Main Muscles involved in the Thoracic Cavity (Week 1)

Question 1

sternocleidomastoid?

Answer 1

origin: 2 heads-
sternal= anterior of manubrium
clavicular= medial 1/3 clavicle

insertion: mastoid process of temporal bone/ superior nuchal line of occipital bone
action: flexes/laterally flexes neck, rotates head

Question 2

scaleni?

Answer 2

3 muscles- scalenus anterior, medius, posterior

origin:
ANTERIOR= anterior tubercles of transverse processes of c3-c6
MEDIUS= transverse processes c2-c7
POSTERIOR= posterior tubercles transverse processes
c4-c6

insertion:
ANTERIOR= scalene tubercle 1st rib
MEDIUS= superior surface 1st rib
POSTERIOR= external surface 2nd rib

action: laterally flexes neck (A,M,P)/ elevates 1st/2nd rib respectively, flexes/rotates neck (A)

Question 3

diaphragm?

Answer 3

origin: xiphoid, internal surfaces 7th-12th costal cartilages/ribs, medial/lateral arcuate ligaments, l1/l3
insertion: central tendon
action: primary muscle of inspiration

Question 4

intercostal muscles?

Answer 4

consist of external, internal and innermost intercostals.

group of muscles that connect adjacent ribs.

involved in movement of ribs; some elevate during inspiration, some depresses during expiration. also provide structural support

Question 5

trapezius?

Answer 5

superior muscle on posterior

origin: external occipital protuberance/superior nuchal line of occipital bone/ nuchal ligament/ spinous processes c7-t12
insertion: posterior lateral 1/3 clavicle/ acromion/ scapula spine
action: elevates, depresses, retracts, upward rotates shoulder girdle (acromioclavicular/sternoclavicular joints)/ extends, laterally flexes head and neck

Question 6

serratus posterior (inferior)?

Answer 6

origin: spinous processes t11-l2
insertion: external surfaces 9th-12th ribs
action: depresses ribs as costovertebral joints

Question 7

serratus posterior (superior)?

Answer 7

deep to trapezius

origin: nuchal ligament/ spinous processes c7-t3
insertion: external surfaces 2nd-5th ribs
action: elevates ribs at costovertebral joints

Question 8

subcostals?

Answer 8

origin: internal surfaces 7th-10th ribs
insertion: internal surfaces 9th-12th ribs
action: depresses ribs at costovertebral joints

Question 9

transversus thoracus?

Answer 9

origin: posterolateral of body/xiphoid process of sternum
insertion: internal surfaces 2nd-6th costal cartilages+ costal ends of adjacent ribs
action: depresses ribs at costal cartilages

Question 10

external oblique?

Answer 10

superior muscle on anterior lower 1/2 trunk

origin: external surfaces/inferior borders of 5th-12th ribs
insertion: anterior super iliac spine/ anterior 1/2 iliac crest/ pubic crest/ linea alba
action: flexes, laterally flexes, rotates trunk/ compresses and supports adjacent ab structures

Question 11

internal olique?

Answer 11

deep to external oblique

origin: thoracolumbar fascia, iliac crest, inguinal ligament
insertion: inferior 10th-12th ribs, adjacent costal cartilages, linea alba, pectin pubis
action: flexes, laterally flexes, rotates trunk/ compresses and supports adjacent ab structures

Question 12

rectus abdiminus?

Answer 12

deep to obliques

origin: pubic crest/ pubic symphysis
insertion: xiphoid process/ costal cartilages 5th-7th ribs
action: flexes trunk/ compresses and supports adjacent ab structures

Question 13

transversus abdominus?

Answer 13

deep to EO/IO/RA

origin: costal cartilages 7th-12th ribs, thoracolumbar fascia, iliac crest, inguinal ligament
insertion: linea alba, pubic crest, pectin pubis
action: compresses and supports adjacent ab structures