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Major Skeletal Muscles

There are more than 600 muscles in the body, but only a few of the major muscles are considered here.

Muscles of Facial Expression And Mastication

Muscles of the face and scalp produce the facial expressions that help communicate feelings, such as anger, sadness, happiness, fear, disgust, pain, and surprise. Most have origins on skull bones and insertions on the dermis of the skin.

BuccinatorLateral surfaces of maxilla and mandibleOrbicularis orisCompresses cheeks inward
EpicraniusThis muscle consists of two parts: the frontal belly and the occipital belly. They are joined by the epicranial aponeurosis, which covers the top of the skull.
Frontal bellyEpicranial aponeurosisSkin and muscles superior to the eyesElevates eyebrows and wrinkles forehead
Occipital bellyBase of occipital boneEpicranial aponeurosisPulls scalp posteriorly
Orbicularis oculiFrontal bone and maxillaeSkin around eyeCloses eye
Orbicularis orisMuscles around mouthSkin around lipsCloses and puckers lips; shapes lips during speech


Fascia of superior chestMandible and muscles around mouthDraws angle of mouth inferiorly
ZygomaticusZygomatic boneOrbicularis oris at angle of the mouthElevates corners of mouth (smiling)

The epicranius is an unusual muscle. It has a large epicranial aponeurosis that covers the top of the skull and two contractile portions: the frontal belly over the frontal bone and the occipital belly over the occipital bone.

Two major pairs of muscles elevate the mandible in the process of mastication (chewing): the masseter and the temporalis.

Muscles That Move The Head

Several pairs of neck muscles are responsible for flexing, extending, and rotating the head. Table below lists two of the major muscles that perform this function: the sternocleidomastoid and the splenius capitis. The trapezius can also extend the head, although this is not its major function.

SternocleidomastoidClavicle and sternumMastoid process of temporal boneContraction of both muscles flexes head toward chest; contraction of one muscle turns head away from contracting muscle
Splenius capitisInferior cervical andMastoid processContraction of both muscles extends head;
superior thoracic vertebraeof temporal bonecontraction of one muscle turns head toward same side as contracting muscle

Muscle of The Abdominal Wall

The abdominal muscles are paired muscles that provide support for the anterior and lateral portions of the abdominal and pelvic regions, including support for the internal organs. The muscles are named for the direction of their muscle fibers: rectus abdominis, external oblique, internal oblique, and transversus abdominis. They are arranged in overlapping layers and are attached by larger aponeuroses that merge at the anterior midline to form the linea alba, or white line.

Rectus abdominisPubic symphysis and pubisXiphoid process of sternum and costal cartilages of ribs 5 to 7Tightens abdominal wall; flexes the vertebral column
External obliqueAnterior surface of inferior eight ribsIliac crest and linea albaTightens abdominal wall; rotation and lateral flexion of the vertebral column
Internal obliqueIliac crest and inguinal ligamentCartilage of inferior four ribs, pubis, and linea albaSame as above
Transversus abdominisIliac crest, cartilages of inferior six ribs, processes of lumbar vertebraePubis and linea albaTightens abdominal wall

Muscles of Breathing


Movement of the ribs occurs during breathing and is brought about by the contraction of two sets of muscles that are located between the ribs. The external intercostals elevate and protract the ribs during inspiration, and the internal intercostals depress and retract the ribs during expiration. The primary breathing muscle is the diaphragm, a thin sheet of muscle that separates the thoracic and abdominal cavities.

DiaphragmLumbar vertebrae, costalCentral tendonForms floor of thoracic cavity;
cartilages of inferior ribs.located at midpointdepresses during contraction.
xiphoid processof musclecausing inspiration
External intercostalsInferior border ofSuperior borderElevates and protracts ribs
rib aboveof rib belowduring inspiration
Internal intercostalsSuperior border of ribInferior borderDepresses and retracts ribs
belowof rib aboveduring expiration

Muscles That Move The Pectoral Girdle


Pectoral girdle muscles originate on bones of the axial skeleton and insert on the scapula or clavicle. Because the scapula is supported mainly by muscles, it can be moved more freely than the clavicle. The trapezius is a superficial trapezoid-shaped muscle that covers much of the superior back. The rhomboid major and minor and the ievator scapulae lie deep to the trapezius. Each serratus anterior is located on the lateral surface of the superior ribs near the axillary region. The pectoralis minor lies deep to the pectoralis major. It protracts and depresses the scapula.

TrapeziusOccipital bone; cervical and thoracic vertebraeClavicle; spine and acromion of scapulaElevates clavicle; adducts and elevates scapula; extends head
Rhomboid major and minorSuperior thoracic vertebraeMedial border of scapulaAdducts and elevates scapula
Levator scapulaeCervical vertebraeSuperior medial margin of scapulaElevates scapula
Serratus anteriorSuperior eight to nine ribsMedial border of scapulaDepresses, protracts, and rotates scapula
Pectoralis minorAnterior surface of superior ribsCoracoid process of scapulaDepresses and protracts scapula

Muscles That Move The Arm And Forearm

Movement of the humerus is enabled by the muscles that originate on the pectoral girdle, ribs, or vertebrae and insert on the humerus. The arrangement of these muscles and the ball-and-socket joint between the humerus and scapula enable great freedom of movement for the arm. The pectoralis major is the large superficial muscle of the chest. The deltoid is the thick muscle that caps theshoulder joint. The supraspinatus, infraspinatus, and teres minor cover the posterior surface of the scapula.

The anterior surface of each scapula is covered by the subscapularis. These four muscles and their tendons surround the head of the humerus at the shoulder joint, making up the rotator cuff The muscles and tendons of the rotator cuff are the only structures stabilizing the shoulder joint; thus the joint is fairly unstable compared to other joints. However, this relative lack of stability is what allows the shoulder’s mobility. The fatissimus dorsi is a broad, sheetlike muscle that covers the inferior back. The teres major assists the latissimus dorsi and is located just superior to it.

Muscles moving the forearm originate on either the humerus or the scapula and insert on either the radius or the ulna. Three flexors occur on the anterior surface of the arm: the biceps brachii, brachialis, and brachioradialis. One extensor, the triceps brachii, is located on the posterior surface of the arm.


Pectoralis majorClavicle, sternum, and cartilages of superior ribsGreater tubercle of humerusAdducts, flexes, and medially rotates arm
DeltoidClavicle and spine, and acromion of scapulaDeltoid tuberosity of humerusAbducts, flexes, and extends arm
Latissimus dorsiInferior thoracic and lumbar vertebrae; sacrum; inferior ribs; iliac crestIntertubercular sulcus of humerusAdducts, extends, and medially rotates arm
Teres majorInferior angle of scapulaDistal to lesser tubercle of humerusSame as above
Rotator cuff musclesThese four muscles stabilize the shoulder joint
SupraspinatusSuperior to spine of scapulaGreater tubercle of humerusAbducts arm
InfraspinatusInferior to spine of scapulaGreater tubercle of humerusLaterally rotates arm
Teres minorLateral border of scapulaGreater tubercle of humerusLaterally rotates arm
SubscapularisAnterior surface of scapulaLesser tubercle of humerusMedially rotates arm


Biceps brachiiCoracoid process and tubercle superior to glenoid cavity of scapulaRadial tuberosity of radiusFlexes forearm and supination, also flexes arm
BrachialisDistal, anterior surface of humerusCoronoid process of ulnaFlexes forearm
BrachioradialisLateral surface of distal end of humerusLateral surface of radius superior to styloid processFlexes forearm
Triceps brachiiLateral and medial surfaces of humerus and tubercle inferior to glenoid cavity of scapulaOlecranon of ulnaExtends forearm, also extends arm

Muscles That Move The Wrist And Fingers

Many muscles that produce the various movements of the wrist and fingers are located in the forearm. Only a few of the larger superficial muscles are considered here. They originate from the distal end of the humerus and insert on carpal bones, metacarpals, or phalanges. Flexors on the anterior surface include the flexor carpi radialis, flexor carpi ulnaris, and palmaris longus. Extensors on the posterior surface include the extensor carpi radialis longus, extensor carpi ulnaris, and extensor digitorum (table 7.11; and figures 7.18 and 7.19). Note that the tendons of these muscles are held in position by a circular ligament at the wrist. Muscles That Move the Wrist and Fingers

Flexor carpi radialisMedial epicondyle of humerusMetacarpals II and IIIFlexes and abducts wrist
Flexor carpi ulnarisMedial epicondyle of humerus and olecranon of ulnaCarpal bones and metacarpal VFlexes and adducts wrist
Palmaris longusMedial epicondyle of humerusFascia of palmFlexes wrist
Extensor carpi radialis longusLateral epicondyle of humerusMetacarpal IIExtends and abducts wrist
Extensor carpi ulnarisLateral epicondyle of humerusMetacarpal VExtends and adducts wrist
Extensor digitorumLateral epicondyle of humerusPosterior surfaces of phalanges II—VExtends fingers

Muscles That Move The Thigh And Leg

Muscles moving the thigh span the hip joint. They insert on the femur, and most originate on the pelvic girdle. The iliacus and psoas major are located anteriorly, the gluteus maximus is located posteriorly and forms the buttocks, the gluteus medius is located deep to the gluteus maximus posteriorly and extends laterally, and the tensor fasciae latae is located laterally. The adductor longus and adductor magnus are both located medially.

The leg is moved by muscles located in the thigh. They span the knee joint and originate on the pelvic girdle or femur and insert on the tibia or fibula. The quadriceps femoris is composed of four muscles that have a common tendon that inserts on the patella. However, this tendon continues as the patellar ligament, which attaches to the tibial tuberosity-the functional insertion for these muscles. The biceps femoris, semitendinosus, and semimembranosus on the posterior surface of the thigh are often collectively called the hamstrings. The medially
located gracilis has two insertions that give it dual actions. The long, straplike sartorius extends diagonally across the anterior surface of the thigh and spans both the hip and knee joints. Its contraction enables the legs to cross.



IliacusFossa of iliumLesser trochanter of femurFlexes thigh
Psoas majorLumbar vertebraeLesser trochanter of femurFlexes thigh
Gluteus maximusPosterior surfaces of ilium, sacrum, and coccyxPosterior surface of femur and iliotibial tractExtends and laterally rotates thigh
Gluteus mediusLateral surface of iliumGreater trochanter of femurAbducts and medially rotates thigh
Tensor fasciae lataeAnterior iliac crestIliotibial tractFlexes and abducts thigh
Adductor longusPubis near pubic symphysisPosterior surface of femurAdducts, flexes, and laterally rotates thigh
Adductor magnusInferior portion of ischium and pubisSame as aboveSame as above


Quadriceps femorisFour muscles of the anterior thigh that extend the leg.
Rectus femorisAnterior inferior iliac spine andPatella; tendon continuesExtends leg and flexes thigh
superior margin of acetabulumas patellar ligament, which attaches to tibial tuberosity
Vastus lateralisGreater trochanter and posterior surface of femurSame as aboveExtends leg
Vastus medialisMedial and posterior surfaces of femurSame as aboveExtends leg
Vastus intermediusAnterior and lateral surfaces of femurSame as aboveExtends leg
HamstringsThree distinct muscles of the posterior thigh that flex leg and extend thigh.
Biceps femorisIschial tuberosity and posteriorHead of fibula and lateralFlexes and laterally rotates
surface of femurcondyle of tibialeg; extends thigh


Ischial tuberosityMedial surface of tibiaFlexes and medially rotates leg; extends thigh


Ischial tuberosityMedial condyle of tibiaFlexes and medially rotates leg; extends thigh


Pubis near pubic symphysisMedial surface of tibiaAdducts thigh; flexes leg and locks knee


Anterior superior iliac spineMedial surface of tibiaFlexes thigh and leg; abducts and laterally rotates thigh

Muscles That Move The Foot And Toes

Many muscles are involved in the movement of the foot and toes. They are located in the leg and originate on the femur, tibia, or fibula and insert on the tarsal bones, metatarsals, or phalanges. The posterior leg muscles include the gastrocnemius and soleus, which insert through a common tendon, the calcaneal (Achilles) tendon, which attaches to the calcaneus. The tibialis anterior is anteriorly located, and the extensor digitorum longus lies lateral to it. Note that although the extensor digitorum extends the toes, as its name implies, it also dorsiflexes the foot. The fibularis longus is located on the lateral surface of the leg.

GastrocnemiusMedial and lateral condyles of femurCalcaneus by the calcaneal tendonPlantar flexes foot and flexes leg
Posterior surface of tibia and fibulaCalcaneus by the calcaneal tendonPlantar flexes foot
Fibularis longusLateral condyle of tibia andMetatarsal I and tarsalPlantar flexes and everts foot;
head and body of fibulabonessupports arch
Tibialis anteriorLateral condyle and surface of tibiaMetatarsal I and tarsal bonesDorsiflexes and inverts foot
Extensor digitorum longusLateral condyle of tibia and anterior surface of fibulaPhalanges of toes II-VDorsiflexes and everts foot; extends toes


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