Back, Thorax, Abdomen, & Perineum Muscles Actions, Insertion, Origin, & Nerve Supply

what is the action of the splenius capitis & cervicis 

extends the head & when active on one side, the head is bent & rotated laterally towards that side

what is the action of the erector spinae: iliocostalis

extends the vertebral column and maintains posture; also laterally flexes the spine to the same side when acting unilaterally.

what is the origin of the erector spinae: iliocostalis

the iliac crests; inferior 6 ribs, & ribs 3-6

what is the insertion of the erector spinae: iliocostalis

angles of ribs, transverse process of C6-C4

what is the action of the erector spinae: longissimus

extend & laterally flex vertebral column when acting on thoracis & cervicis; acting on one side causes lateral flexion; capitis extends rotates towards same side

what is the origin of the erector spinae: longissimus

transverse process of lumbar through cervical vertebrae

what is the insertion of the erector spinae: longissimus

transverse process of thoracic or cervical vertebrae & to ribs

superior to origin; capitis inserts into mastoid process

what is the action erector spinae: spinalis

extends vertebral column

what is the origin of erector spinae: spinalis

spines of upper lumbar & lower thoracic vertebrae

what is the insertion of the erector spinae: spinalis

spines of upper thoracic & cervical vertebrae

what is the action of quadratus lumborum

flexes vertebral column laterally when acting separately acting joint, lumbar spine extends, 12th rib is fixed, maintains posture & helps w/ inspiration

what is the origin of the quadratus lumborum

iliac crest & lumbar fascia

what is the insertion of the quadratus lumborum

transverse process of upper lumbar vertebrae & lower margin of 12th rib

what is the action of the trapezius?

stabilizes, elevates, retracts, & rotates scapula ; middle fibers retract scapula, superior fibers elevate scapula or extend head when fixed, inferior depresses scapula 

what is the origin of the trapezius

occipital bone, ligamentum nuchae, spines of C7 & all thoracic vertebrae

what is the insertion the trapezius

continuous insertion along acrominon & spine of scapula & lateral third of clavicle

what is the action of the levator scapulae

elevates & adducts scapula in synergy w/ superior fibers of trapezius; rotates scapula downward or flexes neck to same side if fixed

what is the origin of the levator scapulae

transverse process of C1-C4

what is the insertion of the levator scapulae

medial border of scapula, superior to the spine

what is the action of the rhomboid major & minor

stabilizes scapula ; act together spinous processes to retract scapula (square shoulders); rotate scapulae downward when arm is lowered against resistance

what is the origin of the rhomboid major?

spinous processes T2-T5

what is the origin of the rhomboid minor?

spinous processes of C7 & T1

what is the insertion of the rhomboid major & minor

medial border of scapula

what is the action of latissimui dorsi

primemover of arm extension, adduction & medial rotation of arm; important role in bringing arm down in a power stroke & pulls body upwards & forward when overhead

what is the origin of the latissmui dorsi

indirect attachment via thoracolumbar fascia into spines of lower six thoracic vertebrae, lumbar vertebrae, lower 3-4 ribs & iliac crest

what is the insertion of the latissmui dorsi

spirals around trees major to insert into floor of intertubercular sulcus of humerus

what is the action of the external intercostals

pulls ribs towards one another to elevate ribcage when first two ribs are fixed; aid in inspiration & synergist of diaphragm

what is the action of the internal intercostal

draws ribs together depresses rib cage; aid in force expiration & are antagonists to external intercostals

what is the action of pectoralis minor

w/ ribs fixed, protracts & rotates scapula downward w/ scapula fixed, draws rib cage superiorly

what is the origin of the pectoralis minor

anterior surfaces of ribs 3-5 or 2-4

what is the insertion of the pectoralis minor

coracoid process of scapula

what is the action of pectoralis major

prime mover of arm flexion; rotates arm medially, adducts arm against resistance; w/ scapula fixed it pulls rib cage upward

what is the origin of the pectoralis major

sternly end of clavicle, sternum, cartilage of ribs 1-6, & aponeurosis of external oblique muscle

what is the insertion of the pectoralis major

fibers converge to insert by short tendon into greater tubercle of humerus

what is the action of the serratus anterior

rotates scapula upward; prime mover to protract & hold scapula against chest wall; important in abductions raising of arm & horizontal arm movements

what is the origin of the serratus anterior

a series of muscle slips from ribs 1-8

what is the insertion of the serratus anterior

entire anterior surface of vertebral border of scapula

what is the action of the external oblique

flex vertebral columns compress abdominal wall when pair contracts; aid muscles of back in trunk rotation & lateral flexion when acting individually

what is the origin of the external oblique

fleshy strips from outer surfaces of lower eight ribs

what is the insertion of the external oblique

most fibers insert into lines alba via a broad aponeurosis

some insert into public crest & tubercles & iliac crest

what is the action of the internal oblique

same as the external oblique

what is the origin of the internal oblique

lumbar fascia, iliac crest & inguinal ligament

what is the insertion of the internal oblique

linea alba, pubic crest, last 304 ribs & costal margin

what is the action of transverse abdominis

compress abdominal contents

what is the origin of the transverse abdominis

inguinal ligament, lumbar fascia, cartilages of last six ribs, iliac crest

what is the insertion of the transverse abdominis

linea alba & pubic crest

what is the action of the rectus abdominis

flex & rotate lumbar region of vertebral column ; fix & depress ribs, stabilizes pelvis during walking & increases intra-abdominal pressure

what is the origin of the rectus abdominis

pubic crest & symphysis

what is the insertion of the rectus abdominis

xiphoid process & costal cartilages of ribs 5-7

what is the action of the superficial transverse perineal muscle

stabilizes & strengthens the perineal body

what is the action of the deep transverse perineal muscle

retards venous drainage & maintains erection of penis or clitoris

what is the action of the bulbospongious

empties male urethra & assists in erection of penis & clitoris

what is the action of the levator ani

supports 3 maintains position of pelvic organs; resist downward

thrusts from intrapelvic pressure, forms sphincter at anorectal

junction & Vagina & lifts anal canal during defecation