Upper limb gross anatomy 1: Pectoral girdle and shoulder Flashcards
What is the function of the clavicle?
A strut that holds the arm clear of the trunk, thus increasing the range of movement of the upper limb.
How is the scapula connected to the axial skeleton?
Via the acromioclavicular joint and by muscles.
Where does the pectoral girdle articulate medially with the trunk?
At the clavicle
What is the most common type of fracture upon falling on an outstretched hand and why?
Clavicle - force of the fall is transmitted to the clavicle.
Describe the basic structure of the clavicle.
Concave in lateral one third, convex in medial two thirds.
Why is the clavicle convex in the medial two thirds?
To allow the passage of the neurovascular bundle supplying the upper limb.
Which ribs lie under the scapula?
2-7
What structure divides the supraspinous and infraspinous fossae of the scapula?
The spine of the scapula.
What are the origins of the trapezius?
Superior nuchal line, external occipital protuberance, medial margin of the ligamentum nuchae, spinous processes of C7-T12 and the related supraspinous ligaments.
What are the insertions of the trapezius?
Superior edge of the crest of the spine of the scapula, acromion, posterior border of lateral one-third of clavicle.
What movements are achieved by the upper fibres of the trapezius?
Elevates the scapula.
What movements are achieved by the middle fibres of the trapezius?
Retract the scapula.
What movements are achieved by the lower fibres of the trapezius?
Depress the scapula.
What movements are achieved by all of the fibres of the trapezius working together?
Rotation of the glenoid cavity superiorly.
What is the nerve supply to the trapezius?
Motor - spinal part of the accessory nerve (CNXI)
Sensory (proprioception) - anterior rami of C3-4
Where does latissimus dorsi attach to the humerus?
Floor of intertubular sulcus of humerus.
What are the actions of latissimus dorsi?
Extends, adducts and medially rotates humerus; raise body towards arms during climbing.
What are the axial attachments of levator scapula?
Posterior tubercles of transverse processes of C1-4.
Medial border of scapula superior to root of scapular spine.
What is the nerve supply to levator scapula?
Dorsal scapular (C4-5) and cervical (C3-4) nerves.
What are the axial attachments of rhomboid minor?
Proximal: Nuchal ligament; spinous processes of C7 and T1.
Distal: Smooth triagular area at medial end of scapular spine.
What is the nerve supply to rhomboid major?
Dorsal scapular nerve (C4-5)
What are the axial attachments of rhomboid major?
Proximal: Spinous processes of T2-5.
Distal: medial border of scapula from level of spine to inferior angle
What is the nerve supply to rhomboid minor?
Dorsal scapular nerve (C4-5)
What are the actions of levator scapulae?
Elevates scapula and rotates the glenoid cavity inferiorly by rotating scapula
What are the actions of rhomboid major and minor?
Retract scapula and rotate glenoid cavity inferiorly; fix scapula to thoracic wall.
What are the origins of deltoid?
Inferior edge of the crest of the scapular spine
Lateral margin of the acromion
Anterior border of the lateral 1/2 of clavicle
What is the insertion of deltoid?
Deltoid tuberosity of humerus.
What are the actions of deltoid as a whole?
Abduction of the arm.
What are the actions of the anterior fibres of deltoid?
Assist pectoralis major in flexing the arm.
What are the actions of the posterior fibres of deltoid?
Assist latissimus dorsi in extending the arm.
What is the innervation of deltoid?
Axillary nerve
What is the proximal attachement of supraspinatus?
Supraspinous fossa of scapula.
What is the distal attachment of supraspinatus?
Superior facet of greater tubercle of humerus.
What is the nerve supply to supraspinatus?
Supracapsular nerve C4-6
What is the proximal attachment of infraspinatus?
Infraspinous fossa of scapula.
What is the distal attachment of infraspinatus?
Middle facet of greater tubercle of humerus.
What is the nerve supply to infraspinatus?
Supracapsular nerve
What are the main actions of supraspinatus?
Initiates and assists deltoid in abduction of arm and acts as with rotator cuff muscles.
What are the actions of infraspinatus?
Laterally rotates arm; acts with rotator cuff muscles.
What is the proximal attachment of teres minor?
Middle part of lateral border of scapula
What is the distal attachement of teres minor?
Middle facet of greater tubercle of humerus.
What is the nerve supply to teres minor?
Axillary nerve C5-6
What are the main actions of teres minor?
Laterally rotates arm and acts with rotator cuff muscles.
What are the proximal attachments of teres major?
Posterior surface of inferior angle of scapula.
What is the distal attachment of teres major?
Medial lip of inter-tubercular sulcus of humerus.
What is the nerve supply to teres major?
Lower subcapsular nerve C5-6
What are the functions of teres major?
Adducts and medially rotates arm.
What are the proximal attachments of subscapularis?
Subscapular fossa (most anterior surface of fossa.
What is the distal attachement of subscapularis?
Lesser tubercle of humerus.
What is the nerve supply to subscapularis?
Upper and lower subcapsular nerves C5-7
What are the main actions of subscapularis?
Medially rotates arm as part of rotator cuff, helps hold the head of the humerus in the glenoid cavity.
What is the mnemonic that helps you recall the attachments of the rotator cuff muscles?
From greater tubercle to lesser tubercle:
Teres minor
Infraspinatus
Supraspinatus
Subscapularis
What are the four borders of the quadrangular space?
Superiorly: teres minor
Inferiorly: teres major
Medially: long head of triceps brachii
Laterally: humerus
Which artery and nerve are located within the quadrangular space?
Axillary nerve and posterior circumflex artery
What movements are possible at the glenohumeral joint and which muscles are involved?
Flexion - clavicular deltoid
Extension - spinal deltoid
Medial rotation - deltoid, teres major, subscapularis
Lateral rotation - spinal deltoid, infraspinatus, teres major
Abduction - acromial deltoid
Adduction - teres major
Which muscle is responsible for the initiation of abduction at the glenohumeral joint?
Supraspinatus
What are the attachments of the long head of biceps brachii?
Arises from the supraglenoid tubercle, crosses head of humerus within cavity of glenohumeral joint.
What are the attachments of the long head of triceps brachii?
Infraglenoid tuberosity
Which muscles produce protraction of the scapula?
Pectoralis major, pectoralis minor and serratus anterior
Which muscles produce retraction of the scapula?
Trapezius (middle fibres), rhomboid major and minor and latissimus dorsi
Contraction of which muscles produce elevation of the scapula?
Trapezius (superior fibres), levator scapula, ?serratus anterior, ?rhomboids
Which muscles contract to produce depression of the scapula?
Pectoralis major, latissimus dorsi, trapezius (inferior fibres)
Which muscles produce medial rotation of the scapula?
latissimus dorsi, pectoralis major, teres major, subscaplaris
