26/9/2016. Anatomy. 1 Nour Erekat Wejdan Amer

Transcription

1 26/9/2016 Anatomy st 1 Nour Erekat Wejdan Amer

2 Notes before we start the lecture. Bring any colored Atlas with you to the lab. The main reference is clinical anatomy by regions by Richard snell the 9 th edition and the handout. There will be a quiz everyday on the material of the previous lecture. I included the handout and the slides. Between the two lectures there is no difference except in the sequence of the lectures. Objectives Describe the principle distinguishing features of scapula, clavicle, and humerus Discuss the intermuscular spaces related to the scapula and their contents List the rotator cuff muscles The axilla: boundaries and contents Describe the components of the shoulder joint Describe the muscles acting on the shoulder joint according to the type and movement they perform Describe the bursae in relation to the shoulder joint List the blood supply and nerve supply of the shoulder joint P a g e 1

3 Regarding the last point in the objectives.. synovial joints are avascular they do not have direct blood supply, however they are supplied indirectly by neighboring structures and that s why you can see anastomosis of arteries surrounding synovial joints but there is still gas exchange nutrients and waste exchange via diffusion. *Shoulder girdle consists of clavicle and scapula -which articulate with one another at the acromioclavicular joint *Clavicle : Long slender subcutaneous bone, that lies horizontally across the root of the neck, it articulates with : -sternum and 1 st the clavicle) costal cartilage medially.(the sternal or medial end of - Acromion process of scapula laterally.(acromial or lateral end of the clavicle) Clavicle medial two thirds is convex forward and the lateral third is concave forward. P a g e 2

4 Scapula: A flat triangular bone, it has a superior angle, inferior angle, medial boarder (vertebral boarder), lateral boarder (axillary boarder). It lies between on the posterior chest wall between the 2 nd and 7 th ribs. -It has a spine on its posterior surface, that projects backward and its lateral end is free and forms the Acromian which articulates with the clavicle. -glenoid cavity or fossa The superolateral angle forms what is called the glenoid cavity or fossa. This is the part that articulates with the head of the humerus to form the shoulder joint. -coracoid process medial to glenoid cavity. That projects upward and forward above the glenoid cavity and it provides attachment for muscles and ligaments. -Suprascapular notch Medial to the base of the coracoid process -The anterior surface of the scapula is concave and forms >> the shallow subscapular fossa. -The posterior surface is devided by the spine into supraspinous fossa above the spine and infraspinous fossa below the spine. -The inferior angle can be palpated easily in the living subject (the only part of scapula that is subcutaneous) and marks the level of the 7 th rib and the spine of the 7 th thoracic vertebra. Note from NH lecture The scapula is kept in position by muscles particularly serratus anterior muscle, that is innervated by long thoracic nerve. If paralysis happen to that muscle a condition results that is called winged scapula, the scapula will be protruding in a way that results in wing like resemblance. Winged scapula is normal posture in children but abnormal in adults. P a g e 3

5 Humerus >> is not part of the shoulder girldle -Articulates with the scapula at the shoulder joint and with the radius and ulna at the elbow joint. -its upper end has a head which articulate with the glenoid cavity of the scapula. The head is immediately above the anatomical neck -greater and lesser tuberosities. Are below the neck and separated from each other by the bicipital groove (bicipital groove is called intertubercular groove in other books because they refer to greater and lesser tuberosities as greater and lesser tubercles) -narrow surgical neck. Where the upper end of the humerus joins the shaft. -deltoid tuberosity. Which is roughened elevation about halfway down the lateral aspect of the shaft. -spiral groove. Behind and below tuberosity. which accommodates the radial nerve. -lower end has medial and lateral epicondyles for the attachment of muscles and ligaments. -rounded capitulum, for articulation with the head of the radius at the elbow joint. -pulley-shaped trochlea, for articulation with the trochlear notch of the ulna. -radial fossa. Above the capitulum. And receives the head of the radius when the elbow is flexed. -coronoid fossa. Above the trochlea anteriorly. And receives the coronoid process of the ulna. -Olecranon fossa. Above the trochlea posteriorly. And receives the olecranon process of the ulna when the elbow joint is extended. P a g e 4

6 P a g e 5

7 Quadrangular space Intramuscular spaces related to scapula. -Is an intramuscular space located immediately below the shoulder joint -It is bounded *above by the teres minor *below by the teres major *medially by the long head of the triceps brachii *laterally by the surgical neck of the humerus. Structures in this space>> axillary nerve, posterior circumflex humeral vessels. This space is clinically significant because those structures can P a g e 6

8 get injured or can be compressed due to trauma resulting in different degrees of weakness of the deltoid muscle. Triangular space the most medial space -it is bounded *inferiorly by the superior border of the teres major. *laterally by the long head of triceps. *superiorly by teres minor. Structures in the space>> it contains scapular circumflex vessels only. The triangular interval It is bounded to *superiorly by teres major. *medially by long head of triceps brachii. *laterally by lateral head of the triceps brachii. The structures in the space > radial nerve and profunda(deep) brachii artery. Axilla -between is a pyramid-shaped space between the upper part of the arm and the side of the chest. -it forms an important passage for nerves, blood and lymph vessels, as they travel from the root of the neck to the upper limb. -its apex is the upper end that is directed into the root of the neck and it is bounded *in front by the clavicle *behind by the upper border of the scapula *medially by the outer border of the first rib P a g e 7

9 -the lower end of the axilla is called Base, is bounded *in front by the anterior axillary fold, called also the anterior axillary line (formed by the lower boarder of the pectoralis major) * behind by the posterior axillary fold (formed by the tendon of latissimus dorsi and the teres major muscle) *medially by the chest wall. Apex of axilla P a g e 8

10 Walls of the axilla. Anterior walls is formed by -pectoralis major, subclavius and pectoralis minor muscles. Posterior wall is formed by -subcapsularis, latissimus dorsi and teres major muscles from above down. Medial wall is formed by -the upper four or five ribs and the intercostal spaces covered by the serratus anterior muscle. P a g e 9

11 lateral wall is formed by -coracobrachial and biceps muscles, in the bicipital groove of the humerus. The base is formed by -skin stretching between the anterior and posterior walls Axilla contains.. Contents of the Axilla 1) axillary artery and its branches which supply blood to the upper limb. 2) axillary vein and its tributaries which drain blood from the upper limb. 3) lymph vessels and lymph nodes which drain lymph from the upper limb and the breast, and from the skin of the trunk, down as far as the level of the umbilicus. 4) brachial plexus(formed by the anterior primary rime of spinal nerves C4 through T1), which innervates the upper limb. Note >> structures in the axilla are embedded in fat. P a g e 10

12 In the picture above pectoralis minor muscle and axillary artery. **Axillary artery is divided into three parts by the pectoralis minor muscle, so from the outer boarder of the first rib to the upper boarder of pectoralis minor muscle you can see the first part of axillary artery and then you can see the second part of axillary artery behind the pectoralis minor muscle, and finally the third part is from the lower boarder of pectoralis minor to the boarder of teres major where the axillary artery continues as the brachial artery. Rotator cuff >> tendons of these muscles are fused with the underlying capsule of the shoulder joint and strengthen the capsule. Those muscles are 4 >> *supraspinatus ( origin from supraspinous fossa),*infraspinatus ( origin from infraspinous fossa), *teres minor and *subscapularis(you can t find it in a posterior view only in anterior view of shoulder joint.) -it plays a very important role in stabilizing the shoulder joint. P a g e 11

13 -it lies on the anterior, superior, and posterior aspects of the joint. -it is deficient inferiorly which is a site of potential weakness. Rotator cuff muscles, it s a posterior view because you can see the spine of the scapula. Shoulder joint. Is formed by articulation between head of humerus and glenoid cavity of scapula. Its articular surfaces are covered by hyaline articular cartilage. Glenoid cavity is deepened by the presence of glenoid labrum, which is fibrocartilaginous rim. -Type: synovial (ball-and socket) joint -It is surrounded by capsule, which is attached medially to the margin of the glenoid cavity outside the labrum, and laterally to the anatomical neck of the humerus. P a g e 12

14 The capsule is also thin and lax, allowing a wide range of movment>> flexion, extention, adduction, abduction, medial rotation, lateral rotation and circumduction. The capsule is strengthened by fibrous slips from the tendons of the rotator cuff muscles. The capsule is lined by synovial membrane, - that is attached to the margins of the cartilage covering the articular surfaces. -It forms a tubular sheath around the tendon of the long head of biceps brachii -and it extends through the anterior wall of the capsule to form the subscapularis bursa(beneath the subscapularis muscle) The shoulder joint is innervated by axillary and suprascapular nerves. This is a sagittal view of the shoulder joint. Sagittal section is a vertical plane that devides an organ or structure into right and left parts. -the glenoid fossa is deepened by the presence of fibrocartilaginous Rim known as glenoid labrum In this view you can see 2 bursae 1)subacromian bursa 2)subscapularis bursa. Bursa are clinically important because they get inflamed bursitis A very painful condition that happens because of trauma or infection. -the capsule is attached to the margins of glenoid cavity medially and to the neck of the humerus laterally, it s outside the glenoid labrum. -bursa is a small sack filled with lubricating fluid to prevent frection between the two surfaces of bone. P a g e 13

15 Shoulder joint has ligaments Glenohumeral ligaments (superior, inferior and middle glenohumeral ligaments) Transverse humeral ligament Corachohumeral ligament Which are three weak bands of fibrous tissue that strengthen the front of the capsule. These muscles are hidden beneath the capsule of the joint, to find them you need to open the capsule and remove the head of the humerus. Which strengthens the capsule and bridges the gap between the two tuberosities of the humerus. Which strengthens the capsule above and stretches from the root of the coracoid process to the greater tuberosity of the humerus. Accessory ligaments are the coracoacromial ligament (extends from coracoid process to acromian process) It extendes between the coracoid process and the acromion, its function is to protect the superior aspect of the joint. P a g e 14

16 Arterial Anastomosis Around shoulder joint, also the joint gets its needs by diffusion indirectly by neighboring tissues. Is formed by *anterior and posterior circumflex humeral arteries(which comes from the axillary artery which is a continuation of the subclavian artery). *circumflex scapular artery(branch of the subscapular artery which is the largest branch of the Axillary artery) *suprascapular artery (branch of the thyrocervical trunk that comes of the subclavian artery.) P a g e 15

17 Radio graphically you can see the two boney parts that articulate forming the shoulder joint you can see the head of the humerus, the glenoid cavity, coracoid process, acromian process, the clavical, the two boarders of the scapula, axillary(lateral boarder of scapula), vertebra and you can also see the first rib, second, third and forth. Because radio graphs are just two dimensional so there is superimposition between anterior and posterior parts. P a g e 16

18 Movements of the shoulder joint Flexion (forward movment of the upper limb) Preformed by the anterior fibers of deltoid, pectoralis major, biceps and coracobrachialis muscles Extension (backward movement of the upper limb) Which is performed by the posterior fibers of the deltoid, latissimus dorsi and teres major muscles. Abduction (moving the upper limb away from body or midline) -Involves middle fibers of the deltoid assisted by the supraspinatus. -it is initiated by supraspinatus muscle > that hold the head of the humerus against the glenoid fossa of the scapula, which allows the deltoid muscle to contract and abduct the humerus at the shoulder joint. Adduction (moving the upper limb toward body or midline) Performed by the pectoralis major, latissimus dorsi, teres major, and teres minor muscles. Lateral rotation Performed by the infraspinatus, teres minor, posterior fibers of the deltoid muscle. Medial rotation (results in the anterior surface of the arm facing medially) Which is performed by the subscapularis, the latissimus dorsi, teres major, and the anterior fibers of the deltoid muscle Circumduction which is a combination of the above movements P a g e 17

19 Now each muscle is attached to two sites there is site of origin and site of insertion, the picture below is an example.. this is the clavicle, The deltoid muscle takes its origin from the lateral part of the clavicle. Pectoralis major muscle takes its origin from more medial part of clavicle. another example, muscles attachments to scapula. P a g e 18

20 Subscapularis muscle origin is subscapular fossa and inserts on the lesser tuberosity of humerus. On the inferior angle and medial boarder of the scapula the serratus anterior muscle inserts. The deltoid muscle inserst on the acromian of scapula and the spine of the scapula. Teres minor and teres major muscles originate from the lateral boarder of scapula. * the site of origin of teres minor is above that of teres major. Supraspinatus originate from supraspinous fossa and inserts on greater tuberosity of humerus. Infraspinatous originate from infraspinous fossa. Teres major and latissimus dorsi insert on the medial lip of bicipital groove of humerus. Pectoralis major inserts on the lateral lip of bicipital groove of humerus. Posterior view you can see the three muscles of the rotator cuff Supraspinatus, infraspinatus and teres minor inserting on greater tuberosity in addition to the capsule of the shoulder joint, whereas subscapularis inserts on lesser tuberosity of humerus, in addition to the capsule of the joint. So all rotator cuff muscles insert on the capsule. *teres minor is one of the rotator cuff muscles not teres major. Dr nour said that you need to know all these muscles however the most important ones are the circled ones. Remmember P a g e 19

21 This is the first tafreegh in our 3 rd year of medicine : ) Good luck. P a g e 20