Upper Limb Pectoral Region & Back Muscles PDF
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Prof. Dr. Mohamed El-Badry Mohamed
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Summary
This document provides detailed information on the muscles of the upper limb's pectoral region and back. It explains the origins, insertions, nerve supplies, and actions of key muscles like the pectoralis major, minor, and subclavius. The text also covers the back muscles including the trapezius, latissimus dorsi, and rotator cuff.
Full Transcript
Prof. Dr. MOHAMED EL-BADRY MOHAMED Upper Li m Upper Limb b Upper Limb Main function of the upper limb: To provide for manipulation of objects So, mobility is of prime importance The joints mostly have a wide range of movement Upper limb girdle is extremely mobile...
Prof. Dr. MOHAMED EL-BADRY MOHAMED Upper Li m Upper Limb b Upper Limb Main function of the upper limb: To provide for manipulation of objects So, mobility is of prime importance The joints mostly have a wide range of movement Upper limb girdle is extremely mobile Muscles tend to be inserted into precise bony points PECTORAL REGION MUSCLES OF THE PECTORAL REGION 1. PECTORALIS MAJOR 2. PECTORALIS MINOR 3. SUBCLAVIUS PECTORALIS MAJOR: Origin: - Clavicular head: Anterior surface of medial half of clavicle - Sternocostal head: Front of sternum, front of upper 6 costal cartilages and aponeurosis of external oblique muscle Insertion: Bilaminar tendon: Lateral lip of bicipital groove of the humerus Nerve supply: - Medial pectoral nerve - Lateral pectoral nerve Action: Adduction, flexion and medial rotation of arm at the shoulder joint. PECTORALIS MINOR Origin: The 3rd, 4th and 5th ribs Insertion: Medial border and upper surface of coracoid process of scapula Nerve supply: Medial pectoral nerve Action: Depression and protraction of scapula SUBCLAVIUS Origin: 1st rib at its costochondral junction Insertion: Groove on inferior surface of clavicle Nerve supply: Nerve to subclavius Action: Steadies clavicle during movements of shoulder girdle CLAVIPECTORAL FASCIA A strong fibrous sheet lies deep to clavicular head of pectoralis major. Extends from pectoralis minor (below) to clavicle (above) where it splits to enclose subclavius Its upper border, along lower border of subclavius, thickened to form costo- coracoid ligament that extends from anterior end of 1st rib medially to coracoid process laterally. Below pectoralis minor, continues as suspensory ligament of axilla and joins fascial floor of the axilla Structures piercing the clavipectoral fascia: 1. Cephalic vein, ends in axillary vein 2. Acromio-thoracic artery, branch of 2nd part of axillary artery 3. Lateral pectoral nerve, supplies pectoralis major 4. Lymph vessels, connect superficial lymph vessels with deep apical nodes MUSCLES OF THE BACK Muscles of upper limb in back are arranged in: I. Superficial layer: 1. Trapezius 2. Latissimus dorsi II. Deep layer: 1. Levator scapulae 2. Rhomboideus minor 3. Rhomboideus major TRAPEZIUS - Large triangular flat muscle - Covers upper ½ of back including back of neck - 2 muscles of both sides form together outline of a trapezium (4-sided figure). Origin: 1. Medial 1/3 of superior nuchal line 2. External occipital protuberance 3. Ligamentum nuchae 4. Spines of 7th cervical and all thoracic vertebrae and their supraspinous ligaments. Insertion: 1. Upper fibers: Posterior border of lateral 1/3 of clavicle 2. Middle fibers: Medial margin of acromion and superior lip of crest of spine of scapula 3. Lower fibers: Tubercle of crest of spine of scapula Nerve supply of the trapezius: - Spinal root of accessory nerve (motor) - 3rd and 4th cervical nerves (sensory) Action of the trapezius: 1. Upper fibers: Elevation of shoulder girdle. - Acting with lower fibers of trapezius and lower digitations of serratus anterior rotate scapula to raise the arm above the head 2. Middle fibers: Retraction of the scapula 3. Lower fibers: Depression of the scapula. Paralysis of trapezius leads to drop shoulder (lesion to spinal part of accessory nerve) LATISSIMUS DORSI Large triangular flat muscle Covers lower ½ of back down to iliac crest Has wide origin (latissimus means wide) Origin: 1. Spines of lower 6 thoracic vertebrae and supraspinous ligaments 2. Posterior layer of thoracolumbar fascia 3. Posterior part of outer lip of iliac crest 4. Lower 4 ribs 5. Back of inferior angle of scapula Insertion: Floor of intertubercular groove of the humerus Nerve supply: Thoracodorsal nerve (C6, 7, 8) Action: Powerful adductor, extensor and medial rotator of the arm at the shoulder joint LEVATOR SCAPULA Origin: Transverse processes of upper 4 cervical vertebrae Insertion: Back of medial border of the scapula, from superior angle to root of its spine Nerve supply: Dorsal scapular nerve (C 5) 3rd and 4th cervical nerves (cervical plexus) Action: Elevation and retraction of the scapula RHOMBOIDEUS MINOR Origin: Lower part of ligamentum nuchae and spines of 7th cervical and 1st thoracic vertebrae Insertion: Back of medial border of scapula opposite root of the spine Nerve supply: Dorsal scapular nerve (C 5) Action: Retraction of the shoulder RHOMBOIDEUS MAJOR Origin: Spines of the 2nd, 3rd, 4th, and 5th thoracic vertebrae and related supraspinous ligaments Insertion: Back of medial border of the scapula from root of the spine to inferior angle of scapula Nerve supply: Dorsal scapular nerve (C 5) Action: Retraction of the shoulder MUSCLES OF SHOULDER REGION (SCAPULAR MUSCLES) 1. Deltoid 2. Subscapularis 3. Supraspinatus 4. Infraspinatus 5. Teres minor 6. Teres major DELTOID MUSCLE Thick, strong, triangular muscle Forms rounded contour of the shoulder Origin: 1. Anterior border of lateral 1/3 of clavicle (anterior part) 2. Lateral margin of the acromion (middle part) 3. Lower lip of crest of spine of scapula (posterior part) Insertion: Deltoid tuberosity of the humerus Nerve supply: Axillary nerve (C 5, 6) Action: 1. Anterior part: Flexion and medial rotation of the arm at shoulder joint 2. Middle part: Abduction of arm from 15 to 90 3. Posterior part: Extension and lateral rotation of arm at shoulder joint Lesion of axillary nerve leads to paralysis of deltoid which results in: 1. Flat shoulder 2. Prominent acromion due to loss of rounded contour of the muscle 3. Loss of abduction from 15 to 90 SUBSCAPULARIS Origin: Medial 2/3 of subscapular fossa Insertion: Lesser tuberosity of the humerus Nerve supply: Upper and lower subscapular nerves (C5, 6) Action: Adduction and medial rotation of the arm SUPRASPINATUS Origin: Medial 2/3 of supraspinous fossa Overlying strong deep fascia Insertion: Uppermost impression of greater tuberosity of the humerus Nerve supply: Suprascapular nerve (C5, 6) Action: Abduction of the arm from 0 to 15 Assists in stabilizing the head of the humerus in the glenoid cavity INFRASPINATUS MUSCLE Origin: Medial 2/3 of infraspinous fossa Overlying strong deep fascia Insertion: Middle impression on greater tuberosity of the humerus Nerve supply: Suprascapular nerve (C5, 6) Action: Adduction and lateral rotation of arm. Stabilization of shoulder joint TERES MINOR Origin: Upper 2/3 of back of lateral border of scapula Insertion: Lowest impression on greater tuberosity of the humerus. Nerve supply: Axillary nerve (C5, 6) Action: Adduction and lateral rotation of arm Stabilization of shoulder joint ROTATOR CUFF MUSCLES: 1. Subscapularis 2. Supraspinatus 3. Infraspinatus 4. Teres minor Lie on anterior, superior and posterior aspects of shoulder joint. Their tone assists in holding head of the humerus in glenoid cavity of the scapula during movements of the shoulder. Therefore, they stabilize the shoulder joint. The cuff is deficient inferiorly; a site of potential weakness. THANK YOU