Muscle Review Chapters 9 & 10
Description: covers forehead and dome of skull – no boney attachments
Origin: galea aponeurotica Insertion: skin of the eyebrows, root of nose Action: raises eyebrows wrinkles forehead
skin horizontally
Epicranius - Frontal belly
Description: overlies posterior occiput; be pulling on the galea, fixes origin of frontalis
Origin: occipital and temporal bones Insertion: galea aponeurotica Action: fixes aponeurosis and pulls scalp
posteriorly
Epicranius – occipital belly
Description: fan-shaped muscle that covers part of the temporal, frontal and parietal bones
Origin: temporal fossa Insertion: coronoid process of mandible via
tendon Action: Closes jaw, elevates and retract
mandible, maintains jaw position at rest
Temporalis
Description: thin, tripartite sphincter muscle of eyelid, surround rim of orbit
Origin: frontal and maxillary bones and ligaments around orbit
Insertion: tissue of eyelid Action: protects eye from intense light and
injury, blinking, squinting, draws eyebrows inferiorly
Orbicularis Oculi
Description: Powerful muscle that covers lateral aspect of mandibular ramus
Origin: zygomatic arch and maxilla Insertion: angle of ramus of mandible Action: prime mover of jaw closers: elevates
mandible
Masseter
Description: muscle pair extending diagonally from cheekbone to corner of mouth
Origin: zygomatic bone Insertion: skin and muscle at corner of
mouth Action: raises lateral corners of mouth
upward (smiling muscle)
Zygomaticus
Description: Complicated multilayered muscle of the lips with fibers that run in many different directions (most run circularly)
Origin: indirectly from maxilla and mandible, fibers blend with fibers of other facial muscles
Insertion: encircles mouth Action: closes lips, purses and protrudes lips
(kissing and whistling muscle)
Orbicularis Oris
Description: Unpaired, thin sheet-like superficial neck muscle, plays a role in facial expression
Origin: fascia of chest (over pectoral and deltoid)
Insertion: lower margin of mandible and skin at corner of mouth
Action: downward sag of mouth, tenses skin of neck for shaving
Platysma
Description: most medial muscle of the neck: thin, superficial except inferiorly, where cover by the sternocleidomastoid
Origin: manubrium and medial end of clavicle
Insertion: lower margin of hyoid bone Action: depresses larynx and hyoid bone if
mandible is fixed may also flex skull
Sternohyoid
Description: two-headed muscle loacted deep to the platysma on anterolateral surface of neck
Origin: manubrium and medial portion of clavicle
Insertion: mastoid process of temporal bone Action: primer mover of head flexion; actin
g alone can rotate head toward shoulder on opposite side, tilts head laterally
Sternocleidomastoid
Description: Flat, thin muscle directly beneath and obscured by pectoralis major
Origin: anterior surface of ribs 3-5 or (2-4) Insertion: coracoid process of scapula Action: With ribs fixed, draws scapula
forward and downward, with scapula fixed draws rib cage superiorly
Pectoralis minor
Description: large, fan-shaped muscle covering upper portion of chest, divided into clavicular and sternal parts
Origin: sternal end of clavicle, cartilage of ribs 1-6 (or 7) and aponeurosis of external oblique
Insertion: greater tubercle of humerus Action: prime mover of arm flexion, rotates
arm medially, assist in climbing, throwing, pushing and forced inspiration
Pectoralis major
Description: fan-shaped muscle; lies deep to the scapula, beneath and inferior to pectoral muscles on lateral rib cage
Origin: ribs 1-8 (or 9) Insertion: entire anterior surface of
vertebral border of scapula Action: prime mover to protract and hold
scapula against chest wall; abduction and raising arm, pushing punching (boxer’s muscle)
Serratus Anterior
Description: partially covered by deltoid and trapezius, named for its scapular location: rotator cuff muscle
Origin: infraspinatus fossa of scapula Insertion: greater tubercle of humerus
posterior to supraspinatus Action: helps to hold the head of humerus in
the glenoid cavity, stabilizing the joint,rotates humerus laterally
Infraspinatus
Description: Thick, rounded muscle located inferior to teres minor
Origin: postrior surface of scapula at inferior angle
Insertion: intertubercular sulcus of humerus; insertion tendon is fused with latisimus dorsi
Action: posteromedially extends, medially rotates and adducts humerus; synergist of lats
Teres Major
Description: two rectangular muscles lying deep to the trapezius and inferior to levator scapulae
Origin: spinous processes of C7 and T5 Insertion: medial border of scapula Action: retract scapula “squaring the
shoulders” rotate glenoid cavity of scapula downward (paddling a canoe) stabilizing shoulder
Rhomboids
Description: broad, flat, triangular muscle of low back
Origin: indirect attachment via lumbodorsal fascia into spines of lower 6 thoracic vertebrae, lumbar vertebrae and lower 3-4 ribs, iliac crest
Insertion: spirals around teres major to insert in floor of intertubercular sulcus of humerus
Action: primer mover of arm extension, arm adduction, medially rotates arm at shoulder
Latissimus dorsi
Description: (external)11 pairs lie between ribs, fibers run obliquely down and forward from rib to rib (internal)11 pairs, run deep and to right angles of external fibers
Origins: (external) inferior border of rib above (internal) superior border of rib below
Insertions: (external) superior border of rib below, (internal) inferior border of rib above
Actions: (external)aid in inspiration, (internal) aid in expiration
Intercostals internal/external
Description: medial superficial muscle pair extend from pubis to rib cage, segmented 3 sections
Origin: pubic crest and symphysis Insertion: xiphoid process and costal
cartilage Action: flex and rotate lumbar region of
vertebral column used in sit-ups and curls
Rectus Abdominis
Description: largest and most superficial of three lateral muscles, fibers run downward and medially
Origin: fleshy strips from outer surface of lower 8 ribs
Insertion: fibers insert into linea alba, pubic crest and tubercle, and iliac crest
Action: aid in flexing vertebral column, trunk rotation and lateral flexion, used in oblique curls
External Oblique
Description: most fibers run upward and medially, fans so some run down and medially
Origin: lumbar fascia, iliac crest, and inguinal ligament
Insertion: linea alba, pubic crest, last 3-4 ribs
Action: same as external oblique
Internal Obliques
Description: deepest muscle of abdominal wall, fiber run horizontally
Origin: inguinal ligament, lumbar fascia, cartilage of last 6 ribs
Insertion: linea alba, pubic crest Action: compresses abdominal contents
Transversus Abdominus
Description: thick, multi-pennate muscle forming rounded shoulder muscle mass
Origin: embraces insertion of trapezius; lateral third of clavicle, acromion and spine of scapula
Insertion: deltoid tuberosity of humerus Action: primer mover of arm abduction
Deltoid
Description: large fleshy muscle of posterior compartment of arm, 3 headed origin
Origin: long head: infraglenoid tubercle of scapula, lateral head: posterior shaft of humerus, medial head: posterior radial shaft distal to radial groove
Insertion: common tendon to olecranon process of ulna
Action: prime mover forearm extensor
Triceps brachii
Description: 2 headed fusiform muscle, bellies unite as approaching insertion
Origin: short head: corocoid process, long head: tubercle above the lip of glenoid cavity
Insertion: by common tendon to radial tuberosity
Action: flexes elbow joint and supinates forearm
Biceps brachii
Description: strong muscle that is immediately deep to biceps on distal humerus
Origin: front of distal humerus; embraces insertion of deltoid
Insertion: coronoid process of ulna Action: major forearm flexor (lifts ulna as
biceps lift radius)
Brachialis
Description: 2 headed muscle seen in superficial view between brachioradialis and flexor carpi radialis
Origin: medial epicondyle of humerus, coronoid process of ulna
Insertion: by common tendon to lateral radius, midshaft
Action: pronates forearm, weak flexor of elbow
Pronator teres
Description: superficial muscle of lateral forearm, extend from distal humerus to distal forearm
Origin: lateral supercondylar ridge at distal end of humerus
Insertion: base of styloid process of radius Action: synergist in forearm flexion
Brachioradialis
Description: Parallels brachioradialis on lateral forearm, and may blend with it
Origin: lateral supercondylar ridge of humerus
Insertion: base of 2nd metacarpal Action: extends wrist in conjunction with
extensor carpi ulnaris and abducts wrist in conjunction with flexor carpi radialis
Extensor carpi radialis longus
Description: runs diagonally across forearm, midway its fleshy belly is replaced by a flat tendon
Origin: medial epicondyle of humerus Insertion: base of 2nd and 3rd metacarpals Action: powerful flexor of wrist, abducts
hand
Flexor carpi radialis
Description: most medial of superficial posterior muscles; long slender muscle
Origin: lateral condyle of humerus and posterior border of ulna
Insertion: base of 5th metacarpal Action: Extends wrist in conjunction with the
extensor carpi radialis and adducts wrist in conjunctions with flexor carpi ulnaris
Extensor carpi ulnaris
Description: small fleshy muscle with a long insertion tendon
Origin: medial epicondyle of humerus Insertion: palmar aponeurosis; skin and
fascia of palm Action: weak wrist flexor; tenses skin and
fascia of palm during hand movement
Palmaris longus
Description: lies medial to extensor carpi radialis brevis; a detached portion of this muscle, called extensor digiti minimi, extends the little finger
Origin: lateral epicondyle of humerus Insertion: by four tendons into distal
phalanges 2-5 Action: prime mover of finger extension;
extends wrist, can abduct (flare) fingers
Extensor digitorum
Description: is a composite of two closely related muscles
Iliacus: large fan-shaped muscle (more lateral) origin: iliac fossa, crest, lateral sacrum
Psoas major: longer thicker more medial muscle (tenderlion) origin: transverse process, disks, bodies of L1-5 and T12
Insertion: lesser trochanter of femur Action: prime mover of flexing thigh and trunk
(bowing)
Iliopsoas
Description: Short, flat muscle; overlies adductor brevis on proximal thigh
Origin: pectineal line of pubis Insertion: inferior from lesser trochanter to
linea aspera of posterior femur Action: adducts, flexes, and medially rotates
thigh
Pectineus
Description: enclosed between fascia layers of anterolateral aspect of thigh, associated with medial rotators and flexors of thigh
Origin: anterior aspect of iliac crest and anterior superior iliac spine
Insertion: iliotibial tract Action: flexes and abducts thigh, rotates
thigh medially; steadies the knee and trunk on thigh by tensing iliotibial tract
Tensor fasciae latae
Description: Strap-like, superficial muscle running obliquely across anterior surface of thigh to knee, longest muscle in the body; crosses both hip and knee
Origin: anterior superior iliac spine Insertion: winds around medial aspect of
knee into medial aspect of tibia Action: flexes, abducts and laterally rotates
thigh, weak flexor of knee, “tailors muscle”
Sartorius
Description: overlies middle aspect of adductor magnus, most anterior of adductor muscles
Origin: pubis, near pubic symphysis Insertion: linea aspera Action: adducts, flexes and medially rotates
thigh
Adductor longus
Description: long, thin, superficial muscle of medial thigh
Origin: inferior ramus and body of pubis and ischial ramus
Insertion: medial surface of tibia, just inferior to its medial condyle
Action: adducts thigh, flexes and medially rotates thigh, especially during walking, flexes knee
Gracilis
Description: superficial muscle of anterior thigh, runs straight down thigh, longest head and only muscle of group to cross the hip
Origin: anterior inferior iliac spine and superior margin of acetabulum
Insertion: patela and tibial tuberosity via the patellar ligament
Action: extends knee and flexes thigh at hip
Rectus femoris
Description: largest head of the group, forms lateral aspect of thigh, common intramuscular injection site
Origin: greater trochanter, linea aspera Insertion: patella and tibial tuberosity Action: extends and stabilizes knee
Vastus lateralis
Description: forms inferomedial aspect of thigh
Origin: linea aspera, intertrochanteric line Insertion: Patella, and tibial tuburosity Action: extends knee; inferior fibers stabilize
patella
Vastus medialis
Description: The iliotibial tract, also known as the iliotibial band, is a thick strip of connective tissue connecting several muscles in the lateral thigh.
Origin: arises at its proximal end from the tendons of the tensor fasciae latae and gluteus maximus muscles.
Insertion: inserting on the lateral epicondyle of the tibia
Action: It also allows the tensor fascia latae and gluteus maximus muscles to support the extension of the knee while standing, walking, running and biking.
Iliotibial tract
Description: thick muscle largely covered by gluteus maximus, site for intramuscular injection
Origin: between anterior and posterior gleteal lines on lateral surface of ilium
Insertion: lateral aspect of greater trochanter
Action: abduct and medially rotates thigh, steadies pelvis, its action is extremely important in walking
Gluteus medius
Description: largest and most superficial muscle, forms bulk of buttock mass
Origin: dorsal ilium, sacrum, coccyx Insertion: gluteal tuberosity of femur,
iliotibial tract Action: major extensor of thigh, complex,
powerful, and most effective when thigh is flexed and force is necessary
Gluteus maximus
Description: a triangular muscle with broad insertion, is a composite muscle that is part adductor and part hamstring in action
Origin: ischial and pubic rami and ischial tuberosity
Insertion: linea aspera and adductor tubercle of femur
Action: anterior part adducts and medially rotates thigh, posterior part is synergist to hamstrings in thigh extension
Adductor magnus
Description: most lateral muscle of group, arises from two heads
Origin: ischial tuberosity, linea aspera, and distal femur
Insertion: head of fibula and lateral condyle of tibia
Action: Extends thigh and flexes knee, laterally rotates leg, especially when knee is flexed
Biceps femoris (hamstrings)
Description: lies medial to bicep femoris, it is quite fleshy, long slender tendon begins about 2/3 of way down thigh
Origin: ischial tuberosity Insertion: medial aspect of upper tibial shaft Action: Extends thigh at hip, flexes knee,
with semimembranosus, medially rotates leg
Semitendinosus
Description: Deep to the semitendinosis Origin: ischial tuberosity Insertion: medial condyle of tibia, via
oblique popliteal ligament to lateral condyle of femur
Action: extends thigh and flexes knee; medially rotates leg
Semimembranosus
Description: superficial muscle of pair, two prominent bellies that form proximal curve of calf
Origin: by two heads from medial and lateral condyles of femur
Insertion: posterior calcaneus via calcaneal tendon
Action: plantar flexes foot when knee is extended, It crosses the knee so it can flex the knee when foot is dorsiflexed
Gastrocnemius
Description: broad, flat muscle, deep to the gastrocnemius on posterior surface of calf
Origin: extensive origin from superior tibia, fibula, and interosseous membrane
Insertion: posterior calcaneus via calcaneal tendon
Action: plantar flexes foot; important locomotor and postural muscle during walking, running and dancing
Soleus
Description: superficial lateral muscle; overlies fibula
Origin: upper portion of lateral fibula Insertion: by long tendon that curves under
foot to first metatarsal and medial cuneiform
Action: plantar flexes and everts foot; may help keep foot flat on ground
Fibularis longus (peroneus)
Description: unipennate muscle on anterolateral surface of leg; lateral to tibialis anterior
Origin: lateral condyle of tibia, proximal ¾ of fibula, interosseous membrane
Insertion: middle and distal phalanges of toes 2-5
Action: prime mover of toe extension ( acts mainly at metatarsophalangeal joints), dorsiflexes foot
Extensor digitorum longus
Description: superficial muscle of anterior leg; laterally parallels sharp anterior margin of tibia
Origin: lateral condyle of upper 2/3 of tibial shaft; interosseous membrane
Insertion: inferior surface of medial cuneiform and first metatarsal
Action: prime mover of dorsiflexion; inverts foot, assists in supporting medial longitudinal arch
Tibialis anterior