Thoracic Spine Bony Landmarks, Musculature, and Structures I BIOL 106 LA

Diaphragm origin

Inferior, internal surface of ribs and sternum

Diaphragm insertion

central tendon

Diaphragm action

Contraction moves the diaphragm downward and increases thoracic volume (inhalation); primary muscle for inspiration

Diaphragm innervation

Phrenic nerve

Multifidus origin

Sacrum, posterior-superior iliac spine

Multifidus insertion

Spinous processes L5-T8 & transverse processes

Multifidus action(s)

Bilaterally: extends vertebral column

Unilaterally: ipsilateral lateral flexion & contralateral flexion

Multifidus innervation

Spinal nerves

External intercostals origin

Inferior border of superior rib

External intercostals insertion

Superior border of the intermediate rib below

External intercostals action

Elevate rib cage

External intercostals and internal intercostals innervation

Intercostal nerve

Internal intercostals action

Depress rib cage

Internal intercostals origin

Internal intercostals insertion

Pectoralis major origin

Medial end of clavicle, sternum, & cartilage of ribs 1-6

Pectoralis major insertion

Bicipital groove, greater tubercle of humerus

Pectoralis major actions

Shoulder adduction & internal rotation

Pectoralis major innervation

Lateral and medial pectoral nerves

Pectoralis minor origin

Anterior surface of ribs 3-5

Pectoralis minor insertion

Coracoid process of the scapula

Pectoralis Minor action

Scapular protraction & downward rotation

Pectoralis minor innervation

Lateral and medial pectoral nerves

Subclavius origin

Costal cartilage of 1st rib

Subclavius insertion

Groove on inferior surface of clavicle

Subclavius action

Depresses pectoral girdle

Subclavius innervation

Subclavian nerve

Serratus anterior origin

Ribs 1-8

Serratus anterior insertion

Medial border of scapula

Serratus anterior action

Upward rotation of the scapula & scapular protraction

Serratus anterior innervation

Long thoracic nerve

Latissimus dorsi origin

Spines of T7-T12

Latissimus dorsi insertion

Bicipital groove of humerus

Latissimus dorsi actions

Shoulder extension and internal rotation

Latissimus dorsi innervation

Thoracodorsal nerve

Rhomboid major origin

Rhomboid major insertion

Medial border of the scapula

Rhomboid major actions

Stabilizes scapula & scapular retraction

Rhomboid major innervation

Dorsal scapular nerve

Rhomboid minor origin

Spinous processes of C7-T1

Rhomboid minor insertion

Medial border of the scapula

Rhomboid minor actions

Stabilizes scapula & scapular retraction (same as Rhomboid Major actions)

Rhomboid minor innervation

Dorsal scapular nerve

Upper trapezeius origin

Occipital bone

Upper trapezeius insertion

Acromion & spine of scapula

Upper trapezeius action

Scapular elevation

Upper trapezeius innervation

Accessory nerve

Middle trapezius origin

C7 & thoracic vertebrae

Middle trapezius insertion

Acromion & spine of scapula

Middle trapezius action

Scapular retraction

Middle trapezius innervation

Accessory nerve

Lower trapezius origin

Thoracic vertebrae

Lower trapezius insertion

Acromion & spine of scapula

Lower trapezius action

Scapular depression

Lower trapezius innervation

Accessory nerve

Radiate ligament

At head of ribs.

Reinforces costovertebral joint

Costotransverse ligament

Stabilizes the rib to the transverse process articulation

Sternocostal ligament

Reinforces the articulation between costal cartilage and the sternum

Costovertebral joint

Rib heads meet vertebral bodies and intervening disc

Sternocostal and costochondral joint

Costal cartilages connect ribs to the sternum and to the ribs, respectively

Costotransverse joint

Rib tubercles meet transverse processes; ribs 11-12 lack these typical joints

Manubriosternal and xiphisternal joint

The sternal angle is the manubriosternal joint; the xiphisternal joint often fuses with age; connects xiphoid with sternum

Sternal angle

junction between manubrium and body of the sternum