Muscles of the back Flashcards
What is the sole connection of the scapula with the axial skeleton?
The clavicle
3 functions of the pectoral girdle?
1) The strut formed by the clavicle transmits the forces applied to the upper limb to the trunk
2) Clavicle holds arm clear of the trunk and the scapula is very mobile allowing a great range of movement at the glenohumeral joint
3) Provides attachments for muscles which produce the wide range of movement of the arm
Is the clavicle concave or convex?
Concave in lateral third
Convex in medial 2/3
Why are the medial 2/3 of the clavicle convex?
To allow the passage of the neurovascular bundle supplying the upper limb
What are the medial and lateral ends of the clavicle called?
Medial = sternal Lateral = acromial
Which ribs does the scapula lie between?
Ribs 2-7
In which direction do the acromion and coracoid process of the scapula project?
They both project anteriorly but the acromion lies superiorly to the coracoid process
What are the 2 condyles of the distal end of the humerus, which lies more laterally?
The capitulum and trochlea
Capitulum lies more laterally
What is the nerve supply to the trapezius?
Motor - spinal part of accessory nerve
Sensory (proprioception) - anterior rami of C3 and C4`
Why are teres major and deltoid not considered rotator cuff muscles?
All rotator cuff muscles insert into the head of the humerus
Teres major and deltoid do not, they attach to the intertubercular fossa and deltoid tuberosity respectively
What is the difference between the actions of the muscles that attach to the greater tuberosity and those that attach to the lesser tuberosity of the humerus?
1) Attached at greater tuberosity - lateral rotators
2) Attached at lesser tuberosity - medial rotators
Which muscle tendon crosses teres major and minor at right angles?
The long head of triceps brachii
What are the 4 borders of the quadrangular space?
Superiorly - teres minor
Inferiorly - teres major
Medially - long head triceps brachii
Laterally - humerus
Which artery and nerve are located within the quadrangular space?
Axillary nerve
Posterior circumflex artery and vein
What are the 4 structures that help stabilise the glenohumeral joint?
1) Glenoid labrum
2) Ligaments
3) Biceps tendon
4) Rotator cuff muscles
Contraction of which muscles produces protraction of the scapula? 3
Pectoralis major and minor
Serratus anterior
Contraction of which muscles produces retraction of the scapula? 3
Rhomboid major and minor
Middle fibres of the trapezius
Contraction of which muscles leads to elevation of the scapula? 4
Upper fibres of the trapezius
Levator scapulae
Rhomboid major and minor
Contraction of which muscles leads to depression of the scapula? 3
Lower fibres of trapezius
Pectoralis minor
Latissimus dorsi
In which direction can the inferior angle of the scapula be moved from its anatomical position and how does this allow the arm to be lifted above the head?
Inferior angle can be moved laterally and cranially from the anatomical position
This movement brings the face of the glenoid cavity upwards and allows the arm to be lifted above the head
What are the attachements and innervations of the latissimus dorsi muscle?
Origins - spinous processes T7-L5, iliac crest, thoracolumbar fascia, inferior angle of scapula, ribs 9-12
Insertions - floor of intertubercular groove of humerus
Innervation - Thoracodorsal nerve C6-8
Which 4 muscles act in elevation of the pectoral girdle?
1) Trapezius
2) Levator scapulae
3) Rhomboids
Which 5 muscles act in depression of the pectoral girdle, what also plays a role?
1) Pectoralis major
2) Pectoralis minor
3) Latissimus dorsi
4) Serratus anterior
5) Inferior fibres of trapezius
Gravity also plays a role
Which 3 muscles act in protraction of the pectoral girdle?
1) Pectoralis minor
2) Pectoralis major
3) Serratus anterior
Which 4 muscles act in retraction of the pectoral girdle?
1) Rhomboids
2) Latissimus dorsi
3) Middle fibres of trapezius
Which 3 muscles act in upward (lateral) rotation of the pectoral girdle?
1) Superior fibres of trapezius
2) Serratus anterior
3) Inferior fibres of trapezius
Which 6 muscles act in downward (medial) rotation of the pectoral girdle, what also plays a role?
1) Levator scapulae
2) Rhomboids
3) Pectoralis major
4) Pectoralis minor
5) Latissimus dorsi
Gravity also plays a role
Sensory (proprioception) fibres from the trapezius are carried in what nerve?
Anterior rami of C3 and C4
