The Elbow

The elbow joint consists of the articulations of the distal humerus, the proximal ulna, and the proximal radius. The movements of the elbow include flexion, extension, pronation, and supination. These

TABLE 12-11 Scapulohumeral Muscles*

Muscles

Origin (Proximal Attachment)

Insertion (Distal Attachment)

Innervation

Action

Deltoid

Lateral third of

Deltoid tuberosity

Axillary nerve (C5

Anterior part: ilexes and

clavicle, acromion

of humerus

and C6)

medially rotates arm

and spine of

Middle part: abducts arm

scapula

Posterior part: extends and laterally rotates arm

Supraspinatus

Supraspinous fossa

Superior facet on

Suprascapular

Helps deltoid abduct arm and

of scapula

greater tubercle of humerus

nerve (C4-C6)

acts with rotator cuff muscles

Infraspinatus

Infraspinous fossa of

Middle facet on

Suprascapular

Laterally rotates arm; helps hold

scapula

greater tubercle

nerve (C5 and

humeral head in glenoid

of humerus

C6)

cavity of scapula

Teres minor

Superior part of

Inferior facet on

Axillary nerve (C5

Laterally rotates arm; helps hold

lateral border of

greater tubercle

and C6)

humeral head in glenoid

scapula

of humerus

cavity of scapula

Teres major

Dorsal surface of

Medial lip of

Lower scapular

Adducts and medially rotates

inferior angle of

intertubercular

nerve (C6 and

arm

scapula

groove of humerus

C7)

Subscapularis

Subscapular fossa

Lesser tubercle of

Upper and lower

Medially rotates and adducts arm;

humerus

subscapular nerve (C5-C7)

helps hold humeral head in glenoid cavity

*See Figure 12-1.

TABLE 12-12

Axiohumeral Muscles

*

Muscles

Origin (Proximal

Insertion (Distal

Innervation

Action

Attachment)

Attachment)

Pectoralis major

Clavicular head: anterior

Lateral lip of

Clavicular head:

Adducts and medially

surface of the medial

intertubercular

lateral and

rotates humerus

half of clavicle

groove of

medial pectoral

Acting alone: clavicular

humerus

nerve (C5 and

head flexes humerus,

C6)

sternocostal head

extends humerus

Latissimus dorsi

Spinous processes of

Floor of

Thoracodorsal

Extends, adducts, and

inferior six thoracic

intertubercular

nerve

medially rotates

vertebrae, thoracolumbar

groove of

humerus

fascia, iliac crest, inferior

humerus

three or four ribs

Serratus anterior

External surfaces of

Anterior surface of

Long thoracic

Protracts scapula and

lateral parts of first to

medial border of

nerve (C5-C7)

holds it against thoracic

eighth ribs

scapular nerve

wall, rotates scapula

*See Figure 12-1.

*See Figure 12-1.

movements occur at three separate joints: a hinge joint between the humerus and the ulna; a pivot joint between the ulna and the radius; and a ball-and-socket joint between the humerus and the radius. Women have a less prominent olecranon process

TABLE 12-13 Elbow Flexor Muscles*

and shallower corresponding fossa, which renders them more liable to overstretch the elbow joint.

Elbow flexor muscles are listed in Table 12-13 (Fig. 12-22). Biceps contribute greatly to the stability of the shoulder joint, in addition to functioning

TABLE 12-13 Elbow Flexor Muscles*

Muscles

Origin (Proximal Attachment)

Insertion (Distal Attachment)

Innervation

Action

Biceps brachii

Short head: tip of coracoid

Tuberosity of radius

Musculocutaneous

Flexes forearm

process of scapula

and fascia of

nerve (C5 and C6)

when it is

Long head: supraglenoid

forearm via bicipital

supine; supinates

tubercle of scapula

aponeurosis

forearm

Brachialis

Distal half of anterior

Coronoid process and

Musculocutaneous

Flexes forearm

surface of humerus

tuberosity of ulna

nerve (C5 and C6)

Brachioradialis

Proximal two thirds of lateral supracondylar ridge of humerus

Lateral surface of distal end of radius

Radial nerve (C5-C7)

Flexes forearm

Pronator teres

Humeral head: medial

Middle of lateral surface

Median nerve

Flexes and pronates

epicondyle of humerus

of radius

(C6 and C7)

forearm

Ulnar head: coronoid

process of ulna

*See Figure 12-22.

Acromion

Tendon Sheath

Acromion

Tendon Sheath

Brachioradialis

Extensor carpi radialis longus

Thenar eminence

Biceps brachii

Brachialis

Flexor retinaculum

Figure 12-22 Elbow flexor muscles.

Pectoralis major

Biceps brachii

Brachialis

Brachioradialis

Extensor carpi radialis longus

Thenar eminence

Pronator teres Flexor carpi radialis Palmaris longus Flexor digitorum superficialis Flexor carpi ulnaris

Flexor retinaculum

Hypothenar eminence

Flexor digitorum superficialis, tendons

Flexor digitorum profundus, tendons

Figure 12-22 Elbow flexor muscles.

as the major elbow flexor. The major elbow extensor is triceps brachii (Table 12-14 and Fig. 12-23). The elbow supinator muscle is described in Table 12-15 and Figure 12-24.

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