PECTORAL REGION AND BACK

ACTIVITY 1: PECTORAL GIRDLE The clavicle and scapula together form the pectoral girdle. a. Describe the clavicle highlighting its characteristics. b. Label the diagrams of the clavicle below. 

     

c. List the muscles attached to the clavicle. Shade the attachments of the muscles in the diagrams above.

Superior surface and anterior border  Deltoid muscle Superior surface                                Trapezius muscle Inferior surface                                  Subclavius muscle Anterior border                                 Pectoralis major muscle Posterior border                               Sternocleidomastoid muscle (clavicular head) Posterior border                               Sternohyoid muscle Posterior border                               Trapezius muscle

 d. Describe the scapula.

Scapula is the bone that connects the humerus (arm bone) with the clavicle (collar bone). The scapula forms the posterior (back) located part of the shoulder girdle. In humans, it is a flat bone, roughly triangular in shape, placed on a posterolateral aspect of the thoracic cage. Structurally, it is divided into anterior and posterior surface. 

Posterior side:  spine of scapula, acromion, supraspinous fossa, infraspinous fossa Anterior side:  coracoid process, subscapular fossa, suprascapular notch, superior angle,

inferior angle, lateral (axillary) border, medial (vertebral) border Lateral side:  glenoid cavity

Function of scapula: The scapula is the mobile bone to which most of the shoulder muscles are attached. It is attached to the back by other muscles. It serves as a broad plate for the strong anchoring of muscles of the upper extremity.  e. Label the diagrams of the scapulae below.

 1.  Acromion process2. Coracoid process3. Glenoid fossa/Glenoid cavity4. Infraglenoid fossa/tubercle5. Subcapsular fossa6. Lateral border7. Infraspinous fossa8. Superior angle9. Spine10. Medial border11. Inferior angle12. Supraglenoid tubercle13. Superior angle

f. List the muscles attached to the scapula. Shade the attachments of the muscles in the diagrams below.

 

  ACTIVITY 2: FRACTURE OF CLAVICLE a. State the weakest point of the clavicle.Middle third of its length. b. How does fracture of the clavicle occur?The lateral fragment is depressed by the weight of the arm and is pulled medially and forward by the strong adductor muscles of the shoulder joint, especially the pectoralis major. The part of the clavicle near the center of the body is tilted upwards by the sternocleidomastoid muscle. 

Children and infants are particularly prone to it. Newborns often present clavicle fractures following a difficult delivery.

c. In fracture of the clavicle, describe and explain the position of the clavicular fragments.After fracture of the clavicle, the sternocleidomastoid muscle elevates the proximal fragment of the bone. The trapezius muscle is unable to hold up the distal fragment owing to the weight of the upper limb, and thus the shoulder droops. The adductor muscles of the arm, such as the pectoralis major, may pull the distal fragment medially causing the bone fragments to override. d. Name the structures that will be at risk of injury in fracture of the clavicle.

Fractures of the middle third of the clavicle have been associated with damage to the neurovascular bundle and the pleural dome.( However, more often than not, this injury is merely cosmetic.)

(Complications occurring after fractures of the medial third of the clavicle resemble those associated with posterior SC dislocations. )

Injuries to intrathoracic and superior mediastinal structures may be complications in as many as 25% of posterior dislocations. Neurovascular injury, pneumothorax, and hemothorax have been reported.

Lateral clavicular fractures and injuries to the AC joint can result in cosmetic deformity or eventually lead to the persistence of nuisance symptoms (eg, clicking, pain). Failure of the bone to unite after these injuries can also lead to progressive shoulder deformity, impaired function, and neurovascular compromise. Fractures of the coracoid process can be complications of AC joint injuries.

 e. How is an uncomplicated fracture of the clavicle treated?

 

  ACTIVITY 3: ANTERIOR THORACOAPPENDICULAR MUSCLES a. List and describe the anterior thoracoappendicular muscles. 

b. Describe clavipectoral fascia.  ACTIVIVTY 4: WINGED SCAPULA a. Describe “winged scapula”.

Medial border or inferior angle of scapula protrude slightly from body. A winged scapula condition may be accompanied by a protracted shoulder girdle. Risk of shoulder injury is compounded with a supraspinatus weakness or an external shoulder rotation inflexibility. Because of the forward tilt of the scapula, complete flexion or external rotation of the shoulder may be seemingly restricted. A winged scapula condition indicates a serratus anterior weakness. The rhomboids may be weak and the pectoralis minor may be short. A winged scapula is considered normal posture in young children, but not older children and adults b. What cause “winged scapula”? A winging scapula is associated with damage or a contusion to the long thoracic nerve of the shoulder and / or weakness in the serratus anterior muscle. If the long thoracic nerve is damaged or bruised it can cause paralysis of the serratus anterior muscle and winging of the scapular or shoulder blade.Damage to the nerve can be caused by a contusion or blunt trauma of the shoulder, heavy weight lifting, repetitive throwing, traction of the neck or can also sometimes follow a viral illness. Some cases of long thoracic nerve injury are of unknown origin.

 c. What will be the disability of a person with a “winged scapula”?

Pain and limited shoulder elevation. Difficulty in lifting weights. Patients can complain of pressure on the scapular from a chair when sitting.

  ACTIVITY 5: POSTERIOR THORACOAPPENDICULAR AND SCAPULOHUMERAL MUSCLES a. List and describe the posterior thoracoappendicular muscles. b. List and describe the scapulohumeral muscles.  ACTIVIVTY 6: PARALYSIS OF LATISSIMUS DORSI AND TRAPEZIUS MUSCLES a. How do latisimus dorsi and trapezius muscles become paralyzed? b. Describe the disabilities in paralysis of latissimus dorsi and trapezius muscles.  ACTIVIVTY 7: ROTATOR CUFF MUSCLES a. List the rotator cuff muscles. 

MuscleOrigin on scapula

Attachment on humerus

Function Innervation

Supraspinatus muscle

supraspinous fossa

greater tubercle abducts the arm Suprascapular nerve (C5)

Infraspinatus muscle

infraspinous fossa

greater tubercleexternally rotates the arm

Suprascapular nerve (C5-C6)

Teres minor muscle

lateral border greater tubercleexternally rotates the arm

Axillary nerve (C5)

Subscapularis muscle

subscapular fossa

lesser tubercleinternally rotates the humerus

Upper and Lower subscapular nerve (C5-C6)

 ACTIVITY 8: ROTATOR CUFF INJURIES a. Describe rotator cuff injuries and subacromial bursitis.                                                                                                Rotator cuff tearThe tendons at the ends of the rotator cuff muscles can become torn, leading to pain and restricted movement of the arm. A torn rotator cuff can occur following a trauma to the shoulder or it can occur through the "wear and tear" of tendons, most commonly that of the supraspinatus under the acromion. It is an injury frequently sustained by athletes whose duties involve making repetitive throws, such as baseball pitchers, American football quarterbacks, volleyball players (due to their swinging motions), water polo players, shotput throwers (due to using poor technique), swimmers, boxers, kayakers, fast bowlers in cricket, tennis players (due to their service motion),and Wii players. This type of injury also commonly affects conductors (music), choral conductor, orchestral conductor,and drummers due to the swinging motions and other movements used to lead their ensemble. It is commonly associated with motions that require repeated overhead motions or forceful pulling motions.

Rotator cuff impingementA systematic review of relevant research found that the accuracy of the physical examination is low.The Hawkins-Kennedy test  has a sensitivity of approximately 80% to 90% for detecting impingement. The infraspinatus and supraspinatus tests have a specificity of 80%.  Subacromial bursitis is a condition caused by inflammation of the bursa that separates the superior surface of the supraspinatus tendon (one of the four tendons of the rotator cuff) from the overlying coraco-acromial ligament, acromion, coracoid ( the acromial arch) and from the deep surface of the deltoid muscle . The subacromial bursa helps the motion of the supraspinatus tendon of the rotator cuff in activities such as overhead work.Primary inflammation of the subacromial bursa is relatively rare and may arise from autoimmune inflammatory conditions (rheumatoid arthritis), crystal deposition (Gout or Pseudo gout), calcific loose bodies (rheumatoid arthritis) and infection . More commonly, subacromial bursitis arises as a result of complex factors, thought to cause shoulder impingement symptoms. These factors are broadly classified as intrinsic (intratendinous) or extrinsic (extratendinous). They are further divided into primary or secondary causes of impingement. Secondary causes are thought to be part of another process such as shoulder instability or nerve injury.