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Chest and trunk |
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|
Muscle |
Origin |
Insertion |
Action |
Notes |
|
Intercostals |
Inferior
border of the rib above |
Superior
border of the rib below |
External
Intercostals: draw the ventral part of the ribs upward,
increasing thoracic cavity space
Internal Intercostals: draw the
ventral part of the ribs downward, decreasing the space
of the thoracic cavity |
Stabilize
the rib cage and assist in respiration.
Meat of spare ribs. |
|
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|
Pectoralis
major |
Sternal ½
of clavicle, sternum to 7th rib, aponeurosis
of external oblique muscle. |
Crest of
greater tubercle of humerus: Lateral lip of bicipital
grove. |
Clavicular
fibers- flexion of humerus
Sternocostal (middle and lower)
fibers- extension of humerus returning from flexion
Adduction, medial rotation |
Forms the
anterior wall of axilla.
Upper and lower fibers are work in
opposite actions making it an antagonist to itself.
Triggerpoints may cause pain,
swelling and
congestion of lymphatic fluids in breast
tissue. |
|
Pectoralis
minor |
Third,
fourth and fifth ribs |
Coracoid
process of
scapula |
Tilts
scapula forward, depresses and abducts scapula, |
Pulls
shoulder forward when rhomboids are weak |
|
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|
Diaphragm |
Sternal:
inner part of ziphoid process
Coastal- inner surface of lower 6
ribs
Lumbar- upper 2-3 lumbar vertebrae |
Central
tendon |
Draws
central tendon down during inspiration, increases volume
of thoracic cavity (increases diameters) |
Forms floor
of thoracic cavity. |
|
Rectus
abdominis |
Crest of
the pubis, pubic symphysis |
Cartilage
of the 5th, 6th and 7th
ribs and ziphoid process |
Flexes the
vertebral column |
Sometimes
origin and insertion are reversed |
|
External
obliques |
Lower eight
ribs (5-12) |
Anterior
part of iliac crest, abdominal aponeurosis to linea alba |
Bilaterally- flexes thorax and compresses abdominal
contents
Unilaterally- laterally flexes spine
and rotates spine to opposite side |
Interdigitates with serratus anterior. Place hands on
hips as if you were reaching into pants pockets to
follow directions of fibers (obliquely downward and
medialward) |
|
Internal
obliques |
Lateral
inguinal ligament, anterior iliac crest, thoracolumbar
aponeurosis |
Cartilage
of lower 3-5 ribs (7-12), abdominal aponeurosis to linea
alba |
Bilaterally- flexes the thorax, compresses abdominal
contents
Unilaterally- laterally flexes spine
and rotates trunk to same side |
Place hands
over abdomen with fingertips on the anterior-superior
iliac spine, your fingertips will follow the direction
of the fibers (obliquely upward and medialward) |
|
Transverse
abdominis |
Lateral
inguinal ligament, anterior iliac crest, thoracolumbar
fascia, cartilage of lower 6 ribs (7-12) |
Abdominal
aponeurosis to linea alba |
Compresses
abdominal contents |
Deepest
layer of abdominals: runs horizontally medialward |
|
Quadratus
lumborum |
Posterior
iliac crest, iliolumbar ligament |
Last rib,
transverse processes of L1-L4 |
Bilaterally- extends the spine
Unilaterally- lateral flexion of
lumbar spine
With spine fixed-elevates hip (hikes
hip up).
Holds 12th rib against the
pull of the diaphragm
Accessory breathing muscle. Spinal
stabilizer |
Composed of
three groups of fibers: Iliocostal fibers run from
medial upper crest of ilium and iliolumbar ligament
upward to 12th rib (vertical) Iliolumbar
fibers run from the ilium to the transverse processes of
L1-L4
Lumbocostal fibers fun from the 12th
rib to transverse processes of lumbar vertebrae |
