GA Scapular and Pectoral Muscles, Vasculature and Innervation Flashcards
Scapulohumeral Muscles
also known as intrinsic shoulder musces, 6 muscles 4 of which are rotator cuff muscles
deltoid muscle, Teres Major muscle, Serratus Anterior, Supraspinatus muscle, Infraspinatus muscle, Teres Minor muscle, Subscapularis muscle
Deltoid Muscle
divided into unipennate and multipennate pares
O- later 1/3 of clavicle; acromion and spine of scapula
I - deltiod tuberosity of humerus
A - Anterior fibers-flexion and MR of humerus, Middle fibbers-ABD from 15-90 degrees, Posterior fibbers-extension and LR of humerus
N - Axillary n. (C5,C6)
B - Ant. and Post. humeral circumflex aa.; acromial and deltoid branches of thoracoacromial trunk
Tere Major Muscle
O - Post. surface of inferior angle of scapula
I - Medial lip IT groove of humerus
A - ADD and MR of humerus; assists with ext. from flexed position
N - Lower subscapular n. (C5,C6)
B - Thoracodorsal a.
Supraspinatus Muscle
one of the rotator cuff muscles, only one that does not rotate humerus
O - Supraspinous fossa of scapula
I - Superior facet greater tubercle of humerus
A - Initiates ABD for first 15 degrees
N - Suprascapular n. (C4,C5,C6)
B - Suprascapular a.
Infraspinatus Muscle
O - Infraspinous fossa of scapula I - Middle facet greater tubercle of humerus A - LR of humerus N - Suprascapular n. (C5,C6) B - Suprascapular a.
Teres Minor Muscle
often hard to separate from infraspinatus m.
O - Middle part, lateral border of scapula
I - Inferior facet greater tubercle of humerus
A - LR of humerus; assists with ADD of humerus
N - Axillary n. (C5,C6)
B - Circumflex scapular aa.
Subscapularis Muscle
O - Subscapular fossa (most anterior surface of scapula)
I - Lesser tubercle of humerus
A - Most powerful MR of humerus; assists in ADD of humerus
N - Upper and lower subscapular nn. (C5,C6,C7)
B - Subscapular a.
Suprascapular artery
from the thyrocervical trunk, passes superior to transverse scapular l. to supraspinous fossa, passes thru spinoglenoid notch to infraspinous fossa, participates in scapular anastomoses
Dorsal Scapular artery
from the subclavian artery, passes thru the trunk of the brachial plexus, runs along the medial border of scapula, also participates in scapular anastomoses
Thoracoacromial trunk
from the 2nd part of axillary artery, gives off the clavicular, acromial, deltoid and pectoral branches
Subscapular artery
from the 3rd part of axillary a., descends along lateral border of subscapularis m.
terminates as thoracodorsal artery and the circumflex scapular artery
Thoracodorsal artery
from the subscapular a. continues path of subscapular a.
Circumflex artery
from the subscapular a., curves around lateral border of scapula, found in the triangular space and is the KEY player in scapular anastomoses
Anterior humeral circumflex artery
from the 3rd part of axillary a., encircles surgical neck of humerus, anastomoses with posterior humeral circumflex a. laterally who it often shares a common trunk with
Posterior Humeral Circumflex artery
from the 3r part of the axillary a., encircles the surgical neck of humerus, traverses the quadrangular space
Suprascapular nerve
from the superior trunk of brachial plexus, often recieves fibers from C4, passes thru suprascapular notch inferior to transverse scapular l., runs with suprascapular a., supplies the supraspinatus and infraspinatus mm.
Axillary nerve
is the terminal branch of posterior cord of brachial plexus, exits axilla posteriorly, passes thru quadrangular space with post. humeral circumflex a., superior lateral cutaneous n. supplies skin over inferior part of deltoid
Upper subscapular nerve
from the posterior cord of brachial plexus, supplies superior portion of subscapularis m.
Lower subscapular nerve
from the posterior cord of brachial plexus, supplies inferior portion of subscapularis m. and teres major
Anterior Axioappendicular Muscles
four anterior muscles that move pectoral girdle, also known as the thoracoappendicular or pectoral arm
pectoralis major muscle, pectoralis minor muscle, subclavian muscle, serratus anterior muscle
Pectoralis Major muscle
has clavicular and sternocostal heads, lateral border of muscle makes up most of anterior wall of axilla, inferior border forms anterior axillary folds
O - Clavicular head-anterior surface of medial 1/2 of clavicle, Sternal head-anterior surface of sternum, sup. 6 costal cartilages, aponeurosis of external oblique m.
I - Lat. lip of IT groove of humerus
A - ADD, MR of humerus; clav head-flexus humerus, sternal head-extends from flexed position
N - Medial and lateral pectoral nn. (Clav head- C5,C6, Sternal Head-C7,C8,T1)
B - Pectoral branches of thoracoacromial trunk
Pectoralis Minor muscle
O - 3-5th ribs (sometimes 6) of costal cartilages
I - medial border of superior surface coracoid process
A - stabilizes scapula by drawing it anterior and inferior against thoracic wall; accessory m. in inspiration
N - Medial perctoral n. (C8,T1)
B - Pectoral branches from thoracoacromial trunk
Subclavius Muscle
O - Junction of 1st rib and its costal cartilage
I - inferior surface, middle 1/3 of clavicle
A - anchors and depresses clavicle
N - Nerve to subclavius (C5,C6)
B - Clavicular branches of thoracoacromial trunk
Serratus Anterior Muscle
O - external surface of lateral parts of 1st-8th ribs (sometimes 9th)
I - Anterior surface of medial border of scapula
A - Scapular protraction and upward rotation; fixes scapula against thoracic wall
N - Long thoracic nerve (C5,C6,C7)
B - Superior and lateral thoracic aa.
