PT Gross Anatomy Superficial Back and Pectoral Region

regions of the back

lumbar, scapular, suprascapular, interscapular, infrascapular

unpaired median regions of the back

vertebral, sacral

Superficial back muscles

trapezius, latissimus dorsi, rhomboid major and minor, levator scapulae

intermediate extrinsic muscles

serratus posterior superior and inferior

intrinsic muscles of the back

act on vertebral column, superficial: splenius muscles, intermediate: erector spinae (spinals, longissimus, iliocostalis), deep: transversospinalis muscles

trapezius

Proximal attachment (O): medial third of superior nuchal line, external occipital protuberance nuchal ligament, spinous processes of C7-T12

Distal attachment (I): lateral third of clavicle, acromion and spine of scapula.

Innervation: CN IX for motor, C3 and C4 for sensory

Action: descending part (upper trapezius)

latissimus dorsi

Proximal attachment (O): spinous processes of T7-12, thoracolumnar fascia, iliac crest, inferior 3 ribs

Distal attachment (I): intertubercular groove

Innervation: thoracodorsal nerve (motor)

Action: adduction, extension, medical rotation of the humerus, helps to pull body up

levator scapulae

Proximal attachment: posterior tubercles of transverse processes of C1-C4

Distal attachment: medial border of scapular above scapular spine

Innervation: dorsal scapular nerve (C4, C5) and cervical nerves (C3, C4)

Action: elevates scapula and rotates glenoid cavity inferiorly by rotating scapula

rhomboid minor

Proximal attachment: nuchal ligament, spinous processes of C7 and T1

Distal attachment: medial border of scapula at the base of the scapular spine

Innervation: dorsal scapular n

Action: retracts the scapula, rotates the glenoid cavity inferiorly, fixes scapula to wall

rhomboid major

Proximal attachment: spinous processes of T2-T5

Distal attachment: medial border of scapula below scapular spine to the inferior angle

Innervation: dorsal scapular nerve

Action: retracts scapula, rotates glenoid cavity inferiorly, stabilizes scapula

serratus posterior superior

Proximal attachment: nuchal ligament, spinous process of C7-T3

Distal attachment: superior border of 2nd-4th rib

Innervation: 2nd through 5th intercostal n

Action: proprioception

serratus posterior inferior

Proximal attachment: spinous process off T11-L2

Distal attachment: inferior border of 8th-12th ribs near their angles

Innervation: anterior rami to T9-T12 thoracic spinal nerves

Action: proprioception (depress ribs)

muscles of the thoracic wall

serratus posterior, lavatories costar, intercostals. subcostals, tranversus thoracis

pectoralis major

Proximal attachment: clavicular head- anterior surface of medial ½ of clavicle, sternocostal head- anterior surface of sternum, superior six costal cartilages, and aponeurosis of external oblique muscle

Distal attachment: lateral lip of inter tubercular groove

Innervation: lateral and medial pectoral n, clavicular head (C5, C6) and sternocostal head (C7, C8, T1)

Action: medially rotates and adducts humerus, draws scapula anteriorly and inferiorly. Acting alone, clavicular head flexes humerus and sternocostal head extends it from the flexed position

pectoralis minor

Proximal attachment: 3rd-5th rib near costal cartilage

distal attachment: medial border and superior surface of coracoid process of scapula

innervation: medial pectoral nerve (C8, T1) Lateral pectoral nerve (variable)

action: stabilizes scapula by drawing its interiorly and anteriorly against the thoracic wall

subclavius

Proximal attachment: junction of 1st rib and its costal cartilage

distal attachment: inferior surface of middle third of clavicle

innervation: nerve to subclavius (C5, C6)

anchors and depresses clavicle

serratus anterior

proximal attachment: external surfaces of lateral parts of 1st-8th ribs

distal attachment: anterior surface of medial border of scapula, including the superior and inferior angles

Innervation: long thoracic n (C5, C6, C7)

action: holds scapula against thoracic wall, rotates scapula, protraction

level of jugular notch

T2

level of manubrium

T3-T4

level of body of sternum

T5-T9

level of xiphisternal joint

T9

Costal margin

formed by the 7th-10th rib’ cartilages

alignment of medial scapula

4th rib

Reference lines for front of the trunk

midclavicular lines, anterior median line

reference lines for side of the trunk

posterior axillary line, midaxillary line, anterior axillary line

reference lines for back of the trunk

scapular lines, posterior median line

level of the nipple for men and young women

4th intercostal space

pectoral fascia

covers anterior thoracic wall, associated with pectorals major

clavipectoral fascia

beneath pectoral fascia, invests pectoralis minor

endothoracic fascia

lines the thoracic cage, connects lung cavity to the thoracic wall

level of the xiphoid process

T10

true ribs

ribs 1-7

false ribs

ribs 8-10

floating ribs

ribs 11-12