Anatomy AFL 1 OINAs

obturator internus

O: internal surface of obturator membrane; anterior pelvic surface of ischium; arcus tendinous levator ani (ATLA)

I: medial greater trochanter

N: obturator nerve

A: laterally rotates hip, abducts flexed hip, stabilizes femoral head in acetabulum

puborectalis

O: posterior surface of pubis

I: anococcygeal ligament

N: pudendal nerve & direct branches from sacral plexus (S2-3)

A: maintenance of continence

pubococcygeus

O: posterior surface of pubis & ATLA

I: anococcygeal ligament

N: pudendal nerve & direct branches from sacral plexus (S2-3)

A: maintenance of continence

iliococcygeus

O: anterior ischial spine & ATLA

I: tip of coccyx and sacrum

N: pudendal nerve & direct branches from sacral plexus (S2-3)

A: maintenance of continence

coccygeus

O: spine of ischium and sacrospinous ligament

I: lateral border of coccyx and inferior sacrum

N: sacral spinal nerves (S3-4)

A: draws coccyx forward

piriformis

O: anterior sacrum, greater sciatic foramen, sacrotuberous ligament

I: superior medial greater trochanter

N: superior gluteal nerve (L5, S1-2)

A: lateral rotation of extended hip, hip extension, stabilize femoral head

external intercostals

O: inferior border of rib above from the tubercle to the costochondral joint

I: superior surface of the rib below

N: Intercostal nerves (T1-12)

A: elevates rib cage during inspiration; pulls ribs up & out; INSPIRATION

internal intercostals

O: inferior border of the ribs at the sternum to the angle of the ribs

I: superior surface of the ribs below

N: intercostal nerves (T1-12)

A: pulls ribs down; used in expiration

innermost intercostals

O: inferior border of ribs close to the articulation of the transverse process

I: extends anterior to the membranous portion of the internal intercostal muscles

N: intercostal nerves (T1-12)

A: acts like intercostals; expiration

transversus thoracis

O: lower third of body of sternum and xiphoid process

I: inner lower border of ribs 2-6

N: intercostal nerves (T1-12)

A: draws ribs down in FORCED expiration

subcostals

O: internal inferior rib near angle in lower thoracic area

I: 2-3 ribs below on the superior border of the rib

N: intercostal nerves (T1-12)

A: depress the ribs

diaphragm

O: posterior xiphoid process, lower ribs, body of lumbar vertebrae 1-2

I: central tendon

N: phrenic nerve (C3,4,5)

A: draws central tendon down; increases thoracic volume = used for normal breathing!!!