L4: Shoulder Anatomy & Physiology Flashcards
How is the shoulder joint anatomically and functionally classified?
Anatomically, it is a synovial ball and socket joint. Functionally, it is a diarthrosis and multiaxial joint.
What bones are involved in the articulation of the shoulder joint?
The glenoid cavity of the scapula and the head of the humerus.
What is the primary function of the shoulder joint?
To provide the greatest range of motion in the body, allowing upper limb movement across different planes for everyday tasks.
what physiological movements take place at the shoulder
flexion
extension
abduction
adduction
medial rotation
lateral rotation
what is the range of flexion at the shoulder
0-180°
what is the range of extension at the shoulder
0-45°/60°
what is the range of abduction at the shoulder
0-150°
what is the range of adduction at the shoulder
30-50°
what is the range of medial rotation at the shoulder
0-70/90°
what is the range of lateral rotation at the shoulder
0-90°
What four articulations make up the shoulder girdle
sternoclavicular (SCJ),
acromioclavicular (ACJ),
glenohumeral (GHJ),
and scapulothoracic (STJ)
which bones articulate in the shoulder joint
clavicle
scapula
humerus
define diarthrosis
a freely moveable joint
label key bony points of the shoulder
describe the sternoclavicular joint
- saddle shaped
- articulated between medial espect of the clavicle and menubrium of the sternum
- has small amount of movement in scapular elevation/depression when humerus is flexed above 90°
desrcibe the acromioclavicular joint
- the articulation between the lateral aspect of the clavicle and the acromion of the scapula
- allows ROM for scapula to glide during shoulder movements
- combination of joint capsule, ligaments and muscle attachments provide joint stability
describe acromioclavicular joint stability
- weak fibrous capsule lined with synovial fluid
- stability is maintained by coracoclavicular (made of trapezoid and conoid ligaments) and the acromioclavicular ligaments
- the attachments of deltoid, trapezius and pectoralis major also contribute to joint stability
what are the major ligaments of the shoulder joint
biceps tendon
coracohumeral ligament
SGHL direct
MGHL
label the major ligaments of the shoulder joint
describe the glenohumeral joint
- synovial ball and socket joint
- it is the most mobile and consequently the least stable joint in the body
- the articulation between head of humerus and glenoid fossa
describe glenohumeral joint stability
- concavity compression (thick suction cup)
- the labrum increases depth of fossa and increases contact with the humeral head
- ligaments within joint capsule to maintain contact between head and fossa (static stability)
- superior, middle and inferior glenohumeral ligaments as well as the coracohumeral ligament and the transverse humeral ligament
- the rotator cuff tendons and long head of biceps tendon attach around the humeral head to provide stability (dynamic stability)
describe the scpulothoracic joint
- not a ‘true’ joint-dependent on congruity of AC and SC joints
- scapula attaches to thoracic wall via fascia and is able to ‘glide’ in a variety of movements
- multiple muscular attachments
- movement of the scapula is integral to normal shoulder kinesiology (scapulohumeral rhythm)
- scapula provides stable base for controlled movements between humeral head and glenoid fossa
label borders of scapula
label bony points of the scapula
what muscles allow flexion of the shoulder
major muscles: anterior deltoid,
pectoralis major
assisting: biceps brachii, coracobrachialis,
what muscles allow extension of the shoulder
major muscles: posterior deltoid, latissimus dorsi, teres major
assisting: long head of triceps
what musces allow abduction of the shoulder
major muscles: middle fibres of deltoid (15-90°)
assisting: supraspinatus (0-15°), trapezius/ serratus anterior produce scapula rotation (90°+)
what muscles allow adduction of the shoulder
major muscles: pectoralis major, latissimus dorsi, teres major
what muscles allow medial rotation of the shoulder
major muscles: subscapularis, teres major
assisting: pectoralis major, latissimus dorsi, anterior deltoid
what muscles allow lateral rotation of the shoulder
major muscles: infraspinatus, teres minor
assisting: posterior fibres of deltoid
what muscles allow scapular elevation
levator scapulae, upper fibres of trapezius
what muscles allow scapula depression
gravity! and the actions of the trapezius and latissimus dorsi
what muscle allows scapula protraction
serratus anterior
what muscles allow scapula retraction
rhomboid major, minor and middle fibres of trapezius
what muscles allow upward rotation of the scapula
trapezius and serratus anterior
what muscles allow downward rotation of the scapula
gravity, and rhomboids
what is the origin and insertion of the anterior deltoid
origin: anterior border of lateral edge of clavicle
insertion: deltoid tuberosity of humerus
what is the origin and insertion of medial deltoid
origin: lateral margin of acromion process
insertion: deltoid tuberosity of the humerus
what is the origin and insertion of posterior deltoid
origin: inferior edge of spine of scapula
insertion: deltoid tuberosity of humerus
what is the origin and insertion of the coracobrachialis
origin: tip of coracoid process
insertion: medial aspect of the humerus
what is the origin and insertion of pectoralis major
origin: clavicle and anterior surface of sternum
insertion: intertubercular sulcus of the humerus
what is the origin and insertion of biceps brachii
origin: Long head = supraglenoid tubercle of scapula. short head: tip of coracoid process
insertion: radial tuberosity
what is the origin and insertion of latissimus dorsi
origin: spinous processes of thoracic T7–T12, thoracolumbar fascia, iliac crest and inferior 3 or 4 ribs
insertion: intertubercular sulcus of humerus.
what is the origin and insertion of teres major
origin: posterior surfacce of inferior angle of scapula
insertion: medial lip of intertubercular sulcus on anterior surface of humerus
what is the origin and insertion of teres minor
origin: lateral bored of scapula
insertion: greater tubercle of humerus
what is the origin and insertion of long head of triceps
origin: infraglenoid tubercle of scapula
insertion: posterior part of alecranon process of unla
what is the origin and insertion of supraspinatus
origin: supraspinatus fossa of scapula
insertion: greater tubercle of humerus
what is the origin and insertion of the trapezius
origin: from nuchal line of occipital bone to spinous processes of T1-12 and C7
insertion: cest of spine of scapula and acromion.
what is the origin and insertion of serratus anterior
origin: lateral surfaces of upper 8 ribs
insertion: medial border of scapula
what is the origin and insertion of levator scapulae
origin: transerse process of C1-4)
insertion: medial border of scapula from superior angle to bottom of spine of scapula
what is the origin and insertion of infraspinatus
origin: infraspinatus fossa of scapula
insertion: greater tubercle of humerus
what is the origin and insertion of rhomboid major
origin: spinous process of T2-5
insertion: medial border of scapula to bottom of spine of scapula
what is the origin and insertion of rhomboid minor
origin: spinous process of C7 and T1
insertion: medial border of sapula at the bottom of the spine of scapula
what is a bursa
a fluid filled sac found within the joint space
what is the purpose of a bursa
It contains synovial fluid whihc prevents friction during movement
what bursa is found in the shoulder joint
subacromial bursa
where is the bursa found in the shoulder joint
located between the acromion, corocoacromial ligament and the rotator cuff
what nerves innervates the anterior part of the shoulder joint
Subscapular (C5/6) axillary, and lateral pectoral (C5/6 also)
which nerves innervate the posterior part of the shoulder joint
suprascapular and small branches of axillary (C5/6)
which nerves innervate scapula depression and elevation
Dorsal scapula nerve (C3-5)
label the bony landmarks of the shoulder girdle
