Gross Anat I Wet Lab 2 Muscles

Latissimus dorsi

Origin: Spinous processes T7-L5, sacrum; iliac crest, ribs 10-12

Insertion: Intertubercular sulcus

Action: Arm extension, adduction, medial rotation; shoulder depression

Innervation: Thoracodorsal nerve

Trapezius

Origin: Sup. nuchal line; ext. occipital protuberance; ligamentum nuchae; spinous processes C7-T12

Insertion: Scapular spine; acromion process; lateral 1/3 of clavicle

Action:

• Upper fibers: Elevation, upward rotation (during abduction above horizontal)

• Middle fibers: Retraction

• Lower fibers: Depression

Innervation:

• Motor: spinal accessory nerve (CN XI)

• Sensory: ant. rami of C3-4

Rhomboid major

Origin: Spinous processes T2-5

Insertion: Medial border of scapula

Action: Retraction/adduction, elevation

Innervation: Dorsal scapular nerve

Rhomboid minor

Origin: Spinous processes C7-T1

Insertion: Medial border of scapula

Action: Retraction/adduction, elevation

Innervation: Dorsal scapular nerve

Levator scapulae

Origin: Transverse processes C1-4

Insertion: Upper medial border of scapula

Action: Elevation

Innervation: Dorsal scapular nerve

Deltoid

Origin: Spine of scapula, acromion process, lateral 1/3 of clavicle

Insertion: Deltoid tuberosity

Action: Abduction; assists flexion and extension

Innervation: Axillary nerve

Supraspinatus (SITS)

Origin: Supraspinous fossa

Insertion: Greater tubercle, superior facet

Action: Abduction, stabilization of GH joint

Innervation: Suprascapular nerve

Infraspinatus (SITS)

Origin: Infraspinous fossa

Insertion: Greater tubercle, middle facet

Action: Lateral rotation, stabilization of GH joint

Innervation: Suprascapular nerve

Teres minor (SITS)

Origin: Lateral border of scapula

Insertion: Greater tubercle, inferior facet

Action: Lateral rotation, stabilization of GH joint

Innervation: Axillary nerve

Subscapularis (SITS)

Origin: Subscapular fossa/costal surface

Insertion: Lesser tubercle

Action: Medial rotation

Innervation: Upper & lower subscapular nerves

Teres major

“Little helper of the latissimus dorsi”

Origin: Inferior angle of scapula

Insertion: Lesser tubercle

Action: Medial rotation, extension, stabilization of GH joint

Innervation: Inferior subscapular nerve

Serratus anterior

“Buddy muscle”

Origin: Upper 8-9 ribs

Insertion: Medial border of scapula

Action: Protraction, assists abduction; keeps med. border/inf. angle opposed to thoracic wall

Innervation: Long thoracic nerve

Triceps brachii - Long head

Origin: 

• Long head: Infraglenoid tubercle

• Lateral head: Posterior humeral shaft

• Medial head: Posterior humeral shaft (deep to long head)

Insertion: Olecranon fossa

Action: Forearm extension, accessory adductor and extensor of arm at GH joint (long head only)

Innervation: Radial nerve

Triceps brachii - Lateral head

Origin: 

• Long head: Infraglenoid tubercle

• Lateral head: Posterior humeral shaft

• Medial head: Posterior humeral shaft (deep to long head)

Insertion: Olecranon fossa

Action: Forearm extension, accessory adductor and extensor of arm at GH joint (long head only)

Innervation: Radial nerve

Triceps brachii - Medial head

Origin: 

• Long head: Infraglenoid tubercle

• Lateral head: Posterior humeral shaft

• Medial head: Posterior humeral shaft (deep to long head)

Insertion: Olecranon fossa

Action: Forearm extension, accessory adductor and extensor of arm at GH joint (long head only)

Innervation: Radial nerve