-
Latissimus Dorsi
(superficial muscle of the back)
- O: Iliac crest, Thoraco-lumbar (T/L) fascia, SP's of last 6 thoracic vertebrae and last 3-4 ribs
- F.D: superior lateral
- Insertion: Floor of the intertubercular groove
- Action: Extension, adduction and medial rotation of the humerus
- Nerve: Thoracodorsal nerve
- Special: Broadest muscle of the back
O and I switch then the action is that the body raises towards the arms (chin up).Thin, superficial and ascends the side of the trunk.
-
Trapezius
(Superficial muscle of the back)
- O: EOP, medial 1/3rd superior nuchal
- line, nuchal ligament and SP’s of C7 to T12
- F.D: upper - inferior lateral . middle - lateral
- lower - superior lateral
- I: Lateral 1/3 of clavicle, acromion
- and spine of scapula
- A: Upper fibers elevate, middle
- fibers retract and inferior fibers depress the scapula
N: Spinal accessory nerve (CN 11)
-
Rhomboid Minor
(superficial muscle of the back)
O: nuchal ligament and SP’s of C7-T1
F.D: inferior lateral
- I: Medial border of scapula at the
- spine of the scapula
- A: Adducts (retracts scapula), fixes
- scapula to thoracic wall (assists serratus anterior)
N: Dorsal scapular nerve
-
Rhomboid Major
(superficial muscle of the back)
O: SP of T2-T5
FD:inferior lateral
- I: Medial border of scapula between
- spine and inferior angle
- A: Adducts (retracts scapula), fixes
- scapula to thoracic wall (assists serratus anterior)
N : Dorsal Scapular nerve
-
Levator Scapulae
(superficial muscle of the back)
- O: Posterior tubercle tubercles of TVP’s
- C1-C4
F.D: inferior posterior
- I: Medial border of scapula superior
- to the root of spine of scapula
- A: Elevates scapula and performs
- downward rotation of the scapula
N: Dorsal scapular nerve
S: deep to upper fibers of trapezius
-
Pectoralis Major
(anterior trunk muscle)
- O:
- Clavicular Head:Anterior surface of
- the medial ½ of the clavicle
- Sternal Head: Anterior sternum, superior
- 6 costal cartilages and aponeurosis of
- the external oblique abdominal muscles
F.D: lateral
- I: Lateral lip of the
- inter-tubercular groove
- of the humerus
- A: Adduct, internal rotation of
- the humerus and extends the arm from 90
- degrees of flexion (The clavicular head
- alone will also aid in flexion of the arm)
- N: Lateral and medial pectoral nerve

-
Pectoralis Minor
(Anterior trunk muscles)
- O: Ribs 3-5 close to their costal
- cartilage
F.D: superior lateral
I: Coracoid process of the scapula
- A: Stabilize the scapula by drawing
- it inferiorly and anteriorly against the thoracic wall
N: Medial pectoral nerve
-
Subclavius
- O: Junction of first rib and it’s
- cartilage
F.D: superior lateral
- I: Inferior aspect of clavicle (middle
- third)
- A: Draws clavicle medially and
- anteriorly
N: Nerve to Subclavius
-
Serratus Anterior
(superfical trunk muscle)
- O: External surfaces of the lateral
- part of the ribs 1-8
F.D: posterior superior
- I: Anterior surface of the medial
- border of scapula
- A: Protracts the scapula and holds it
- against the thoracic wall, upward rotation of scapula
N: Long thoracic nerve
-
External Intercostal Muscle
- O: Inferior border of the superior
- ribs
F.D:Anterior inferior
- I: Superior border of the inferior
- ribs
- A: Elevates the ribs during
- inspiration
N: Intercostal nerves
•This muscle has an anteroinferior fiber direction (“hands in my pocket”)
•Medial to the costochondral junction, this muscle becomes the external intercostal membrane
-
Internal Intercostal
- O: Superior border of the inferior
- rib
F.D: anterior superior
- I: Inferior border of the superior
- rib
- A: Depress the ribs during forced
- expiration
N: Intercostal nerves
- •This muscle lies deep to the
- external intercostal muscle
- •This muscle has a anterior-superior
- direction
- •Posteriorly from the angle of the
- rib (to the tubercle) this muscle becomes the internal intercostal membrane
-
Thoracic Diaphragm
- O:
- Sternal attachments: internal aspect of the xiphoid process
- Costal attachments: Costal
- cartilages of ribs 6 – 10 and ribs 10-12
Lumbar attachment: lumbar vertebral bodies of L1-L3(4) on the right and L1-L2(3) on the left
F.D: central
I: Central tendon
A: Primary muscle of inspiration
I: C3,C4,C5 ventral/anterior primary rami
SS: Its the only muscle that inserts onto itself
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