Muscles Gross Anatomy A&P1 UMKC 2026

Frontalis

Raises eyebrows; draws scalp anteriorly (14)

Orbicularis oculi

Closes eye (blink) (16)

Nasalis

Wrinkles nose, dilates nostrils (19)

Orbicularis oris

Closes lips (kissing), used to pucker lips (20)

Zygomaticus

Elevates & Abducts upper lip (21)

Buccinator

Retracts angle of mouth, flattens check (22)

Risorius

Abducts corner of mouth, laughing muscle (24)

Depressor labii inferioris

Pulls lower corner of mouth inferiorly (pouting) (26)

Temporalis

Elevates and retracts mandible & Elevates and protracts mandible/close the jaw (15)

Masseter

Elevates and retracts mandible & Elevates and protracts mandible/close the jaw (23)

Pterygoid muscles (lateral)

Deep muscle; depresses the mandible, provides the sideways movement of chewing (APR/Table)

Pterygoid muscles (medial)

Deep muscle; elevates the mandible, provides the sideways movement of chewing (APR/Table)

Sternocleidomastoid

Rotates & Extends head; flex neck (28)

Splenius capitis

Extends & Rotates head (29)

Levator scapulae

Elevates the scapula (30)

Scalenes (anterior, middle, posterior)

Lift 1st & 2nd rib, flex neck to same side (31-33)

Trapezius

Extends & abducts head, rotates & adducts scapula (1)

Latissimus dorsi

Extends, adducts & medially rotates arm; draws shoulder inferiorly (2)

Rhomboid major

Adducts scapula (draws the together) (4)

Rhomboid minor

Adducts scapula (5)

Iliocostalis (1 or 3 from erector spinae group)

Postural muscles (erector spinae) (12)

Pectoralis major

Flexes, adducts, and medially rotates arm (18)

Serratus anterior

Keeps scapula against thoracic wall, abducts scapula (19)

Pectoralis minor

Stabilizes scapula, raises ribs for deep inhalation (20)

External intercostal muscles (wrap anteriorly)

Elevates ribs (increases thoracic volume = inspiration) (13)

Internal intercostal

Depresses ribs (decreases thoracic volume = expiration) (22)

External abdominal oblique (hands in pocket fiber orientation)

Compresses abdominal wall, trunk rotation (26)

Internal abdominal oblique (hand over heart fiber orientation)

Compresses abdominal wall, trunk rotation (29)

Transversus abdominis

Compresses abdominal wall, trunk rotation (31)

Rectus abdominis

Flexes vertebral column, compresses abdominal wall (28)

Diaphragm

Contraction = inspiration; relaxation = expiration (32)

Subscapularis (Rotator cuff 1, 2, 4, 5)

Medially rotates arm (1)

Supraspinatus

Abducts arm (2)

Infraspinatus

Laterally rotates arm (4)

Teres minor

Extends, adducts, & laterally rotates arm (5)

Teres major

Extends, adducts, medially rotates arm (6)

Deltoid

Flexes, extends, and abducts arm (3)

Triceps brachii

Extends and adducts arm, extends forearm (12)

Biceps brachii

Flexes arm & forearm; supinates hand (9)

Brachialis

Flexes forearm (10)

Brachioradialis

Flexes forearm (13)

Extensor carpi radialis longus

Extends & abducts hand; damage to extensor muscles of the forearm = “tennis elbow” (14)

Extensor carpi radialis brevis

Extends & abducts hand; damage to extensor muscles of the forearm = “tennis elbow” (15)

Extensor digitorum

Extends fingers & hand (24)

Flexor carpi radialis

Flexes writs radially (abducts hand) (17)

Flexor carpi ulnaris

Flexes wrist toward ulna (adducts hand) (19)

Flexor digitorum superficialis

Flexes digits (20)

Gluteus maximus

Extends, abducts, and laterally rotates thigh; braces knee (1)

Gluteus medius

Abducts and medially rotates thigh (2)

Piriformis

Laterally rotates thigh, abducts hip, gluteal region landmark (3)

Sartorius

Flexes thigh and leg; laterally rotates thigh (cross leg); “tailor’s muscle” (9)

Vastus medialis

Extends leg (11)

Quadriceps Femoris

Extends leg (11-14)

Vastus lateralis

Extends leg (12)

Rectus femoris

Flexes thigh; extends leg; common site for IM injection especially in infants (13)

Vastus intermedius

Extends leg (deep muscle) (14)

Gracilis

Adducts thigh, flexes leg (15)

Adductor longus

Adducts, flexes, and laterally rotates thigh (16)

Adductor magnus

Adducts, extends, and laterally rotates thigh (18)

Semitendinosus Hamstrings

Extends thigh, flexes and medially rotates leg (19)

Hamstrings

Extends thigh, flexes and medially rotates leg (19-21)

Semimembranosus

Extends thigh, flexes and medially rotates leg (20)

Biceps femoris

Extends thigh, flexes and laterally rotates leg (21)

Tibialis anterior

Dorsiflexes and inverts foot; excessive stress to this muscles = "shin splints” (22)

Extensor digitorum

Extends toes, dorsiflexes and everts foot (23)

Fibularis longus

Plantarflexion support, everts foot (“rolled your ankle” muscle) (24)

Gastronemicus

Plantarflex foot (26)

Soleus (Soleus + gastrocnemius tendon = calcaneal (Achilles) tendon)

Plantarflex foot, standing support (maintains tension to keep you from falling forward) (27)