OCT 509: Anatomy Exam 2

components of the shoulder girdle

scapula, clavicle, sternum

also includes SC, AC, and scapulothoracic joints

purpose of the shoulder girdle

interacts with shoulder and arm to provide mobility for upper extremity

shoulder joint

articulation of the head of humerus and the glenoid fossa of the scapula

Ball and socket, for movement

plane of the scapula

about 30 degrees forward of the frontal plane, somewhat midway between flexion and abduction

Scaption

describes movements of the shoulder joint in the scapular plane rather than the sagittal or frontal plane

Scapular elevation and depression

Elevation- scapula moves in a superior direction

Depression- scapula moves inferiorly

Scapular protraction

aka scapular abduction

scapula moves away from the vertebral column

Scapular retraction

aka scapular adduction

scapula moves toward vertebral column

Scapular upward rotation

rotation of the inferior angle of scapula laterally and superiorly away from vertebral column

Scapular downward rotation

rotation of the inferior angle of scapula medially and inferiorly toward vertebral column

Plane and axis for scapular upward and downward rotation

Both occur in the frontal plane about a horizontal axis

Scapular tilt

rotation of inferior angle posteriorly

occurs in sagittal plane about a horizontal axis

Scapular winging

movement of medial border posteriorly away from thoracic cage

common in children due to serratus anterior not being strengthened

Resting position of the scapula on thoracic cage

Goes from 2nd rib to 7th rib

Scapulohumeral rhythm

relationship of movement between the shoulder girdle and shoulder joint

first 30 degrees of shoulder abduction- only at glenohumeral joint

What is the 2:1 ratio for scapulohumeral rhythm?

After the first 30 degrees of shoulder abduction, this occurs where for every 2 degrees of shoulder abduction there is also 1 degree of scapular upward rotation

Advantages of scapulohumeral rhythm

1. Maintains functional length-tension relationship

2. Upward scapular rotation avoids contact of greater tubercle and acromion process

3. Requires smaller arthrokinematic movements in glenohumeral joint to move head of humerus in glenoid fossa

Landmarks of the clavicle

Sternal end

Body

Acromial end

Landmarks of sternum

Manubrium- top

Body

Xiphoid process- bottom

3 joints of the shoulder girdle

1. Sternoclavicular (SC) joint

2. Acromioclavicular (AC) joint

3. Scapulothoracic joint

Sternoclavicular (SC) joint

synovial joint, little movement here

articulation of the manubrium of sternum with the medial end of clavicle

only direct attachment of upper extremity appendicular skeleton to axial

Ligaments of the sternoclavicular (SC) joint

1. Sternoclavicular ligament

2. Costoclavicular ligament

3. Interclavicular ligament

Sternoclavicular ligament

anterior- anterior aspect of manubrium to anterior clavicle, limits anterior movement of medial end during retraction

posterior- posterior aspect of manubrium to posterior clavicle, limits posterior movement of medial end during protraction

Costoclavicular ligament

between clavicle and first rib

limits clavicular elevation

Interclavicular ligament

connects superior and medial ends of clavicles

limits clavicular depression

Acromioclavicular (AC) joint

synovial and plane joint, minimal motion

articulation of the acromion process with the lateral end of clavicle

Ligaments of the Acromioclavicular (AC) joint

1. Acromioclavicular ligament

2. Coracoclavicular ligament

3. Coracoacromial ligament

Acromioclavicular ligament

Superior- reinforces superior portion of joint capsule

Inferior- reinforces inferior portion of joint capsule

Coracoclavicular ligament

Has 2 portions: lateral trapezoid and medial conoid

limits posterior movement of clavicle and rotation of scapula

Coracoacromial ligament

forms roof over head of humerus

protects humerus head, limits superior movement of humeral head with upward force

5 main muscles for moving shoulder girdle

1. Trapezius

2. Levator scapula

3. Rhomboid

4. Serratus anterior

5. Pectoralis minor

Upper trapezius

O: External occipital protuberance, superior nuchal line, spinous processes of cervical vertebrae via nuchal ligament

I: Lateral third of clavicle, acromion process

A: Scapular elevation, upward rotation, retraction

N: Spinal accessory (CN 11), C3 and C4 for sensory

Middle trapezius

O: Spinous process of C7-T3 via supraspinal ligament

I: Medial aspect of acromion and spine of scapula

A: Scapular retraction, minimal upward rotation

N: Spinal accessory (CN 11), C3 and C4 for sensory

Lower trapezius

O: Spinous processes of T4-T12 via supraspinal ligament

I: Base of spine of scapula

A: Scapular depression, upward rotation, retraction

N: Spinal accessory (CN 11), C3 and C4 for sensory

Levator scapula

O: Transverse processes C1-C4

I: Vertebral border of scapula between superior angle and spine of scapula

A: Scapular elevation, downward rotation

N: Third and fourth cervical nerves and dorsal scapular nerve (C5)

Rhomboids

O: Spinous processes of C7 through T5 via nuchal and supraspinal ligaments

I: Vertebral border of scapula between inferior angle and base of spine of scapula

A: Scapular retraction, elevation, and downward rotation

N: Dorsal scapular nerve (C5)

Serratus anterior

O: Lateral surface of first (1st) through eighth (8th) ribs

I: Vertebral border of scapula, anterior surface

A: Scapular protraction and upward rotation

N: Long thoracic nerve (C5-C7)

Pectoralis minor

O: Anterior surface, 3rd-5th ribs

I: Coracoid process of scapula

A: Scapular depression, protraction, downward rotation, tilt

N: Medial pectoral nerve (C8, T1)

Muscles of the posterior shoulder girdle

Serratus anterior, trapezius, levator scapula, rhomboids

Muscles of the anterior shoulder girdle

Pectoralis minor and serratus anterior

Muscles in force couple for scapular upward rotation

1. Upper trapezius

2. Lower trapezius

3. Serratus anterior

Muscles in force couple for scapular downward rotation

1. Levator scapulae

2. Rhomboids

3. Pectoralis minor

Walking with crutches

creates a closed kinetic chain, causes the pec minor and lower trapezius to elevate the body on the shoulder girdle

Changes the configuration

Clavicular fractures

occur in body of clavicle, due to upward force

During flexion, what occurs at the shoulder girdle?

upward rotation, protraction

During extension, what occurs at the shoulder girdle?

downward rotation, retraction, slight scapular tilt

During abduction, what occurs at the shoulder girdle?

Upward rotation

During adduction, what occurs at the shoulder girdle?

Downward rotation

During medial rotation, what occurs at the shoulder girdle?

Protraction

During lateral rotation, what occurs at the shoulder girdle?

Retraction

During horizontal abduction, what occurs at the shoulder girdle?

Retraction

During horizontal adduction, what occurs at the shoulder girdle?

Protraction

Shoulder flexion ROM degrees

0-180

Shoulder extension ROM degrees

0-60

Shoulder abduction ROM degrees

0-180

Shoulder adduction ROM degrees

0-120

Shoulder medial rotation ROM degrees

0-70

Shoulder lateral rotation ROM degrees

0-90

Supraglenoid tubercle

attachment site for long head of biceps brachii

Infraglenoid tubercle

attachment site for long head of triceps brachii

Labrum

Fibrocartilaginous ring attached to the rim of glenoid fossa, deepens articular cavity and increases the stability of the shoulder

Subacromial bursa

bursa located between the acromion and the coracoacromial ligament and the joint capsule

Subdeltoid bursa

large bursa located between the deltoid muscle and joint capsule

3 portions to the glenohumeral ligament

1. Superior glenohumeral ligament

2. Middle glenohumeral ligament

3. Inferior glenohumeral ligament

All 3 reinforce anterior portion of capsule

Coracohumeral ligament

attaches to dorsal lateral side of coracoid process and humerus

goal: reinforce superior portion of joint capsule

Transverse humeral ligament

attaches to tubercles and lips of bicipital groove

goal: maintains tendon of long head of biceps in the bicipital groove

what type of shoulder dislocation is most common?

anterior

shoulder capsular pattern

ER > ABD> IR

To improve ER, IR must be focused on first and then ABD

4 muscles of the rotator cuff

1. Subscapularis

2. Infraspinatus

3. Supraspinatus

4. Teres minor

SITS muscles

Main goal of the rotator cuff

To keep the humeral head in the glenoid fossa

Thoracolumbar fascia

Fibrous sheet, attachment for lats, superficial to sacropinalis muscles

Axillary nerve innervates what muscles

Teres minor and deltoids

Musculocutaneous nerve innervates what muscles

coracobrachialis, biceps brachii, and brachialis

Anterior deltoid

O: Lateral third of the clavicle

I: Deltoid tuberosity

A: Shoulder abduction, flexion, medial rotation, and horizontal adduction

N: Axillary nerve (C5,C6)

Middle deltoid

O: Acromion process

I: Deltoid tubeosity

A: Shoulder abduction

N: Axillary nerve (C5,C6)

Posterior deltoid

O: Spine of scapula

I: Deltoid tuberosity

A: Shoulder abduction, extension, lateral rotation, horizontal abduction

N: Axillary nerve (C5,C6)

Biceps brachii

O: Long head: supraglenoid tubercle of scapula, Short head: coracoid process of scapula

I: Radial tuberosity of radius

A: Shoulder flexion, elbow flexion, forearm supination

N: Musculocutaneous nerve (C5, C6)

Coracobrachialis

O: Coracoid process of scapula

I: Medial surface of the humerus near the midpoint

A: Shoulder flexion, adduction, stabilizes shoulder

N: Musculocutaneous nerve (C5-C7)

Clavicular portion of pectoralis major

O: Medial third of clavicle

I: Lateral lip of bicipital groove of humerus (inferior to the sternal portion)

A: Shoulder flexion first 60 degrees, medial rotation, adduction, horizontal adduction

N: Lateral and medial pectoral nerves (C5-C8, T1)

Sternal portion of pectoralis major

O: Sternum, costal cartilage of first six ribs

I: Lateral lip of bicipital groove of humerus (superior to the clavicular portion)

A: Medial rotation, adduction, horizontal adduction

N: Lateral and medial pectoral nerves (C5-C8, T1)

Latissimus Dorsi

O: Via the thoracolumbar fascia, the spinous processes of T7 through L5, posterior surface of iliac crest and sacrum, lower 3 ribs

I: Floor of bicipital groove

A: Shoulder extension, adduction, medial rotation

N: Thoracodorsal nerve (C6-C8)

Teres major

O: Inferior axillary border of scapula near inferior angle

I: Medial lip of bicipital groove

A: Shoulder extension, adduction, and medial rotation

N: Lower subscapular nerve (C5-C7)

Triceps brachii

O: Long head: infraglenoid tubercle of scapula

Lateral head: inferior to greater tubercle on posterior humerus

Medial head: posterior surface of humerus

I: Olecranon process of ulna

A: Shoulder extension, elbow extension

N: Radial nerve (C6-C8)

Supraspinatus

O: Supraspinous fossa of the scapula

I: Greater tubercle of the humerus
A: Shoulder abduction, stabilizes shoulder

N: Suprascapular nerve (C5, C6)

Infraspinatus

O: Infraspinous fossa of scapula

I: Greater tubercle of humerus

A: Shoulder lateral rotation, horizontal abduction, stabilizes shoulder

N: Suprascapular nerve (C5, C6)