonally.

Transversus abdominis

Function: Compresses the abdomen.

Location: Deep abdominal muscle, running horizontally.

Shoulder Muscles

Deltoid

Function: Abducts, flexes, and extends the arm.

Location: Covers the shoulder joint.

Rotator Cuff Muscles

Supraspinatus

Function: Abducts the arm.

Location: Upper part of the scapula.

Infraspinatus

Function: Externally rotates the arm.

Location: Below the scapular spine.

Subscapularis

Function: Medially rotates the arm.

Location: Anterior surface of the scapula.

Teres major

Function: Adducts and medially rotates the arm.

Location: Below the scapula.

Teres minor

Function: Externally rotates the arm.

Location: Just above the teres major, on the scapula.

Arm Muscles

Biceps brachii

Function: Flexes the elbow and supinates the forearm.

Location: Front of the upper arm.

Coracobrachialis

Function: Flexes and adducts the arm.

Location: Medial upper arm.

Brachialis

Function: Flexes the elbow.

Location: Underneath the biceps brachii.

Brachioradialis

Function: Flexes the elbow.

Location: Forearm, near the thumb.

Forearm Muscles

Triceps brachii

Function: Extends the elbow.

Location: Back of the upper arm.

Pronator teres

Function: Pronates the forearm.

Location: Proximal forearm, near the elbow.

Pronator quadratus

Function: Pronates the forearm.

Location: Distal forearm, near the wrist.

Supinator

Function: Supinates the forearm.

Location: Proximal forearm.

Flexor compartment (forearm)

Function: Flexes the wrist and fingers.

Location: Anterior forearm.

Extensor compartment (forearm)

Function: Extends the wrist and fingers.

Location: Posterior forearm.

Hip and Thigh Muscles

Gluteus maximus

Function: Extends and externally rotates the thigh.

Location: Buttocks.

Gluteus medius

Function: Abducts and medially rotates the thigh.

Location: Upper buttocks, near the hip.

Gluteus minimus

Function: Abducts and medially rotates the thigh.

Location: Underneath the gluteus medius.

Tensor fascia latae (TFL)

Function: Abducts and stabilizes the thigh.

Location: Lateral thigh.

Semitendinosus

Function: Extends the thigh, flexes the knee.

Location: Back of the thigh.

Semimembranosus

Function: Extends the thigh, flexes the knee.

Location: Back of the thigh, underneath semitendinosus.

Biceps femoris

Function: Extends the thigh, flexes the knee.

Location: Lateral side of the back of the thigh.

Iliacus

Function: Flexes the thigh.

Location: Inner pelvis.

Psoas major

Function: Flexes the thigh.

Location: Runs from the lower spine to the femur.

Psoas minor

Function: Weakly flexes the lumbar spine.

Location: Runs from the lower spine to the pelvis.

Rectus femoris

Function: Extends the knee and flexes the thigh.

Location: Center of the thigh.

Vastus lateralis

Function: Extends the knee.

Location: Lateral thigh.

Vastus medialis

Function: Extends the knee.

Location: Medial thigh.

Vastus intermedius

Function: Extends the knee.

Location: Between vastus lateralis and medialis, beneath rectus femoris.

Sartorius

Function: Flexes, abducts, and laterally rotates the thigh.

Location: Runs diagonally across the front of the thigh.

Leg Muscles

Gracilis

Function: Adducts the thigh and flexes the knee.

Location: Inner thigh.

Adductor magnus

Function: Adducts the thigh.

Location: Inner thigh.

Adductor longus

Function: Adducts the thigh.

Location: Inner thigh.

Adductor brevis

Function: Adducts the thigh.

Location: Inner thigh.

Tibialis anterior

Function: Dorsiflexes and inverts the foot.

Location: Front of the lower leg.

Tibialis posterior

Function: Inverts and plantarflexes the foot.

Location: Back of the lower leg.

Fibularis longus

Function: Everts and plantarflexes the foot.

Location: Lateral side of the lower leg.

Fibularis brevis

Function: Everts and plantarflexes the foot.

Location: Lower lateral leg.

Gastrocnemius

Function: Plantarflexes the foot and flexes the knee.

Location: Calf, back of the lower leg.

Soleus

Function: Plantarflexes the foot.

Location: Underneath the gastrocnemius in the calf.