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2 Shoulder and Arm •Agonist: •muscle that causes specific movement or possibly several movements to occur through the process of its own contraction Antagonist: muscle that acts in opposition to the specific movement generated by the agonist and is responsible for returning a limb to its initial position. •Synergist •muscle which performs, or assists in performing, the same set of joint motions as the agonists Shoulder Complex comprised of 3 bones: •Clavicle : “aka” collar bone; •acromioclavicular: joint laterally • sternoclavicular: joint medially (single attachment between the axial and appendicular skeleton) •Synovial joints •Scapula: •16 muscles attach to scapula •scapulothoracic joint is false joint •Along with clavicle important in stabilization and movement of the arm •Humerus: •Articulates with glenoid fossa to form glenohumeral joint •Synovial ball and socket joint. Bones of the Shoulder and Arm CLAVICLE – convex medially, concave laterally Bony Landmarks Bony Landmarks Bony Landmarks Intertubercular groove is also known as the bicipital groove Radial fossa – where the head of radius hits the humerus Coronoid fossa – where the coronoid process of ulna hits the humerus Trochlea – medial condyle of humerus; on both anterior and posterior of humerus Capitulum – lateral condyle of humerus; only on anterior of humerus Bony Landmarks Olecranon fossa – where the olecranon process of ulna hits the humerus Trochlea - continues from anterior of humerus to posterior of humerus (Capitulum does not) Bony Landmark Trails Bony Landmark Trails Spine of the Scapula •Superficial ridge •Oblique angle from acromion to the medial border •Attachment site for: •posterior deltoid •middle and lower trapezius •Separates the supraspinatus and infraspinatus fossa Medial Border •Runs parallel to the vertebral column •Deep to the trapezius muscle •Attachment site for: •Rhomboids •Serratus anterior Lateral Border Extends superiorly and laterally from the inferior angle of the scapula towards the axilla (armpit) Infraglenoid Tubercle Located at the most superior aspect of the lateral border Serves as attachment site of the long head of the triceps brachii Infraspinous Fossa Triangular area inferior to the spine of the scapula Filled with infraspinatus muscle Supraspinous Fossa Deep depression superior to the spine of the scapula Supraspinatus muscle attaches and lies in this fossa Subscapular Fossa Located on the scapula’s anterior (underside) surface, against the rib cage Attachment site for the subscapularis muscle Scapulothoracic joint – “pseudoarthrotic joint”; it moves like a joint, but it is attached to the thorax by muscle, so it is not a true joint between two bones (it is just suspended there) Inferior Angle Located at the inferior end of the medial border of the scapula Superior Angle Located at the superior end of the medial border of the scapula Acromion Lateral aspect of the spine of the scapula Located at the top of the shoulder Articulates with the acromial end of the clavicle Clavicle S-shaped bone that is horizontally positioned across the upper thorax Lateral (acromial) end articulates with the acromion •relatively flat Medial (sternal) end articulates with the sternum • rounded Acromioclavicular Joint (AC joint) Synovial joint / diarthrosis Articulation between the the acromion of the scapula and the (acromial end) of the clavicle. The lateral end of the clavicle is flat and sits slightly higher than the acromion Sternoclavicular Joint (SC joint) Synovial joint / diarthrosis Where the sternum articulates with the medial (sternal end) of the clavicle. Contains a fibrous disk The medial end of the clavicle is rounded The S/C joint is the only bony attachment of the upper extremity to the axial skeleton Coracoid Process Anterior, beak-like projection of scapula Located inferior to the shaft of the clavicle It can be located in the deltopectoral groove Deltoid Tuberosity Small, low bump Located on the lateral side of the midhumeral shaft Serves as attachment site of the deltoid muscle fibers Greater Tubercle Located inferior and lateral to the acromion on the proximal end of the humerus Attachment site for 3 of the 4 rotator cuff muscles •Supraspinatus •Infraspinatus •Teres minor Lesser Tubercle and Intertubercular Groove Lesser tubercle - smaller than and medial to the greater tubercle •Attachment site for subscapularis muscle Intertubercular groove (bicipital groove) - lies between the greater and lesser tubercles •Tendon of the long head of the biceps brachii muscle travels through here Muscles of the Shoulder and Arm Muscles of the Shoulder and Arm Muscles of the Shoulder and Arm Deltoid Triangle shaped muscle Composed of anterior, medial and posterior fibers. All fibers abduct the humerus. Deltoid Trail Guide: Deltoid Trapezius Divided into 3 groups: •Upper (descending) fibers •Middle fibers •Lower (ascending fibers) Upper and lower fibers act as antagonists in elevation and depression respectively Trapezius (CN XI) and C2, 3, 4 Upper, Middle and Lower Fibers of the Trapezius Trail Guide: Trapezius Latissimus Dorsi Broadest muscle of the back Intertubercular groove of the humerus Latissimus Dorsi Trail Guide: Latissimus Dorsi Teres Major Called the “lats little helper” because it is a synergist with the latissimus dorsi Teres major and minor act antagonistically in medial and lateral rotation •Teres minor= laterally rotates •Teres major= medially rotates Latissimus Dorsi and Teres Major Both are termed the handcuff muscles Rotator Cuff Muscles Supraspinatus Infraspinatus Teres Minor Subscapularis Rotator Cuff Muscles Rotator Cuff Muscles Stabilize head of the humerus in glenoid cavity Rotator Cuff Muscles Stabilize head of the humerus in glenoid cavity Upper 2/3 Rotator Cuff Muscles Supraspinatus Infraspinatus Teres Minor Subscapularis Rotator Cuff Tendons Supraspinatus tendon Infraspinatus Tendon Teres Minor Subscapularis Supraspinatus Tendon Medially rotate and extend arm(Handcuff position) Just anterior and inferior to the acromion Infraspinatus and Teres Minor Tendons Flex shoulder to 90 degrees. Deep to deltoid just inferior to the acromion Subscapularis Tendon Trail Guide: Rotator Cuff Rotator Cuff Injuries Supraspinatus is the strongest abductor of the shoulder The major muscle that is usually involved is the supraspinatus muscle. •Rotator Cuff Tendonitis •Rotator Cuff Tears •Instability Impingement •Rotator Cuff Tendonitis •Also known as "bursitis" or "impingement syndrome" •Occurs when the rotator cuff gets irritated on the undersurface of the acromion. •Multiple causes(etiologies). •Some people are born with a "hooked" acromion that will predispose them •Rotator cuff weakness that causes the humerus to ride up and pinch the supraspinatus tendon •The bursa — a waterballoon type structure that acts as a cushion between the rotator cuff and acromion/humerus — gets inflamed. •Rotator Cuff Tears •Occurs when tendonitis in the rotator cuff becomes chronic and it wears down one of the rotator cuff tendons (Supraspinatus tendon). •Tears can occur due to a traumatic event as a result of over tensioning the tendon or shoulder instability. •Can be a “pop” in the shoulder, usually with immediate pain (this is called an "acute rotator cuff tear"). Instability Impingement •Dislocations Head of the humerus completely pops out of the socket. •Initially most commonly due to significant trauma (although it can occur in some people without significant trauma) •In time it becomes easier and easier for the joint to dislocate. •Most shoulder dislocations are anterior. •Subluxations This is the feeling that the shoulder slips slightly out of socket, then immediately comes back in place. •Often happens without any major trauma. "loose-jointed". •Can occur in all directions "multidirectional instability". • Common in throwing athletes and swimmers Acute rotator cuff tear Sudden tearing sensation followed by severe pain shooting from the upper shoulder area (both in front and in back) down the arm toward the elbow. Decreased range of motion of the shoulder because of pain and muscle spasm. Acute pain from bleeding and muscle spasm: This may resolve in a few days. Large tears may cause the inability abduct the arm (raise it out to the side) due to significant pain and loss of muscle power. Chronic rotator cuff tear Pain usually is worse at night and may interfere with sleep. Gradual weakness and decreased shoulder motion develop as the pain worsens. Decrease in the ability to abduct the arm. Difficult to use the injured arm for activities that entail lifting the arm as high as or higher than the shoulder, to the front or side. May develop “Frozen Shoulder” Rotator cuff tendinitis More common in women 35-50 years of age Deep ache in the shoulder also felt on the outside upper arm over the deltoid muscle Point tenderness may be appreciated over the area that is injured Pain comes on gradually and becomes worse with lifting the arm away from the body(abduction) or turning it inward (internal rotation) May lead to a chronic tear: When a rotator cuff tendon becomes inflamed (tend=tendon +itis=inflammation), it runs the risk of losing its blood supply, causing some tendon fibers to die. This increases the risk that the tendon can fray and partially or completely tear. Rhomboid Major and Minor Rhomboids Trail Guide: Rhomboids Levator Scapula •Located along lateral and posterior side of the neck •Inferior portion is deep to the upper trapezius •More superficial on the lateral side of the neck Levator Scapula C3 and C4 Levator Scapula Trail Guide: Levator Scapulae Serratus Anterior •Lies along the posterior and lateral rib cage •Most of the muscle is deep to the scapula, latissimus dorsi or pectoralis major. •Superficial portion of the muscle lies inferior to the axilla •Works to abduct the scapula as an antagonist to the rhomboids Serratus Anterior External surfaces of upper eight or nine ribs Winging of the Scapula Mostly due to a lesions of the long thoracic nerve (serratus anterior). Rarely, but may also be due to spinal accessory nerve (trapezius) and dorsal scapular nerve (rhomboids). Breast Tissue •Composed of subcutaneous fat and supported by suspensory ligaments connecting skin with deep fascia anterior to the pectoralis major. •2/3 of the breast covers the pectoralis major. •The inferior and lateral aspects cover the serratus anterior muscle Pectoralis Major •Broad powerful muscle •Divided into 3 segments •Clavicular fibers •Sternal fibers •Costal fibers •The upper fibers and lower fibers act as antagonists to themselves •Upper fibers= flexion at the shoulder •Lower fibers=extension at the shoulder Pectoralis Major Upper fibers: Lateral pectoral Lower fibers: Lateral and medial pectoral Trail Guide: Pectoralis Major Pectoralis Minor •Lies deep to the pectoralis major along the rib cage •Fibers run perpendicular to pectoralis major •Brachial plexus, axillary artery and vein cross underneath pectoralis minor Pectoralis Minor Assist to elevate thorax during forced inhalation Trail Guide: Pectoralis Minor Pectoralis Minor Syndrome Definition: A form of Thoracic Outlet Snydrome (TOS) causing pain, numbness, tingling, and/or weakness in the arm and hand due to pressure against the nerves or blood vessels that supply the arm. Causes: tight muscles, ligaments, bands, or bony abnormalities in the thoracic outlet area of the body causing pressure on nerves (most common) or blood vessels. Symptoms: numbness and tingling in the fingers; pain in the neck, shoulder, and arm; headaches in the back of the head; weakness of the arm and dropping things from the hand; worsening of the symptoms when elevating the arm to do such things as comb or blow dry one's hair or drive a car; and coldness and color changes in the hand. Worse at night or when using the arm for overhead activities Subclavius (underneath clavicle) Depress the clavicle and draw it anteriorly Inferior surface of middle 1/3 of clavicle Biceps Brachii Long head (lateral) and short head (medial) Tendon of the long head passes through the intertubercular groove Intertubercular groove helps stabilize the tendon Biceps Brachii Trail Guide: Biceps Brachii Triceps Brachii •Only muscle located on the posterior arm •Antagonist to the biceps brachii •Three heads: •Long head •Lateral head •Medial head Triceps Brachii Trail Guide: Triceps Brachii Coracobrachialis Synergists – Muscles Working Together Shoulder (glenohumeral joint) Shoulder (glenohumeral joint) Shoulder (glenohumeral joint) Shoulder (glenohumeral joint) Shoulder (glenohumeral joint) Shoulder (glenohumeral joint) Scapula (scapulothoracic joint) Scapula (scapulothoracic joint) Scapula (scapulothoracic joint) Other Structures of the Shoulder and Arm Axilla Other Structures of the Shoulder and Arm Axilla 4 walls Lateral wall= biceps brachii + coracobrachialis Posterior wall= subscapularis + latissimus dorsi Anterior wall= pectoralis major Medial wall= rib cage and serratus anterior Other Structures of the Shoulder and Arm Axilla Sternoclavicular Joint Ligaments of the Shoulder and Glenohumeral Joint Ligaments of the Shoulder and Glenohumeral Joint Glenohumeral Joint Glenohumeral Joint Coracoclavicular Ligament •Provide stability for the AC joint •Composed of trapezoid and conoid ligaments •Run from coracoid process of the scapula to the inferior surface of the clavicle Coracoacromial Ligament •Attaches the scapula’s coracoid process to the acromion •Coracoacromial ligament + Acromion = Coracoacromial arch •Protects the rotator cuff tendons and subacromial bursa from direct trauma by the acromion Subacromial Bursa •Aka “Subdeltoid bursa” •Fluid filled sac •Abduction of the arm compresses the bursa, therefore can indicate subacromial bursitis if painful abduction. Axillary Lymph Nodes Brachial Artery •Continuation of the axillary artery. •Branches at elbow into radial and ulnar arteries •Runs between the biceps brachii and triceps brachii muscles on the medial arm