Muscles Of The Thorax
Name. Position. Origin. Insertion. Action. Nerve Supply.
Anterior
Upper and Flexes arm,
surface of Outer margin
Pectoralis fore part of raises body to External
sternum, occipital
chest, and in arms, rotates anterior
clavicle, seven groove of
major. front of inwards, thoracic.
upper costal humerus.
axilla. adducts.
cartilages.
Pectoralis Under Coracoid Depresses Internal
Third, fourth,
pectoralis process point of anterior
fifth ribs.
minor. major. scapula. shoulder. thoracic.
Between From fifth
Cartilage, first Under surface Draws down
Subclavius. clavicle and and sixth
rib. clavicle. clavicle.
first rib. cervical.
Between ribs Extends arm
Serratus and scapula at Vertebral forwards, Posterior
Eight upper
upper part border of assists in
ribs.
magnus. and side of scapula. raising ribs in thoracic.
chest. inspiration.
External
Fills Superior
intercostals Inferior borders Raises ribs in
intercostal borders of Intercostal.
(eleven in of ribs. expiration.
spaces. ribs below.
number).
Internal
Fills Superior
intercostals Inferior borders Depresses ribs
intercostal borders of Intercostal.
(eleven in of ribs. in inspiration.
spaces. ribs below.
number).
Lower third,
By digitations
posterior
into lower
surface of Draws down
Triangularis borders of
Inner wall of sternum, costal
costal Intercostal.
front of chest. ensiform cartilages in
sterni. cartilages of
cartilage, costal expiration.
second to
cartilage of four
sixth rib.
lower true ribs.
On the back
Transverse
between
Levators process,
seventh
costarum seventh cervical Each to the Raise ribs in
cervical and Intercostal.
(twelve in and eleven rib below. inspiration.
eleven upper
number). upper dorsal
dorsal
vertebrae.
vertebrae.
Diaphragm. Forms floor Ensiform into central Respiration Phrenic,
Name. Position. Origin. Insertion. Action. Nerve Supply.
Anterior
Upper and Flexes arm,
surface of Outer margin
Pectoralis fore part of raises body to External
sternum, occipital
chest, and in arms, rotates anterior
clavicle, seven groove of
major. front of inwards, thoracic.
upper costal humerus.
axilla. adducts.
cartilages.
Pectoralis Under Coracoid Depresses Internal
Third, fourth,
pectoralis process point of anterior
fifth ribs.
minor. major. scapula. shoulder. thoracic.
Between From fifth
Cartilage, first Under surface Draws down
Subclavius. clavicle and and sixth
rib. clavicle. clavicle.
first rib. cervical.
Between ribs Extends arm
Serratus and scapula at Vertebral forwards, Posterior
Eight upper
upper part border of assists in
ribs.
magnus. and side of scapula. raising ribs in thoracic.
chest. inspiration.
External
Fills Superior
intercostals Inferior borders Raises ribs in
intercostal borders of Intercostal.
(eleven in of ribs. expiration.
spaces. ribs below.
number).
Internal
Fills Superior
intercostals Inferior borders Depresses ribs
intercostal borders of Intercostal.
(eleven in of ribs. in inspiration.
spaces. ribs below.
number).
Lower third,
By digitations
posterior
into lower
surface of Draws down
Triangularis borders of
Inner wall of sternum, costal
costal Intercostal.
front of chest. ensiform cartilages in
sterni. cartilages of
cartilage, costal expiration.
second to
cartilage of four
sixth rib.
lower true ribs.
On the back
Transverse
between
Levators process,
seventh
costarum seventh cervical Each to the Raise ribs in
cervical and Intercostal.
(twelve in and eleven rib below. inspiration.
eleven upper
number). upper dorsal
dorsal
vertebrae.
vertebrae.
Diaphragm. Forms floor Ensiform into central Respiration Phrenic,
