PECTORAL REGION
I. SUPERFICIAL LANDMARKS
A. Surface Anatomy
1. Clavicle lies subcutaneously - palpable
2. Sternum
a. Jugular notch - level of T2-T3
b. Sternal angle - opposite sternal end of second rib - level of T4-T5
c. Xiphoid process
d. Xiphisternal junction - at level of T9
3. Costal margin -L2
4. Infrasternal angle
B. Cutaneous nerves of thorax
1. Ventral primary rami of spinal nerves
a. Upper group: T3-6 to chest
b. Lower group: T7-11 to chest and abdomen
2. Lateral cutaneous nerves
a. pierce musculature at midaxillary line
b. anterior (lateral mammary) and posterior branches
c. intercostobrachial-T2--arm
3. Anterior cutaneous nerves
a. emerge at border of sternum
b. medial and lateral (mammary) branches
C. Superficial tissues
1. Langer’s lines are transverse
2. Deep fascia = pectoral fascia - covers pectoralis major
a. continues into axilla as "floor" of axilla (axillary fascia)
3. Subcutaneous veins form a plexus that continues into abdomen, shoulder and neck
a. subcutaneous areas receive blood from deep arteries but veins may differ
b. Thoracoepigastric system of veins
i. inferior end drains
ii. via superficial epigastric v. to femoral
iii. via umbilical vv. to portal system
c. Lateral thoracic system
4. Platysma muscle - located in subcutanea
II. MUSCLES
A. Pectoralis major
a. Attachments: Clavicle (sternal portion), sternum to 7th rib, cartilages of true ribs to biceptal groove of humerus
b. Nerve: medial and lateral pectoral - from brachial plexus
c. Artery: pectoral br. of thoracoacromial, internal thoracic
d. Action: adducts arm, draws it forward and rotates medially
B. Pectoralis minor
a. Attachments: upper margin ribs 3-5 to coracoid process of scapula
b. Nerve: medial pectoral
c. Artery: thoracoacromial and intercostals, lateral thoracic
d. Action: pulls scapula forward and down
C. Subclavius
a. Attachments: upper part of first rib to under surface of clavicle
b. Nerve: C5-6 - nerve to subclavius - from brachial plexus
c. Artery: clavicular br. of thoracoacromial
d. Action: draws clavicle down and forward
D. Serratus anterior
a. Attachments: ribs 1-9 to vertebral border of scapula
b. Nerve: long thoracic (C5-7) brachial plexus
c. Artery: lateral thoracic
d. Action: abducts scapula
E. Deltopectoral triangle - contains cephalic v.
F. Clavipectoral fascia
III. MOVEMENTS OF THE THORACIC WALL
A. Vertical diameter of thorax
1. Inspiration
a. vertical diameter is increased as diaphragm is lowered
2. Expiration
a. diameter returns to normal
B. Transverse diameter of thorax
1. increased by action of intercostal muscles
2. "bucket handle" (“up ‘n’ out”)movements
C. Anteroposterior diameter of thorax
1. increased by action of intercostals
2. "pump handle" movement – costovertebral and costotransverse joints
3. primarily R2-6 involved
D. Quiet inspiration - diaphragm