pectoralis major
origin
by two heads
Sternocostal head:
anterior surface of the sternum.
Upper 6 costal cartilages.
External abdominal oblique aponeurosis.
clavicular head:
from anterior surface of the medial 1/2 of the clavicle.
nerve supply(double)
Lateral and medial pectoral nerves.
insertion
The upper fibers are twisted and inserted downward forming the anterior lamina.
The lower fibers are twisted and inserted upward forming the posterior lamina.
actions
Adduction and medial rotation of the arm.
Flexion of the arm by clavicular head.
Elevates the ribs during deep inspiration.
Sternocostal part acts together with latissimus dorsi, teres major and deltoid: draw the trunk up during climbing and gymnastic.
subclavius
origin
from the upper surface of first rib and first costal cartilage
insertion
into subclavian groove on the lower surface of the clavicle
nerve supply
nerve to sublcavius from upper trunk of brachial plexus ( C 5&6)
action
fixation of the clavicle during movments of the shoulder girdle
serratus anterior
origin
by fleshly digitations from the upper eight ribs.
The first digitation takes origin from the 1st and 2nd ribs.
insertion
anterior surface of the medial border of the scapula.
a) The first digitation: anterior surface of the superior angle
b)The 2nd and 3rd digitations: anterior surface of medial border
c)The lower five digitations: anterior surface of inferior angle
nerve supply
long thoracic nerve (nerve of Bill C5, 6, &7) passes superficial to the muscle
actions
Protraction of the scapula (pulls the scapula forward with pectoralis minor)
Lower 5 digitations, Abduction of the arm above 90 degree,acting with the trapezius muscle
Fixation of the scapula during movement of the upper limb
pectoralis minor
origin
from the 3rd,4th and 5th ribs
insertion
superior surface of the coracoid process
actions
protraction the scapula (forward movment)
elevates the ribs during deep inspiration
please check out slide 13 ***
c) Lateral pectoral Nerve
b) Thoraco-acromial Artery
The structures pierced the fascia:
4- Laterally, the coracoid process.
3- Medially, the first rib.
2- Inferiorly, it splits to enclose pectoralis minor, then fuse together to form suspensory ligament of the axilla. It attaches to the axillary fascia
1- Superiorly, it splits into two laminae which enclose subclavius and attached to the margins of subclavian groove.
• Test of the muscle: ask the patient to push the wall with the outstretched hand. If the muscle is affected the winging is increased
• A protrusion of the medial border of the scapula away from the posterior chest wall.
• Winging of the scapula, due to paralysis of the muscle
• It descends in the midaxillary line on the superficial surface of the muscle
Injury of the long thoracic nerve
Deltopectoral groove between deltoid and pectoralis major containing: 1- Cephalic Vein.2- Deltoid branch of thoracoacromial Artery.
It is the only muscle of the upper limb supplied by 5 segments from brachial plexus.
SO the anterior fold of the axilla is higher than the posterior fold
Pectoral region is the region in front of the upper part of the chest, its Muscles connecting the chest wall to the arm