the pectoral girdle Flashcards
sternoclavicular joint
This is between the sternum and the clavicle. The sternoclavicular ligament helps to stabilize this joint.
acromioclavicular joint
it is the junction between the acromion (part of the scapula that forms the highest point of the shoulder) and the clavicle.
-this joint is stabilized by the acromioclavicular, coracoacromial, and coracoclavicular ligaments
It is a plane synovial joint.
sternoclavicular ligament
It is a ligament that extends from the posterior aspect of the sternal end of the clavicle to the posterosuperior manubrium
acromioclavicular ligament
extending between the upper part of the acromial end of the clavicle and the adjoining part of the upper surface of the acromion.
stabilizes the acromioclavicular joint
coracoacromial ligament
- is a strong triangular band, extending between the coracoid process and the acromion.
- It is attached to the acromion just in front of the articular surface for the clavicle; and to the lateral border of the coracoid process
- runs superfically over the supraspinatus
coracoclavicular ligament
- coracoclavicular ligament serves to connect the clavicle with the coracoid process of the scapula.
- forms a efficient means of retaining the clavicle in contact with the acromion.
- runs superficially over the supraspinatus
glenohumeral joint
- a ball and socket joint between the scapula and the humerus.
- It is the major joint connecting the upper limb to the trunk.
- it is one of the most mobile joints in the human body, at the cost of joint stability.
articular capsule of glenohumeral joint
- sac enclosing a joint, formed by an outer fibrous membrane and an inner synovial membrane. joint capsule.
- so this is the joint capsule of the shoulder joint, it completely surrounds the joint
glenoid labrum
is a fibrocartilaginous structure rim attached around the margin of the glenoid cavity in the shoulder blade
- it is a ring of tissue surrounding the glenoid fossa
- Expands the depth of the glenoid fossa by approximately 50 percent to allow for increased motion
scapulothoracic joint
- not a true articulation. It is considered a functional joint between the scapula and the thoracic wall.
- is formed by the convex surface of the posterior thoracic cage and the concave surface of the anterior scapula.
trapezius
- function is to stabilize and move the scapula
- a large superficial back muscle that resembles a trapezoid. It extends from the occipital bone to the lower thoracic vertebrae and laterally to the spine of the scapula
Action:
Superior fibers: Elevate and superiorly rotate scapula
Middle fibers: Retract scapula
Inferior fibers: Depress scapula
innervation: Accessory nerve (CN XI)
rhomboid major
- is larger and inferior to the rhomboid minor
Action: Elevates, retracts, and inferiorly rotates scapula
Insertion: Medial border of scapula
Innervation: Dorsal scapular nerve
rhomboid minor
is thinner and located between the rhomboid major and the levator scapulae
Action: Elevates, retracts and inferiorly rotates scapula
Insertion: Superior medial border of scapula
Innervation: Dorsal scapular nerve
levator scapulae
is the most superior of rhomboid major, rhomboid minor, and levator scapulae.
Action: Elevates and inferiorly rotates scapula
Insertion: Superior medial border of scapula
Innervation: Dorsal scapular nerve
pectoralis minor
- only acts on the scapulothoracic joint
- smaller and deep to pectoralis major
Action: Protracts and depresses scapula
insertion: Coracoid process of scapula
Innervation: Medial pectoral nerve
serratus anterior
- on the anterior aspect of the scapula running from the thoracic wall to the medial border of the scapula
Action: Protracts and superiorly rotates scapula; stabilizes scapula
insertion: Anterior medial border of scapula
Innervation: Long thoracic nerve
subclavius
- this is just inferior to the scapula
Action: Stabilizes and depresses clavicle
Innervation: Nerve to subclavius
Latissimus dorsi
- just inferior to teres major
- fans out over the back region, with fibers merging near its insertion at the intertubercular groove of the humerus
- runs to insert on the anterior aspect of the humerus. (This is important to appreciate to understand how it contribute to internal rotation of the glenohumeral joint)
Action: Extends, adducts & medially rotates GH joint (“swimmer’s muscle”)
insertion: Intertubercular groove of humerus
Innervation: Thoracodorsal nerve
pectoralis major
- larger and superficial to pectoralis minor
- acts on the glenohumeral and scapulothoracic joints
Action: Arm flexion; adducts and medially rotates GH joint
insertion: Intertubercular groove of humerus
Innervation: Lateral pectoral and medial pectoral nerves
deltoid
- on the lateral aspect of the shoulder.
- This muscle wraps around the shoulder superiorly and comes together at a common insertion point on the humerus
- the orientation of the fibers changes as it wraps around the shoulder from anterior to posterior. This is why the functions of the posterior, middle, and anterior fibers of the deltoid differ from each other.
Action:
- Anterior fibers: Flex and medially rotate GH joint
- Middle fibers: GH abduction
- Posterior fibers: Extend and laterally rotate GH Joint
insertion: Deltoid tuberosity of humerus
Innervation: Axillary nerve
coracobrachialis
- is normally pierced by the musculocutaneous nerve in the middle portion of the muscle belly
Action: Adducts and flexes GH joint
Origin: Coracoid process
insertion: Middle medial shaft of humerus
Innervation: Musculocutaneous nerve
teres major
- just inferior to teres minor
- runs to insert on the anterior aspect of the humerus. (This is important to appreciate to understand how it contribute to internal rotation of the glenohumeral joint)
Action: Extends, adducts, and medially rotates GH joint
Origin:Inferior lateral border and inferior angle of scapula
insertion: Lesser tubercle and intertubercular groove of humerus
Innervation: Lower subscapular nerve
triceps brachii as it acts on the Glenohumeral Joint
The long head is superficial and in the middle, and this is the only portion of the triceps brachii that crosses the glenohumeral joint
Action: Extends and adducts GH joint
Origin:Infraglenoid tubercle
insertion: Olecranon process
Innervation: Radial nerve
biceps brachii as it acts on the Glenohumeral Joint
This muscle has two heads.
- this is just medial to the Brachialis
Action: Flexes GH joint
Origin:
long head: Supraglenoid tubercle
short head: coracoid process of the scapula
insertion: Radial tuberosity and bicipital aponeurosis
Innervation: Musculocutaneous nerve
