Lab 12 A&P 2401 Muscles Dr. Kerins

internal intercostals

Action: Expiration; antagonistic to external intercostals. Origin: Superior border of rib below Insertion: Inferior border (costal groove) of rib above.

External intercostals

Action: Inspiration; synergist of diaphragm Origin: superior border of the rib above. Insertion: Superior border of rib below

quadriceps femoris

Arises from four separate heads that form the flesh of front and sides of thigh. These heads have common insertion tendon the quadriceps tendon, which inserts into the patella and then via the patellar ligaments into tibial tuberosity. Powerful knee extensor used in climbing, jumping, running, and rising from seated positon.

flexor hallucis longus

Bipennate muscle; lies lateral to inferior aspect of tibialis posterior Origin: midshaft of fibula; interosseous membrane Insertion: tendon runs under foot to distal phalanx of great toe. Action: Plantar flexes and inverts foot; flexes great toe at all joints

Orbicularis oris

Complicated multilayered muscle of the lips with fibers that run in many different directions; most run circularly Origin: arises indirectly from the maxilla and mandible Insertion: Encircle mouth, inserts into muscle and skin at angles of the mouth

Epicranius (Occipitofrontalis)

Covers the forehead and dome of the skull; no bony attachments. Consists of the Frontal belly and the Occipital belly

supinator

Deep muscle at posterior aspect of elbow; largely concealed by superficial muscles. Origin: lateral epicondyle of humerus; proximal ulna insertion: proximal end of radius action: assists biceps brachii to forcibly supinate forearm.

extensor pollicis brevis

Deep muscle pair with extensor pollicis brevis; share a common origin and action; overlain by extensor carpi ulnaris. Origin: dorsal shaft of radius and ulna; interosseous membrane Insertion: base of proximal (brevis) and distal (longus) phalanx of thumb. action: extends thumb

extensor pollicis longus

Deep muscle pair with extensor pollicis brevis; share a common origin and action; overlain by extensor carpi ulnaris. Origin: dorsal shaft of radius and ulna; interosseous membrane Insertion: base of proximal (brevis) and distal (longus) phalanx of thumb. action: extends thumb

pronator quadratus

Deepest Muscle of distal forearm; passes downward and laterally; only muscle that arise solely from ulna and inserts solely into radius. Origin: Distal portion of anterior ulnar shaft Insertion: Distal surface of anterior radius Action: Prime mover of forearm pronation.

transverse abdominis

Deepest muscle of abdominal wall; fibers run horizontally. Origin: Inguinal ligament, lumbar fascia, cartilages of last six ribs; iliac crest Insertion: Linea alba, pubic crest Action: Compresses abdominal contents.

flexor digitorum profundus

Extensive origin; overlain entirely by flexor digitorum superficialis origin: coronoid process, anteromedial surface of ulna, and interosseous membrane, insertion: by four tendons into distal phalanges of second to fifth fingers. Action: flexes distal interphalangeal joints.

Temporalis

Fan shaped muscle that covers parts of the temporal, frontal, and parietal bones. Origin: Temporal fossa Insertion: Coronoid process of manidible via a tendon tha tpasses deep to zygomatic arch Action: Closes jaw

Pectoralis major

Large fan shaped muscle covering superior portion of chest; forms anterior axillary fold; divided into clavicular and sternal parts. Origin: sternal end of clavicle, sternum, cartilage of ribs 1-6 and aponeurosis of external oblique muscle Insertion: fibers converge to insert by a short tendon into intertubercular sulcus and greater tubercle of humerus. Action: adducts and medially rotates arm against resistance. Clavicular part assists in flexion when arm is extended and sternal part assists in extension when the arm is flexed; with scapula and arm fixed pulls on rib cage upward thus can help in climbing throwing pushing and forced inspiration.

External oblique

Largest and most superficial of the three lateral muscles. Fibers run downward and medially (like hands in pants pocket) Origin: fleshy strips from outer surfaces of lower eight ribs. Insertion: most fibers insert into linea alba via a broad aponeurosis; some insert into pubic crest and tubercle and iliac crest. Action: When the pair contract simultaneously, flex vertebral column and compress abdominal wall and increase intraabdominal pressure; acting individually aid muscle of back in rotating trunk and flexing laterally.

vastus lateralis

Largest head of the group. forms lateral aspect of thigh a common intramuscular injection site particularly in infants who have poorly developed buttock and arm muscles. Origin: greater trochanter, intertrochanteric line, linea aspera Insertion: patella and tibial tuberosity via patellar ligament.

abductor pollicis longus

Lateral and parallel to extensor pollicis longus ; just distal to supinator Origin: posterior surface of radius and ulna insertion: base of first metacarpal and trapezium Action: Abducts and extends thumb.

semitendinosus

Lies medial to biceps femoris although its name suggests that this muscle is largely tendinous, it is quite fleshy; its long slender tendon begins about two thirds of the way down thigh. origin: ischial tuberosity in common with long head of biceps femoris Insertion: medial aspect of upper tibial shaft action: extends thigh and flexes leg.

Extensor digitorum

Lies medial to extensor carpi radialis brevis; a detached portion of this muscle called extensor digiti minimi extends little finger. Origin: lateral epicondyle of humerus insertion: by four tendons into extensor expansions and distal phalanges of second to fifth fingers. Action: prime mover of finger extensions. Can abduct (flare) fingers. extends hand.

flexor digitorum longus

Long, narrow muscle; runs medial to and partially overlies tibialis posterior Origin: extensive origin on the posterior tibia Insertion: tendon runs behind medial malleolus and inserts into distal phalanges of second to fifth toes. Action: plantar flexes and inverts foot; flexes toes.

Internal oblique

Most fibers run upward and medially; muscle fans. Origin: lumbar fascia, iliac crest, and inguinal ligament insertion: linea alba, pubic crest, last three or four ribs and costal margin Action: same as for external oblique

Sternohyoid

Most medial muscle of the neck: thin; Origin: manubrium and medial end of clavicle Insertion: Lower margin of hyoid bone Action: Depresses larynx and hyoid bone if mandible is fixed.

flexor carpi ulnaris

Most medial muscle of this group; two headed; ulnar nerve lies lateral to its tendon Origin: Medial epicondyle of humerus; olecranon and posterior surface of ulna Insertion: pisiform and hamate bones and base of firth metacarpal.

Extensor carpi ulnaris

Most medial of superficial posterior muscles; long slender muscle Origin: Lateral epicondyle of humerus and posterior border of ulna Insertion: base of 5th metacarpal Action: Extends hand in conjunction with extensor carpi radialis and adducts hand in conjunction with flexor carpi ulnaris.

trapezius

Most superficial muscle of posterior thorax; Origin: occipital bone and spinous processes of Cervical spine and all throacic vertebrae Insertion: a continuous insertion along acromion and spine of scapula and lateral third of clavicle Action stabilizes elevates retracts and rotates scapula.

Zygomaticus minor and major

Muscle pair extending diagnoonally from cheekbone to corner of the mouth. Origin: Zygomatic bone Insertion Skin and muscle at corner of the mouth Action: Raises the lateral corner of lip laterally.

hypothenar muscles

Muscles impacting the little finger. Includes abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi

thenar muscles

Muscles in the ball of the thumb. They include the abductor pollicis brevis, the flexor pollicis brevis, opponens pollicis and the abductior pollicis. All of them have some action on the thumb.

adductor magnus

ORIGIN Adductor portion: ischiopubic ramus. Hamstring portion: lower outer quadrant of posterior surface of ischial tuberosity INSERTION Adductor portion: lower gluteal line and linea aspera. Hamstring portion: adductor tubercle ACTION Adductor portion: adducts and medially rotates hip. Hamstring portion: extends hip

adductor longus

ORIGIN Body of pubis inferior and medial to pubic tubercle INSERTION Lower two thirds of medial linea aspera ACTION Adducts and medially rotates hip

iliacus

ORIGIN Iliac fossa within abdomen INSERTION Lowermost surface of lesser trochanter of femur ACTION Flexes medially rotates hip

adductor brevis

ORIGIN Inferior ramus and body of pubis INSERTION Upper third of linea aspera ACTION Adducts hip

biceps femoris

ORIGIN Long head: upper inner quadrant of posterior surface of ischial tuberosity. Short head:middle third of linea aspera, lateral supracondylar ridge of femur INSERTION Styloid process of head of fibula. lateral collateral ligament and lateral tibial condyle ACTION Flexes and laterally rotates knee. Long head extends hip

gracillis

ORIGIN Outer surface of ischiopubic ramus INSERTION Upper medial shaft of tibia below sartorius ACTION Adducts hip. Flexes knee and medially rotates flexed knee

pectineus

ORIGIN Pectineal line of pubis and narrow area of superior pubic ramus below it INSERTION A verticle line between spiral line and gluteal crest below lesser trochanter of femur ACTION Flexes, adducts and medially rotates hip

psoas major

ORIGIN Transverse processes of L1-5, bodies of T12-L5 and intervertebral discs below bodies of T12-L4 INSERTION Middle surface of lesser trochanter of femur ACTION Flexes and laterally rotates hip

tibialis anterior/peroneus

ORIGIN Upper half of lateral shaft of tibia and interosseous membrane INSERTION Inferomedial aspect of medial cuneiform and base of 1st metatarsal ACTION Extends and inverts foot at ankle. Holds up medial longitudinal arch of foot

tensor fasciae latae

ORIGIN Outer surface of anterior iliac crest between tubercle of the iliac crest and anterior superior iliac spine. INSERTION Iliotibial tract ACTION Maintains knee extended (assists gluteus maximus) and abducts hip.

vastus inermedius

Obscured by rectus femoris; lies between vastus lateralis and vastus medialis on anterior thigh. Origin: anterior and lateral surfaces of proximal femur shaft insertion: as for rectus femoris Action Extends leg.

Frontal Belly

Origin: Epicranial aponeurosis Insertion: Skin of eyebrows and root of nose Action: raises the eyebrows, wrinkles forehead skin horizontally

superior oblique

Origin: body of sphenoid Insertion: superior sclera of eye Action: abducts, depresses, and medially rotates eye

Lateral rectus

Origin: common tendinous ring Insertion: lateral sclera of eye Action: abducts front of eye (looks toward ear)

medial rectus

Origin: common tendinous ring Insertion: medial sclera of eye Action: adducts front of eye (cross eyed)

Superior rectus

Origin: common tendinous ring Insertion: superior sclera of eye Action:elevates front of eye

Inferior oblique

Origin: floor of orbit Insertion: lateral sclera of eye Action: abducts, elevates, and medially rotates eye

inferior rectus

Origin: sonnon tendinous ring Insertion: inferior sclera of eye Action: depresses front of eye

Occipital belly

Overlies posterior occipital; by pulling on the epicranial aponeurosis, fixes the origin of the frontal belly. Origin: Ociipital and Temporal bones Insertion Epicranial aponeurosis Action: Fixes aponeurosis and pulls scalp posteriorly.

Extensor carpi radialis longus

Parallels brachioradialis on lateral forarm, and may blend with it. Origin: Lateral supracondylar ridge of humerus Insertion: base of second metacarpal Action: Extends hand in conjunction with extensor carpi ulnaris and abducts hand in conjunction with flexor carpi radialis

flexor pollicis longus

Partly covered by flexor digitorum superficialis. parallels flexor digitorum profundus laterally origin: anterior surface of radius and interosseous membrane insertion: distal phalanx of thumb action: flexes distal phalanx of thumb.

Massester

Powerful muscle that covers lateral aspect of mandibular ramus. Origin: zygomatic arch and zygomatic bone Insertion: angle and ramus of mandible Action: prime mover of jaw closure

flexor carpi radialis

Runs diagonally across forearm; midway, its fleshy belly is replaced by a flat tendon that becomes cordlike at the wrist. Origin: Medial epicondyle of humerus Insertion: base of second and third metacarpals; insertion tendon easily seen and provides guide to position of radial artery at wrist. Action: Powerful flexor and abductor of hand; weak synergist of elbow flexion.

teres minor

Small elongated muscle; lies inferior to infraspinatus and may be inseparable from that muscle; a rotator cuff muscle. Origin: lateral border of dorsal scapular surface Insertion Greater tubercle on anterior humerus; insertion tendon fused with that of latissimus dorsi Extends medially rotates, and adducts arm. Synergist of latissimus dorsi.

palmaris longus

Small fleshy muscle with a long insertion tendon; often absent; may be used as a guide to find median nerve that lies lateral to it at wrist. Origin: medial epicondyle of humerus Insertion: palmar aponeurosis (fascia of palm) Action: tenses skin and fascia of palm during hand movements weak wrist flexor; weak synergist for elbow flexion.

brachialis

Stong muscle that is immediately deep to biceps brachii on distal humerus Origin: Front of distal humerus; embraces insertion of deltoid muscle Insertion: coronoid process of ulna and capsule of elbow joint. Action: A major forearm flexor. Lifts ulna as biceps lifts the radius.

rectus femoris

Superficial muscle of anterior thigh; runs straight down thigh longest head and only muscle of group to cross hip joint. origin: anterior inferior iliac spine and superior margin of acetabulum Insertion Patella and tibial tuberosity via patellar ligament Action: extends leg and flexes thigh at hip.

brachioradialis

Superficial muscle of lateral forearm; forms lateral boundary of cubital fossa; extends from distal humerus to distal forearm. Origin lateral supracondylar ridge at distal end of humerus Insertion: base of radial styloid process Action: Synergist in flexing the forearm

gastrocnemius

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 leg is extended.

Mylohyoid

Suprahyoid muscle. Flat triangular muscle just deep to digastric muscle. Muscle pair make a sling that forms the floor of the anterior mouth. Origin: medial surface of mandible Insertion: Hyoid bone Action: Elevates hyoid bone and floor of mouth, enabling tongue to exert backward and upward pressure that forces food into pharnyx.

stylohyoid

Suprahyoid muscle. Slender muscle below angle of jaw; parallels posterior belly of digastric muscle. Origin: styloid process of temporal bone Insertion: Hyoid bone action elevates and retracts hyoid, thereby elongating floor of mouth during swallowing.

calcaneal tendon (achilles tendon)

The Achilles tendon is a tough band of fibrous tissue that connects the calf muscles to the heel bone (calcaneus). The Achilles tendon is also called the calcaneal tendon. The gastrocnemius and soleus muscles (calf muscles) unite into one band of tissue, which becomes the Achilles tendon at the low end of the calf.

iliopsoas

The iliopsoas muscle consists of: Psoas major muscle: originates from the 1st to 4th lumbar vertebrae, the costal processes of all lumbar vertebrae and the 12th thoracic vertebrae and inserts at the lesser trochanter of the femur. Iliacus muscle: runs from the iliac fossa to the lesser trochanter.

gluteus medius

Thick muscle largely covered by gluteus maximus; important site for IM injection. Considered safer than dorsal gluteal site because less chance of injuring the sciatic nerve. origin: between anterior and posterior gluteal lines on lateral surface of ilium Insertion: by short tendon into lateral aspect of greater trochanter of femur. Action: abducts and medially rotates thigh.

deltoid

Thick; multipennate muscle forming rounded shoulder muscle mass; a common site for intramuscular injection particular in males where it tends to be quite fleshly. origin: embraces insertion of the trapezius; lateral third of clavicle acromion and spine of scapula insertion: deltoid tuberosity of humerus action: prime mover of arm abduction when all its fibers contract simultaneously. antagonist of pectoralis major and latissimus dorsi which adduct the arm. Can be a synergist of pectoralis major

Buccinator

Thin horizontal cheek muscle; principal muscle of cheek; deep to masseter. Origin: molar region of maxilla and mandible Insertion: obicularis oris Action: Compresses cheek as in sucking and whistling

orbicularis oculi

Thin, flat sphincter muscle of eyelid; surrounds rim of the orbit Origin: Frontal and maxillary bones and ligaments around orbit Insertion: Tissue of eyelid Action: Closes eye

popliteus

Thin, triangular muscle at posterior knee; passes inferomedially to tibial surface Origin: lateral condyle of femur and lateral meniscus of knee Insertion: proximal tibia Action: flexes and rotates leg medially to unlock extended knee when flexion begins.

sternocleidomastoid

Two headed muscle located on anterolateral surface of neck; fleshy parts on either side of neck delineate limits of anterior and posterior triangles; key muscular landmark in neck. Origin: Manubrium of sternum and medial portion of clavicle Insertion: mastoid process of temporal bone and superior nuchal line of occipital bone. Action: Flexes and laterally rotates the head.

flexor digitorum superficialis/sublimis

Two headed muscle more deeply placed overlain by muscles above but visible at distal end of the forearm. Origin: medial epicondyle of humerus, coronoid process of ulna; shaft of radius Insertion: by four tendons into middle phalanges of second to fifth fingers. Action: Flexes wrist and middle phalanges of second to fifth fingers.

Rhomboid minor

Two roughly diamond shaped muscles lying deep to trapezius and inferior levator scapulae; rhomboid minor is the more superior muscle origin: spinous processes of C7 and T1 Insertion: medial border of scapula Action: stabilize the scapula

rhomboid major

Two roughly diamond shaped muscles lying deep to trapezius and inferior levator scapulae; rhomboid minor is the more superior muscle origin: spinous processes of T2-T5 Insertion: medial border of scapula Action: stabilize the scapula

biceps brachii

Two-headed fusiform muscle; bellies unite as insertion point is approached tendon of long head helps stabilize shoulder joint Origin: short head: coracoid process; long head: supraglenoid tubercle and lip of glenoid cavity; tendon of long head runs within capsule and into intertubercular sulcus of humerus Insertion: by common tendon into radial tuberosity Action: Flexes and supinates forearm. (ex. opening a bottle of win, it turns the corkscrew and pulls the cork)

pronator teres

Two-headed muscle; seen in superficial view between proximal margins of brachioradialis and flexor carpi radialis; forms medial boundary of cubital fossa Origin: medial epicondyle of humerus; coronoid process of ulna Insertion: by common tendon into lateral radius, midshaft Action: pronates forearm; weak flexor of elbow

supraspinatus

a rotator cuff muscle. posterior aspect of scapula. origin: supraspinous fossa of scapula Insertion: superior part of greater tubercle of humerus. Action: Initiates abduction of arm, stabilzes shoulder joint helps prevent downward dislocation of humerus as when carrying a heavy suitcase.

cranial aponeurosis

aponeurosis (a tough layer of dense fibrous tissue) which covers the upper part of the cranium in humans and various other animals.

diaphram

broad muscle pierced by the aorta, inferior vena cava and esophagus forms floor of thoracic cavity; dome-shaped in relaxed state; fibers converge from margins of thoracic cage toward a boomerang-shaped central tendon origin: inferior, internal surface of rib cage and sternum, costal cartilages of last six ribs and lumbar vertebrae insertion: central tendon Action: Prime mover of inspiration; flattens on contraction

soleus

broad, flat muscle, deep to gastrocneumius on posterior surface of calf Origin: extensive origin from superior tibia, fibula, and interosseous membrane Insertion posterior calcaneus via calcaneal tendon Action: stabilizes the tibia on the calcaneus limiting forward sway.

Latissimus dorsi

broad; flat; triangular muscle of lower back. Origin: indirect attachement via lumbodorsal fascia into spines of lower six thoracic fvertebrae, lumbar vertebrae, lower 3 to 4 ribs, and iliac cres; also from scapula's inferior angle. Insertion: spirals around teres major to insert in floor of intertubercular sulcus of humerus. Action: a very powerful rotator of the trunk.

digastric

consists of two bellies. forms a v shape under the chin. Origin: Lower margin of mandible and mastoid process of temporal bone. Insertion: by a connective tissue loop to hyoid bone action: open mouth and depress mandible. Synergist the digastric muscles elevate hyoid bone and steady it during swallowing and speech.

semimembranosus

deep to semitendinosus Origin: ischial tuberosity insertion: medial condyle of tibia via oblique popliteal ligament to lateral condyle of femur action extends thigh and flexes leg; medially rotates leg.

serratus anterior

fan shaped muscle lies deep to scapula, deep and inferior to pectoral muscles on lateral rib cage. Has a serrated (saw tooth) appearance. Origin: By a series of muscle slips from ribs 1-8 Insertion: entire anterior surface of vertebral border of scapula Action: roates scapula so its inferior angle moves laterally and upward. Prime mover to protract and hold scapula against chest wall. raises point of shoulder. imporant rold in abducting and raising arm and in horizontal arm movements. Boxer's muscles.

vastus medialis

forms inferomedial aspect of thigh. Origin: linea aspera intertrochanteric and medial supracondylar lines. Insertion: as for rectus femoris Action: extends leg

thyrohyoid

infrahyoid muscle. Appears as a superior continuation of sternothyroid muscle. Origin: Thyroid cartilage Insertion hyoid bone action: depresses hyoid bone or elevates larynx if hyoid is fixed.

triceps brachii

large fleshy muscle; the only muscle of posterior compartment of arm; three headed origin; long and lateral heads lie superficial to medial head. origin: long head; infraglenoid tubercle of scapula; lateral head: posterior shaft of humerus; medial head: posterior humeral shaft distal to radial groove. Insertion: by common tendon into olecranon of ulna Action: powerful forearm extensor. Prime mover. Antagonist of forearm flexors

Gluteus maximus

largest and most superficial gluteus muscle; forms bulk of buttock mass; fibers are thick and coarse; site of IM injections. Overlies large sciatic nerve; covers ischial tuberosity only when standing; when sitting, mover superiorly, leaving ischial tuberosity exposed in the subcutaneous position. origin: dorsal illum, sacrum and coccyx Insertion: gluteal tuberosity of femur; illotibial tract Action: Major extensor of the thigh

Scalenes

located more laterally than anteriorly on neck. Origin: transverse processes of cervical vertebrae Insertion: anterolaterally on first two ribs. elevate first two ribs. (Aid in inspiration) flex and rotate neck.

Rectus abdominis

medial superficial muscle pair; extend from pubis to rib cage; ensheathed by aponeuroses of lateral muscles; segmented by three tendinous intersections. Origin pubic crest and symphysis Insertion xiphoid process and costal cartilages of ribs 5-7 Action: Fex and rotate lumbar region of vertebral column; fix and depress ribs, stabilize pelvis during walking. Used in sit ups and curls.

infraspinatus

partially covered by deltoid and trapezius; named for its scapular location; a rotator cuff muscle. Origin; infraspinous fossa of scapula Insertion: greater tubercle of humerus posterior to insertion of supraspinatus Action: Rotates arm laterally. Helps hold the head of the humerus in glenoid cavity, stabilizing the shoulder joint.

omohyoid

straplike muscle with two bellies united by an intermediate tendon lateral to sternohyoid. origin: superior surface of scapula Insertion: hyoid bone; lower border action: depresses and retracts hyoid bone

sartorius

straplike superficial muscle running obliquely across anterior surfaces of thigh to knee, longest muscle in body; crosses both hip and knee joint Origin: anterior superior iliac spine Insertion: winds around medial aspect of knee and inserts into medial aspect of proximal tibia Action: flexes abducts, and laterally rotates thigh.

fibularis longus

superficial lateral muscle overlies fibula origin: head and upper protion of lateral fibula insertion: by long tendon that curves under foot to first metatarsal and medial cuneiform. action: plantar flexes and everts foot

Teres Major

thick, rounded muscle; located inferior to teres minor; helps form posterior wall of axilla along with latissimus dorsie and subscapularis Origin: posterior surface of scapula at inferior angle Insertion: crest of lesser tubercle on anterior humerus; insertion tendon fused with that of latissimus dorsi Action: Extend medially rotates and adducts arm. Synergist of latissimus dorsi