Muscles of Upper Limb/Pectoral Region Flashcards
Pectoralis Major
Origin: Clavicular head - medial half of clavicle
Sternocostal head: sternum and costal cartilages 1-6
Insertion: Lateral lip of bicipital groove (intertubercular sulcus)
Action: whole muscle - adducts and medially rotates the arm;
clavicular head - flexes the arm
sternocostal head - assists in respiration when shoulder is fixed
Nerve: medial and lateral pectoral nerves from medial and lateral cords of brachial plexus
Muscles of the pectoral region (4)
- Pectoralis Major
- Pectoralis Minor
- Serratus Anterior
- Subclavius
Pectoralis Minor
Origin: 3rd to 5th ribs near cartilages
Insertion: Coracoid process of scapula
Action: depresses scapula; elevates ribs of origin to assist in respiration when the shoulder is fixed
Nerve: medial pectoral
Serratus Anterior
Origin: upper 8 ribs
Insertion: medial (vertebral) border of scapula
Action: rotates scapula; draws scapula forward around thoracic wall (protraction); holds scapula against thoracic wall
Nerve: long thoracic (nerve to serratus anterior)
Subclavius
Origin: 1st costal cartilage
Insertion: Inferior surface of the clavicle
Action: anchors and depresses clavicle during upper limb movements
Nerve: nerve to subclavius
Muscles of the Shoulder (6)
- Deltoid
- Supraspinatus
- Infraspinatus
- Teres Minor
- Subscapularis
- Teres Major
Deltoid
Origin: clavicular part - lateral 1/3 of clavicle
acromial part - acromion
spinal part - scapular spine
Insertion: deltoid tuberosity of humerus
Action: clavicular part - flexes, medially rotates arm
acromial part - adducts arm
posterior part - extends, laterally rotates arm
Nerve: Axillary
Supraspinatus
Origin: supraspinous fossa of scapula
Insertion: great tubercle of humerus
Action: Initiates abduction of arm; stabilizes shoulder joint
Nerve: suprascapular
Infraspinatus
Origin: infraspinous fossa of scapula
Insertion: great tubercle of humerus
Action: laterally rotates arm; stabilizes shoulder joint
Nerve: suprascapular
Teres Minor
Origin: upper lateral border of scapula
Insertion: great tubercle of humerus
Action: laterally rotates arm; stabilizes shoulder joint
Nerve: axillary
Subscapularis
Origin: subscapular fossa of scapula
Insertion: lesser tubercle of humerus
Action: medially rotates arm; stabilizes shoulder joint
Nerve: upper and lower subscapular
Teres Major
Origin: lower lateral/inferior border of scapula
Insertion: medial lip of the intertubercular groove (bicipital groove) of humerus
Action: medially rotates and adducts arm
Nerve: lower subscapular
What 4 muscles make up the rotator cuff?
- Supraspinatus
- Infraspinatus
- Teres Minor
- Subscapularis
- their function is to hold the head of the humerus against the glenoid cavity while the limb is being moved
Muscles of the Arm (5)
- Biceps brachii - short head/long head
- Coracobrachialis
- Brachialis
- Triceps brachii - long head/lateral head/medial head
- Anconeus
Biceps Brachii (long and short heads)
Origin: short head - coracoid process
long head - supraglenoid tubercle of the scapula
Insertion: radial tuberosity and bicipital aponeurosis over anterior forearm muscles
Action: powerful flexor of forearm at elbow joints; powerful supinator of forearm when flexed; very weak flexor of arm at glenohumeral joint
Nerve: musculocutaneous
Coracobrachialis
Origin: coracoid process
Insertion: mid-shaft humerus on medial side
Action: flexion of arm at glenohumeral joint
Nerve: musculocutaneous
Brachialis
Origin: distal half of the anterior humerus
Insertion: ulnar tuberosity
Action: flexes forearm
Nerve: musculocutaneous
Triceps Brachii (long, lateral, medial heads)
Origin: long head - infraglenoid tubercle of the scapula
lateral head - posteriolateral surface of humerus, proximal to
radial groove
medial head - posteriomedial surface of humerus, distal to
radial groove
Insertion: olecranon of ulna
Action: extends forearm
Nerve: radial
Anconeus
Origin: lateral humeral epicondyle of humerus
Insertion: olecranon of ulna
Action: extends forearm (assists triceps); abducts ulna during pronation; tightens elbow joint
Nerve: radial
Muscles of the superficial anterior forearm (4)
- Pronator Teres (humeral and ulnar heads)
- Flexor carpi radialis
- Palmaris Longus (variable)
- Flexor carpi ulnaris (humeral and ulnar heads)
Pronator Teres (humeral/ulnar heads)
Origin: humeral head - medial epicondyle of humerus
ulnar head - coronoid process of ulna
Insertion: lateral radius, midshaft
Action: pronates forearm
Nerve: median
Flexor carpi radialis
Origin: medial epicondyle of the humerus
Insertion: base of the 2nd metacarpal (variable on base of 3rd metacarpal)
Action: flexes and abducts (radially deviates) hand at wrist joint
Nerve: median