move the limbs Flashcards
- These muscles are responsible for moving the scapula and consequently, the upper limb.
- These muscles are known as the extrinsic shoulder muscles because the run from the ribs and vertebral column to the pectoral or shoulder girdle. They have two primary functions: either to fix the scapula in place, or to move the scapula so that the range of motion of the upper limb can be increased.
- The anterior muscles include the pectoralis major and minor, serratus anterior and subclavius.
- The posterior muscles include the latissimus dorsi and trapezius, and the underlying levator scapulae and rhomboids.
superficial muscles of the anterior and posterior thorax
- is a small muscle that extends from the first rib to the underside of the clavicle (green arrow).
- It helps to stabilize and depress the pectoral girdle to allow for precise movements of the upper limb.
- Under the clavicle, extending from the clavicle to the first rib.
- Steadies the clavicle during movement of the pectoral girdle.
The subclavius
- draws the scapula forward and downward when the ribs are fixed. However, if the scapula is fixed, contraction of the __ __ pulls the rib cage superiorly. Thus, the ___ __ muscle can be considered an accessory muscle of forced inspiration. Patients suffering from chronic obstructive pulmonary diseases such as emphysema will extend their upper limbs against a table top to brace (fix) the scapula, and use the contractions of the __ __ muscles to help them breathe.
- Thin muscle deep to the pectoralis major.
- With ribs fixed, moves scapula so glenoid cavity can rotate downward
- Assists in forced inspiration when scapula is held fixed because it elevates the ribs.
pectoralis minor
- gets its name from its jagged or “saw-toothed” appearance.
- Its origin is from slips of muscle arising from the first nine ribs. These join together to insert on the entire anterior surface of the vertebral border of the scapula.
- The main action of the __ __ is to rotate the scapula so that the inferior angle moves laterally and upward. This rotation of the scapula allows you to raise your arm above your head.
- also works to protract and hold the scapula against the posterior rib cage, and permits arm movements such as pushing or punching. That’s why it is nick-named the boxer’s muscle.
serratus anterior
- Stabilizes, raises, retracts and rotates the scapula.
- is a superficial, flat triangular muscle extending from skull and vertebral column medially to the pectoral girdle. The two ___ muscles form a diamond on the superficial back.
- The action of the ___ depends on which region of this large muscle is active. The middle fibers retract or adduct the scapula; the superior fibers elevate the scapula and work with the levator scapulae to shrug the shoulders or can help extend the head when the scapula is fixed. The inferior fibers depress the scapula and shoulder.
The trapezius
- Elevate and adduct the scapula
- lie deep to sternocleidomastoid and trapezius. These muscles work along with the superior fibers of the trapezius to elevate the scapula as when shrugging the shoulders or lifting a weight over the head.
levator scapulae
stabilize the scapula and work with the middle fibers of the trapezius to retract (adduct) the scapula as when “squaring” the shoulders.
The rhomboids
- Covers the superior thorax
- Two origins: Clavicular head (small) and sternocostal head.
- Prime mover of Arm: flexes, adducts & medially rotates arm
- is a large, flat muscle with convergent fibers that have multiple origins from the clavicle, sternum, costal cartilages of ribs 1-7, and the aponeurosis of the external oblique muscles. The fibers converge to insert by a short tendon into the intertubercular sulcus and greater tubercle of the humerus.
- a prime mover of arm flexion, medial rotation and adduction.
- It functions when climbing, throwing, pushing and in forced inspiration.
pectoralis major
- Inferior part of back
- Power stroke; strike a blow
- Swimming muscle
- Prime mover of Arm: extension, adduction, medially rotates arm
- is a broad, flat, triangular shaped muscle with numerous origins from the lumbodorsal fascia, spines of the six inferior thoracic vertebrae, lower 3-4 ribs, and iliac crest with a bit coming from the inferior angle of the scapula.
- inserts on the intertubercular sulcus of the humerus. This muscle is a prime mover of arm extension (and so in this action it is an antagonist of the pectoralis major). It is also a powerful arm adductor and medially rotates the arm at the shoulder.
- It functions in common activities such as hammering, swimming, and rowing.
The latissimus dorsi
- is considered to be a prime mover of the arm.
- is a thick, triangular shaped multipectinate muscle. It has a complex origin with fibers arising from the lateral third of the clavicle, acromion and spine of the scapula. It is the prime mover of arm abduction when all its fibers contract simultaneously. It is an antagonist of the pectoralis major and latissimus dorsi which adduct the arm.
- When only the anterior fibers are active, the ___ can be a powerful flexor and medial rotator of the arm. However, if only the posterior fibers are active, the __ assists in arm extension and lateral rotation.
- It is also active in the swinging of our arms when we walk.
- covers shoulder joint and forms the rounded contour of the shoulder. (clavicle, acromion, scapula)
- Common site of intramuscular injections
- Three origins for three sets of muscle fibers.
- Give rise to different movements of the arm
- Prime mover of arm Abduction, aids in flexion, medial rotation, extension and lateral rotation.
- Antagonist of pectoralis major and latissimus dorsi (adduct)
deltoid
- Helps to form part of posterior axillary wall.
- Extends, medially rotates & adducts the arm.
Teres major
- Flexion & adduction of the arm; synergist of pectoralis major
- Musculocutaneous nerve pierces belly
Coracobrachialis
- Fills the subscapular fossa & forms part of posterior wall of axilla.
- Inserts on the lesser tubercle of humerus.
- Helps to hold head of humerus in glenoid cavity.
- Medial rotator of the arm.
Subscapularis
- (prevents downward dislocation of humerus)
- Supraspinous fossa of the scapula, deep to trapezius.
Supraspinatus
Infraspinous fossa
Infraspinatus
Often inseparable from the infraspinatus
Teres minor
Repetitive overhead motion causes continual pinching of the supraspinatus tendon causes inflammation, pain and eventual degeneration which can result in the muscle pulling away from the humerus.
Impingement syndrome
- Two heads, long and short
- Originate from scapula (supraglenoid tubercle & coracoid process) and insert on radial tuberosity and bicipital aponeurosis.
- Spans both the shoulder and elbow joint
- Flexes forearm at elbow joint and shoulder joint.
- Supinates the forearm at the radioulnar joints,
Biceps brachii
- (humerus to ulna)
- Deep to biceps brachii
- Most powerful flexor of the forearm at the elbow joint
Brachialis
- (above lateral epicondyle of humerus to styloid process of radius)
- Flexes forearm at elbow joint when a quick movement is required or when a weight is lifted slowly during flexion of forearm (stabilizes elbow).
Brachioradialis
- Posterior surface of arm
- Most powerful of the forearm extensors at the elbow joint.
- Three heads of Origin: Long, lateral and medial heads
- Long head from the scapula and two from the humerus
- Long head crosses the shoulder joint
- Infraglenoid tubercle of scapula to olecranon of ulna
Triceps brachii
- (= elbow)
- Lateral epicondyle of humerus to olecranon
- Assists triceps in extending the forearm.
Anconeus
- Forearm pronators
- Medial epicondyle of humerus and coronoid process of ulna to midlateral surface of radius
Pronator teres
- Forearm pronator
- Distal ulna to distal radius
Pronator quadratus