Anatomy 1: Pectoral and Axillary Region PDF

Anatomy 1 PECTORAL AND AXILLARY REGION ELMOR G. GICARO III, MD Ancillary Division Head Deputy Quality Management Representative The Doctors’ Hospital Inc. Associate Professor USLS - College of Medicine RCI - College of Phys...

Anatomy 1 PECTORAL AND AXILLARY REGION ELMOR G. GICARO III, MD Ancillary Division Head Deputy Quality Management Representative The Doctors’ Hospital Inc. Associate Professor USLS - College of Medicine RCI - College of Physical Therapy Pectoralis Major Origin : 2 heads; Clavicular head: Medial ½ of the front of the clavicle. Sternocostal head: Sternum, Upper 6 costal cartilages and aponeurosis of the external oblique muscle. Insertion: Lateral lip of bicipital groove. Nerve supply: Medial & lateral pectoral nerves. Action: Adduction and medial rotation of the arm. Clavicular head helps in flexion of arm (shoulder). Pectoralis Minor Origin: From 3rd ,4th, & 5th ribs close to their costal cartilages. Insertion: Coracoid process. 3 4 Nerve supply: 5 Medial pectoral nerve. Action: Depression of the shoulder. Draw the ribs upward and outwards during deep inspiration. Subclavius Origin: From 1st rib at its costal cartilage. Insertion: Subclavian groove in the middle 1/3 of the inferior surface of clavicle. Nerve supply: Nerve to subclavius from upper trunk of brachial plexus. Action: Fixes the clavicle during movement of shoulder joint. Clavipectoral Fascia It is a thickened membrane of deep fascia between the subclavius and pectoralis minor. It is pierced by : Lateral pectoral nerve. Thoracoacromial artery Cephalic vein. Few lymph vessels. Clavipectoral Fascia It is a thickened membrane of deep fascia between the subclavius and pectoralis minor. It is pierced by : Lateral pectoral nerve. Thoracoacromial artery Cephalic vein. Few lymph vessels.  Serratus anterior Origin: Upper 8 ribs. Insertion: Anterior aspect of the medial border and inferior angle of scapula. Nerve supply: Long thoracic nerve (from roots of brachial plexus,C5,6,7). Action: Draws the scapula forward in boxing, (protrusion). Rotates scapula outwards in raising the arm above 90 degree.  AXILLA A pyramid-shaped space between the upper part of the arm and the side of the chest through which major neurovascular structures pass between neck & thorax and upper limbs. Axilla has an apex, a base and four walls.  Boundaries of the Axilla Apex: Is directed upwards & medially to the root of the neck. I It is called: V Cervicoaxillary canal. It is bounded, by 3 bones: ○ Clavicle ○ Upper border of the scapula ○ Outer border of the first rib Base: Formed by skin stretching between the anterior and posterior walls. Bounded by: ○ In front by the anterior axillary fold (formed by the lower border of Pectoralis major). ○ Behind by the posterior axillary fold (formed by tendons of latissimus dorsi and teres major). ○ Medially by upper 4 to 5 ribs & the chest wall.  Clavipectoral fascia Anterior wall: Is formed by : ○ Pectoralis major ○ Pectoralis minor ○ Subclavius ○ Clavipectoral fascia: Pectoralis minor Pectoralis major Posterior wall: Is formed by: Subscapularis Latissimus dorsi Teres major muscles Medial wall: It is wide and formed by: ○ Serratus anterior ○ Upper 4-5 ribs & Intercostal muscles Lateral wall: It is narrow and formed by: ○ Coracobrachialis. ○ Biceps brachii. ○ Bicipital groove of the humerus.  Contents of the Axilla Brachial plexus Cords and branches of the brachial plexus Axillary artery and its branches. Axillary A. & Axillary vein and its V. tributaries. Axillary lymph nodes. Axillary fat. Loose connective tissue. The neurovascular bundle is enclosed in connective tissue sheath, called ‘axillary sheath’  Brachial Plexus Brachial Plexus is a network of nerves that present at the root of the neck to enter the upper limb. Location & Formation: Brachial Plexus is present in the posterior triangle of the neck & axilla. It is formed by the union of the anterior rami of the 5th, 6th, 7th & 8th cervical and the 1st thoracic spinal nerve. Roots of C5 & C6 unite to form - Upper trunk Root of C7 continuous as the - Middle trunk Roots of C8 & T1 unite to form - Lower trunk 15 The Plexus can be divided into 5 stages: Roots: in the posterior Trunks: in the posterior Divisions: behind the clavicle (in Cervicoaxillary canal) Cords: in the axilla Branches: in the axilla The first 2 stages lie in the posterior triangle, while the last 2 stages lie in the axilla. 16  The anterior divisions of the upper and middle trunks unite to form the Lateral cord. The anterior division of the lower trunk continues as the Medial cord. All the posterior divisions of three trunks join to form the Posterior cord. 17  Lateral cord: 3 Medial cord: 5 Posterior cord: 5 Lateral pectoral nerve. Medial pectoral nerve. Axillary nerve. Musculocutaneous nerve. Ulnar nerve. Radial nerve. Median nerve (lateral root). Median nerve (medial root). Upper & lower subscapular nerves. Medial cutaneous nerve of Thoracodorsal or N. to arm & forearm. latissimus dorsi.  SUMMARY Muscles of the pectoral region are connecting the upper limb with anterior and lateral thoracic wall: ○ Pectoralis major ○ Pectoralis minor ○ Subclavius ○ Serratus anterior The axilla is a pyramidal space situated between the upper part of arm and the side of the chest, it has 4 walls (anterior, posterior, medial and lateral), base, and apex. The axilla is an important space as it transmits the neurovascular bundle from the neck and thorax to the upper limb. It contains: ○ Axillary vessels ○ Cords and branches of the brachial plexus ○ Axillary lymph nodes  Lesion of long thoracic nerve and paralysis of Serratus Dislocation of shoulder joint: anterior muscle: Winging of Scapula Winging of scapula