Shoulder Region Flashcards
What is the structure of the shoulder girdle?
Bones: Scapula, Clavicle, Sternum.
Joints: Acromioclavicular (AC) joint, Sternoclavicular (SC) joint, Scapulothoracic junction.
What is the primary function of the shoulder girdle?
Increases the range of movement of the upper limb by changing the position of the glenoid fossa.
The clavicle absorbs tension and compression, transmitting forces from the upper limb to the trunk.
Describe the bony landmarks of the clavicle.
Medial end: Convex anteriorly, articulates with the sternum at the SC joint.
Lateral end: Concave anteriorly, articulates with the acromion at the AC joint.
Notable features: Deltoid tubercle, trapezoid line, conoid tubercle, subclavian groove, costal tuberosity.
What are the main muscle attachments on the clavicle?
Muscles: Sternocleidomastoid, Pectoralis Major, Trapezius (upper), Deltoid (anterior), Subclavius.
Describe the bony landmarks of the scapula.
Borders: Medial, lateral, superior.
Angles: Inferior, superior.
Surfaces: Anterior (costal), posterior (dorsal).
Notable features: Spine of scapula, acromion, coracoid process, supraspinous fossa, infraspinous fossa, subscapular fossa, glenoid cavity.
What is the acromioclavicular (AC) joint?
Type: Synovial plane joint.
Movements: Small gliding.
Ligaments: Acromioclavicular ligament, Coracoclavicular ligament.
Describe the sternoclavicular (SC) joint.
Type: Synovial saddle joint.
Articular surfaces: Clavicle (convex), manubrium (concave), costal cartilage.
Ligaments: Anterior/posterior SC ligaments, interclavicular ligament, costoclavicular ligament.
Movements: Small gliding.
What is the scapulothoracic junction?
Not a true joint.
Articulation of scapula with the thorax.
Movements depend on the AC and SC joints.
What are the movements of the shoulder girdle?
Elevation: Upper trapezius, Levator scapulae.
Depression: Serratus anterior, Pectoralis minor.
Protraction: Serratus anterior, Pectoralis minor.
Retraction: Rhomboid major/minor, Middle trapezius.
Upward rotation: Upper/lower trapezius, Serratus anterior.
Downward rotation: Rhomboid major/minor, Levator scapulae, Pectoralis minor.
What are the muscles acting on the shoulder girdle?
Anterior muscles: Subclavius, Pectoralis Minor, Serratus Anterior.
Posterior muscles: Trapezius, Levator Scapulae, Rhomboid Major/Minor.
Describe the trapezius muscle.
Proximal attachment: Superior nuchal line, external occipital protuberance, ligamentum nuchae, C7-T12 spinous processes.
Distal attachment: Lateral 1/3 clavicle, acromion, scapular spine.
Nerve supply: Accessory nerve, C3-4.
Actions: Elevation, depression, retraction, lateral scapular rotation.
Describe the serratus anterior muscle.
Proximal attachment: Lateral surfaces of upper 8-9 ribs.
Distal attachment: Anterior medial border of scapula.
Nerve supply: Long thoracic nerve (C5-7).
Actions: Protraction, lateral rotation of scapula.
What are the attachments and actions of levator scapulae?
Proximal attachment: Transverse processes of C1-C4.
Distal attachment: Superior medial border of scapula.
Nerve supply: Dorsal scapular nerve (C4-5).
Actions: Elevation, medial rotation of scapula, cervical extension (bilateral), cervical side flexion (unilateral).
What is the function of the subclavius muscle?
Proximal attachment: 1st rib costochondral junction.
Distal attachment: Inferior middle 1/3 clavicle.
Nerve supply: Subclavian nerve (C5-6).
Actions: Stabilizes the SC joint, depresses lateral clavicle.
Describe the clinical relevance of the AC joint and clavicle.
AC Joint: Susceptible to sprains and dislocations.
Clavicle: Common site of fractures due to falls on the shoulder.
What bones are part of the shoulder region?
Humerus
Scapula
What is the primary joint in the shoulder region?
Glenohumeral joint: A synovial ball-and-socket joint between the humeral head and the glenoid fossa of the scapula.
Describe the proximal humerus and its key landmarks.
Head
Anatomical neck
Greater tubercle
Lesser tubercle
Intertubercular sulcus
Surgical neck
Mid-shaft: Deltoid tuberosity, radial groove.
What are the bony landmarks of the distal humerus?
Medial and lateral supracondylar ridges
Medial and lateral epicondyles
Trochlea
Capitulum
Coronoid fossa
Radial fossa
Olecranon fossa
What are the key features of the glenohumeral joint?
Type: Synovial ball-and-socket joint.
Articular surfaces: Hyaline cartilage covers the humeral head and glenoid fossa.
Labrum: Fibrocartilaginous structure that deepens the glenoid cavity.
Capsule: Loose, with an inferior fold to allow abduction.
What ligaments support the glenohumeral joint?
Superior Glenohumeral Ligament
Middle Glenohumeral Ligament
Inferior Glenohumeral Ligament
Transverse Humeral Ligament
Coracohumeral Ligament
Coracoacromial Ligament
What are the bursae associated with the shoulder joint?
Subtendinous bursa of subscapularis
Subacromial bursa
Subcoracoid bursa
Why is the glenohumeral joint inherently unstable?
The glenoid cavity is shallow, while the humeral head is large.
The joint capsule is loose, allowing a wide range of movement.
Stability is provided by:
Glenoid labrum.
Ligaments.
Surrounding muscles, particularly the rotator cuff and long head of the biceps tendon.
What are the clinical issues associated with the glenohumeral joint?
Frozen Shoulder (Adhesive Capsulitis): Stiffness due to capsule tightening.
Shoulder Instability: May result from musculoskeletal or neurological issues.
What is the significance of the labrum in the shoulder joint?
Increases the depth of the glenoid cavity.
Enhances joint stability.
Reduces the risk of dislocations.
Describe the movements available at the glenohumeral joint.
Flexion/Extension
Abduction/Adduction
Internal/External Rotation
Circumduction
