The Shoulder PDF Western University Canada Anatomy

 The Shoulder Dr. Sean McWatt, PhD [email protected] © Danny Quirk Artwork Learning Outcomes By the end of this lesson, you will be able to… Identify and describe the bones, joints, and ligaments related to...

 The Shoulder Dr. Sean McWatt, PhD [email protected] © Danny Quirk Artwork Learning Outcomes By the end of this lesson, you will be able to… Identify and describe the bones, joints, and ligaments related to the shoulder Describe basic movements of the scapula and humerus Identify muscles that act to move the scapula and humerus, and describe their innervations and functions Predict functional implications of musculoskeletal injuries to the shoulder region Regions of the Upper Limb Deltoid region Shoulder Scapular region Axillary region Armpit We will run through the anatomy of the upper limb according to these regions, from proximal to distal. Dorsal Palmar Back Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Posterior view © 2010, Icon Learning Systems, LLC. A subsidiary of MediMedia, USA, Inc. All right reserved Bones of the Upper Limb Clavicle Sternoclavicular joint Shoulder joint Scapula The clavicle articulates with the manubrium of the sternum to form Humerus the sternoclavicular joint. The humerus articulates with the scapula proximally to form the shoulder joint, distinguishing the shoulder from the arm. Anterior view Posterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Bones, Joints, and Ligaments Bones of the Pectoral Girdle Can you distinguish Acromial end Sternal Sternal end between a left and end Acromial end right clavicle? Shaft How? Superior view Inferior view Clavicle The proximal part of the upper limb (shoulder) region consists Scapula of three bones: the clavicle, Pectoral scapula, and humerus. girdle Together, the clavicle and the spine of the scapula comprise the pectoral girdle. Superior view Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins Scapula Suprascapular notch Coracoid process Superior angle Lateral Spine of angle Subscapular the scapula fossa Glenoid Infraspinous cavity fossa The scapula is a complex bone with lots of major landmarks serve as muscle attachments. Anterior view Inferior It is also quite thin in its Posterior view angle center; however, the rotator cuff muscles have broad attachments that surround and protect the bone. Lateral view (right) Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Palpable Surface Landmarks Acromion process Clavicle Can you locate these landmarks Coracoid process on yourself or a partner? Greater and lesser tubercles Anterior view Spine of the scapula TIII Inferior angle TVIII http://tiny.cc/7y40cz There are several palpable landmarks in the shoulder region that can be used in physical assessment. Posterior views Posterior view Drake, Gray’s Anatomy for Students, 2nd Ed., Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Copyright © 2009 by Churchill Livingstone Scapulothoracic Joint What’s a scapulothoracic joint? Dr. David Morton | The Noted Anatomist https://www.youtube.com/wat Sternoclavicular ch?v=8VmW9nZDoWI Acromioclavicular joint joint Subacromial Scapulothoracic Superior view ‘joint’ space The only thing (other http://tiny.cc/g680cz Initial ~90° of abduction than muscle) that occurs at the glenohumeral joint connects our upper Glenohumeral limb to our body is Elevation of the scapula joint the clavicle at the at the sternoclavicular joint allows for sternoclavicular movement beyond 90° joint. Movement of Maximal abduction the scapula occurs requires lateral (upward) rotation of at this joint. the scapula Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Movements of the Scapula Elevation and Lateral depression (upward) The scapula glides rotation across the ribs in what is known as the scapulothoracic ‘joint’. Since the scapulothoracic ‘joint’ is not a synovial (or Medial other type of) junction (downward) between bones, it is Retracted rotation not really a joint. Therefore, the movement is technically occurring at the sternoclavicular joint (with some movement at Protracted the acromioclavicular joint). Superior views Posterior views Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Clavicular Ligaments Sternoclavicular joint Sternoclavicular ligament Costoclavicular ligament Acromioclavicular joint Acromioclavicular ligament Clavicle Clavicle Ligaments are connective tissues that connect bone to bone to stabilize joints. Anterior view Scapula They restrict external separation forces (i.e., forces that pull the Anterior view bones apart). Other ligaments Coracoacromial ligament Coracoclavicular ligaments Superior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Shoulder Separation Separated shoulder These ligaments resist Grade 3 external forces to stabilize Coracoclavicular the bones of the shoulder. Acromioclavicular ligament ligaments When they tear, it results in a shoulder separation (not a dislocation). The coracoacromial ligament stretches between two parts of the scapula and, therefore, does not stabilize a joint. Instead, it helps to deepen Coracoacromial the joint socket, reducing ligament risk of superior dislocation Limits superior dislocation of the humerus of the humerus. Superior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Humerus Lesser tubercle Head of the humerus Greater tubercle Anatomical neck Epiphysial plate Intertubercular The head of the humerus Surgical neck groove articulates with the glenoid cavity of the scapula within the Deltoid tuberosity glenohumeral (shoulder) joint. Clavicle There are several bony Radial grove prominences on the proximal end of the humerus at which Scapula Shaft of the shoulder muscles attach and humerus act to move the humerus (arm) at the glenohumeral joint. Glenoid cavity Anterior view Posterior view Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme  Glenohumeral Joint The glenohumeral labrum Subacromial space cradles the head of the humerus Site of impingement of the supraspinatus m. within the glenoid cavity. https://www.shoulderdoc.co.uk/imag es/uploaded/labrum_depth.jpg Sternoclavicular Synovial Acromioclavicular joint joint membrane Subacromial Scapulothoracic Wrapped in a space ‘joint’ ligamentous joint capsule (next slide) Tendon of biceps brahii m. http://tiny.cc/g680cz Anterior view Glenohumeral The tendon of the biceps brachii joint m. (long head) passes through the joint cavity to attach on the above the glenoid fossa, stabilizing and acting on the glenohumeral joint. Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Glenohumeral Joint Capsule Glenohumeral joint ligaments Synovial Ball and socket Coracohumeral ligament Multiaxial Superior glenohumeral ligament Middle glenohumeral ligament Inferior glenohumeral ligament Tendon of biceps Bursae brahii m. The joint capsule is relatively thin, but it is supported by various ligaments. Bursae allow muscles to glide smoothly over the tubercles and head of the humerus during movement. Sheath for Joint capsule Joint capsule Joint labrum Tendon of Sagittal view (right) biceps brahii m. Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Glenohumeral Joint Movements Abduction Think of flexion at any joint as movement into the ‘fetal position’ and extension as movement out of it. Superior view Circumduction Combination of As a multiaxial “ball and movements socket” joint, many actions occur at the glenohumeral (shoulder) joint. These can often occur in combination, making them difficult Rotation to visualize. Medial/internal and lateral/external Anterior views Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill  Shoulder Dislocation Anterior/superior dislocation Inferior dislocation Dislocation of humerus from the glenoid cavity can impact neurovascular structures in the axilla. Lateral cord Musculocutaneous n. How would you test these Axillary n. nerves? From posterior cord Anterior view Netter, Atlas of Human Anatomy 6th Ed., Copyright © 2014 by Elsevier Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme  NOTE! The remainder of the lecture focuses on muscle anatomy. I have given you very detailed information about the muscles’ attachments. These are there for your reference and explanation purposes, but you do not need memorize them. You will find a muscle chart at the end of the lecture with the detail that you are expected to know. Muscles of the Rotator Cuff Muscles of the Rotator Cuff Muscles pull, not push! A muscle can only cause Subscapularis m. an action at a joint if it Origin: crosses that joint. Anterior scapula Insertion: Lesser tubercle The subscapularis m. acts on the humerus at Innervation: the glenohumeral Upper and lower subscapular nn. (shoulder) joint. (C5 – C6) It contributes to medial (internal) rotation. This is an example of a “front-to-front” muscle. Anterior views Anterior view Gilroy, Anatomy: An Essential Textbook, Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2013 by Thieme Copyright © 2009 by Churchill Livingstone Muscles of the Rotator Cuff Supraspinatus m. Infraspinatus m. Origin: Innervation: Supraspinous fossa Origin: The rotator cuff mm. Infraspinous fossa Suprascapular n. Insertion: (C5 – C6) Greater tubercle Insertion: act on the humerus at Greater tubercle (superior facet) the glenohumeral (middle facet) (shoulder) joint. The supraspinatus m. contributes to the initiation of abduction (~15°). Teres minor m. Origin: Inferior The infraspinatus m. facet Lateral border of scapula and teres minor m. Insertion: Subscapularis m. Greater tubercle Medial (internal) rotation contribute to lateral (inferior facet) (external) rotation. Innervation: Axillary n. Posterior view (C5 – C6) Sagittal views (right) Drake, Gray’s Anatomy for Students, 2nd Ed., Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Copyright © 2009 by Churchill Livingstone Muscles of the Rotator Cuff The S.I.t.S. muscles Together, the four rotator cuff mm. act to stabilize the Supraspinatus m. humerus in the glenohumeral (shoulder) joint. Infraspinatus m. Origin: S Origin: I Supraspinous fossa Infraspinous fossa Notice, the subscapularis m. is Insertion: Greater tubercle S Insertion: Greater tubercle (superior facet) the only one that does not (middle facet) t insert onto the greater tubercle! Teres minor m. Origin: Lateral border of scapula Subscapularis m. “Painful arc (impingement) syndrome” Insertion: Origin: Greater tubercle The supraspinatus m. runs (inferior facet) Subscapular fossa between the acromion and the Insertion: Lesser tubercle humerus, so it is susceptible to being pinched, causing pain between 60°–120° of abduction. Sagittal view (right) Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Muscles of the Shoulder Muscles of the Shoulder The deltoid m. acts on the humerus Deltoid m. at the glenohumeral (shoulder) joint. Origin: Pectoral girdle Mid. Intramuscular Insertion: injection The anterior part contributes to Deltoid tuberosity flexion and medial (internal) Innervation: rotation. The middle part contributes Axillary n. (C5 – C6) to abduction. The posterior part contributes to extension and lateral (external) rotation. The deltoid m. does almost everything! Superior view Posterior view Sagittal views (right) Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins Muscles of the Shoulder Clavicular head The pectoralis major m. acts on the humerus at the Sternocostal head glenohumeral (shoulder) Pectoralis major m. joint. It contributes to Origin: Clavicle, sternum, ribs Abdominal head multiple actions because of Insertion: its large area of attachment. Lateral lip of intertubercular groove All heads contribute to medial (internal) rotation, Anterior view adduction, and transverse Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone adduction. Innervation: The superior fibers Medial and lateral contribute to flexion and the pectoral nn. (C5 – C7; C8 – T1) inferior fibers contribute to extension back to neutral. Anterior view Anterior view Gilroy, Anatomy: An Essential Textbook, Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Thieme Copyright © 2013 by Lippincott Williams and Wilkins Muscles of the Shoulder Inferior view The subclavius m. acts as a Subclavius m. Origin: stabilizer of the clavicle at the Rib 1 sternoclavicular joint. Insertion: Inferior surface of clavicle Innervation: N. to subclavius (C5 – C6) The pectoralis minor m. acts on the scapula at the Pectoralis minor m. sternoclavicular joint (and Origin: Ribs 3 – 5 scapulothoracic ‘joint’). Insertion: Coracoid process of scapula Innervation: Medial (and lateral) pectoral nn. (C5 – C7; C8 – T1) It contributes to protraction and depression of the scapula. It can also assist with forced inhalation when the scapula is fixed. Anterior view Gilroy, Anatomy: An Essential Anterior view Textbook, © 2013 by Thieme Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Muscles of the Shoulder Paralysis of the Serratus anterior m. Sagittal view (right) serratus anterior Origin: muscle leads to The serratus anterior m. acts Lateral aspects of ribs winged scapula! Insertion: on the scapula at the Medial border of scapula sternoclavicular joint (and Posterior view scapulothoracic ‘joint’). Innervation: Long thoracic n. (C5 – C7) It contributes to protraction of the scapula and can also Superior view assist with forced inhalation when the scapula is fixed. The superior part contributes to downward rotation (lowering the raised arm) and the inferior part contributes to upward rotation (to raise the arm fully) of the scapula. Anterolateral view (right) Gilroy, Anatomy: An Essential Textbook, Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Copyright © 2013 by Thieme Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins  Muscles of the Shoulder Teres major m. Origin: Lateral border and Innervation: inferior angle of scapula Lower subscapular n. Insertion: (C5 – C6) Medial lip of intertubercular groove The teres major m. acts on the humerus at the glenohumeral (shoulder) joint. It contributes to adduction, extension, and medial (internal) rotation. This is an example of a “back-to-front” muscle. Posterior view Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Extrinsic Back Muscles Also known as the thoracoappendicular muscles because they originate on the thorax and insert on the appendage (upper limb)  Extrinsic Back Muscles Latissimus dorsi m. Origin: Thoracolumbar fascia Innervation: P.L.T. Insertion: Floor of the intertubercular groove of humerus Thoracodorsal n. (C6 – C8) sandwich Pectoralis major m. Teres major m. Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme The latissimus dorsi m. acts on the humerus at the glenohumeral (shoulder) joint. Thoracolumbar It contributes to adduction, fascia extension, and medial (internal) rotation. Posterior views Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins Extrinsic Back Muscles Trapezius m. The trapezius m. acts Origin: Vertebral column on the scapula at (base of skull to TXII) the sternoclavicular Insertion: Pectoral girdle joint (and scapulothoracic ‘joint’). It contributes to elevation, retraction, Innervation: and upward rotation. Spinal accessory n. (CN XI) Deltoid m. Acting on the neck, it abducts (tilts) the head to the ipsilateral (same) side. Posterior views Superior view Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins  Extrinsic Back Muscles That’s way too many actions… Levator scapulae m. I need to review! Origin: Dr. David Morton | The Noted Anatomist Transverse processes https://www.youtube.com/ Innervation: of vertebrae watch?v=XhuQOZzjh-A Dorsal scapular n. Insertion: (C5) Superior angle of scapula All three muscles act on Rhomboid minor m. the scapula at the Origin: Spinous processes of vertebrae sternoclavicular joint (and Insertion: scapulothoracic ‘joint’). Medial border of scapula They all contribute to Rhomboid major m. elevation (mostly levator Origin: Spinous processes of vertebrae scapulae m.) and retraction Insertion: (mostly the rhomboid mm.) Medial border of scapula of the scapula. Posterior view Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Full Range of Moton Glenohumeral joint Sternoclavicular and scapulothoracic joints Range: 0-15° Range: 15°-90° Range: 90°-160° Range: 160°-180° Muscle: Supraspinatus Muscle: Deltoid Muscle: Trapezius Muscle: Serratus anterior Nerve: Suprascapular n. Nerve: Axillary n. Nerve: Spinal accessory n. (CN IX) Nerve: Long thoracic n. Abduction of the upper limb at the shoulder joint involves four different muscles, supplied by four different nerves, to achieve the full range of motion from 0°-180° Upper Limb Radiology Tutorial - https://www.mededportal.org/doi/10.15766/mep_2374-8265.10167 Simplified Muscle Chart Attachments Muscle Group Muscle Origin Insertion Main action(s) Innervation Subscapularis Med. rotation Upper/lower subscapular Supraspinatus Initiates abduction Proximal Rotator cuff Scapula Suprascapular humerus Infraspinatus Lat. rotation Teres minor Axillary Deltoid Scapula/clavicle Abduction, rotation, flexion, extension Axillary Shaft of humerus Pectoralis major Thorax/clavicle Adduction, med. rotation, flexion, extension Medial/lateral pectoral Pectoralis minor Ribs Scapula Protraction Shoulder Subclavius Thorax Clavicle Stabilization N. to subclavius Thoracoappendicular Serratus anterior Ribs Scapula Protraction, rotation Long thoracic Teres major Scapula Adduction, med. rotation Lower subscapular Shaft of humerus Latissimus dorsi Adduction, extension, med. rotation Thoracodorsal Trapezius Scapula/clavicle Elevation, depression, retraction, rotation Spinal accessory (CN XI) Extrinsic back Levator scapulae Vertebrae Elevation Rhomboid major Scapula Dorsal scapular Retraction Rhomboid minor Learning Outcomes By now, you should better understand how to… Identify and describe the bones, joints, and ligaments related to the shoulder Describe basic movements of the scapula and humerus Identify muscles that act to move the scapula and humerus, and describe their innervations and functions Predict functional implications of musculoskeletal injuries to the shoulder region  © [email protected]