Anatomy & Physiology: Major Skeletal Muscles

The major skeletal muscles are described in following tables and figures.

TABLE 1

Muscles of the Head and Neck

Muscle	Origin/Insertion	Action
Epicranius:frontalis	O: galea aponeurotica I: skin around eyes	raises eyebrows; surprised
Epicranius:occiptalis	O: occipital bone I : galea aponeurotica	pulls scalp back; surprised
Orbicularis oculi	O: maxillary & frontal bones I: eyelids	closes eyelids; blinking
Orbicularis oris	O: muscle fibers around mouth I: skin around mouth	closes lips; kissing
Buccinator	O: maxilla & mandible I: orbicularis oris	compresses cheek; whistling
Platysma	O: fascia in upper chest I: mandible & corner of mouth	lowers mandible; opens mouth
Mentalis	O: mandible I: skin of chin	protrudes lower lip; pouting
Risorius	O: fascia on masseter muscle I: skin at corner of mouth	lateral movement of lips; grimacing
Zygomaticus	O: zygomatic bone I: skin around mouth	raises edges of mouth; smiling
Levator labi superioris	O: infroarbital margin of maxilla I: skin of upper lip	raises upper lip; as in disgust
Depressor labi inferioris	O: mandible I: skin of lower lip	lowers lower lip
Temporalis	O: parietal bone I: mandible	raises mandible; closes mouth
Masseter	O: zygomatic arch I: mandible	raises mandible; closes mouth
Medial pterygoid	O: sphenoid & maxilla I: mandible	raises mandible; side-to-side mouth motion
Lateral pterygoid	O: sphenoid & maxilla I: mandible	raises mandible; side-to side mouth motion
Sternocleidomastoid	O: ternum & clavicle I: temporal bone	flexes & rotates head
Splenius capitis	O: cervical & thoracic vertebrae I: temporal bone	rotates, bends, or extends head
Semispinalis capitis	O: cervical & thoracic vertebrae I: occipital bone	rotates or extends head
Longissimus	O: cervical & thoracic vertebrae I: temporal bone	rotates, bends, or extends head
Omohyoid	O: scapula I: hyoid bone	depresses hyoid bone
Sternohyoid	O: sternum & clavicle I: hyoid bone	depresses hyoid bone

TABLE 2

Muscles of the Neck, Shoulder, Thorax, and Abdominal Wall

Muscle	Origin/Insertion	Action
Semispinalis capitis	O: cervical & thoracic vertebrae I: occipital bone	extends & rotates head
Splenius capitis	O: c & t vertebrae I : occipital & temporal bone	extends and rotates head
Deltoid	O: clavicle & scapula I: humerus	abducts, flexes, extends, & rotates arm
Pectoralis major	O: clavicle, sternum, ribs I: humerus	flexes, adducts, & rotates arm
Infraspinatus	O: scapula I: humerus	rotates arm
Teres major	O: scapula I: humerus	extends, rotates arm
Latissimus dorsi	O: vertebrae, ribs, ilium I : humerus	extends, adducts, rotates arm
Levator scapulae	O: cervical vertebrae I: scapula	elevates scapula
Pectoralis minor	O: ribs I: scapula	stabilizes scapula, elevates ribs
Serratus anterior	O: ribs I: scapula	stabilizes scapula, elevates ribs
Trapezius	O: occipital bone & c & t vertebrae; I : scapula & clavicle	elevates, adducts, & rotates scapula
Rhomboideous major/Rhomboideus minor	O: c & t vertebrae I: scapula	adducts & rotates scapula
Rectus abdominis	O: pubic crest & symphysis I: xiphoid process & ribs	flexes vertebral column, compresses abdomen
External oblique	O: ribs I : linea alba, ilium	compresses abdomen, rotates trunk
Transverse abdominis	O: ilium, ribs I: linea alba, xiphoid process	compresses abdomen
External intercostals	O: lower border of rib above I: upper border of rib below	elevates ribs, aids inspiration
Internal intercostals	O: upper border of rib below I: lower border of rib above	pulls ribs together, aids expiration
Diaphragm	O: lower ribs, sternum I: central tendon	aids inspiration
Spinalis	O: lumbar & thoracic vertebrae I: thoracic & cervical vertebrae	extends vertebral column
Longissimus	O: lumbar & cervical vertebrae I : temporal bone, vertebrae	extends vertebral column
Iliocostalis	O: ilium, ribs I: ribs	extends vertebral column

TABLE 3

Muscles of the Arm and Forearm

Muscle	Origin/Insertion	Action
Coracobrachiolis	O: scapula I: humerus	flexes & adducts arm
Biceps brachii	O: scapula, glenoid cavity I: radius	flexes arm, flexes forearm, & rotates hand
Brachialis	O: humerus I: ulna	flexes forearm
Brachioradialis	O: humerus I: radius	flexes forearm
Triceps brachii	O: humerus I: ulna	extends forearm
Anconeus	O: humerus I: ulna	extends forearm
Pronator teres	O: humerus, ulna I: radius	rotatesforearm
Pronator quadratus	O: ulna I: radius	rotates forearm
Supinator	O: ulna I: radius	rotates forearm
Flexor carpi radialis	O: humerus I : metacarpals	flexes & abducts wrist
Flexor carpi ulnaris	O : humerus, ulna I : carpals, metacarpals	flexes & abducts wrist
Flexor digitorum superficialis	O: humerus, ulna, radius I: phalanges	flexes finger 2–5
Flexor digitorum profundus	O: ulna I: phalanges	flexes distal fingers 2–5
Palmaris longus	O: humerus I : flexor retinaculum	flexes wrist
Extensor carpi radialis longus	O : humerus I : second metacarpal	extends & abducts wrist
Extensor carpi ulnaris	O: humerus, ulna I: fifth metacarpal	extends & adducts wrist
Extensor digitorum	O: humerus I: distal phalanges	extends fingers 2–5
Extensor pollicis brevis	O: radius I: phalanx of thumb thumb	extends
Extensor pollicis longus	O: radius I: phalanx of thumb	extends thumb
Extensor indicis	O: ulna I: index finger	extends index finger
Abductor pollicis longus	O: radius & thumb I: first metacarpal	abducts & extends thumb

TABLE 4

Muscles of the Thigh and Leg

Muscle	Origin/Insertion	Action
Gluteus maximus	O: ilium, sacrum, coccyx I: femur	extends & rotates thigh
Gluteus medius	O: ilium I: femur	abducts & rotates thigh
Pectineus	O: pubis I: femur	adducts & flexes thigh
Adductor longus	O: pubis I: femur	adducts, flexes, & rotates thigh
Adductor brevis	O: pubis I: femur	adducts, flexes, & rotates thigh
Adductor magnus	O: pubis, ischium I: femur	adducts, flexes, & rotates thigh
Gracilis	O: pubis I: tibia	adducts thigh & flexes leg
Sartorius	O: ilium I: tibia	flexes & rotates thigh, flexes leg
Quadriceps femoris: rectus femoris	O: ilium, femur I: patella, tibia	extends leg, flexes thigh
Quadriceps femoris: vastus lateralis	O: ilium, femur I: patella, tibia	extends leg
Quadriceps femoris: vastus medialis	O: ilium, femur I: patella, tibia	extends leg
Quadriceps femoris: vastus intermedius	O: ilium, femur I: patella, tibia	extends leg
Biceps femoris (hamstrings)	O: ischium, femur I: fibula	flexes & rotates leg, extends thigh
Semitendinosus (hamstrings)	O: ischium I: tibia	flexes & rotates leg, extends thigh
Semimembranosus	O: ischium I: tibia	flexes & rotates leg, extends thigh
Tibialis anterior	O: tibia I: 1^st metatarsal & cuneiform	dorsiflexes & inverts foot
Extensor digitorum longus	O: tibia, fibula I: phalanges of toes	dorsiflexes & everts foot, extends toes
Gastrocnemius	O: femur I: calcanues	plantar flexes foot, flexes leg
Soleus	O: tibia, fibula I: calcaneus	plantar flexes foot