Muscles - Origins, Insertions, Actions & Innervations

Origin for External Intercostal

Space from rib tubercles to the costochondral junctions of ribs (11 pairs)

Insertion for External Intercostal

Anterior and inferior from rib above to rib below

Action of External Intercostal

Elevates ribs; inspiration

What muscles have an innervation of internal intercostal nerve at that level?

External intercostal, internal intercostal, innermost intercostal, subcostals, transverse thoracis, serratus posterior superior, and serratus posterior inferior

List the muscles of expiration.

Internal intercostal, innermost intercostal, subcostals, transverse thoracis, and serratus posterior inferior

Origin of Internal Intercostal

Space from angle of rib posteriorly and sternum anteriorly

Insertion of Internal Intercostal

Run inferior to posterior from floor of costal groove and attach to superior border of rib below

Origin of Innermost Intercostal

Deep to internal intercostals but separated by intercostal nerves and vessels

Insertion of Innermost Intercostal

Same as internal intercostals but deeper

Origin of Subcostals

Lower thoracic wall; internal surface of the angle of one rib

Insertion of Subcostals

Internal surface of 2nd or 3rd rib inferior (similar to internal intercostals)

Origin of Transverse Thoracis

4-5 slips from xiphoid and inferior sternum

Insertion of Transverse Thoracis

Ribs 2-6 costal cartilage

Origin of Serratus Posterior Superior

Spinous process and upper thoracic vertebrae

Insertion of Serratus Posterior Superior

Upper ribs

Origin of Serratus Posterior Inferior

Spinous Process of lower 2 thoracic and upper 2 lumbar vertebrae

Insertion of Serratus Posterior Inferior

Lower ribs

Action of Serratus Posterior Superior

elevation of ribs; inhalation

Origin of Levator Costorum

Transverse processes of C7 to T11

Insertion of Levator Costorum

Run inferolateral to costal tubercle

Action of Levator Costorum

Inspiration and proprioception?

Innervation of Levator Costorum

Dorsal rami of spinal nerves

Origin of Quadratus Lumborum

Iliac crest and iliolumbar ligament

Insertion of Quadratus lumborum

lower border of 12th rib and transverse processes of L1-L4

Action of Quadratus Lumborum

Lateral bending of vertebral column; aids in forced expiration and deep inspiration

List the muscles with innervation of ventral rami T12-L4

Quadratus lumborum, psoas major, and iliacus.

Origin of Iliacus

Iliac crest, iliac fossa, ala of sacrum, anterior sacroiliac ligaments

Action of Iliacus

Flex thigh at hip; stabilize hip joint; rotate femur laterally

Origin for Psoas Major

Sides of T12-L5 and transverse processes of L1-L5

What muscles have the insertion of the conjoined tendon into lesser trochanter?

Psoas major and iliacus

Origin of Piriformis

Anterior surface of sacrum and sacrotuberous ligament

Insertion of Piriformis

Superior border of the greater trochanter of the femur

Which muscles have the action of external rotation of the femur, abduct flexed thigh

Piriformis and obturator internus

Innervation for Piriformis

Nerve to Piriformis (S1-2)

Origin for Obturator Internus

Posterior aspect of ischial ramus, pubic ramus, and obturator membrane

Insertion for Obturator Internus

Greater trochanter of femur

Origin for Ischiococcygeus

ischial spine

Insertion for Ischiococcygeus

coccyx and sacrum

Action of Ischiococcygeus

Elevate pelvic floor and supports coccyx

Innervation of Ischiococcygeus

Ventral rami of S3-4

What are the Levator Ani muscles?

Iliococcygeus, pubococcygeus, puborectalis

Action of the Levator Ani muscles

Resist intraabdominal pressure, elevates diaphragm and the puborectalis pulls anal canal forward to avoid defecation

Innervation of Levator Ani muscles

S3-4 and perineal branch of pudendal nerve

Origin of Superficial Transverse Perineus

Ischial tuberosity

Insertion of Superficial Transverse Perineus

Perineal body of perineum

Action of Superficial Transverse Perineus

Stabilization of perineal body

Which muscles are innervated by the perineal branch of pudendal nerve?

Superficial Transverse Perineus, Bulbospongiosus, Ischiocavernosus, Deep transverse perineus, and external urethral sphincter

Innervation for External Anal Sphincter

Inferior rectal branch of pudendal nerve and S4