Shoulder and arm Flashcards
What are the bones of the shoulder? (x3)
Scapula, clavicle and humerus.
What is the arm technically defined as?
The region between the shoulder and elbow. The forearm is defined as the region below the elbow.
What is the anatomy of the scapula?
Spine of the scapula separates the supraspinous and infraspinous fossa. The subscapular fossa is found on the anterior region.
Acromion extends over laterally with the coracoid process, and articulates with the clavicle.
Glenoid cavity contains the humerus.
Superior and inferior angle.
What is the surface anatomy of the scapula?
Overlying 2nd to 7th ribs. Spine is at the 3rd rib.
What is the anatomy of the clavicle?
FLATTENED at its lateral, acromion end, and ROUNDED, BROAD at its medial, manubrium sternum end.
Superior region of the clavicle is smoot; inferior region is rough.
On the inferior surface, the clavicle contains subclavian groove (where subclavius muscle attaches), impression for costoclavicular ligament, conoid tubercle (bony prominence) and trapezoid line (attachment to the trapezoid ligament).
What is the anatomy of the humerus?
Humerus has two necks: the anatomical neck (the true neck of the humerus) and the surgical neck (more commonly damaged in trauma).
Radial (spiral) groove – a groove for the radial nerve and deep brachial artery.
Deltoid tuberosity on anterolateral surface – attachment of deltoid muscle.
Inter-tubercular groove – separates the greater and lesser tubercle and lodges the tendon of the biceps brachii between the tendons of the pectoralis major and teres major. The insertion of the latissimus dorsi is also found here.
Condyles – found at the distal end and are the articular parts of the bone. The condyles are called the Trochlea and Capitulum.
Medial and Lateral Epicondyles – rounded regions of bone above condyles.
Medial and Lateral supracondylar ridges.
Coronoid, radial and olecranon fossae.
What’s the difference between a tubercle and tuberosity in bone anatomy?
They are both bony projections. Tubercles tend to be rounder; tuberosity is rougher.
What are the old and current terms for muscular attachments?
Uses to be ‘origin’ and ‘insertion’, but now considered incorrect. Now, we use the terms ‘proximal attachment’ and ‘distal attachment’.
What are the compartments of the shoulder and arm?
REMEMBER: The arm is between the shoulder and elbow. Compartments describe different areas of muscular anatomy, separated by deep fascia. Anterior and posterior pectoral girdle muscles. Intrinsic shoulder muscles. Anterior and posterior compartments of the arm.
What is contained within the anterior pectoral girdle muscles? (x4)
Pectoralis major. Pectoralis minor. Subclavius. Serratus anterior (runs between anterior and posterior pectoral girdle compartments).
What is the anatomy of the pectoralis major? Action of the pectoralis major? (x3)
Proximal attachments: on the medial third of the clavicle superiorly, the sternum and the costal cartilages inferiorly.
Distal attachments: lateral lip of the intertubercular groove (or intertubercular sulcus).
Adducts and medially rotates the humerus. Lesser actions on the scapula.
What is the anatomy of the pectoralis minor? Action of the muscle?
Distal attachments: coracoid process of the scapula.
Proximal attachments: fans out with finger-like extensions to the 2nd-5th ribs.
Pulls scapula antero-inferiorly.
What is the anatomy of the subclavius? Action of the muscle?
Proximal attachment: first rib – costochondral joint.
Distal attachment: inferior part of the clavicle.
Anchors the clavicle.
What is the anatomy of the serratus anterior? Action of the muscle?
Attaches to medial border of scapula.
Runs anteriorly over the surface of the ribs and attaches to the ribs – usually from the 2nd to 9th ribs.
Hold the scapula down onto the wall of the ribs.
How are the muscles of the anterior pectoral girdle innervated?
PEC MAJOR: medial and lateral pectoral nerves. PEC MINOR: medial pectoral nerve. SUBCLAVIS: C5-6. SER. ANT.: long thoracic nerve.
What are the muscles of the posterior pectoral girdle? (x4)
Trapezius
Latissimus dorsi.
Levator scapulae.
The Rhomboids.
What is the anatomy of the trapezius? Action of the muscle?
Proximal attachments: nuchal line of the skull and the spinous processes of the cervical and thoracic vertebrae.
Distal attachments: posterior border of lateral clavicle, acromion process and scapula spine.
The different regions of the scapula are called the superior (or ascending), middle and inferior (or descending) parts of the trapezius.
Movement of the scapula.
What is the anatomy of the latissimus dorsi? Action of the muscle? (x2)
Proximal attachments: spinous processes of vertebrae T7-L5, iliac crest, thoracolumbar fascia (indicated by triangle in photo), inferior angle of scapula.
Distal attachments: floor of the intertubercular groove of the humerus.
Extends, adducts and rotates the humerus; pulls the body up to the arm during climbing.
What is the deltopectoral groove?
Soft tissue landmark – triangle bounded by clavicle superiorly, deltoid laterally, and pectoralis major medially.
What is the anatomy of the rhomboids? Action of the muscle?
Proximal attachments: spinous processes of C7 to T5.
Distal attachments: medial border of the scapula.
Made up of the RHOMBOID MAJOR and MINOR muscle. Rhomboid major attaches from T2-T5 while rhomboid minor attaches from C7-T1.
Retracts, rotates and fixes the scapula.
What is the nuchal ligament?
Ligament that extends from the external occipital protuberance at the back of the skull, down the spinous processes of the cervical vertebrae. Muscles attached to the spinous processes of the cervical curvature are attached to this ligament.
What is the anatomy of the Levator scapulae? Action of the muscle?
Proximal attachments: transverse processes of C1-C4 vertebrae.
Distal attachments: superior part of the medial border of the scapula.
Elevates and rotates the scapula (hence the name).
How are the muscles of the posterior pectoral girdle innervated?
TRAPEZIUS: Spinal Accessory Nerve (CN XI). !!! LAT. DORS: Thoracodorsal nerve. LEV. SCAP: dorsal scapular nerve (and C3,4). Rhomboids: dorsal scapular nerve.
What are the intrinsic shoulder muscles? (x3)
Deltoid.
Teres major.
Rotator cuff muscles.
What is the anatomy of the deltoid? Action of the muscle?
Proximal attachments: anterior border and superior surface of the lateral third of the clavicle, acromion, spine of scapula.
Distal attachments: deltoid tuberosity of the humerus.
The various proximal attachments determine the names of the ‘parts’ of the muscle: clavicular (anterior), middle and spinal (posterior) parts.
Abducts the arm.
What is the anatomy of the rotator cuff muscles? Action of these muscles? (x3)
SUPRASPINATUS, INFRASPINATUS, TERES MINOR and SUBSCAPULARIS.
Supraspinatus: attached to supraspinous fossa and superior facet of greater tubercle – posterior.
Infraspinatus: attached to infraspinous fossa and middle facet of greater tubercle – posterior.
Teres minor: attached to lateral border of scapula and inferior facet of greater tubercle – posterior.
Subscapularis: attached to subscapular fossa and lesser tubercle of humerus – ANTERIOR.
Fix the head of the humerus into the glenoid fossa – the fossa isn’t actually very deep, so these are particularly important. Supraspinatus is important in initiating abduction of the arm for the FIRST 15 DEGRES, then deltoid takes over. The rest of the rotator cuff muscles ROTATE the humerus.
What is the anatomy of the teres major? Action of this muscle?
Proximal attachment: posterior aspect of the inferior angle of the scapula.
Distal attachment: medial lip of the intertubercular groove of the humerus.
Adducts and medially rotates arm.
What is the anatomy of the biceps brachii? Actions of this muscle? (x3)
Has a short and long head. Short head is more medial.
PROXIMAL ATTACHMENTS: Short head = coracoid process; Long head = long tendon through the intertubercular groove (held by transverse humeral ligament), and attaches to supraglenoid tubercle of the scapula at the glenoid fossa.
DISTAL ATTACHMENTS: the two heads merge and eventually form a tendon which attaches to the RADIAL TUBEROSITY. The distal end of the biceps brachii also forms a structure called the BICEPS APONEUROSIS (ligamentous sheet) which merges with the fascia of the region.
Flexes the elbow, flexes and abducts the shoulder, supinates the radioulnar joint in the forearm.
What is the anatomy of the coracobrachialis? Actions of this muscle? (x2)
Attaches proximally to the coracoid process, and distally to the anteromedial surface of the humerus.
Adducts humerus and flexes the arm at the shoulder.
What is the anatomy of the brachialis? Action of this muscle?
Attaches to medial part of the humerus, and distally to the coronoid process of the ulna.
Flexion of the elbow joint.
What is the anatomy of the triceps brachii? Action of this muscle?
Made up of three heads – the latera, medial and long head.
Lateral and medial head: proximal attachment = posterior shaft of the humerus, above and below the radial groove of the humerus.
Long head: proximal attachment infraglenoid tubercle of scapula.
All three heads form the triceps tendon, which crosses the elbow and attaches to the olecranon process of the ulna = distal attachment.
Extends the forearm.
What is the anatomy of the aconeus? Action of this muscle?
Proximal attachment: lateral epicondyle of the humerus.
Distal attachment: posterior surface of the ulna and olecranon process of the ulna.
Stabilise the elbow joint during certain movements inc. pronation.
What is the anatomy of the gleno-humeral (shoulder) joint?
Ball-and-socket SYNOVIAL joint.
Glenoid fossa is shallow, so rotator cuff muscles depresses the head of the humerus into the fossa for joint stability.
Shallow fossa makes joint prone to dislocation.
Cartilaginous labrum forms a ring around the glenoid fossa, which deepens the fossa to provide extra stability.
What are the movements of the shoulder joint, and which muscles mediate each movement? !!! (x6 movements)
- Abduction: swing arm up - deltoid and supraspinatus (initial part of the movement).
- Adduction: swing arm down - pectoralis major, latissimus dorsi.
- Flexion: swing arm forward - pectoralis major and deltoid.
- Extension: swing arm backwards - deltoid, latissimus dorsi.
- Lateral rotation: thumb out - teres minor and infraspinatus.
- Medial rotation: thumb in - subscapularis.
What are the movements of the scapula-thoracic joint? (x6)
This joint is described as the movement of the scapula over the posterior surfaces of the ribs.
Elevation/depression e.g. shrugging of shoulders.
Protraction/retraction of scapula.
Rotation of the scapula.
What are the anatomical landmarks of the boundaries of the axilla?
Pyramidal shape.
BASE: composed of skin, subcutaneous tissue and fascia.
APEX: lies between the first rib, the clavicle and the superior border of the subscapularis muscle.
ANTERIOR WALL: formed by the pectoralis major and pectoralis minor.
POSTERIOR WALL: formed by the scapula, the subscapularis superiorly, and the teres major and latissimus dorsi inferiorly.
MEDIAL WALL: formed by the 1st-4th ribs and serratus major.
LATERAL WALL: intertubercular groove of the humerus.
Where do the contents of the axilla enter?
Most vessels and nerves pass over rib 1 to enter the axilla. Below clavicle.
What are the contents of the axilla?
MUSCLES: biceps brachii and coracobrachialis.
ARTERIES: contains the axillary artery and its branches. Axillary artery has three parts: first part gives off one branch, second part gives two, and third part gives off three.
VEINS: contains the axillary vein and its tributaries – basilic, brachial and cephalic veins.
LYMPHATIC VESSLES AND LYMPH NODES: axillary lymph nodes.
NERVES: the infraclavicular part of the brachial plexus, long thoracic nerve and the intercostobrachial nerves.
What are the arteries of the shoulder and arm? Anatomical landmarks?
Subclavian passes over first rib to become the axillary artery. Axillary, at the lower border of the teres major becomes the brachial artery. The brachial artery divides at the level of the elbow into the ulnar and radial arteries. During its course, the brachial artery gives off many muscular branches, the largest of which is the profunda brachii artery which follows the radial nerve.
What are the veins of the shoulder and arm? Anatomical landmarks?
Venous return is via superficial and deep vessels.
The superficial veins are: CEPHALIC which runs up lateral border of the arm and BASILIC which runs up medial border of the arm. Basilic passes through the deep fascia at the level of the lower border of the teres major to join venae comitantes of the brachial artery (deep). This form the axillary vein. Meanwhile, cephalic joins the axillary vein directly in the axilla.
Axillary vein becomes the subclavian vein at the level of the first rib.
What is the lymphatic drainage of the shoulder and arm? (x3 groups)
Superficial and deep veins run with the lymphatics.
Most nodes are found in the axilla: AXILLARY LYMPH NODES include humeral, pectoral, subscapular, central and apical. These drain into the subclavian lymph trunk and into the right lymphatic duct on the right side or the thoracic duct on the left side.
DELTOPECTORAL LYMPH NODES: found beside the cephalic vein and drain into apical axillary nodes.
CUBITAL LYMPH NODES: found in medial side of the elbow.
What is the brachial plexus? Brief structure?
Plexus of spinal roots from C5-T1. Supplies MOST of the upper limb.
Spinal roots form trunks –> divisions –> cords –> terminal branches.
Some terminal branches come off earlier e.g. subscapular nerve, long thoracic nerve and various infraclavicular nerves.
What are the largest nerves of the brachial plexus? (x5) Function and brief anatomical course?
Axillary nerve (C56): supplies deltoid muscle.
Musculocutaneous nerve (C567): supplies anterior arm compartment.
Ulnar nerve (C8T1): doesn’t supply anything in the arm; innervates hand.
Median nerve (C678T1): doesn’t supply anything in the arm; innervates forearm.
Radial nerve (C5678T1): muscles of the posterior arm and posterior forearm compartment.
Anatomical course can be seen in photo.
