Muscles 1 OIA Flashcards
Pectoralis minor
Origin: Ribs 3-5 and overlying fascia
Insertion: Coracoid process of scapula
Action: Draws scapula laterally and forward around chest wall; rotates scapula and depresses apex of shoulder
Serratus anterior
Origin: All or nearly all ribs
Insertion: Medial border of scapula
Action: Draws scapula laterally and forward around chest wall; protracts scapula; aids in rotating scapula to elevate apex of shoulder; fixes scapula during abduction of arm
Trapezius
Origin: External occipital protuberance, medial 1/3 of superior nuchal line, nuchal ligament, lateral 1/3 of clavicle anterior rami of C3-C4 spinous processes of vertebrae C7-T3 or T4
Insertion: Acromion and spine of scapula, lateral 1/3 of clavicle
Action: Stabilizes scapula and shoulder during arm movements; elevates and depresses apex of shoulder; rotate and retract scapula
Levator scapulae
Origin: Transverse processes of vertebrae C1-C4
Insertion: Superior angle to medial border of scapula
Action: Elevates scapula if cervical vertebrae are fixed; flexes neck laterally if scapula is fixed; retracts scapula and braces shoulder; rotates scapula and depresses apex of shoulder
Rhomboid major
Origin: Spinous processes of vertebrae T2-T5
Insertion: Medial border of scapula
Action: Retracts scapula and braces shoulder; fixes scapula during arm movements
Rhomboid minor
Origin: Spinous processes of vertebrae C7-T1, nuchal ligament
Insertion: Medial border of scapula
Action: Retracts scapula and braces shoulder; fixes scapula during arm movements
Pectoralis major
Origin: Medial half of clavicle, costal cartilages 1-7, aponeurosis of external oblique
Insertion: Lateral lip of intertubercular sulcus of humerus
Action: Flexes, adducts, and medially rotates humerus; Aids in deep inspiration.
Latissimus dorsi
Origin: Vertebrae T7-L5, lower three or four ribs, iliac crest, thoracolumbar fascia
Insertion: Floor of intertubercular sulcus of humerus
Action: Adducts and medially rotates humerus; extends the shoulder joint; pulls body forward and upward, as in climbing; aids in deep inspiration
Deltoid
Origin: Acromion and spine of scapula; clavicle
Insertion: Deltoid tuberosity of humerus
Action: Anterior fibers flex and medially rotate arm; lateral fibers abduct arm; posterior fibers extend and laterally rotate arm
Supraspinatus
Origin: Supraspinous fossa of scapula
Insertion: Greater tubercle of humerus
Action: Aids deltoid in abduction of arm; resists downward slippage of humeral head
Infraspinatus
Origin: Infraspinous fossa of scapula
Insertion: Greater tubercle of humerus
Action: Modulates action of deltoid, preventing humeral head from sliding upward; rotates humerus laterally
Teres major
Origin: Inferior angle of scapula
Insertion: Medial lip of intertubercular sulcus of humerus
Action: Extends and medially rotates humerus
Teres minor
Origin: Lateral border and adjacent posterior surface of scapula
Insertion: Greater tubercle of humerus; posterior surface of joint capsule
Action: Modulates action of deltoid, preventing humeral head from sliding upward as arm is abducted; rotates humerus laterally
Subscapularis
Origin: Subscapular fossa of scapula
Insertion: Lesser tubercle of humerus, anterior surface of joint capsule
Action: Modulates action of deltoid, preventing humeral head from sliding upward as arm is abducted; rotates humerus medially
Coracobrachialis
Origin: Coracoid process
Insertion: Medial aspect of humeral shaft
Action: Flexes and medially rotates arm; resists deviation of arm from frontal plane during abduction
Biceps brachii, short head
Origin: coracoid process
Insertion: Tuberosity of radius, fascia of forearm
Action: Rapid or forceful supination of forearm; synergist in elbow flexion; slight shoulder flexion
Biceps brachii, long head
Origin: superior margin of glenoid cavity
Insertion: Tuberosity of radius, fascia of forearm
Action: Rapid or forceful supination of forearm; synergist in elbow flexion; slight shoulder flexion; tendon of long head stabilizes shoulder by holding humeral head against glenoid cavity
Brachialis
Origin: Anterior surface of distal half of humerus
Insertion: Coronoid process and tuberosity of ulna
Action: Prime mover of elbow flexion
Brachioradialis
Origin: Lateral supracondylar ridge of humerus
Insertion: Lateral surface of radius near styloid process
Action: Flexes elbow
Triceps brachii, lateral head
Origin: posterior surface of proximal end of humerus
Insertion: Olecranon, fascia of forearm
Action: Extends elbow
Triceps brachii, long head
Origin: inferior margin of glenoid cavity and joint capsule
Insertion: Olecranon, fascia of forearm
Action: Extends elbow; long head extends and adducts humerus
Triceps brachii, medial head
Origin: posterior surface of entire humeral shaft
Insertion: Olecranon, fascia of forearm
Action: Extends elbow
Anconeus
Origin: Lateral epicondyle of humerus
Insertion: Olecranon and posterior surface of ulna
Action: Extends elbow; may help to control ulnar movement during pronation
Pronator quadratus
Origin: Anterior surface of distal ulna
Insertion: Anterior surface of distal radius
Action: Prime mover of forearm pronation; also resists separation of radius and ulna
Pronator teres
Origin: Humeral shaft near medial epicondyle; coronoid process of ulna
Insertion: Lateral surface of radial shaft
Action: Assists pronator quadratus in pronation, but only in rapid or forceful action; weakly flexes elbow
Supinator
Origin: Lateral epicondyle of humerus; supinator crest and fossa of ulna just distal to radial notch; anular and radial collateral ligaments of elbow
Insertion: Proximal 1/3 of radius
Action: Supinates forearm
Flexor carpi radialis
Origin: Medial epicondyle of humerus
Insertion: Base of metacarpals II-III
Action: Flexes wrist anteriorly; aids in radial flexion of wrist
Flexor carpi ulnaris
Origin: Medial epicondyle of humerus; medial margin of olecranon; posterior surface of ulna
Insertion: Pisiform, hamate, metacarpal V
Action: Flexes wrist anteriorly; aids in ulnar flexion of wrist
Palmaris longus
Origin: Medial epicondyle of humerus
Insertion: Flexor retinaculum, palmar aponeurosis
Action: Anchors skin and fascia of palmar region; resists shearing forces when stress is applied to skin
Extensor carpi radialis longus
Origin: Lateral supracondylar ridge of humerus
Insertion: Base of metacarpal II
Action: Extends wrist; aids in radial flexion of wrist
Extensor carpi radialis brevis
Origin: Lateral epicondyle of humerus
Insertion: Base of metacarpal III
Action: Extends wrist; aids in radial flexion of wrist
Extensor carpi ulnaris
Origin: Lateral epicondyle of humerus; posterior surface of ulnar shaft
Insertion: Base of metacarpal V
Action: Extends and fixes wrist when fist is clenched or hand grips an object; aids in ulnar flexion of wrist
Extensor digitorum
Origin: Lateral epicondyle of humerus
Insertion: Dorsal surfaces of phalanges II-V
Action: Extends wrist, metacarpophalangeal, and interphalangeal joints; tends to spread digits apart when extending metacarpophalangeal joints
Rectus abdominis
Origin: Pubic symphysis and superior margin of pubis
Insertion: Xiphoid process, costal cartilages 5-7
Action: Flexes lumbar region of vertebral column, producing forward bending at the waist
Erector Spinae
Origin: Nuchal ligament, ribs 3-12, thoracic and lumbar vertebrae, median and lateral sacral crests, thoracolumbar fascia
Insertion: Mastoid process, cervical and thoracic vertebrae, and all ribs
Action: Extension and lateral flexion of vertebral column;
Semispinalis thoracis
Origin: Vertebrae T6-T10
Insertion: Vertebrae C6-T4
Action: Extension and contralateral rotation of vertebral column
Multifidus
Origin: Vertebrae C4-L5, posterior superior iliac spine, sacrum, aponeurosis of erector spinae
Insertion: Laminae and spinous processes of vertebrae superior to origins
Action: Stabilization of adjacent vertebrae, maintenance of posture, control of vertebral movement when erector spinae acts on vertebral column
Quadratus lumborum
Origin: Iliac crest, iliolumbar ligament
Insertion: Rib 12 and vertebrae L1-L4
Action: Aids respiration by fixing rib 12 and stabilizing inferior attachments of diaphragm.
- Unilateral contraction causes ipsilateral flexion of lumbar vertebral column;
- bilateral contraction extends lumbar vertebral column.
External oblique
Origin: Ribs 5-12
Insertion: Anterior half of iliac crest, pubic symphysis, and superior margin of pubis
Action: Supports abdominal viscera against pull of gravity; stabilizes vertebral column; maintains posture; compresses abdominal organs; unilateral contraction causes contralateral rotation of waist
Internal oblique
Origin: Inguinal ligament, iliac crest, and thoracolumbar fascia
Insertion: Ribs 10-12, costal cartilages 7-10, pubis
Action: Supports abdominal viscera against pull of gravity; stabilizes vertebral column; maintains posture; compresses abdominal organs; unilateral contraction causes ipsilateral rotation of waist
Transverse abdominis
Origin: Inguinal ligament, iliac crest, thoracolumbar fascia, costal cartilages 7-12
Insertion: Linea alba, pubis, aponeurosis of internal oblique
Action: Compresses abdominal contents
External intercostals
Origin: Inferior margins of ribs 1-11
Insertion: Superior margin of next lower rib
Action: When scalenes fix rib 1, external intercostals elevate and protract ribs 2-12, expanding the thoracic cavity and creating a partial vacuum causing inflow of air; exercise a braking action during expiration so that expiration is not overly abrupt
Internal intercostals
Origin: Superior margins and costal cartilages of ribs 2-12; margin of sternum
Insertion: Inferior margin of next higher rib
Action: Elevates and depresses ribs to aid in inspriation and expiration
