ANATOMY LIMBS; Session 2, 3, 4 and 5 - The shoulder and arm (shoulder to elbow), The elbow, forearm and wrist, the hand and the brachial plexus Flashcards
What are the bones of the shoulder and arm?
Scapula, clavicle and humerus are the main ones
What are the key features of the scapula?
What are the key features of the clavicle?
What are the key features of the humerus?
NB: the surgical neck is more commonly damaged than the anatomical neck; epicondytes are important for muscle attachment; intertubercular groove is important for muscle and tendon attachments
What are the muscular compartments of the arm and shoulder?
Anterior pectoral girdle muscles, posterior pectoral girdle muscles, intrinsic shoulder muscles, anterior compartment of upper arm and posterior compartment of upper arm
Which muscles are present in the anterior pectoral girdle muscles?
Pectoralis major, pectoralis minor, subclavius, serratus anterior (between ant and post compartments)
What are the proximal and distal attachments; movement of pectoralis major?
Proximal: Medial 1/3rd of clavicle, the sternum and costal cartilages.
Distal: lateral lip of intertubercular sulcus (groove).
Movement: Adducts and medially rotates humerus with lesser action on scapula
What are the proximal and distal attachments of pectoralis minor?
Proximal: Ribs/costochondral joints.
Distal: coracoid process of scapula
What is the subclavius and its function?
Anchors the clavicle
Where does the serratus anterior attach to and what nerve supplies it?
Runs from medial border of scapula to anterior attachments on ribs (1-9); supplied by long thoracic nerve
Which muscles are present in the posterior pectoral girdle?
Trapezius, Latissimus dorsi, Levator scapulae, Rhomboids
Where is the trapezius attached and what are its functions/supplied by?
Motor supply by CNXI; major actions on scapula
Proximal attachment: Spinous process of ribs
Distal attachment: spine of scapula and clavicle/acromion process
What is the latissimus dorsi and what is its nerve supply/function?
Supplied by thoracodorsal nerve
Extends, adducts, rotates the humerus; pulls body up to arms during climbing and important in rowing.
Proximal attachment: spinous processes (S1-T8) and IlIac crest forming thoracolumbar fascia
Distal attachment: intertubercular groove
What are the rhomboids and what is their nerve supply/function?
Supplied by dorsal scapular nerve; retracts, rotates and fixes the scapula.
Major is broader than minor.
What is the levator scapulae and what is its nerve supply/function?
Supplied by dorsal scapular nerve (+C3/4); elevates and rotates the scapula.
Distal attachment: superior angle of scapula
Proximal attachment:Transverse processes of C1-4
What are the intrinsic shoulder muscles?
- Deltoid
- Teres major
- Rotator cuff muscles
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
What is the deltoid and what is its nerve supply/function?
Supplied by axillary nerve; abducts arm
Proximal attachment: Attaches to spine of scapula (spinal deltoid) and clavicle (clavicular deltoid).
Distal attachment: deltoid tuberosity
What is the rotator cuff?
Acts to fix the head of the humerus in the glenoid fossa -> supraspinatus important in initiating abduction of arm for first 15’ then deltoid takes over.
Converge on head of humerus and attaches onto spine of scapula.
What is the Teres Major and what is its nerve supply/function?
Adducts and medially rotates arm; innervated by lower subscapular nerve.
Forms thick spindle of muscle
Proximal attachment: Inferior angle of scapula
Distal attachment: medial lip of intertubercular sulcus
What is the anterior compartment of the arm?
- Biceps brachii (form a bicepetal tendon and attaches to radial tuberosity and supraglenoid tubercle of scapula)
- Brachialis (attaches to shaft of humerus and below coronoid process of ulna)
- Coracobrachialis (comes of coracoid process and shaft of humerus)
Supplied by musculocutaneous nerve
What is the posterior compartment of the arm?
- Triceps brachii (infraglenoid tubercule, form triceps tendon which attaches to olecranon process of ulna - crosses shoulder joint so can act there)
- Aconeus (crosses elbow joint - attaches to lateral epicondyte)
Supplied by radial nerve (all posterior muscles supplied by radial nerve)
What are the joints present in the arm?
Sterno-clavicular joint, acromio-clavicular joint, gleno-humeral joint (shoulder), Scapulo-thoracic joint (not a joint, just scapula rubbing against thoracic wall), elbow joint
Which joints make up the pectoral girdle?
- SCJ (has an articular disc from which the whole arm hangs off so has a lot of back muscles and core muscles which help to balance the weight of the limb)
- ACJ (capsule to hold it together)
- GHL
- STJ
What is the gleno-humeral joint?
- Ball-and-socket synovial joint
- Glenoid labrum is a thin line of cartilage which helps stabilise into the shallow socket
- Stability of the joint comes from the ligaments and muscles not from the bony articulation
- Joint held together by the rotator cuff muscles.
What is the function of the rotator cuff and the shoulder joint?
To hold humeral head within the glenoid; rotator cuff depresses humeral head. Nb: no muscles underneath the shoulder joint so common dislocation of humerus is downwards
What are the movements of the shoulder joint and which muscles produce these movements?
- Flexion: clavicular head of pec. major, coracobrachialis, ant. fibres of deltoid and biceps
- Extension: lat. dorsi
- Abduction: supraspinatus (1st 15’) and central fibres of deltoid (after 15’)
- Adduction: Pec. major, lat.dorsi
- Internal rotation: subscapularis
- External rotation: infraspinatus, Teres minor
What are the movement of the scapulo-thoracic joint and which muscles are responsible?
All of scapula.
- Elevation: Sup trapezius, levator scapulae and rhomboids.
- Depression: Inf. trapezius, pec minor, serratus anterior.
- Protraction: Pec. minor, serratus anterior.
- Retraction: Rhomboids, middle trapezius, lat. dorsi.
- Rotation: glenoid fossa faces upwards or downwards as scapula rotates
- up: sup trapezius, inf. trapezius, serratus ant.
- down: pec minor, lat. dorsi, rhomboids and levator scapulae
What is the axilla?
Gateway for nerves and blood vessels to enter and leave the upper limb; shaped like truncated pyramid
What are the structures present in the axilla?
Arteries (axillary artery and branches), veins (axillary veins and tributaries), lymphatic vessels and lymph nodes, nerves (brachial plexus)
What are the neurovascular contents of the axilla?
What are the arteries of the arm?
- SCA over first rib ->
- Axillary artery at lower border of teres major ->
- Brachial artery giving off profunda brachii and divides at elbow into ->
- Ulnar and radial arteries.
Also have subscapular arteries which anastomose quite heavily
What are the veins of the arm?
- Cephalic vein (superficial) up lat. border of arm;
- Basilic vein (sup) up medial border of arm joining Venae comitantes (groups of veins that accompany the artery which join into basilic vein) to form:
- Axillary vein in arm (joined by cephalic vein in axilla) and then
- Becomes SCV at level of 1st rib.
What is the lymphatic drainage of the arm?
- Superficial and deep systems, run with veins;
- Cubital lymph nodes;
- Delto-pectoral LN;
- Axillary LN;
- SC lymph trunk;
NB: long thoracic nerve and thoracodorsal nerve can become damaged when LN removed during surgery
Why are the axillary lymph nodes so important?
Drain the breast as well; so when breat cancer occurs and they need to be removed can cause lymphoedema of the arm, forearm and hand
What are the nerves in the brachial plexus of the arm?
Lateral and medial pectoral nerve supply the pectorals. The musculocutaneous nerve supplies anterior compartment of the arm
What are the largest nerves of the brachial plexus?
- Axillary nerve (C5),
- musculocutaneous nerve (C567),
- Ulnar nerve (C8T1),
- Median nerve (C678T1),
- Radial nerve (C5678T1 - main posterior supply of arm e.g. triceps)
Where are the common sites of damage?
Dislocation affects the axillary nerve
What is the main function of the arm?
The functions of all the muscles revolve around that of the hand - to hold objects and manipulate them
What is the sterno-clavicular joint?
Synovial joint; Composed of 2 portions separated by fibrocartilage articular disc -> very strong which arises from the very strong sterno-clavicular ligaments -> when damaged can result in sterno-clavicular subluxation or dislocation. Only connection of the clavicle to the axial skeleton and allows movement of clavicle in 3 different planes
What is the acromio-clavicular joint?
Synovial joint between acromial end of clavicle and acromion -> joint stabilised by: acromioclavicular ligament, coracoclavicular ligament (conoid and trapezoid ligaments) and coraco-acromial ligament (often cause of impingement of glenohumeral joint, but weak)
What are the common injuries to the ACJ?
Frequently injured when falling onto outstretched hand; minor dislocations occur when the acromioclavicular joint is torn; severe dislocations when the coraco-clavicular is also torn
Where does the capsule of the glenoid-humeral joint extend to?
- Capsule of shoulder joint extends from the glenoid to the humeral head,
- the subacromial bursa (above humeral head to underlying acromion - often site of pathology in impingement of GHJ)
- extension around long head of biceps as it lies within inter-tubercular groove of humerus
What are the important ligaments of the GHJ?
Coraco-acromial ligament (prevents rising of the humerus against the acromion, forming an arch); beneath coraco-acromial arch is the subacromial bursa and supraspinatus tendon; gleno-humeral ligaments ,(strengthen the anterior portion of shoulder capsule); coracohumeral ligament (strengthens capsule sup.) and transverse humeral ligament (holds tendon of long head of biceps in intertubercular tube)
Which muscles are involved in resisting dislocation at the gleno-humeral joint?
Rotator cuff muscle (hold humeral head against glenoid cavity); deltoid; coracobrachialis; short and long head of biceps
What are the boundaries of the axilla?
- Base: skin, subcut tissue extending from arm to chest;
- apex between first rib, clavicle and sup. border of subscapularis;
- ant wall formed by pec. major and minor;
- post wall by scapula and subscapularis (sup) and teres major and lat dorsi (inferiorly);
- medial wall: chest wall (rib 1-4) and serratus anterior;
- lateral wall formed by intertubercular groove of humerus
Which nerve supplies the supraspinatus/infraspinatus?
Suprascapular nerve
Which nerve supplies pectoralis major?
Medial/Lateral pectoral nerve
What does the axillary nerve supply?
Teres minor and deltoid (with skin overlapping)
What are the vertebral levels of the scapula landmarks?
Sup angle = T2; medial end of scapular spine lies at T3; inferior angle at T7
What is the delto-pectoral groove?
Triangle bounded by the clavicle sup, deltoid laterally and pec major medially
How do you test the sternocleidomastoid actions and what nerve supplies it?
Turn head R/L against resistance -> spinal accessory CNXI and C3/4
How do you test trapezius actions and nerve supply?
Raise both shoulders against resistance -> CNXI, C3/4
How do you test Pec major actions and nerve supply?
Adduct the abducted arm against resistance -> latera/mdial pectoral C5678 T1
How do you test serratus anterior actions and nerve supply?
Both arms outstretched with palms against wall and asked to press forward strongly -> Long thoracic C56
How do you test Teres major actions and nerve supply?
Adduct arm against resistance; see and palpate muscle in post axillary fold -> lower subscapular C56
How do you test Lat dorsi actions and nerve supply?
Abduct arm to 90’ and adduct against resistance; see and palpate in post. axillary fold -> thoracodorsal C678
How do you test deltoid actions and nerve supply?
Abduct upper arm against resistance -> axillary nerve C56
How do you test biceps actions and nerve supply?
Flex the elbow against resistance
Which muscles are responsible for elbow flexion?
Biceps, brachialis, brachioradialis (pronator teres)
Which muscles are responsible for elbow extension?
Triceps (anconeus)
Which bones are present in the elbow, forearm and wrist?
Humerus, radius, ulna and carpal bones -> proximal row: scaphoid, lunate, triquetrum, pisiform; distal row: trapezium, trapezoid, capitate, hamate.
NB: Radial is on thumb side which is lateral side of arm
What are important features of the bones of the elbow?
Fossae for radius, coronoid fossa, olecranon process on posterior
What are the bones of the forearm?
Olecranon is on the ulna; distal ends have styloid process (stability of wrist joint and muscle attachment); connected via an interosseus membrane (similar to a joint)
What is an important feature of the interosseus membrane?
The interosseous membrane separates the anterior and posterior compartments, and is a site of attachment for muscles in the forearm
What are the bones of the wrist?
The distal ends of the radius and ulna articulate with the proximal row of carpal bones, with the exception of pisiform (a sesamoid bone).
What are the muscle compartments of the elbow and forearm?
Ant/post compartment of arm; anterior compartment of forearm (sup compartment and deep compartment); post compartment of forearm
Which muscles act on the elbow from the ant. compartment of arm?
Radial tuberosity (flexion and supination of forearm) and biceps aponeurosis merges with fascia of the region
What are the functions of the forearm muscles?
Hand and wrist operated by remote control y these muscles; actially take origin from distal humerus and radius/ulna
What is pronation and supination?
Supination is palms forward and pronation is palm down -> most relaxed in mid prone position
Which muscles are present in the sup. ant. compartment of the forearm?
Pronator teres (PT), Flexor carpi radialis (FCR), Palmaris longus (PL), Flexor digitorum superficialis (FDS), Flexor carpi ulnaris (FCU)
Which muscles are present in the deep ant. compartment of the forearm?
Flexor digitorum profundus (FDP), Flexor pollicis longus (FPL), Pronator quadratus (PQ)
Which muscles are present in the anterior compartment of the forearm?
Have a deep and superficial pronator;
NB: all the muscles cross the elbow joint apart from the pronators
What are the fascia present in the forearm?
The flexor retinaculum forms the roof of the carpal tunnel and is an important structure; antebrachial fascia (palmar carpal ligament) holds down the tendons in the wrist
Which muscles are present in the extensor compartment of the forearm?
Note that some parts of the proximal attachments are on the interosseous membrane.
Which muscles are present in the extensor compartment of the forearm that move the wrist joint?
Extensor carpi radialis longus (ECRL) Extensor carpi radialis brevis (ECRB) Extensor carpi ulnaris (ECU)
Which muscles are present in the extensor compartment of the forearm that move the digits?
Extensor digitorum (ED) Extensor indicis (EI) Extensor digit minimi (EDM)
Which muscles are present in the extensor compartment of the forearm that move the thumb?
Abductor pollicis longus (APL) Extensor pollicis brevis (EPB) Extensor pollicis longus (EPL)
Important notes about anatomical terminology:
Carpi = wrist mover and acts on radial/ulnar bones. Digitorum muscles act on group of digits - pollicis=thumb, indicis=index and digiti minimi= little finger
What is the anatomical snuff box in the forearm?
Scaphoid is easily broken and can trap the radial artery and cause necrosis of distal end of thumb