Shoulder & Axilla Anatomy and Brachial Plexus PDF

Anatomy of shoulder and Axilla Department of human Anatomy and Embryology Faculty of Medicine Mansoura National University, Egypt  Intended Learning Outcomes (ILOs) 1. Enumerate ligaments of shoulder joint. 2. Recognize shoulder joint and shoulder gi...

Anatomy of shoulder and Axilla Department of human Anatomy and Embryology Faculty of Medicine Mansoura National University, Egypt  Intended Learning Outcomes (ILOs) 1. Enumerate ligaments of shoulder joint. 2. Recognize shoulder joint and shoulder girdle. 3. Identify the boundaries of Axilla. 4. Identify contents of the axilla. 5. Recognize Brachial plexus and its divisions.  Agenda 1. What are nerves supplying muscles of the shoulder? 2. What are muscles producing upward rotation of the scapula? 3. What are the boundaries of Axilla? 4. What are the contents of the Axilla? 5. Mention brachial plexus roots, trunks, divisions and branches.  Shoulder girdle Bones forming it: clavicle & scapula. it is formed of 2 joints: A. Acromioclavicular Type: synovial plane. Ligaments: 1) Superior acromiocalvicular. 2) Inferior acromioclavicular. 3)Coracoclavicular. It has an articular disc. B. Sternoclavicular Type: synovial saddle. Ligaments: 1) Anterior sternoclavicular. 2) Posterior sternoclavicular. 3) Costoclavicular. 4) Interclavicular.  Shoulder girdle Elevation Depression Protraction Retraction Levator Serratus Rhomboids scapulae. Pectoralis minor anterior Middle & Rhomboids Lower trapezius Pectoralis lower Upper minor trapezius trapezius Downward rotation of Upward Rotation of scapula adduction scapula Levator scapulae Upper trapezius. Rhomboids Serratus anterior. Pectoralis major and minor Latissimus dorsi abduction Return to anatomical position  Shoulder girdle Muscles of pectoral region Superficial muscles of the back  Shoulder joint Type: synovial ball & socket. Articular surface: head of humerus & glenoid cavity of scapula. Ligaments: 1. Coracohumeral. 2. Glenohumertal: 3: superior, middle & inferior. 3. Transverse humeral. 4. Labrum glenoidale: fibrocartilage attached to the margin of the glenoid cavity. Shoulder joint  Movements of Shoulder joint Medial Rotation Lateral Rotation Pectoralis major Infraspinatus Latissimus dorsi. Teres minor Teres major. Deltoid Deltoid (anterior (posterior fibers) fibers). Subscapularis.  Muscles of Shoulder joint Deltoid muscle Origin: ▪ Anterior fibers: from the anterior border of the lateral 1/3 of the clavicle. ▪ Middle (lateral) fibers: from the lateral border of the acromion process. ▪ Posterior fibers: from the lower lip of the crest of the spine of the scapula. Insertion: Into the deltoid tuberosity of the humerus. Nerve supply: The axillary nerve Action: ▪ Anterior fibers: flex the arm and rotate it medially. ▪ Posterior fibers: extend the arm and rotate it laterally. ▪ Middle fibers; abduct the shoulder joint (15°-90°).  Muscles of Shoulder joint Deltoid muscle Action: ▪ Anterior fibers: flex the arm and rotate it medially. ▪ Posterior fibers: extend the arm and rotate it laterally. ▪ Middle fibers: abduct the shoulder joint (15°-90°).  Quiz One of the following muscles is responsible for abduction 15-90 degrees? A)Pectoralis minor B)Deltoid muscle C)Serratus anterior D)Lattismus dorsi E)Teres major Answer: B  Rotator cuff Muscles 4 muscles: supraspinatus, infraspinatus, teres minor, and subscapularis form what is termed the rotator cuff. The tone of these muscles help to steady the head of the humerus in the glenoid cavity. Therefore, this assists in stabilizing the shoulder joint.  Muscles of Shoulder joint Supraspinatus Infraspinatus Teres minor Subscapularis Origin supraspinous infraspinous upper 2/3 of the the subscapular fossa fossa dorsum of the fossa lateral border of the scapula. Insertion greater tuberosity of the humerus. Lesser tuberosity of the humerus Nerve supply Suprascapular nerve Axillary nerve Upper and lower subscapular nerves Action: abduction of Lateral Adduction Adduction the arm (0° to rotation of and lateral and medial 15°). the arm. rotation of rotation of steady the steady the the arm. the arm. head of the head of the steady the steady the humerus in humerus head of the head of the the glenoid during humerus in humerus in cavity abduction. the glenoid the glenoid cavity. cavity.  Muscles of Shoulder joint Teres major Origin: From the lower 1/3 of the dorsum of the lateral border of the scapula. Insertion: Into the medial lip of the bicipital groove. Nerve supply: Lower subscapular nerve (C. 5,6). Action: Extension, adduction, and medial rotation of the arm.  Inter-muscular spaces Quadrangular space Upper triangular Lower triangular space space Boundaries: Superiorly; Subscapularis. Superiorly; Teres Superiorly; Teres major. Inferiorly; Teres major. minor. Medially; Long head of triceps. Medially; Long head of Inferiorly; Teres major. Laterally; Shaft of the humerus. triceps. Laterally; Long head Quadrangular Laterally; Surgical neck of the of triceps. space humerus. Contents: 1- Axillary (circumflex) nerve. The circumflex 1- Radial nerve. 2- Posterior circumflex scapular artery branch 2- Profunda brachii Upper triangular space humeral vessels. of the subscapular artery artery. lower triangular space  The Axilla Definition: Is a space between the upper part of the chest and the upper part of the arm. Shape: It is a pyramidal in shape. It has apex, base and 4 wails.  The Axilla ❖ Anterior wall: formed by; 1. The pectoralis major. 2. The subclavius and the pectoralis minor. 3. The clavipectoral fascia. NB. The anterior fold of the axilla is formed by the pectoralis major. ❖ Posterior wall: Is formed by the scapula overlaid by 3 muscles. 1. The subscapularis above. 2. The teres major 3. Latissimus dorsi below. NB. The posterior fold of the axilla is formed by the latissimus dorsi and by the teres major  The Axilla ❖ Medial wall: Is formed by; 1. The upper 2nd - 6th ribs. 2. The upper 6 intercostal muscles. 3. The upper part of the serratus anterior. ❖ The lateral wall: It is formed by; 1. The bicipital groove of the humerus. 2. The corachobrachialis and the biceps muscles.  The Axilla ❖ Apex: Is directed upwards towards the root of the neck. It is the triangular bony space called cervicoaxillary canal bounded by; Anteriorly: The posterior surface of the clavicle. Posteriorly: The superior border of the scapula. Medially: The outer border of the1st rib. It transmit the axillary vessels and nerves from the neck to the upper limb. ❖ The base (floor): It is formed by the skin and fascia.  The Axilla Contents of the axilla: 1- The axillary vessels (axillary artery and vein). 2- The cords and branches of the brachial plexus. 3- The lateral branches of the intercostal nerves. 4- The axillary lymph nodes. 5- The axillary tail of the breast. 6- Fat and loose areolar tissue.  The Axilla Posterior wall Medial wall Lateral wall Anterior wall  Serratus anterior muscle Origin: Arises by 8 digitations from the outer surface of the upper 8 ribs. Insertion: The 1st digitation: is inserted into the front of the superior angle of scapula. The 2nd and 3rd digitations: in the whole length of the medial border of scapula from the front. The lower 5 digitations: front of the inferior angle of scapula. Nerve supply: Long thoracic nerve. Action (Girdle): Protract or pull the scapula forward. The lower 5 digitations help in raising the arm above the head (abduction above 90°). It raises the ribs in forced inspiration. N.B. When the muscle is paralyzed it leads to Winged scapula.  Brachial plexus Definition: The brachial plexus is formed by the anterior rami of the lower 4 cervical and the 1s1 thoracic nerves. Formation: It is divided into five stages 1- Roots; in the neck The roots are the ventral rami of the 5th ,6th , 7th and 8th cervical and the 1st thoracic nerves. 2- Trunks; 3 in the neck Upper trunk; the union of the 5th and 6th cervical roots. Middle trunk; is the continuation of the 7th cervical root. Lower trunk; the union of the 8th cervical and the 1st thoracic root.  Brachial plexus 3- Divisions; 6 behind the clavicle Each of the 3 trunks divides into an anterior and posterior divisions. 4- Cords; 3 in the axilla. Lateral cord; the union of the anterior division of the upper and middle trunks. Medial cord; the anterior division of the lower trunk. Posterior cord; the union of the posterior division of the upper, middle, and lower trunks.  Brachial plexus 5- Branches of the plexus: a) From the roots; 1- Dorsal scapular nerve (Nerve to rhomboid) 2- Long thoracic nerve (Nerve to serratus anterior) b) From the trunks; only the upper trunk gives. 1- Nerve to subclavius 2- Suprascapular nerve c) From the cords; I) From the lateral cord 1- Lateral pectoral nerve 2- Musculocutaneous nerve 3- Lateral root of median nerve  Brachial plexus II) From the medial cord 1- Medial pectoral nerve 2- Medial cutaneous nerve of the forearm 3- Medial cutaneous nerve of the arm 4- Medial root of median nerve 5- UInar nerve III) From the posterior cord 1- Upper subscapular nerve 2- Lower subscapular nerve 3- Thoracodorsal nerve 4- Axillary nerve 5- Radial nerve Brachial plexus  Axillary lymph nodes The axillary lymph nodes are arranged in 5 groups. 1. Anterior (Pectoral) group: Site: on the anterior wall along the lower border of the pectoralis minor. 2- Posterior (Subscapular) group; Site: on the posterior wall (in front of the subscapularis muscle). 3-Lateral (Brachial) group; Site: on the lateral wall (along the axillary vein). 4- Central group; Site: on the fascia of the base. 5- Apical group; Site: at the apex of the axilla along the medial side of axillary vein.  Quiz The anterior fold of the axilla is made by? A)Pectoralis minor B)Pectoralis major C)Serratus anterior D)Lattismus dorsi E)Teres major Answer: B