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Muscles of the Upper Extremity (Anterior Glenohumeral Group (Pectoralis…
Muscles of the Upper Extremity
Superior Glenohumeral Group
Medial Deltoid
Insertion: Superior facet of greater tubercle of humerus
Innervation: Axillary nerve
Origin: Lateral third of clavicle; acromion and spine of scapula
Actions:Abducts arm
Posterior Deltoid
Insertion: Superior facet of greater tubercle of humerus
Innervation: Axillary nerve
Origin: Lateral third of clavicle; acromion and spine of scapula
Action: Extends and laterally rotates arm
Anterior Deltoid
Insertion: Superior facet of greater tubercle of humerus
Origin: Lateral third of clavicle; acromion and spine of scapula
Action: Flexes and medially rotates arm
Innervation: Axillary nerve
Posterior Glenohumeral Group
Lat Dorsi
Insertion: floor of intertubercular sulcus
Innervation: Thoracodorsal nerve
Origin: Spinous process of inferior 6 thoracic vertebrae, thoracolumbar fascia, illiac crest, and inferior 3 or 4 ribs
Action: Extends, adducts, and medially rotates humerus; raises body toward arms during climbing
Long Head of Triceps
Insertion: Proximal end of olecranon of ulna and fascia of forearm
Innervation: Radial nerve
Origin:
Long head
: infraglenoid tubercle of scapula.
lateral head
: posterior surface of humerus, superior to radial groove.
medial head
posterior surface of humerus, inferior to radial groove
Action: Chief extensor of forearm; long head resists dislocation of humerus especially important during adduction
Teres Major
Origin: Posterior surface of inferior angle of scapula
Insertion: Medial lip of intertubercular sulcus of humerus
Innervation: Lower subscapular nerve
Action: Adducts and medially rotates arm
Anterior Glenohumeral Group
Pectoralis Minor
Proximal Attachment
3rd-5th ribs near their costal cartilages
Distal Attachment
medial border and superior surface of coracoid process of scapula
Innervation
Medial pectoral nerve (C8,T1)
Main Action
Stabilizes scapula by drawing it
inferiorlly
and
anteriorly
against thoracic wall
Subclavius
Proximal Attachment
Junction of 1st rib and its costal cartilage
Distal Attachment
inferior surface of middle third of clavicle
Innervation
Medial pectoral nerve (C8,T1)
Main action
ANCHORS and DEPRESSES scapula
Pectoralis Major
Proximal attachement
: Clavicular head: anterior surface of medial half of clavicle.......Sternocostal head: anterior surface of sternum, superior six costal cartilages, and aponeurosis of external oblique muscle
Distal Attachment
Lateral lip of intertubercular sulcus of humerus
Innervation
Lateral and medial pectoral nerves; clavicular head (C5,C6) and Sternocostal head (C7,C8,T1)
Main Action
ADDUCTS and MEDIALLY rotates humers: draws scapula anteriorly and inferiorly
Acting alone; clavicular head flexes humerus and sternocostal head extends it from the flexed psition
Two Parts of the Pectoralis Major: Clavicular Head. Because of this fiber direction, this part of the pec majo will perform
extension
(only half way up) The Sternocostal head will help pull the arm up further to full extension.. Think about the way the muscle fibers run...
Coracobrachialis
Proximal Attachment
Tip of coracoid process of scapula
Distal Attachment
Middle Third of medial surface of humerus
Innervation
Musculocutaneous Nerve (C5,
C6,
C7)
Muscle Action
Helps
Flex
and
Adduct
arm; resists dislocation of shoulder
Biceps long/short head
Biceps Brachii
Proximal Attachment
Short Head
Tip of coracoid process of scapula
Long Head
Supraglenoid tubercle of Scapula
Distal Attachment
Tuberosity of radius and fascia of forearm via bicipital aponeurosis
Innervation
Musculocutaneous nerve (C5,
C6,
C7)
Muscle Action
Supinates forearm and when it is supine, flexes, forearm;
short head
resists dislocation of shoulder
Scapular Group
Rhomboid Min, Maj
Insertion: Minor: smooth triangular area at medial end of scapular spine. Major: medial border of scapula from level of spine to inferior angle
Innervation: Dorsal scapular nerve
Origin: minor: nuchal ligament; spinous processes of C7 and T1 vertebrae. Major: Spinous process of T2-T5 vertebrae
Retract scapula and rotate its glenoid cavity inferiorly; fix scapula to thoracic wall
Trapezius
Innervation: Spinal accessory nerve (CNXI)
Action: Descending part elevates; ascending part depresses; and middle part (or all parts together) retracts scapula; descending and ascending parts act together to rotate glenoid cavity superiorly
Origin: medial third of superior nuchal line; external occipital protuberance; nuchal ligament; spinous processes of C7-T12
Insertion: Lateral third of clavicle; acromion and spine of scapula
Serratus Anterior
Proximal Attachment
External surfaces of lateral parts of 1st-8th ribs
Distal Attachment
Anterior surface of medial border of scapula
Innervation
Long thoracic nerve (C5,
C6,C7
)
Muscle Action: Protracts scapula and holds it against thoracic wall; Rotates scapula
Rotator Cuff Group
Subscapularis
Proximal Attachment: Subscapula foss (most anterior surface of scapula
Distal Attachment: Lesser tubercle of humerus
Innervation: Upper and lower subscapular nerve: C5,C6,C7
Main action: Medially rotates arm; as part of the rotator cuff; helps hold head of humerus in glenoid cavity
Supraspinatus
Origin: Supraspinous fossa of scapula
Insertion: superior facet of greater tubercle of humerus
Action: Initiates and assists deltoid in abduction of arm and acts with rotator cuff muscles
Innervation: Suprascapular
Teres minor
Proximal attachment: Middle part of the
lateral
border of the scapula
Distal Attachment: inferior facet of the greater tubercle
Innervation:
Axillary
nerve (C5,C6)
Muscle action: Lateral rotation; acts with other muscles of the RC group.
Infraspinatus
Proximal Attachment: infraspinous fossa of scapula
Distal Attachment: middle facet of greater tubercle of humerus
Suprascapular Nerve
(C5,C6)
Main action: Lateral rotation; with other RC muscles