Myology: Shoulder and Arm (Anatomy 1) - 2024-2025 PDF

Myology: Shoulder and Arm Module: Anatomy 1 Academic Year : 2024-2025 www.um6ss.ma  Contents General Concepts Revision of Osteology Rotator Cuff muscles Neurovascular supply Upper arm Myology Motion Sh...

Myology: Shoulder and Arm Module: Anatomy 1 Academic Year : 2024-2025 www.um6ss.ma  Contents General Concepts Revision of Osteology Rotator Cuff muscles Neurovascular supply Upper arm Myology Motion Shoulder Concepts  Concepts Ball & Socket Joint Stabilised by ligaments Movements by muscles – Rotator Cuff Muscles  Concepts Muscles have an origin & insertion Muscles become tendinous on insertion Muscles that cross a joint – move it Agonist vs Antagonist  Blood supply Arterial blood supply Venous drainage Nerve Supply All muscles have a specific nerve supply Nerves originate from spine Nerves send signals to muscle to act No nerves – no power Shoulder Joint  Abduction Adduction Movements at the Flexion shoulder Extension joint Internal rotation External rotation Circumduction  Brain signals to spine Nerve signal to relevant muscles Muscles contract to produce movement over the shoulder joint How does these movements occur? Shoulder muscles  Named in relation to spine of scapula Latin terminology Above spine of scapula – Supra Below spine – Infra Posterior View of Shoulder Muscles  Supraspinatus Origin: supraspinatous fossa of scapula muscle Insertion: greater tubercle of humerus Innervation: suprascapular nerve (C4, C6) Function: initiation of abduction of arm to 15° at glenohumeral joint Infraspinatus Origin: infraspinatous fossa of muscle scapula Insertion: greater tubercle of humerus Innervation: suprascapular nerve (C5, C6) Function: external rotation of arm at glenohumeral joint Rotator Teres minor muscle Origin: lateral border of scapula Insertion: greater tubercle of humerus Innervation: axillary nerve Cuff (C5, C6) Function: external rotation and adduction of arm at glenohumeral joint Muscles Subscapularis muscle Origin: medial two-third of the subscapular fossa Insertion: lesser tubercle of the humerus Innervation: upper and lower subscapular nerves (C5, C7) Function: internal rotation of arm; stabilization of humeral head in glenoid cavity. Mnemonic Rotator cuff SITS on the shoulder ( Supraspinatus, Infraspinatus, Teres minor, Subscapularis) Rotator cuff SITS on the shoulder Supraspinatus Origin Supraspinous fossa of scapula Insertion Greater tubercle of humerus Action Shoulder joint: abduction of arm to 15 degrees Rotator cuff SITS on the shoulder  Origin Infraspinous fossa of scapula Insertion Greater tubercle of humerus Infraspinatus Action Shoulder joint: Arm external rotation Rotator cuff SITS on the shoulder  Teres Minor Origin Lateral border of scapula Insertio Greater tubercle of n humerus Action Shoulder joint: Arm external rotation, arm adduction Rotator cuff SITS on the shoulder Subscapularis Origin Subscapular fossa of scapula Insertion Lesser tubercle of humerus Action Shoulder joint: Arm internal rotation  Supraspinatus Origin: supraspinatous fossa of scapula muscle Insertion: greater tubercle of humerus Innervation: suprascapular nerve (C4, C6) Function: initiation of abduction of arm to 15° at glenohumeral joint Infraspinatus Origin: infraspinatous fossa of scapula Insertion: greater tubercle of humerus Innervation: suprascapular nerve (C5, C6) Function: external rotation of arm at glenohumeral Rotator Teres minor joint; Origin: lateral border of scapula Insertion: greater tubercle of Cuff humerus Innervation: axillary nerve (C5, C6) Function: external rotation and adduction of arm at Muscles glenohumeral joint Subscapularis Origin: medial two-third of the subscapular muscle fossa Insertion: lesser tubercle of the humerus Innervation: upper and lower subscapular nerves (C5, C7) Function: internal rotation of arm Mnemonic Rotator cuff SITS on the shoulder ( Supraspinatus, Infraspinatus, Teres minor, Subscapularis)  Pneumonic – Supraspinatus ABD Teres minor ER – Supscapularis IR Supscapularis IR Infraspinatus ER  Other muscles Teres Latissimus Serratus Major Dorsi Anterior Deltoid Pectoralis Trapezius Major Pectoralis Major Origin Clavicular part, sternocostal and costal cartilages of ribs of rectus sheath Insertion Crest of greater tubercle of humerus Action Shoulder joint: Arm adduction, Arm internal rotation, Arm flexion (clavicular head), Serratus Anterior Origin Superior part: Ribs 1-9 Insertion Scapula Function Scapulothoracic joint: Draws scapula anterolaterally,  Deltoid Origins Lateral 1/3 of Clavicle, Acromion Spine of Scapula Insertion Deltoid tuberosity of humerus Function Clavicular part: flexion and internal rotation of the arm, Acromial part: abduction of the arm beyond the initial 15° Spinal part: extension and external rotation of the arm. Teres Major Origins Inferior angle and lower part of the lateral border of the scapula Insertion Intertubercular sulcus (medial lip) of the humerus Function Extension and internal rotation of the humerus (arm)  Latissimus Dorsi Origin S p i n o u s p ro c e s s e s o f vertebrae T7-T12, Posterior third of crest of ilium Scapular part: Inferior angle of scapula Ribs Insertion Intertubercular sulcus of the humerus, between pectoralis major and teres major muscles Function Shoulder joint: Arm internal s rotation, Arm adduction, Arm extension; Assists in respiration Trapezius Muscle Origin Nuchal line, transverse spine processes of vertebrae Insertion lateral third of clavicle, medial acromial margin, superior crest of spine of scapula Action Draws scapula superomedially Lateral extension of head Summary of movements Blood Supply Subclavian Artery Axillary Artery Axilla means under- arm  Axillary supply Subscapular artery Source Subclavian artery Branches Superior thoracic, Thoracoacromial, Lateral thoracic, Anterior circumflex humeral, Posterior circumflex humeral, Subscapular Supplies The axilla, upper limb, lateral thoracic region Anterior/posterior Circumflex humeral arteries Deltoid Muscle/ Teres Minor  Supraspinatus/Infraspinatus Posterior View Subscapular nerve Subscapularis Upper Arm Terminology Upper arm Anterior Posterior Agonist Antagonist Compartments Muscles of upper arm move the elbow Supination  Muscle Concepts Muscles become tendinous at When crossing a joint, muscle insertion moves it  Concepts Muscles have an origin & insertion Muscles become tendinous on insertion Muscles that cross a joint – move it Agonist vs Antagonist  Concept of compartments A group of muscles enclosed within fascia that have similar function Anterior Compartment Posterior Compartment Muscle Compartments  Anterior Compartment  Short head Biceps Brachii Origin Short head - Apex of the Coracoid process of the scapula Long head - Supraglenoid tubercle of the scapula Insertion Radial tuberosity of the radius Function Flexion and supination of the forearm at the elbow joint Brachialis Origin Distal half of anterior surface of humerus Insertion Coronoid process of the ulna; Tuberosity of ulna Function Strong flexion of forearm at the elbow joint Coracobrachialis Origin Coracoid process of the scapula Insertion Anteromedial surface of the humerual shaft Action Adduction and flexion of the arm at the shoulder joint Posterior Compartment  Triceps Origins Long head - infraglenoid tubercle of the scapula Medial head - posterior surface of the humerus Lateral head - posterior surface of the humerus Insertion Olecranon of ulna Action Elbow joint: extension of the forearm Shoulder joint: extension and adduction of the arm (long head)  Blood supply subclavian => axillary => brachial Axillary artery Anterior/posterior Circumflex humeral arteries Brachial Artery Musculocutaneous Nerve  Musculocutaneous nerve Biceps brachii Brachialis Coracobrachialis Radial Nerve Elbow Joint Wrist Joint  Humerus Diagram of biceps/ triceps – flexion and extension at elbow Elbow Joint joint Radius Ulna  Flexion Movements Extension at Elbow& Wrist Joints Pronation Supination  Summary Different shoulder movements SITS – rotator cuff muscles Arm compartments Blood/nerve supply Important for treatment of injury!