Shoulder, Arm, Axilla and Brachial Plexus Flashcards
Upper limb is divided into:
Shoulder
Arm
Forearm
Hand
The bones of the shoulder include:
Scapula
Clavicle
Proximal end of the humerus
These two bones for the pectoral girdle
Clavicle
Scapula
Shoulder joints
Acromioclavicular joint
Sternoclavicular joint
Glenohumeral Joint
Which shoulder joint is known as the “real” shoulder joint?
Glenohumeral Joint
Acromioclavicular joint
Is given stability by coracoclavicular ligament and acromioclavicular ligament
Sternoclavicular joint
Is given stability by costoclavicular ligament
Glenohumeral Joint
Synovial Ball and Socket
Round 1/3 of the head of the humerus is in direct contact with the glenoid cavity. By this, it is permitted free movement of the joint.
Glenohumeral Joint
Is given stability by glenoid labrum and Joint capsule
Glenoid labrum
Gives stability to the glenohumeral joint
Joint capsule
Gives flexibility to the glenohumeral joint
Anterior Extrinsic muscles of the Shoulder
Pectoralis major
Pectoralis minor
Subclavius
Serratus Anterior
Pectoralis major
It has three heads:
Clavicular
Sternocostal
Abdominal
Intervated:
Lateral and medial pectoral nerves
Function:
Adduction and medial rotation of the arm when acting together
Clavicular head is innervated by…
C5,C6
Sternocostal head is innervated by…
C7, C8, T1
The function of the clavicular head is…
Flex the humerus
The function of the sternocostal head is…
Extend it back from the flexed position
Pectoralis minor
Attached to the anterior ends of the 3rd-5th ribs near their costal cartilages
Innervated by Medial Pectoral Nerve
Function:
Stabilizes the scapela
Used when stretching the upper limb forward to touch an object that is just out of reach
Subclavius
Protects the subclavian vessels and brachial plexus
Innervated by:
Nerve to the subclavius
Function:
Supports and maintain the sternal end of the clavicle in its place while we move the shoulder
Serratus Anterior
Innervated by:
Long thoracic nerve
Function:
Protracts the scapula and hold it against the thoracic wall
Inferior part of the serrates
Anterior rotates the scapula, elevating its glenoid cavity so the arm can be raised above the shoulder
Participates in the abduction of the shoulder after 90 degrees
Posterior Extrinsic Muscles
Trapezius
Lattisimus dorsi
Rhomboid Major and Minor
Levator Scapulae
Trapezius
Provides a direct attachment of the pectoral girdle to the trunk
Contains Ascending, Middle and Descending part
Trapezius Descending Part function is
Elevate the tip of the shoulder (scapula)
Trapezius middle part function
retract the scapula
Trapezius ascending part function
depress the scapula and lower shoulder
Together they rotate the scapula laterally
Trapezius and serratus anterior
Lattisimus dorsi
Innervation
Thoracodorsal Nerve
Funtion: Extends, adducts and medially rotates the humerus
These two muscles work together to produce adduction and depression of the shoulder (pull up movement)
Latissimus Dorsi and Pectoralis major
Rhomboid Major and Minor
Innervation:
Dorsal Scapular nerve
Function:
Retract the scapula and rotate the glenoid cavity inferiorly
Fix the scapula to the thoracic wall
Assist the serratus anterior in holding the scapula against the thoracic wall and fixing the scapula during movements of the upper limb
Levator Scapulae
Innervation:
Dorsal Scapular and cervical nerves (C3,C4)
Function:
Elevates the scapula and rotates the glenoid cavity inferiorly
In combination with the acts with the descending part of the trapezius to elevate or fix the scapula.
Intrinsic muscles of the shoulder
Deltoid
Teres Major
Rotator Cuff
Subscapularis
Deltoid
Attaches the clavicle and the scapula to the humerus
Contains three heads
Innervation:
Axillary Nerve
Principal function:
Major abductor of the arm (15-90 degrees)
The three heads of the deltoid are called:
Clavicular (anterior)
Acromial (middle)
Spinal (posterior)
Teres Major
Important stabilizer of the humeral head in the glenoid cavity
Innervation:
Lower subscapular nerve
Function: adducts and medially rotates the arm
Rotator Cuff
Provide the stability of the glenohumeral joint
SITS Muscle
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Subscapularis
Forms part of the posterior wall of the axilla
Its tendon forms the anterior part of the rotator cuff
Function: Primary medial rotator of the shoulder
Innervation:
Upper and lower subscapular nerves
Posterior part of the rotator cuff
Supraspinatus
Infraspinatus
Teres Minor
Supraspinatus
Assist the deltoid in the initial 15 degrees of abduction of the shoulder
Innervation: Suprascapular nerve
Infraspinatus
Function: Lateral rotation of the humerus
Innervation:
Suprascapular nerve
Teres Minor
Function:
Works with the infraspinatus to rotate the arm laterally and assist in its adduction.
Innervation:
Axillary nerve
The arm is the region between
the shoulder and the elbow
The bony structure of the arm is:
Humerus
The anterior compartment of the arm contains the…
Flexor muscles
The posterior compartment of the arm contains the…
Extensor muscles
The anterior compartment is the innervated by…
Musculocutaneous nerve
The posterior compartment is innervated by…
Radial Nerve
Anterior compartment of the arm is composed of
Biceps brachii
Coracobrachialis
Brachialis
Posterior compartment of the arm is composed of
Triceps brachii
Anconeus
Biceps brachii innervation and muscle action
Musculocutaneous nerve (C5,C6,C7)
Supinates forearm and when it is supine, flexes forearm; short head resist dislocation of shoulder
Coracobrachialis innervation and muscle action
Musculocutaneous nerve (C5,C6,C7)
Helps flex and adduct arm: resists dislocation of shoulder
Brachialis innervation and muscle action
Innervación Dual
Musculocutaneos nerve (C5,C6) and Radial Nerve (C5,C7)
Flexes forearm in all positions
Triceps brachii innervation and muscle action
Radial Nerve (C6,C7,C8)
Chief extensor of forearm; long head resists dislocation of humerus; significant during adduction
Anconeus innervation and muscle action
Radial nerve (C7,C8,T1)
Assists triceps in extending forearm; stabilizes elbow joint may abduct ulna during pronation
Quadrangular space
is an intermuscular space through which the axillary nerve and posterior circumflex humeral vessels pass through backward to encircle the surgical neck of the humerus.
Triangular space
Anterior wall:
Pectoralis major
Pectoralis minor
Medial wall:
Serratus anterior
Posterior wall:
Humerus
Teres Major
Latissimus Dorsi
Subscapularis
Scapula
Major blood supply of the arm
Axillary artery
Axillary artery is divided in
three parts
Axillary artery 1st part
From the clavicle until the superior border of pectoralis minor
Axillary artery 2nd part
From the superior border pectoralis minor until inferior border of pectorals minor
Axillary artery 3rd part
From inferior border of pectoralis minor to inferior border of teres major
