Anatomy 16 Flashcards
What is the clavicle?
Slender S shaped bone, collar bone
What does the clavicle articulate with?
Sternum medially (sternoclavicular joint)
Acromion of scapula laterally (acromioclavicular joint)
What types of joints are the sternoclavicular and acromioclavicular joint?
Synovial joints
What is the function of the clavicle?
Holds the limb away from the trunk so it can move freely
What is the scapula?
Flat bone with some bony projections, shoulder bone
What does the posterior surface of the scapula bear?
A ridge of bone called the spine which is easily palpable
What does the lateral end of the spine expand to form?
The acromion (shoulder blade)
What bones make up the pectoral girdle?
Clavicle
Scapula and attached muscles
What does the lateral aspect of the scapula contain?
Glenoid fossa - shallow fossa
What does the glenoid fossa articulate with?
Proximal humerus to form the shoulder joint
What is the name for the shoulder joint?
Glenohumeral joint
Why is the glenoid fossa a poor fit for the humerus?
It’s too shallow
What does the glenoid fossa being a poor fit for the humerus lead to?
Increases range of movement possible at the shoulder
But compromises the stability of the joint
What projections are found superior and inferior to the glenoid fossa?
Supraglenoid tubercle
Infraglenoid tubercle
What is the humerus?
Long bone of the arm
What does the head of the humerus articulate with?
Glenoid fossa
What is the name of the groove that the head of the humerus bears?
Anatomical neck
What projections of bones does the proximal humerus bear laterally?
Greater tubercle
Lesser tubercle - is a smaller anterior projection
What is the surgical neck region?
Region where the humerus bone becomes more narrow and continuous with the shaft
Why is the surgical neck region clinically important?
It is commonly fractured
The axillary nerve runs close to this region and can be injured by fractures of the surgical neck or dislocation of the humeral head
What is the deltoid tuberosity?
Slight protuberance on the upper lateral aspect of the humeral shaft - site of attachment for the deltoid muscle
What is the radial/spiral groove?
Marks the path of the radial nerve over the posterior aspect of the upper part of the humeral shaft
How can the radial nerve be injured?
Mid-shaft humeral fractures
What are the movements of the scapula?
Protraction
Retraction
Elevation
Depression
Rotation
Why is rotation of the scapula very important?
When raising the arm above the head, for every 2 degrees of abduction of the shoulder, the scapula rotates 1 degree
What determines the direction in which the scapula moves when the muscles contract?
Attachment points of the muscles
Orientation of the muscle fibres
What is the key muscle involved in protraction of the scapula?
Serratus anterior
What are the two large superficial muscles of the posterior pectoral girdle?
Trapezius
Latissimus dorsi
What does the latissimus dorsi attach to?
Anterior aspect of the proximal humerus
What are the 3 smaller, deeper muscles that attach the medial border of the scapula to the vertebral column?
Levator scapulae
Rhomboid major
Rhomboid minor
What movement does the trapezius execute?
Elevates, retracts, depresses and rotates the scapula
What movement does the latissimus dorsi execute?
Extends, adducts and medially rotates the humerus
What movement does the levator scapulae execute?
Elevates the scapula
What movement does the rhomboid major execute?
Retracts the scapula
What movement does the rhomboid minor execute?
Retracts the scapula
What are the origins of the trapezius?
Skull
Cervical and thoracic vertebrae
What are the insertions of the trapezius?
Clavicle
Scapula (spine and acromion)
What are the origins of the latissimus dorsi?
Lower thoracic vertebrae
What are the insertions of the latissimus dorsi?
Humerus - upper anterior