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Lecture

PEDS100 Lecture Notes - Shoulder Girdle, Sternoclavicular Joint, Spine Of Scapula


Department
Physical Education and Sport
Course Code
PEDS100
Professor
Gail Amort- Larson

Page:
of 3
Muscles of the Pectoral Girdle and Upper Limbs
Four groups: muscles that position pectoral girdle, muscles that move the arm,
muscles that move the forearm and hand, muscles that move the hand and
fingers
Any muscle that attaches to ribs can be an accessory muscle of respiration
Pectoral girdle
Made of clavicle and scapula
Clavicle: Holds shoulder in place, increases range of motion, only bone with
bony attachment in axial skeleton
-Smooth superior surface, rough inferior surface
-Medial end/Sternal end(rounder,smaller) connects clavicle to sternum at
sternoclavicular joint
-Lateral end/acromial(broader/flatter) end connects clavicle at acromioclavicular
joint with scapula
-Conoid tubercle is on the inferior surface at acromial end
-Costal tuberosity is at sternal end
Sternum:
-Manubrium (where clavicle connects, called sternoclavicular joint)
-Xiphoid process(usually cartilage)
Scapula: -Usually sits over ribs 2-7
-triangular in shape
-Superior border, lateral border(axillary border), medial border(vertebral border)
-There are 3 projections:
1. Scapular spine comes across posterior side,divides dorsal body of scapula in
two parts
2. Acromion: flat enlargement on posterior lateral end
3. Coracoid process: is small anterior projection
Scapula Bone Markings
-Suprascapular notch: indentation medial to the base of the coracoid process
-Supraspinous fossa: Area superior to the scapular spine
-Infraspinous fossa: Area inferior to the scapular spine
-Glenoid cavity: proximal end of humerus sits here
-Subscapular fossa:forms most of the anterior side of scapula
-Supraglenoid tubercle: Marks origin of biceps brachii long head
-Infraglenoid tubercle: Marks origin of triceps brachii long head
-Glenohumeral joint: shoulder joint
Sternoclavicular Joint
synovial joint between medial end of clavicle and manubrium of sternum
serves to anchor scapula to axial skeleton, considered part of shoulder joint
divided into two synovial cavities by an articular disc
articular capsule is tense and dense, provides stability but limiting movement.
reinforced by 2 accessory ligaments, anterior sternoclavicular ligament and
posterior sternoclavicular ligament
Also two extracapsular ligaments:
Interclavicular ligament: interconnects clavicles and reinforces superior
portions of adjacent articular capsules, firmly attached to superior border of
manubrium, prevents dislocation when shoulder is depressed
Costoclavicular ligament: broad, extends from costal tuberosity of clavicle to
superior and medial borders of first rib and first costal cartilage. prevents
dislocation when shoulder is elevated
Sternoclavicular joint primarily plane joint, but capsular fibers permit slight
rotation and circumduction of clavicle
Muscles that Position the Pectoral Girdle
Trapezius Muscles: Cover back and part of neck, extending to base of skull.
Forms a broad diamond, opposite fibers do opposing actions in same muscle
-Origin: Occipital bone, ligamentum nuchae(thick tendon runs down back of
neck , and spinous processes(bumps down spine) T1-T12
-Insertion: Clavicle, acromion, and scapular spine
-Action: Elevates(upper fibers), retracts(middle fibers), depress(lower fibers), or
rotate scapula upward(upper and lower fibers) and/or clavicle; can extend neck
Rhomboids (Major and Minor): Deep to the trapezius muscles
-Origin: Spinous processes C7-T5
-Insertion: Along vertebral border of each scapula, between spine and inferior
angles
-Action: Retracts scapula and medially rotates scapula downward which causes
glenoid cavity to move inferiorly and inferior angle of scapula to move medially
and superiorly.
Levator scapulae: Deep to trapezius muscles, above rhomboids
-Origin: Transverse processes of first four cervical vertebrae C1-C4
-Insertion: Vertebral border of scapula near superior angle, above root of the
scapula spine
-Action: Elevates scapula (medially rotates)
Pectoralis minor muscle:not palpable
-Origin: Anterior surface and superior margin of ribs 3-5
-Insertion: Coracoid process of scapula
-Action: Depresses and helps protracts shoulder, medially rotates scapula so
glenoid cavity moves inferiorly, elevates ribs if scapula is stationary
Serratus anterior muscle:Fan shaped
-Origin:anterior and superior surfaces of ribs 1-8
-Insertion:anterior margin of vertebral border of scapula from superior to inferior
angle
-Action:Major protractor of scapula and laterally rotates scapula, holds scapula
against trunk(if it doesn’t, you get winging scapula, nerve lies above muscle and
is exposed when shoulders retract)
Subclavius muscle: (dont need to know) under clavicle
-Origin: Along ventral surface of first rib
-Insertion: Inferior border of clavicle
-Action: Depresses and protracts scapular end of clavicle, shoulder joint and
scapula move too due to ligaments attaching them to this end of clavicle
Exam question may be:What are the medial rotators? pectoralis minor,rhomboids