Musculature
functional (inhale or exhale)
anatomical (where they are in the body: thoracic or abdominal)
Primary muscles for inhalation
diaphragm
external intercostals
Accessory muscles for inhalation
scalenes
sternocleidomastoid
serratus anterior
subclavis
pectoralis minor
pectoralis major
serratus posterior superior
levatores costarum
Primary muscles for exhalation
external oblique
internal oblique
rectus abdominus
transverse abdominus
Accessory muscles for exhalation
internal intercostals
serratus posterior inferior
quadratus lumborum
transverse thoracics
subcostals
Diaphragm
pulls the central tendon
down and forward
increases volume of rib cage
decreases thoracic pressure (volume increases, pressure decreases)
Act to flare lowers ribs
External intercostals
stronger of intercostals
increase transverse (left/right) by elevating the ribs
Origin
- Lower border of upper rib
Course
- inferior (down) and towards the center
Insert
-upper surface of rib below
Action
- up and out (transverse is increased)
Levatores Costarum
elevator of the ribs, continuation of external intercostals
Origin
- C7, T1-T11
Course
- Inferior and lateral (down and towards the side)
Insert
- Posterior and surface of ribs below
Action
- Elevate the ribs
Serratus Posterior Superior
on upper posterior aspect of the thorax
Origin- C7, T1-T3
Course- inferior and lateral
Insert- ribs 2-5 near angle
Action- thought to elevate ribs 2-5
Pectoralis major
shoulder muscle
large fan shaped muscle on upper anterior wall of thorax
Origin - Humeruous bone of upper arm
Course - fans out widely
Insert- upper costal cartilages (between ribs and sternum)
Action- rotation of the arm
Pectoralis minor
shoulder muscle
large thin muscle lying deep into the pectoralis major
Origin - anterior surface of scapula
Course - inferior and medial
Insert - anterior medial portion of ribs 3-5
Action - with scapula fixed, left ribs 3-5 shoulder extensor
Subclavius
shoulder muscle
small narrow muscle
Origin- underside of clavicle, near scapula
Course- slightly inferior and medial
Insert - junction of rib 1 and its cartilage
Action- with clavicle brace, lift rib 1 and draw shoulder forward
Serratus anterior
shoulder muscle
Large thin muscle on side wall of thorax
Origin - anterior surface of scapula
Course - anterior, around side of the rib cage
Insert - ribs 1-8 or 9, near costal cartilages
Action - it can lift ribs 1-8, fixate and protract scapula
Sternocleidmoastoid
Large muscle on side of the
neck
Origin - bony skull, behind the ear at mastoid process
Course - inferior, in two divisions
Insert - superior surface of clavicle and sternum
Action - with head fixed, elevate sternum
Scalenes
group of three muscles deep in
neck
, interior to sternocleidmastoid
Anterior, medial, posterior
Origin - Transverse process of C2-C7
Course - inferior and slightly lateral
Insert - ribs 1 and 2
Action - raise ribs 1 and 2
Abdominal aponeurosis
Broad tendonous sheet of tissue that all the abdominal muscles insert into
strong connective tissue
Extends from superior (Pectoralis Major) to inferior (pubic bone)
Rectus Abdominus
long ribbon-like muscle on ventral aspect of abdominal cavity, almost entirely enclosed by aponeurosis, MOST INFRONT
Origin - Anterior edge of pubic bone
Course - superior, parallel to midline
Insert - cartilages of ribs, 5-7, xiphoid process
External Oblique
Largest, strongest and most superficial
Broad, flat muscle on lateral and anterior portions of lower thorax and abdomen
Origin- illac crest and aponeurosis
Course- superior and lateral
Insert- ribs 5-12
Internal oblique
Opposite direction of external oblique, up and in, insert to aponeurosis
Origin - anterior � of the iliac crest and inguinal ligament
Course - fans out superiorly and medially
Insertion - abdominal aponeurosis and inferior
Transverse Abdominus
deepest abdominal muscle, under internal oblique
Left/right (horizontal) and connects to aponeurosis
Helps in bringing air out
Origin- lower 7 ribs
Course- horizontal and anterior
Insertion- abdominal aponeurosis
Action of abdominal muscles
Flexor of vertebral column�moving you forward - bend forward
Enclose and support abdominal contents -- enclosure
Respiration - draws ribs down, helps push the air out, decrease the size of the thorax
COMPRESS ABDOMEN
Internal intercostals
lie beneath the externals
Goes from lower rib to the upper rib (towards the sternum), pulls ribs down
Origin- superior surface of each rib
Course- superior towards sternum
Insertion- lower border of rib above
Action- pull ribs down
Transverse thoracics
on inner surface of anterior thoracic wall
Origin- inner surface of sternum and costal cartilages 5-7
Course- fan out superiorly and laterally
Insertion- inner surface of ribs 2-6
Action- Depress ribs
Serratus Posterior Inferior
on lower posterior portion of the thorax
Origin- T11-12, L 1-3
Course- superior and lateral
Insertion- lower border of ribs 8-12
Action- depress (pull down) lower ribs
Quadratus Lumborum
Posterior muscle of the abdomen, flat sheet of muscle on lateral dorsal aspect of abdominal wall
Origin- iliac crest
Course- superior
Insertion- Transverse process of L1-4, rib 12
Action- pull down the last rib
Rib cage expands vertically in inhalation...
diaphragm contracts & goes down
abdomen decreases and rib cage increases
(sagittal)
Rib cage expands transversely in inhalation...
Elevation of curved ribs from the external intercostals
water bucket analogy
Rib cage expands anteroposteriorly in inhalation...
anterior and superior movement of sternum
external intercostals pull ribs up and out
pump handle analogy