Brachial Plexus and Axilla PDF

 Faculty of Physical Therapy ❑Course Title: Anatomy I ❑Course Code: FM 101 ❑Department: Anatomy and embryology ❑Lecture Title: Axilla and brachial plexus ❑Lecturer Name : Pr.Dr. Morsy Abdelfattah Morsy Axilla ❑The axilla is an irregularly shaped pyramidal area...

 Faculty of Physical Therapy ❑Course Title: Anatomy I ❑Course Code: FM 101 ❑Department: Anatomy and embryology ❑Lecture Title: Axilla and brachial plexus ❑Lecturer Name : Pr.Dr. Morsy Abdelfattah Morsy Axilla ❑The axilla is an irregularly shaped pyramidal area formed by muscles and bones of the shoulder and the lateral surface of the thoracic wall. ❑The apex or inlet opens directly into the lower portion of the neck. ❑The skin of the (armpit) forms the floor. ❑All major structures that pass between the neck and arm pass through the axilla. ❑The axilla has apex (inlet) ,base(outlet) and four walls(Anterior, Posterior, Medial and Lateral). ❑ Axilla is pyramidal in shape between upper end of arm and lateral thoracic wall. ❑ Cubital fossa is triangular depression in front of elbow joint. ❑ Carpal tunnel is quadrilateral space in front of carpal bones. ❑ Inlet of the axilla: It is a triangular space bounded by: ✓ 1st rib medially, ✓ Clavicle anterior. ✓ Upper border of scapula posterior. ❑ Walls of the axilla: It has inlet (apex) ,outlet (base), and 4 walls (medial , lateral , anterior and posterior ) ❑ Outlet of the axilla It is bounded by Serratus anterior medially, pectoralis major anterior and lower border of latissimus dorsi posteriorly. ❑ Anterior wall of the axilla: 1- Pectoralis major muscle. 2- Pectoralis minor muscle. 3- Clavipectoral fascia. ❑ Posterior wall of the axilla: 1-Subscapularis muscle. 2-Teres major muscle. 3-Latissimus dorsi. 1 3 2 ❑ Medial wall of the axilla: 1- Upper five ribs and related intercostal spaces. 2- Upper 5 digitation of Upper Serratus anterior muscle. 5 ribs 3- Long thoracic nerve. ❑ Lateral wall of axilla: 1-Upper end of humerus. 2-Biceps brachii muscle. 3-Coracobrachialis muscle. 1 2 3 ❑ Contents of Axilla: 1-Axillary artery. A.artery C &B of A. vein brachial plexus 2-Axillary vein. 3-Cords and branches of 4 brachial plexus. 4-Axillary lymph nodes. 4 4 5-Axillary fat. 4 4 ❖Gateways in the posterior wall of the axilla: 1-Quadrangular space: The quadrangular space provides a passageway for nerves and vessels between the axilla and posterior scapular and deltoid regions. The boundaries are formed by: 1. Superiorly by inferior margin of the subscapularis muscle. 2. Laterally by surgical neck of the humerus. 3. Inferiorly by superior margin of the teres major muscle; 4. Medially by lateral margin of the long head of the triceps brachii muscle.  The structures passing through the quadrangular space are: 1. Axillary nerve 2. Posterior circumflex humeral artery and vein. 2-Triangular space (upper triangular space): The triangular space is an area of communication between the axilla and the posterior scapular region. Their boundaries are formed by: 1. laterally by medial margin of the long head of the triceps brachii muscle. 2. Inferiorly by superior margin of the teres major muscle. 3. Superiorly by inferior margin of the subscapularis muscle.  The structures passing through the triangular space are: 1. The circumflex scapular artery and vein. 3-Triangular interval (lower triangular space): The boundaries of triangular interval is formed by: 1. Medially by lateral margin of long head of the triceps brachii muscle. 2. Laterally by the shaft of the humerus. 3. Superiorly by the lower border of teres major muscle.  The structures passing through the triangular interval are: 1. The radial nerve passes out of the axilla traveling through this interval to reach the posterior compartment of the arm. 2. Profunda brachii artery. ❑ Brachial plexus: The brachial plexus is formed by the anterior rami of C5 to C8 and T1. It originates in the neck, passes laterally and inferiorly over the 1st rib and enters the axilla. The parts of the brachial plexus, from medial to lateral, are Roots, Trunks, Divisions, and Cords. All major nerves that innervate the upper limb originate from cords the brachial plexus. Proximal parts of the brachial plexus are posterior to the subclavian artery in the neck, while more distal regions of the plexus surround the axillary artery. ❑Brachial plexus: 1-Roots :C5,6,7,8 &T1. 2-Trunks: Upper, Lower and Middle trunks. 3-Divisions: three anterior and three posterior. 4-Cords: Medial, Lateral and Posterior. 5-Branches: three from lateral cord, five from medial cord and five from posterior cord. ❑Roots: The roots of the brachial plexus are the anterior rami of C5 to C8, and T1. ❑Trunks: Three from the roots. Upper trunk is formed by the union of C5 and C6 roots. Middle trunk is a continuation of the C7 root. Lower trunk is formed by the union of the C8 and T1 roots. ❑Divisions: ❖ Each of the three trunks of the brachial plexus divides into an anterior and posterior divisions. ❖ The three anterior divisions form parts of the brachial plexus that give rise peripheral nerves innervates the anterior compartments of the arm and forearm. ❖ The three posterior divisions combine to form parts of the brachial plexus that give rise nerves innervate the posterior compartments. ❑Cords: The three cords of the brachial plexus originate from the divisions and are related to the second part of the axillary artery. the lateral cord results from the union of the anterior divisions of the upper and middle trunks (C5 to C7), lateral to the second part of the axillary artery; the medial cord is medial to the second part of the axillary artery and is the continuation of the anterior division of the lower trunk(C8 and T1). the posterior cord occurs posterior to the second part of the axillary artery and originates as the union of all three posterior divisions (C5 to T1). 1-The roots and trunks of brachial plexus are present in the neck in front of scalenus medius muscle behind scalenus anterior muscles. 2-Trunks are present in posterior triangle around the subclavian artery. 3-Divisions is present behind the clavicle. 4-Cords and branches are present in the axilla around the axillary artery. ❖ Stages of brachial plexus. ❖ Relations of the cords and Lateral cord branches of brachial plexus to axillary artery. Posterior cord Branches of brachial plexus. Medial Cord Axillary artery ❑ Branches of the brachial plexus: 1- From roots 2 branches. 2- From upper trunk 2 branches. 3- From lateral cord 3 branches. 4- From medial cord 5 branches. 5- From posterior cord 5 branches. Summary for branches of brachial plexus Summary for branches of brachial plexus Summary for branches of brachial plexus Summary for branches of brachial plexus ❖ Common injuries of the brachial plexus: 1-Erb’s paralysis (Tip taking position): ✓ Due to lesion of the upper trunk of the brachial plexus (C.5,6). ✓ The deltoid ,infraspinatus, biceps, brachialis and supinator muscles are paralyzed. ✓ The arm is medially rotated and cannot be abducted. ✓ The forearm is extended and pronated. 2-Klumpke’s paralysis: ✓ Due to a lesion of the lower trunk of the brachial plexus (C.8,T.1). ✓ All muscles supplied by this trunk (Ulnar nerve) are paralyzed. ✓ All intrinsic muscles of the hand and some flexors of the wrist and digits. ✓ The deformity is called (Claw hand).  MCQ 1-Which of the following muscles form the anterior wall of the axilla? a. Pectoralis major b. Latissimus dorsi c. Biceps brachii d. Subscapularis 2- Erb,s paralysis results from lesion in which of the following parts of brachial plexus? a. Upper trunk b. Lower trunk c. Middle trunk d. Medial cord 3-Long thoracic nerve is branch from which of the following parts of brachial plexus? a. Roots b. Upper trunk c. Medial cord d. Lower trunk 4-Upper end of humerus form a part of which wall of axilla? a. Medial b. Lateral c. Posterior d. Anterior 5-Which of the following nerves is a branch of medial cord of brachial plexus? a. Ulnar b. Axillary c. Radial d. Musculocutaneous.  References 1-Gray H, Anatomy of the Human Body. 20th ed. New York: Bartleby 2000. 2-Gray, s anatomy for students by Richard Drake and A. Wayne Vogel, 2019. 3-Snell R. " Clinical Anatomy by Regions ' 8th ed. Lippincott Williams and Wilkins, Philadelphia, 2008. 4-Agur A. & Dalley A. " Atlas of Anatomy" Lippincott Williams and Wilkins, Philadelphia, 2005 Thanks, with the best wishes. Pr.Dr/Morsy Abdelfattah.