The Muscular System Types of Muscles. Skeletal Muscles There are close to 700 muscles in the body You will learn about 60 of them and this is a monumental

The Muscular SystemTypes of Muscles

Skeletal Muscles

There are close to 700 muscles in the body You will learn about 60 of them and this is a

monumental task The job of learning all of these muscles will still

require a great effort on your part Memorization will be easier if you apply what you

have learned so far Start with the name of the muscle and identifying it on

a figure Then figure out its points of attachments To learn their functions act it out on your own body!

Skeletal Muscles

Muscles can’t push; they can only pull (contraction) Body movements are the result of two or more

muscles acting together Insertion (attachment on a movable bone) moves

towards origin (immovable point of attachment) The fleshy part of the muscle between the two

tendons of the origin and insertion is the belly

Functional Groups

Movements are usually the result of several skeletal muscles acting as a group rather than acting alone

Most skeletal muscles are arranged in opposing pairs at joints

Muscles can be classified into four functional groups

Prime mover (agonist) Muscle with the major responsibility for a certain movement

Ex: The biceps brachii is the prime mover of elbow flexion

Antagonist Muscle that opposes or reverses a movement

Ex: The triceps act as antagonists for the biceps in elbow flexion

If the triceps is also considered a prime mover of the elbow extension, then what muscle would be the antagonist?

Functional Groups

Synergist Muscle that helps a prime mover by adding a little extra force to

the same movement or reducing undesirable movements that might occur

Ex: Finger-flexor muscles cross both the wrist and the finger joints. You can make a fist without bending your wrist because synergist muscles stabilize the wrist joints.

Fixator Synergists that immobilize a bone or a muscle’s origin so that the

prime mover has a stable base on which to act

Ex: fixator muscles that run from the axial skeleton to the scapula can immobilize the scapula so that only desirable movements occur at the shoulder joint; erector spinae group

Naming Skeletal Muscles

Skeletal muscles are named for structural or functional characteristics

Direction of muscle fibers

Some muscles reveal the direction in which their fibers run in reference to some imaginary line in the body (midline)

Ex: rectus (parallel); oblique (diagonal); transverse (perpendicular)

Relative size of the muscle

Ex: maximus (largest), minimus (smallest), longus (long), brevis (short), latissimus (widest), longissimus (longest), magnus (large), major (larger), minor (smaller), vastus (huge)


Location of the muscle

Some muscle names indicate the bone or body region with which they are associated

Ex: temporalis (temporal), frontalis (frontal), intercostals (costal = ribs)

Number of origins

Some muscles have more than one origin or head

Ex: biceps (two), triceps (three), quadriceps (four)

Location of the attachments (insertion and origin)

Some muscles are named according to their points of origin and insertion

The origin is always named first

Ex: sterno (on the sternum), cleido (clavicle). mastoid (mastoid process); sternocleidomastoid

Shape of the muscle

Some muscles are named for their distinctive shapes

Ex: deltoid (triangular); trapezius (trapezoid), orbicularis (circular), platys (flat), quadratus (square, four-sided), gracilis (slender)


Action of the muscle

Some muscles are named for the movement that they produce

Ex: flexor (decreases angle), extensor (increases an angle), abductor (away from midline), adductor (towards the midline)

Often several criteria are combined in naming a muscle

Ex: Extensor carpi radialis longus

Muscle’s action = extensor

Location = carpi (wrist); radialis (over radius)

Size = longus

Naming Muscles Video


Gross Anatomy of Skeletal Muscles

Facial and Neck Muscles

Frontalis

Orbicularis oculi

Orbicularis oris

Buccinator

Zygomaticus

Masseter

Temporalis

Platysma

Sternocleidomastoid

Trunk Movement1. Muscles that assist in breathing in (inspiration) and out (expiration)

2. Muscles that move the trunk and compress the abdomen

3. Muscles of the abdominal wall; help move the vertebral column

External intercostals

Internal intercostals

Diaphragm

Rectus abdominus

External oblique

Internal oblique

Transversus abdominus

Back Extension

Erector Spinae Group

Iliocostalis

Longissimus

Spinalis

Scapula Movement

Trapezius

Movement of Humerus Pectoralis major

Deltoid

Latissimus Dorsi

Movement of Elbow

Biceps brachii

Brachialis

Brachioradialis

Triceps brachii

Movement of Wrist

Flexion

Flexor carpi radialis

Flexor carpi ulnaris

Extension

Extensor carpi ulnaris

Extensor carpi radialis longus

Movement of the Hip

Iliopsoas

Iliacus

Psoas major

Adductor group(3)

Adductor magnus

Adductor longus

Adductor brevis

Gluteus maximus

Gluteus medius

Movement of the Hip and Knee

Sartorius

Quadriceps Group (4)

Rectus Femoris

Vastus lateralis

Vastus medialis

Vastus intermedius

Gracilis

Hamstrings Groups (3)

Biceps femoris

Semitendinosus

Semimembranosus

Muscles of the Ankle

Gastrocnemius (knee also)

Tibialis anterior Fibularis longus Fibularis brevis Soleus Tibialis posterior Extensor digitorum

longus (toes also) Flexor digitorum

longus (toes also)

Anterior Muscles

Posterior Muscles

Figure 6.21


Muscles that provide the ability to express emotions

Muscles usually insert directly into skin; therefore the skin is what moves


Frontalis

Orbicularis oculi

Orbicularis oris

Buccinator

Zygomaticus

Masseter

Temporalis

Platysma

Sternocleidomastoid

Facial Muscles

Muscle Origin Insertion FunctionFrontalis

Covers the frontal boneNo bony attachments

Cranial aponeurosis

Skin of eyebrows

Raises eyebrowsWrinkles skin of foreheadPulls scalp anteriorly

Facial Muscles

Muscle Origin Insertion FunctionOrbicularis oculi

Orb = circularOculi = eye

Frontal bone and maxilla bone

Tissue of eyelid Closes eye, squint, blink and wink

Facial Muscles

Muscle Origin Insertion FunctionOrbicularis oris

“The Kissing Muscle”Oris = mouth

Muscles encircling mouth

Skin of at corner of mouth

Closes and protrudes lipsCompresses lips against teeth

Facial Muscles

Muscle Origin Insertion FunctionBuccinator

Bucc = cheek

Maxilla and mandible

Orbicularis oris

Draws corners of mouth laterallyHolds food between teeth when chewingCompresses cheeks against teeth Used in whistling, blowing and suckingWell developed in infants

Facial Muscles

Muscle Origin Insertion FunctionZygomaticus

“Smiling Muscle”

Zygomatic bone Skin and muscle at corner of lips

Raises corners of lips

Facial Muscles

Muscle Origin Insertion Function Type

Masseter

Masseter = chewer

Maxilla and zygomatic arch

Ramus of mandible

Elevates mandibleCloses jaw

Prime mover

Facial Muscles

Muscle Origin Insertion Function TypeTemporalis Temporal

boneMandible Closes jaw

Elevates mandibleSynergist to masseter

Neck Movement

Muscle Origin Insertion FunctionPlatysma

platy = broad, flat

Fascia (CT) over pectoralis major and deltoid muscles

Mandible and skin around mouth

Tenses skin of neckPulls corners of mouth inferiorlyProduces downward sag of mouth

Neck Movement

Muscle Origin Insertion Function TypeSternocleidomastoid

Anterior surface of neck“Two-headed”Sterno = sternumCleido = clavicleMastoid = mastoid process

1. Manubrium of sternum

2. Clavicle

Mastoid process of temporal bone

Flexes neckRotates head“The Prayer Muscle”

Prime mover

Trunk Movement

External intercostalis

Internal intercostalis

Diaphragm

Rectus abdominus

External oblique

Internal oblique

Transversus abdominus

1. Muscles that assist in breathing in (inspiration) and out (expiration)

2. Muscles that move the trunk and compress the abdomen

3. Muscles of the abdominal wall; help move the vertebral column

Breathing Muscles

Muscle Origin Insertion Function TypeExternal Intercostalis

External = outsideInter = betweenCostals = ribs

Inferior border of rib above (1-11)

Superior border of rib below (2-12)

InhalationElevates ribs Increases thoracic volume

Synergists to diaphragm

Breathing Muscles

Muscle Origin Insertion Function TypeInternal Intercostalis

Internal = insideInter = betweenCostals = ribs

Superior border of rib below (1-11)

Inferior border of rib above (2-12)

ExhalationDepresses rib cage Decreases thoracic volume

Antagonist to external intercostals

Breathing Muscles

Muscle Origin Insertion Function TypeDiaphragm

Dia = acrossPhragm = partitionSeparates the thoracic and abdominal cavities

Xiphoid process, ribs 10-12, lumbar vertebrae

Central tendon

Contraction causes it to flatten Resulting in inhalation

Prime mover

Abdominal Compression

Four paired muscles that protect the abdominal cavity

All muscles meet at the midline to form the linea alba, a tough, fibrous band that extends from the xiphoid process to the pubic symphysis

Abdominal compression of these muscles assists in urination, defecation, childbirth, vomiting, coughing, sneezing, screaming, burping, and nose blowing

Muscle Origin Insertion FunctionRectus abdominus

Rectus= straightAbdom = abdomenLong, medial superficial muscle

Pubic crest and pubic symphysis

Xiphoid process and ribs 5-7

Flexes vertebral columnCompresses abdomen Stabilizes pelvis Used in sit-ups“Six pack”


Muscle Origin Insertion FunctionExternal oblique

Largest and most superficialExternal = outsideOblique = running at an angle (downward and medially)

Lower eight ribs (5-12)

Linea alba and iliac crest

Flex vertebral columnCompress abdomenLateral rotates trunk


Muscle Origin Insertion FunctionInternal oblique

Internal = deepOblique = running at an angle (upward and medially)

Inguinal ligament and iliac crest

Linea alba and last four ribs

Flex vertebral columnCompress abdomen Laterally rotates trunk


Muscle Origin Insertion FunctionTransversus abdominus

Transversus = running straight acrossDeepest muscle

Inguinal ligament, ribs 7-12, iliac crest

Xiphoid process, linea alba and pubis

Compress abdomen


Back Extension


Iliocostalis

Longissimus

Spinalis

Three columns of paired, deep muscles of back

Prime mover of back extension

Provide resistance to control bending forward

Extensors that promote return to erect position

Back Extension

Muscle Origin Insertion Function TypeIliocostalis

Ilio = iliumCostal = ribsMost lateral of the group

Iliac crestRibs 3 - 12Vertebrae

Ribs, thoracic and cervical vertebrae

Rotates and extends vertebral column and headMaintain posture



Iliocostalis

Longissimus

Spinalis

Back Extension

Muscle Origin Insertion Function TypeLongissimus

Middle of the groupLongissimus = longest

Transverse processes of lumbar through cervical

Transverse processes of thoracic through cervical, ribs

Rotates and extends vertebral column and headExtends head and turns the face toward the same side



Iliocostalis

Longissimus

Spinalis

Back Extension

Muscle Origin Insertion Function TypeSpinalis

Spin = vertebral columnMost medial of the group

Spinous process of upper and lower thoracic vertebrae

Occipital boneSpinous process of upper thoracic and cervical vertebrae

Rotates and extends vertebral column

Prime Mover


Iliocostalis

Longissimus

Spinalis

Scapula Movement

Muscle Origin Insertion FunctionTrapezius

Trapezoid = irregular four-sided figureLarge muscle in upper back

Occipital bone, spinous process of C7-T12

Acromion and spine of scapula; clavicle

Stabilizes, elevates,rotates and adducts scapula (shrugging shoulders)Extends neck

Trapezius

Movement of Humerus Pectoralis major

Deltoid

Latissimus Dorsi

Muscle Origin Insertion Function TypePectoralis Major

Pectus = chestMajor = largerSuperior portion of chest

Clavicle, sternum and ribs 1-7

Greater tubercle of humerus

Flexion, adduction and medial rotation of armPulls rib cage upwardUsed in movements for climbing, throwing, etc

Prime mover of arm flexion and adduction

Movement of Humerus

Muscle Origin Insertion Function TypeDeltoid

Delta = triangularRounded shoulder muscleCommonly used for IM injection

Clavicle, acromion and spine of scapula

Deltoid tuberosity of humerus

Flexion and medial rotation of arm (anterior)Extension and lateral rotation of the arm (posterior) Arm abduction (lateral)

Prime mover of arm flexion (anterior), extension (posterior), and abduction

Movement of Humerus

Muscle Origin Insertion Function TypeLatissimus dorsi

Latissimus = widestDorsi = backBroad, flat muscle of lower back“The Lats”

T7-T12 , L1-L5, sacrum, ribs 10-12, iliac crest

Proximal humerus

Extension and adduction of armMedially rotates arm at shoulderDraws arm inferiorly and posteriorly

Prime mover of arm extension and adduction

Movement of Humerus

Movement of Elbow

Muscle Origin Insertion Function TypeBiceps brachii

Bi = twoBrachii = armLocated on anterior side of the upper arm

1. Coracoid process2. Glenoid cavity of

scapula

Radial tuberosity

Flexes elbowSupinationFlexes arm

Prime mover of elbow flexion

Biceps brachii

Brachialis

Brachioradialis

Triceps brachii

Movement of Elbow


Brachialis

Deep to biceps

Anterior, distal humerus

Coronoid process of ulna

Flexes forearm (lifts the ulna as biceps lift the radius)

Prime mover

Brachioradialis

Superficial muscle of lateral forearmRadi = radius

Lateral, distal end of humerus

Styloid process of radius

Flexes forearm (elbow) Synergist to biceps and brachialis

Movement of Elbow

Muscle Origin Insertion Function TypeTriceps brachii

Tri – threePosterior side of upper arm

1. Scapula2. & 3. proximal

humerus

Olecranon process of ulna

Elbow extensionArm extensionAdducts arm

Prime mover of elbow extensionAntagonist of forearm flexion

Movement of Wrist

Flexion



Extension



Flexors are usually on anterior side of the body

Extensors are usually on the posterior side of the body

Exception: Knee flexion and extension

Movement of Wrist

Muscle Origin Insertion Function TypeFlexor carpi radialis

Flex = decrease angleCarpi = wristRadi = radiusRuns diagonally across forearm (anterior)

Medial epicondyle of humerus

Metacarpal 2 and 3

Wrist flexion and abduction

Prime mover for wrist flexion

Flexion



Movement of Wrist

Muscle Origin Insertion Function TypeFlexor carpi ulnaris

Ulnar = ulna(anterior)

Medial epicondyle of humerus and proximal ulna

Metacarpal 5 Wrist flexionWrist adduction

Prime mover of wrist flexion

Flexion



Movement of Wrist

Muscle Origin Insertion FunctionExtensor carpi ulnaris

Most medial of superficial muscles (posterior)Extend = increase angle between two bones

Lateral epicondyle of humerus and proximal ulna

Metacarpal 5 Wrist extensionWrist adduction

Extension



Movement of Wrist

Muscle Origin Insertion FunctionExtensor carpi radialis longus

Humerus Metacarpals 2 & 3 Wrist extension Wrist abduction

Extension



Movement of the Hip

Most originate on pelvis and insert on femur

Iliopsoas

Iliacus

Psoas major

Adductor group (3)

Adductor magnus

Adductor longus

Adductor brevis

Gluteus maximus

Gluteus medius


Iliacus

Iliac = iliumLarge, fan-shaped lateral muscle

Iliac fossa and sacrum

Lesser trochanter of femur

Flexion of thighLateral rotation of thighFlexion of trunk

Prime Mover hip flexion

Psoas major

Psoa = loin muscleTenderloin in beefLonger, thicker and more medial muscle

Transverse processes of L1-L5 and T12

Lesser trochanter of femur

Flexes thighLateral rotation of thighFlexes lumbar vertebrae

Prime mover hip flexion

Iliopsoas

Iliacus

Psoas major

Movement of the Hip

Muscle Origin Insertion FunctionAdductor Magnus

Magnus = largeTriangular muscle with broad insertion

Ischium and pubis

Femur Adducts thighMedially rotates thighExtends thigh (posterior)

Adductor Muscles

Magnus

Longus

Brevis

Form medial aspect of thigh

Adduct = movement towards midline

“Pulled groin”

Movement of the Hip

Muscle Origin Insertion FunctionAdductor Longus

Longus = long

Pubis crest and pubic symphysis

Femur Adducts thighFlexes thighMedially rotates thigh

Adductor Muscles

Magnus

Longus

Brevis

Movement of the Hip

Movement of the Hip

Muscle Origin Insertion FunctionAdductor brevis

Brevis = short

Inferior ramus of pubis

Femur Adducts thighsFlexes thighMedially rotates thigh

Adductor Muscles

Magnus

Longus

Brevis

Muscle Origin Insertion Function TypeGluteus maximus

Glutos = buttockMaximus = largestLarge, superficial posterior muscle at the top of each legSite of IM injection

Iliac crest, sacrum, and coccyx

Tuberosity of femur

Thigh extensionLateral rotation of thighAbducts thigh

Prime mover of thigh extension

Movement of the Hip

Muscle Origin Insertion Function TypeGluteus medius

Medius = middleDeep to gluteus maximusIM injection site

Outer ilium Greater trochanter of femur

Abducts thighMedially rotates thighStabilizes pelvis

Prime mover of thigh abduction

Movement of the Hip


Sartorius

Quadriceps Group (4)

Rectus femoris

Vastus lateralis

Vastus medialis

Vastus intermedius

Gracilis

Hamstrings Groups (3)

Biceps femoris

Semimembranosus

Semitendinosus

Muscle Origin Insertion FunctionSartorius

Sartor = tailor “Tailor’s muscle” – crossing the legLongest muscle in the bodyRuns obliquely across anterior surface of thighCrosses both hip and knee joints

Anterior iliac spine

Medial side of proximal tibia

Thigh flexionThigh abductionLaterally rotation thighKnee flexion (weak)


Muscle Origin Insertion FunctionGracilis

Gracilis = slenderLong, thin superficial muscle of medial side

Pubis Medial surface of tibia Adducts thighMedial rotation of thighKnee flexion



Muscle Origin Insertion Function TypeRectus femoris

Rectus = straightFemoris = femurSuperficial muscle of anterior thigh

Anterior iliac spine (pelvis)

Tibial tuberosity via patellar ligament

Knee extensionThigh flexion

Prime mover of knee extension

Quadriceps Femoris = 4 heads

Rectus femoris

Vastus lateralis

Vastus medialis

Vastus intermedius

4 heads share insertion at quadriceps tendon which inserts into the patella which continues as the patellar ligament and into the tibial tuberosity

Muscle Origin Insertion Function TypeVastus lateralis

Vastus = largeLateralis = lateralCommon IM injection site

Greater trochanter (femur)

Patella and tibial tuberosity

Extend kneeStabilizes knee

Prime mover of knee extension

Quadriceps Group = 4 heads

Rectus femoris

Vastus lateralis

Vastus medialis

Vastus intermedius


Muscle Origin Insertion Function TypeVastus medialis

Medialis = medial

Femur Patella and tibial tuberosity

Extend knee Prime mover of knee extension


Rectus femoris

Vastus lateralis

Vastus medialis

Vastus intermedius


Muscle Origin Insertion Function TypeVastus intermedius

Intermedius = intermediate

Proximal femur

Patella tendon and tibia

Extend knee Prime mover of knee extension


Rectus femoris

Vastus lateralis

Vastus medialis

Vastus intermedius



Hamstring Group (posterior)

Biceps femoris

Semimembranosus

Semitendinosus

Posterior thigh muscles

Cross both hip and knee joints

Name comes from butchers using their tendons to hang hams

Muscle Origin Insertion Function TypeBiceps femoris

Bi = twoLateral muscle of group

1. Ischial tuberosity2. Distal femur

Proximal fibula Thigh extensionKnee flexionLaterally rotates leg when knee is flexed

Prime mover of thigh extension and knee flexion

Muscle Origin Insertion Function TypeSemimembranosus

Membranosus = membraneDeep to semitendinosus

Ischial tuberosity

Medial condyle of tibia

Extends thighFlexes knee

Prime mover of knee flexion



Biceps femoris

Semimembranosus

Semitendinosus

Muscle Origin Insertion Function TypeSemitendinosus

Semi = halfTendinosus = tendonMedial to biceps femoris

Ischial tuberosity

Medial tibia Extends thighFlexes knee

Prime mover of knee flexion



Biceps femoris

Semimembranosus

Semitendinosus


Gastrocnemius (knee also)

Soleus

Tibialis posterior

Tibialis anterior

Fibularis longus

Fibularis brevis

Muscles of Ankle and Toes

Extensor digitorum longus (anterior)

Flexor digitorum longus (posterior)


Muscle Origin Insertion Function TypeGastrocnemius

Gastro = bellycneme = leg Two bellied muscle“Dancer’s Toe”

Medial and lateral condyles of femur

Calcaneus via Achilles tendon

Plantar flexionKnee flexion

Prime mover of plantar flexion


Muscle Origin Insertion Function TypeSoleus

Soleus = a type of flat fishBroad, flat muscleDeep to gastrocnemius on posterior surface

Posterior tibia and fibula

Calcaneus via Achilles tendon

Plantar flexion Prime mover of plantar flexion


Muscle Origin Insertion Function TypeTibialis posterior

Posterior = backThick, flat muscle deep to soleus

Posterior tibia and fibula

Metatarsals 2-4 and tarsals

Foot inversion Plantar flexion

Prime mover of inversion


Muscle Origin Insertion Function TypeTibialis anterior

Anterior = frontSuperficial muscle of anterior leg

Lateral tibia

1st metatarsal and tarsal

DorsiflexionInversion

Prime mover of dorsiflexion


Muscle Origin Insertion FunctionFibularis longus

Superficial lateral muscle over fibula

Proximal fibula and lateral condyle of tibia

1st metatarsal and tarsal

Plantar flexionEversion


Muscle Origin Insertion FunctionFibularis brevis

Brevis = shortSmaller muscleDeep to fibularis longus

Distal fibula shaft

Proximal end of 5th metatarsal

Plantar flexion Eversion

Muscle Origin Insertion Function TypeExtensor digitorum longus

Digit = toesLateral to tibialis anterior muscle

Lateral condyle of tibia and fibula

Distal phalanges 2-5

Extends toes 2-5Dorsiflexion

Prime mover of toe extension 2-5

Muscles of the Ankle and Toes

Muscles of the Ankle and Toes

Muscle Origin Insertion Function TypeFlexor digitorum longus

Long, narrow muscleRuns medial to tibialis posterior

Posterior tibia

Distal phalanges of toes 2-5

Toe flexionPlantar flexionInversionHelps foot grip ground

Prime mover of toe flexion 2-5

Anterior Muscles

Posterior Muscles

Documents

The Muscular System Types of Muscles. Skeletal Muscles There are close to 700 muscles in the body You will learn about 60 of them and this is a monumental