Upper Limb Anatomy Lecture 5 PDF

Objectives: ▪ To define the axilla ▪ To describe axillary inlet ▪ To recognize axillary walls ▪ To define the axillary vessels and their main branches ▪ To list the groups of axillary lymph nodes  The axilla Definition: The axilla (armpit...

Objectives: ▪ To define the axilla ▪ To describe axillary inlet ▪ To recognize axillary walls ▪ To define the axillary vessels and their main branches ▪ To list the groups of axillary lymph nodes  The axilla Definition: The axilla (armpit) is a pyramid-shaped space between the upper part of the arm and the side of the chest. Q:what is the main function of axilla ? Functions: It forms an important passage for nerves, blood and lymph vessels as they travel from the root of the neck to the upper limb. ! When the arm is adducted the axilla is a narrow space but it increases in size as the arm is abducted.  Boundaries of the axilla The axilla has an apex, base and 4 walls (Anterior, posterior, medial and lateral walls). Axillary inlet (the apex): I 2 " The apex is bounded by the clavicle, upper border of the 3 scapula and the outer border of the first rib. " It is channel of communication between axilla and the neck. " Through this opening the vessels, nerves.. reach the axilla from the body. # The shape and size of the axilla varies, depending on the position of the arm. It almost disappears when the arm is fully abducted — a position in which its contents are vulnerable. *** Anterior Wall 1. Pectoralis major. 2. Pectoralis minor. 3. Subclavius muscles. 4. Clavipectoral fascia. Posterior wall Is formed by : Subscapularis. Latissimus dorsi. Terrs major muscles. The medial wall ▪ It is wide and formed by : Serratus anterior. Upper 4-5 ribs and intercostal muscles. The lateral wall ▪ It is narrow and formed by : Coracobrachialis. Biceps brachii. Bicepital groove of the humerus.  Serratus Anterior Origin — Superior 8 or 9 ribs Insertion — vertebral border and inferior angle of scapula. Action - Abduction and rotates the scapula upward. - Elevate ribs when scapula stabilized. - Also known as “boxer’s muscles”. Nerve supply - Long thoracic nerve.  Contents of the axilla Axillary artery Axillary Vein Brachial plexus Axillary lymph nodes  Axillary artery Beginning: The axillary artery begins at the lateral border of the first rib as a continuation of the subclavian artery. Termination: at the lower border of the teres major muscle, where it continues as the brachial artery. The artery is closely related to the cords of the brachial plexus and their branches and is enclosed with them in a connective tissue sheath called the axillary sheath. If this sheath is traced upward into the root of the neck, it is seen to be continuous with the prevertebral fascia. Axillary sheath: axillary artery and brachial plexus enclosed by axillary fascia called axillary sheath. axillary vein is not the content of axillary sheath to allow free expand of vein during increased venous return. axillary sheath ‫ بداخل ال‬axillary vein ‫صادر تعتبر ال‬0‫"بعض ا‬  Parts of the axillary artery The pectoralis minor muscle crosses in front of the axillary artery and divides it into three parts: $ First part above the pectoralis minor muscle. & Second part behind the pectoralis minor muscle. % Third part below the pectoralis minor muscle. Branches: First part: Superior thoracic artery: (Highest thoracic artery) - small artery runs between the two pectoral muscles. - supplies the side of the chest in the upper 2 intercostal spaces. Second part: Lateral thoracic artery: - passes along the lower border of P minor. - Supplies pectoral muscles, Serratus anterior and the breast. Thoracoacromial artery: - Passes along the upper border of P minor. - Pierces the clavioectoral p fascia. ⑮ - Divides into 4 branches (pectoral, acromial, clavicular and deltoid). Third part: Subscapular artery: - Largest brach. - Passes towards the inferior angle of scapula. 8 - Accompanied by thoracodorsal nerve. - Gives the circumflex scapular brach and thoracodorsal branch. Third part: Anterior circumflex humeral artery: - Surrounds the surgical neck of humerus anteriorly. Posterior circumflex humeral artery: - Leaves the axilla through the quadrangular space. - Surrounds the surgical neck posteriorly. Both circumflex arteries anastomose with each other and are important for the supply of the shoulder joint. The axillary vein: - This large vein is the continuation of the brachial vein at the lower margin of the teres major. - It becomes the subclavian vein at the outer border of the first rib. - Has similar tributaries to the branches axillary artery. of ancillary - Lies on the medial side of the artery. Axillary lymph nodes: " Around 20-30 LN. " Embedded in axillary fat around the branches of axillary artery. " They drain an extensive area of the UL and trunk. " They are arranged in 5 groups. " The arrangement reflects the pyramidal shape of the axillary space. ! Axillary lymph nodes drain from all those areas # : 1. All lymphatics from the upper limb 2. The upper back and shoulder 3. The lower neck 4. The chest 5. The upper anterolateral abdominal wall 6. Approximately 75% of the mammary gland (breast) ! Are generally divided into five groups on the basis of location into: 1. Humeral (lateral) 2. Pectoral (anterior) ( & 3. Subscapular (posterior) ' 4. Central nodes & 5. Apical nodes % % $ $  ' Humeral (lateral) nodes ) Located posteromedial to the axillary vein ) They drain the whole upper limb except the upper lateral part of the arm. $ Pectoral (anterior) nodes ) Located along the inferior margin of the pectoralis minor muscle deep to pectoralis major along the course of the lateral thoracic vessels. ) They drain lymph from the upper lateral quadrant of the breast, the anterolateral part of the chest & the anterior abdominal wall down to the level of the umbilicus. % Subscapular (posterior) nodes ) Located on the posterior axillary wall on the anterior surface of subscapularis in association with the subscapular vessels. ) drain the posterior axillary wall, the shoulder, the neck and the back down to the level of iliac crest. ( Central nodes ) Location: Are embedded in axillary fat ) Receive tributaries from humeral, subscapular, and pectoral groups of nodes. & Apical nodes ) are the most superior group of nodes in the axilla ) Drain all other groups of nodes in the region. ) In addition, they receive lymphatic vessels that accompany the cephalic vein as well as vessels that drain the superior region of the mammary gland. " Infraclavicular (Deltopectoral) nodes: Lie in the deltopectoral groove (between deltoid & P major) & drain lymph from the upper lateral part of the arm. Efferent Lymphatic Vessels ) Efferent vessels from the apical group converge to form the subclavian trunk. * On the left side: the subclavian trunk usually joins the thoracic duct in the base of the neck. * On the right side: the subclavian trunk joins the venous system at the junction between the right subclavian vein and the right internal jugular vein in the neck. Passage ways Exiting the Axilla # There are three main routes by which structures leave or enter the axilla. $ The main route of exit is immediately inferiorly and laterally, into the upper limb. The majority of contents of the axilla region leave by this method. & The quadrangular space. This is a gap in the posterior wall of the axilla, allowing access to the posterior arm and shoulder area. Structures passing through include the axillary nerve and posterior circumflex humeral artery (a branch of the axillary artery). % the deltopectoral groove (clavipectoral triangle) : which is an opening in the anterior wall of the axilla. It is bounded by the pectoralis major, deltoid and clavicle. The cephalic vein enters the axilla via this triangle, while the lateral pectoral nerve leave.