Anatomy of the Limbs 2 - Shoulder and Arm Flashcards
Define the muscular compartments of the shoulder and arm
Shoulder
- Anterior
- Posterior
- Intrinsic
Arm
- Anterior
- Posterior
List the posterior pectoral muscles
- Trapezius
- Latissimus dorsi
- Levator scapulae
- Rhomboids
List the intrinsic shoulder muscles
- Deltoid
- Rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis)
- Teres major
List the anterior pectoral muscles
- Pectoralis major
- Pectoralis minor
- Subclavis
- Serratus anterior
List the muscles in the anterior compartment of the arm
- Coracobrachialis
- Brachialis
- Biceps brachii
List the muscles in the posterior compartment of the arm
- Triceps
- Anconeus
List the bones of the arm and shoulder
- Humerus
- Scapula
- Clavicle
How is the anterior and posterior compartment of the arm separated?
- By the humerus
- By medial and lateral intermuscular septa (attaches to the sides of the humerus)
What is the main action of muscles in the arm?
Move the forearm at the elbow joint
List the motor nerves of the arm (upper and lower)
- Musculocutaneous nerve
- Median nerve
- Radial nerve
- Ulnar nerve
What is the function of the musculocutaneous nerve?
- Motor to all the muscles in the anterior compartment of the arm
- Sensory to skin on the anterolateral side of the forearm
What is the function of the median nerve?
- Motor to most flexors in the forearm
- Motor to thenar muscles in the hand
- Sensory to the palmar surface of the lateral three and one-half digits
What is the function of the radial nerve?
- Motor to all muscles in posterior compartment of arm (triceps and anconeus) and forearm
- Sensory to skin on the posterior surface of the forearm and the dorsolateral surface of the hand
What is the function of the ulnar nerve?
Motor to:
- Intrinsic muscles in the hand
- Flexor carpi ulnaris
- Medial half of flexor digitorum profundus in forearm
Sensory to
- Medial one and one-half digits of the finger
What nerve supplies the flexor component of the arm?
Musculocutaneous nerve (C5,6,7)
What are the general attachments of the flexor compartment of the arm?
- Arise from scapula or flexor surface of humerus
- Attach to flexor surface of proximal forearm
Which muscle is the most powerful supinator of the forearm?
- Biceps
- Due to attachment to the radius
List the joints in the arm and shoulder region
- Sternoclavicular
- Acromio-clavicular
- Gleno-humeral
- Scapulo-thoracic
- Elbow
Which joints are involved in the pectoral girdle?
- Sterno-clavicular
- Acromio-clavicular
- Gleno-humaral
- Scapulo-thoracic
List the qualities of the sterno-clavicular joint and the possible injuries
- Synovial joint, composed of two portions separated by a fibrocartilage articular disc
- Strong due to the sternoclavicular ligaments
- Injury results in sternoclavicular subluxation and dislocation
- Only connection of the pectoral girdle to the axial skeleton
What type of joint is the acromioclavicular joint?
Synovial
List the clinically important ligaments stabilising the ACJ
- Acromio-clavicular
- Coraco-clavicular (coracoid process of the scapula to the clavicle)
- Coraco-acromial ligament (often a cause of impingement of the gleno-humeral joint)
When is the ACJ frequently injured?
- Falls onto the outstretched hand
What type of joint is the gleno-humeral joint? List its qualities.
- Synovial ball and socket
- Great mobility, low stability
- Stability comes from the muscles, ligaments and capsular attachments around it. The head stays in its socket due to rotator cuff muscles (depress the humeral head)
- Glenoid cavity is deepened by the glenoid labrum (rim of cartilage)
List the extensions of the capsule of the shoulder joint
- Glenoid to the humeral head
- Subacromial bursa (form a bursa between the humeral head
and the overlying acromial process) - An extension around the long head of biceps as it lies within
the inter-tubercular grove of the humerus
What is the coracoacromial arch?
- Above the gleno-humaral joint
- Acromion, coracoid process and coraco-acromial ligament
- Prevents the humerus rising superiorly
List the movements of the gleno-humeral joint and the muscles that perform them
Flexion
- Clavicular head of pectoralis major
- Anterior fibres of deltoid
- Coracobrachialis
- Biceps
Extension
- latissimus dorsi
Abduction
- Supraspinatus (first 15 degrees)
- Central fibres of deltoid (after 15 degrees)
Adduction
- Pectoralis major
- Latissimus dorsi
Internal rotation
- Subscapularis
External rotation
- Infraspinatus
- Teres minor
What is the scapulothoracic joint?
- The scapulo-thoracic ‘joint’ is essentially a theoretical concept,
but represents the ‘articulation’ between the scapula and the
chest wall. - Elevation, depression, protraction, retraction and rotation of the scapula
What are the movements of the sacupulo-thoracic joint?
- Elevation and depression of the scapula
- Protraction of the scapula i.e. forward and lateral movement
of the scapula against the chest wall - Retraction of the scapula i.e. backward and medial
movement of the scapula against the chest wall - Rotation of the scapula.
List the arteries of the shoulder and arm
- Subclavian artery becomes the axillary artery as it passes over the first rib
- Axillary artery becomes the brachial artery at the inferior border of teres major
- Axillary artery divided into 3 parts according to its relation with the pectoralis major muscle (superior, deep and inferior)
- Brachial artery is the main artery, dividing to form the radial and ulnar arteries
Describe the venous drainage of the arm and scapula
- Cephalic vein is lateral, basilic vein is medial
- Axillary vein formed by the basilic vein joining the venae comitantes of the brachial artery
- Axillary vein becomes the subclavian vein at the level of the 1st rib
Describe the lymphatics of the arm and scapula
- Ultimately there is drainage to axillary lymph nodes
- Cubital, delto-pectoral, axillary, subclavian
- Drain into the subclavian lymphatic trunk, and ultimately the right lymphatic trunk (right side) and thoracic duct (left side)
List the important nerves of the pectoral and arm region
- Long thoracic
- Suprascapular
- Medial and lateral pectoral
- Thoracodorsal
- Axillary
- Musculocutaneous (C5,6,7)
- Ulnar (C8 T1)
- Median (C6,7,8 T1)
- Radial (C5,6,7,8 T1)
Which muscles are supplied by the axillary nerve?
- Deltoid
- Teres minor
Which muscles are supplied by the thoracodorsal nerve?
Latissimus dorsi
Which muscles are supplied by the long thoracic nerve?
Serratus anterior
Which muscles are supplied by the lateral and medial pectoral nerves?
Pectoralis major and minor
List the proximal attachments of the pectoralis major
Medial 1/3rd of clavicle, sternum and costal cartilages
What is the distal attachment of the pectoralis major?
Lateral lip of the intertubercular sulcus
List the functions of the pectoralis major
- Adducts and medially rotates the humerus
- Lesser actions on the scapula
What is the function of the subclavius muscle?
Anchors the clavicle
Where are the attachments of the serratus anterior muscle?
From medial border of scapula to anterior attachments on the ribs (usually 1-9)
List the functions of the latissimus dorsi
- Extends, adducts and rotates the humerus
- Pulls the body up to the arms during climbing.
- Also important in rowing.
Which muscles are supplied by the dorsal scapular nevre?
- Rhomboids
- Levator scapulae
List the functions of the rhomboid muscle
- Retracts, rotates and fixes the scapula
List the functions of the levator scapulae
Elevates and rotates the scapula
What is the function of the deltoid?
Abducts the arm, supraspinatus is important in initiating the first 15 degrees
What is the function of the teres major?
Adducts and medially rotates the arm
Which neck of the humerus is more commonly damaged?
Surgical neck
What is the significance of the deltoid tuberosity?
The proximal attachment of the deltoid muscle to the humerus
List the attachments of the pectoralis minor
- Proximal attachemtn to the coracoid process
- Distal attachments to ribs 2-4
What is the function of the pectoralis minor?
Pulls the scapula forwards and down
List the attachments of the subclavis
- Distal clavicle
- Proximal 1st rib
List the attachments of the trapezius
- Nuchal ligament (descending), cervical and thoracic vertebrae (middle and ascending)
- Spine of the scapula
- Acromion and clavicle
List the attachments of the latissimus dorsi
- Proximally thoracolumbar fascia (down to sacrum and up to T8)
- Distally forms a strap like muscle that attaches to the floor of the intertubercular groove
List the attachments of the rhomboids
- Spinous processes of lower part of the neck and thoracic vertebrae
- Attaches to medial border of scapula
List the attachments of the levator scapulae
- Superior angle of scapula
- Transverse processes of C1-4
List the attachments of the deltoid muscle
- Acromion
- Lateral border of clavicle
- Spine of scapula
- Deltoid tuberosity
List the attachments of the teres major muscle
- Inferior angle of scapula
- Humerus (intertubercular sulcus)
List the attachments of the biceps brachii muscle
- Two heads (lateral long head and medial short head)
- Short head proximal attachment to coracoid process
- Long head crosses over the shoulder joint to attach to the superior part of the rim of the glenoid fossa (supraglenoid tubercle)
- Heads merge to form distal attachments (tendon attaches to the radial tuberosity, and forms biceps aponeurosis)
List the attachments of the coracobrachialis
- Coracoid process
- Shaft of humerus
List the attachments of the brachialis muscle
- Middle part of shaft of humerus
- Attaches to coronoid process of the ulnar bone
List the attachments of the triceps
- Lateral head and medial head attached to posterior shaft of humerus
- Long head attaches to the infraglenoid tubercle of the scapula
- Distally form triceps tendon, which attaches to olecranon process of ulna
List the attachments of the anconeus
- Olecranon process of the ulna
- Posterior ulna
What is the importance of the axilla?
- Gateway for nerves and blood vessels to enter and leave the upper limb
- Pyramid shaped
- Arteries, veins, lymphatics, nerves contained
List the functions of the rotator cuff muscles
- Supraspinatus muscle abducts the arm
- Infraspinatus muscle externally roatates the arm
- Subscapularis medially rotates the arm and adducts it
- All muscles stabilise the shoulder joint
What does “Lady between two majors” mean?
- Latissisimus dorsi muscle attaches to the intertubercular sulcus between the pectoralis major and teres major
- Pec major attaches to the lateral lip
- Teres major attaches to the medial lip
List the attachments of the rotator cuff muscles
Attach around the head of the humerus, and proximally to the scapula
- Teres minor is most lateral
- Infraspinatus
- Supraspinatus greater tubercle of humerus
- Subscapularis lesser tubercle of humerus
How is the sternocleidomastoid muscle tested? Which nerve does this test?
- Turn the head right or left against resistance
- Accessory nerve
How is the trapezius muscle tested? Which nerve does this test?
- Shrug shoulders against resistance
- Accessory nerve
How is the pectoralis major muscle tested? Which nerve does this test?
- Adduct abducted arm against resistance
- Lateral nad medial pectoral nerves
How is the serratus anterior muscle tested? Which nerve does this test?
- Press strongly against the wall with arms outstretched
- Long thoracic nerve
How is the teres major muscle tested? Which nerve does this test
- Adduct the arm against resistance. Palpate the muscle in the posterior axillary fold
- Lower subscapular nerve
How is the latissimus dorsi muscle tested? Which nerve does this test?
- Abduct arm to 90 degrees, then adduct against resistance. See and palpate the muscle in the axillary fold
- Thoracodorsal nerve
How is the deltoid muscle tested? Which nerve does this test?
- Abduct the upper arm against resistance
- Axillary nerve
