Muscles connecting the UL to Trunk-Updated.pdf

Muscles Connecting the Upper Limb to the Trunk Muscles Connecting the Upper Limb to the Trunk The muscles are divided into two groups: Anterior Posterior Group Anterior Group 1. Pectoralis Major muscle of chest 2. Pectoralis Minor muscle benea...

Muscles Connecting the Upper Limb to the Trunk Muscles Connecting the Upper Limb to the Trunk The muscles are divided into two groups: Anterior Posterior Group Anterior Group 1. Pectoralis Major muscle of chest 2. Pectoralis Minor muscle beneath chest, connected to ribs 3. Serratus Anterior muscle between ribs 4. Subclavius muscle under clavicle Pectoralis muscles Pectoralis major Origin: non-movable bone Clavicular part: anterior surface of the medial half of the clavicle Sternocostal part: anterior surface of sternum, Costal cartilages of ribs 1-6 Abdominal part: Anterior layer of the rectus sheath Insertion: Crest of the greater tubercle of the humerus Pectoralis major Action: Adduction, medial rotation & flexion of the arm. Extension of the arm from a flexed position. It also helps in respiration. Innervation: by Medial & lateral pectoral nerves  Pectoralis Minor Origin: Anterior surface, costal cartilages of ribs 3-5 Insertion: Coracoid process of the scapula Action: Depression of the scapula and helps in respiration. Innervated by medial pectoral nerve Innervation: by Medial pectoral nerve  Subclavius Origin First rib and costal cartilage Insertion Inferior surface of the middle 1/3 of the clavicle Action: Depresses the lateral end of the clavicle. Innervation Innervated by the nerve to subclavius.  Serratus anterior Origin: 1st to 9th rib Insertion: superior angle, medial border and inferior angle of the scapula Action: Protrusion and superior rotation of the scapula. Innervation: by the long thoracic nerve. Rotation of the scapula Posterior Group 1. Trapezius 2. Latissimus dorsi 3. Levator scapulae 4. Rhomboid minor 5. Rhomboid major  Posterior Group Trapezius:  Posterior Group Trapezius: Elevation, depression, retraction & superior rotation of the scapula. Innervated by the spinal root of the accessory nerve.  Posterior Group Latissimus dorsi: Origin Spinous processes of vertebrae T7- T12 Thoracolumbar fascia Iliac crest 9-12 Ribs Inferior angle of scapula Insertion Lateral crest of the biceptal groove. Posterior Group Latissimus dorsi: Adduction, extension & medial rotation of the arm. Innervated by the thoracodorsal nerve.  Posterior Group Levator scapulae: Elevation of the scapula. Innervated by dorsal scapular nerve.  Posterior Group Rhomboid major: Retraction & inferior rotation of the scapula. Innervated by dorsal scapular nerve Rhomboid minor: Retraction of the scapula. Innervated by dorsal scapular nerve.  Muscles acting on the scapula (Scapulohumeral Muscles) Scapulohumeral Muscles 1. Deltoid 2. Supraspinatus 3. Infraspinatus 4. Teres major 5. Teres minor 6. Subscapularis Deltoid muscle It is a triangular muscle that covers the shoulder joint and forms the rounded shape of the shoulder. Has three fibers: anterior, posterior and lateral. Anterior fibers: medial rotation & flexion of the humerus. Posterior fibers: lateral rotation & extension of the humerus. Lateral fibers: abduction of the humerus. Innervated by the Axillary nerve Supraspinatus muscle Abduction of the humerus. Innervated by the suprascapular nerve Infraspinatus muscle Lateral rotation of the arm Innervated by the Suprascapular nerve Teres major muscle Medial rotation & Adduction of the arm Innervated by the Lower subscapular nerve Teres minor muscle Lateral rotation of the arm Innervated by the axillary nerve  Subscapularis muscle Medial rotation the humerus. Innervated by the subscapular nerve Suprspinatus, infraspinatus, teres minor and subscapularis are called ROTATOR CUFF. Their tendons blend closely with the shoulder joint capsule and are important factors in maintaining shoulder joint stability.  Axilla It is a fat filled space between the lateral thoracic wall and the upper limb. It is pyramidal in shape. Medial wall: upper ribs & their intercostal muscles and serratus anterior muscle. Lateral wall: coracobrachialis & biceps muscles Anterior wall: Pectoralis major, pectoralis minor & subclavius muscles Posterior wall: subscapularis, latissimus dorsi and teres major muscles. Base: Axillary fascia & skin. Apex: interval between clavicle, scapula & first rib. Contents of the axilla Axillary artery & its branches Axillary vein & its tributaries Branches of brachial plexus Coracobrachilais & biceps brachii muscles lymph vessels & lymph nodes  Axillary artery It is the continuation of the subclavian artery beyond the first rib. It passes downward & laterally to become the brachial artery at the lower border of teres major muscle. Branches of the Axillary artery 1. Highest (supreme) thoracic artery 2. Thoracoacromial artery 3. Lateral thoracic artery 4. Subscapular artery 5. Anterior & Posterior circumflex humeral artery  Axillary vein Begins at the lower border of teres major muscle Formed by the union of the basilic vein & brachial vein. Continues as the subclavian vein at the border of the first rib.  Lymph nodes of the Axilla There are six groups of LN in the axilla 1. Anterior (pectoral) group 2. Posterior (subscapular) group 3. Lateral group 4. Central group 5. Infraclavicular (deltopectoral) group 6. Apical group