L3 Upper Limb 1 mHY PDF - Systemic Anatomy of The Human Body

ACB 2200A Systemic Anatomy of The Human Body Upper Limb 1: Shoulder Dr. Michele Barbeau [email protected] MSB 489  Lecture Objectives 1. General Introduction: Overall structure and function of the upper and lower limbs. 2. Describe the bony structures of...

ACB 2200A Systemic Anatomy of The Human Body Upper Limb 1: Shoulder Dr. Michele Barbeau [email protected] MSB 489  Lecture Objectives 1. General Introduction: Overall structure and function of the upper and lower limbs. 2. Describe the bony structures of the upper limb including pectoral girdle, humerus, radius, ulna and hand. 3. Describe the 6 muscles that anchor the pectoral girdle to the axial skeleton. 4. Describe the rotator cuff muscles.  Why Study the Limbs? A detailed understanding of the form and function of the upper and lower limbs is essential for many medical career specializations: 1) Orthopedics 7) Massage Therapy 2) Chiropractic 8) Acupuncture 3) Kinesiology 9) “Biomechanics” research 4) Physical Education 10) Podiatry 5) Rehab/Sports Medicine 11) Radiology 6) Physical Therapy 12) Occupational Therapy  General Features of the Limbs The upper and lower limbs share a common general outline arm Both upper and lower limbs consist of three somewhat analogous sections hand forearm The UPPER LIMB: Hand, Forearm and Arm The LOWER LIMB: Foot, Leg, and Thigh thigh leg foot  Development of the Limbs Early Development Early Development Week 5 Week 7 Body Movements Flexion/Extension Abduction/Adduction Lateral/Medial Rotation Protraction vs Retraction Protraction: e.g. Pushing Forward Retraction: e.g. Pulling back UPPER LIMB: POWER MOVEMENTS, Fine Movements… Overview: Osteology of the Upper Limb Pectoral Girdle (Scapula/Clavicle) Humerus Radius Ulna Bones of the Wrist and Hand  The Pectoral Girdle The Pectoral Girdle consists of: the SCAPULA (posterior) and the CLAVICLE (anterior) The name itself is a misnomer since the two scapulae do not physically meet on the back: i.e. not a true “girdle” ! Major functions: provides attachment for the upper limb to the axial skeleton; provides great movement flexibility in various planes  THE PECTORAL GIRDLE: THE CLAVICLE AND SCAPULA o Serves to attach the upper limbs to the Axial Skeleton o The pectoral girdle is highly mobile, but the price of this mobility, is increased weakness and proneness to injury….  The Clavicle An “S” shaped bone with two ends: medially, the “sternal end” attaches to the manubrium of the sternum and the lateral “acromial” end attaches to the acromion process of the scapula. Major functions: – muscle attachment site – the clavicles are “braces” by holding the scapulae and arms out laterally from the thorax. Also, the clavicles transmit “compression force” from the upper limbs to the axial skeleton… THE CLAVICLE  Clavicular Fractures The Clavicle is a relatively weak structure, prone to fractures. When this occurs, the brace-like function of the clavicle becomes obvious, since the entire shoulder region collapses medially…  The Scapulae Also called “shoulder blades” are located on the dorsal rib cage between rib 2 and rib 7. A triangular structure with three anatomical borders: 1) Superior border (short & sharp); 2) Medial border (parallel to the spinal column) and 3) Lateral border, which is thicker, and ends in the “glenoid cavity” which is the joint cavity that articulates with the humerus. There are three important “angles” : the lateral angle which contains the glenoid cavity; the superior angle where the superior and medial borders meet, and the inferior angle where the medial and lateral borders meet. The Scapulae The Scapulae Lateral view  The Humerus The only bone of the arm (brachium) Proximally, the head articulates with the glenoid cavity of scapula Distally, the humerus meets the radius and ulna, forming the elbow joint The distal end forms two “epicondyles” a lateral one and medial one which are attachment sites for forearm muscles Finally, the distal end forms two articulation structures called the “capitulum” (which articulates with the radius and a medial one called the “trochlea” which articulates with the ulna Greater tubercule Greater tubercule Lesser tubercule Lateral epicondyle Capitulum Trochlea The Glenohumeral Joint: Shoulder Joint Dislocation of the Shoulder Due to the ill-fitted glenohumeral joint, the shoulder is the most common form of dislocation accounting for about 85% of all dislocations Most dislocations are in the anterior plane, but they can also occur posteriorly, or inferiorly. Shoulder Displacement Transmitted Forces Shoulder Dislocation Normal Ant. Dislocation Muscle Attachments Prime mover – Major Action (agonist) Antagonist – muscle which opposes action Synergist – muscle that assists action  Muscles That Act On The Scapula Posterior Thorax Anterior Thorax § Trapezius (considered § Pectoralis minor as 3 muscles) § Serratus anterior § Levator scapulae § Subclavius § Rhomboids (Minor and major); consider as 1 muscle  Movements of the Scapula 1) Elevation (shrugging shoulders) and Depression 2) Protraction (like a punching movement) and Retraction (standing at attention) 3) Upward and Downward Rotation (as in moving arms over head, and down again) POSTERIOR MUSCLES: Trapezius: Stabilizes, raises, retracts and rotates scapula Levator Scapulae: Elevates and retracts scapula Rhomboids: Stabilizes and helps retract the scapula ANTERIOR MUSCLES: Pectoralis minor: draws scapula forward Serratus anterior: Rotates scapula lateral and upward; important role in raising the Arm and horizontal arm movements (pushing, punching) Subclavius: Helps stabilize and depress pectoral girdle POSTERIOR THORAX MUSCLES That Act On The Scapula: Trapezius, Rhomboids, Levator Scapulae  LEVATOR SCAPULAE Origin: Transverse processes of vertebrae C1-C4 Insertion: Superior part of medial scapula Action: Elevates scapula and tilts glenoid fossa inferiorly by rotating scapula Innervation: Dorsal scapular (C5) and cervical nerves (C3-C4)  TRAPEZIUS Origin: Med. 1/3 of superior nuchal line; external occipital protuberance; nuchal ligament and spinous processes of C7- T12 Insertion: Lateral 1/3 of clavicle, acromion and spine of scapula Action: Elevates, retracts and rotates scapula; superior fibers elevate, medial fibers retract and inferior fibers depress scapula. Innervation: Accessory Nerve (CN XI)  RHOMBOID (major and minor) Origin: Minor: nuchal ligament and spinous processes of C7-T1 Major: spinous processes of T2-T5 Insertion: Medial border of scapula Action: Retracts scapula and rotates it to depress the glenoid cavity; fixes scapula to thoracic wall Innervation: Dorsal scapular nerve Brachial Plexus Review ANTERIOR THORAX muscles that act on the Scapula: Pectoralis Minor, Serratus Anterior; Subclavius  PECTORALIS MINOR Origin: 3rd to 5th ribs near their costal cartilages 1 Insertion: Coracoid process of the scapula 2 Action: stabilizes scapula by drawing it inferiorly and anteriorly against the 3 thoracic wall 4 Innervation: Medial Pectoral Nerve 5  SERRATUS ANTERIOR (boxer’s muscle) Origin: fleshy slips from upper ribs Insertion: costal aspect of medial margin of scapula Action: protracts and stabilizes scapula, assists with upward rotation Innervation: long thoracic nerve Brachial Plexus Review Medial Pectoral nerve  Rotator Cuff Muscles 4 muscles that originate on the scapula and cross the shoulder joint to insert on the humerus. They include the 1) subscapularis, 2) supraspinatus, 3) infraspinatus, and the 4) teres minor All encircle the shoulder joint (like a cuff) and help to anchor the head of the humerus into the glenoid cavity of the shoulder joint. Some (3/4) act to rotate the humerus (either medially or laterally); one (supraspinatus) acts to abduct the arm. Supraspinatus, Teres Minor, Infraspinatus ALL insert into the GREATER tubercle of humerus but Subscapularis, inserts into the LESSER tubercle. The Rotator Cuff Muscles Supraspinatus Subscapularis Infraspinatus Teres minor Lateral view  Actions of the Rotator Cuff Muscles Subscapularis: Primary Medial Rotator of the humerus and also holds the head of the humerus in the glenoid cavity, stabilizing the shoulder joint, innervation by subscapular nerve Supraspinatus: Initiates abduction, stabilizes shoulder and prevents Downward dislocation of humerus; innervation by suprascapular nerve Infraspinatus: Rotates humerus laterally, helps to hold head of humerus in glenoid cavity which stabilizes the shoulder joint; innervation by suprascapular nerve Teres Minor: Same action as infraspinatous; innervation by axillary nerve Brachial Plexus Review *Subscapular nerves  Summary Movement of the limbs Pectoral girdle: scapulae and clavicle Posterior muscles: levator scapulae, trapezius, rhomboids Anterior muscles: pectoralis minor, subclavius, serratus anterior Rotator cuff muscles (supraspinus, infraspinus, subscapularis, teres minor) Humerus  Homework Try a yoga class for shoulder and upper limb Some things to think of while you do the class: 1. What movement is occurring at the shoulder and elbow joints? 2. What muscles are being stretched? 3. What muscles are contracting? 4. Try to visualize the muscle and the origin and insertion points https://www.youtube.com/watch?v=JUP_YdYyfQw