Week 5 Anatomy - Upper Limb Flashcards
What are the articulations of the clavicle?
Manubrium sternum medially (large and triangular)
Acromion of scapula laterally (flat)
What is the functional importance of the scapula?
Only bony articulation of the scapula to axial skeleton (i.e. scapula doesn’t have any other skeletal points of contact for anchoring the shoulder joint)
What type of joint is the sternoclavicular joint?
Synovial - does have almost saddle type joint characteristics, as clavicle can move with movement of shoulder and respiration
What ligaments are involved in sternoclaviular joint?
Sternoclavicular ligaments (anterior and posterior)
Costo-clavicular ligaments
Interclavicular ligament
What ligaments are involved in the AC joint?
Conoid ligament (from conoid tubercle of clavicle to coracoid process of scapula)
Trapezoid ligament (coracoid to scapula)
What are the important bony features of the scapula?
Triangular shaped, flat/thin body. Laterally, glenoid fossa, coracoid process and acromion. Lateral border thicker than medial. Spine of scapula posteriorly continuous with the acromion.
What are the important features of the proximal humerus?
Rounded articulating part = head of humerus (articulates with glenoid fossa)
Laterally, greater tubercle (Supraspinatus, Infraspinatus, Teres minor)
Medially, lesser tubercle (subscapularis)
Compare anatomical versus surgical neck of humerus?
Anatomical neck = the groove immediately inferior to the head of humerus (superior to the tubercles)
Surgical neck is inferior to the tubercles , more likely to be site of fracture
What are the important mid-shaft features of the humerus?
- Radial groove runs in a spiral fashion posteriorly behind the humerus to bring it from posterior part of arm eventually into cubital fossa
- Deltoid tuberosity laterally
Which epicondyle sticks out further? What nerve relates to it?
Medial epicondyle - ulnar nerve runs inferiorly
What muscle group largely originates from medial epicondyle?
Anterior/flexor compartment of the forearm
What muscle group largely originates from lateral epicondyle?
Extensor muscles of forearm
What is the articulating surface of the humerus?
What are the two major components?
The condyle
Trochlea - articulates with ulna (medial)
Capitulum - articulates with head of radius (laterally)
Name the fossae at the distal end of the humerus that participate in the elbow joint? (hint, both anteriorly and posteriorly)
Medially = coronoid fossa
Laterally = radial fossa
Posteriorly = olecranon fossa
What are the important features of the proximal ulna?
What functional purpose does it serve?
- Olecranon on posterior aspect, articulates with the trochlear of humerus. Pronounced hinge joint.
Forms site of attachment for triceps brachii for elbow extension
- Coronoid process of ulna, also acts to be important part of hinge joint, and disappears into the the coronoid fossa of humerus when in full flexion
What is the connective tissue membrane that links the radius and the ulna?
Interosseous membrane
What are the important distal landmarks of the ulna?
Styloid process
Head of the ulna
What part of the humerus does the head of the radius articulate with?
Capitulum
What is the name of the tuberosity on the medial aspect of the proximal radius, and what is its purpose?
Radial tuberosity
Site of attachment for biceps brachii tendon
What two carpal bones does radius primarily articulate with?
Scaphoid laterally
Lunate medially
What is the role of the ulna notch?
Site of articulation of ulna and radius distally
What is the origin and insertion and innervation of the deltoid muscle?
Originates from the lateral 1/3 clavicle and spine of scapula.
Inserts onto deltoid tuberosity of humerus.
Innervated by the axillary nerve (C5-C6)
What are the two major functions of the deltoid muscle?
Abduction of shoulder
Support of glenohumeral joint/stability
What movements does deltoid assist in other than abduction?
Also forward flexion and extension (depending on what fibres are being used)
What is the origin, insertion and innervation of the trapezius muscle?
Originates from medial 1/3 superior nuchal line, occipital protuberance, and spinous processes of C7-T12.
Inserts onto lateral 1/3 posterior clavicle, acromion, and spine of scapula.
Innervated by spinal accessory nerve.
What is the major function of trapezius?
Suspends clavicle and scapula from axial skeleton.
Descending/superior aspect of muscle elevates scapula.
Ascending/inferior part depresses scapula
What is the origin, insertion, and innervation of the latissimus dorsi?
Originates from spinous process of inferior 6 thoracic vertebrae (7-12), posterior 1/3 iliac crest, and inferior 3-4 ribs.
Inserts onto the proximal humerus (inter tubercular groove).
Innervated by thoracodorsal nerve C6-C8W
What is the major function of latissimus dorsi?
Extension of humerus, as well as adduction and medial rotation.
Known as the ‘climber’s muscle, powerful muscle that helps extend humerus relative to axial skeleton.
What is the origin, insertion and innervation of pectoralis major?
Originates from medial half of clavicle and anterior surface of sternum and superior 6 costal cartilages, as well as aponeurosis of the external oblique muscle.
Inserts onto lateral lip intertubercular groove of humerus.
Innervated by Lateral and medial pectoral nerves
What is the major function of the pectoralis major muscle?
Think, throwing a ball
Adduction and medial rotation of the humerus. Bringing arm across body, responsible for throwing a ball.
Accessory muscle of inspiration when upper limb in fixed abduction (i.e. tripod)
What is the origin, insertion and innervation of pectoralis minor?
Originates from 3rd-5th ribs near costal cartilages.
Inserts onto medial border and superior surface of coracoid process.
Innervated by medial pectoral nerve
What is the origin, insertion and innervation of serratus anterior?
Originates from external surfaces of ribs 1-8
Inserts onto anterior surface of medial border of scapula.
Innervated by long thoracic nerve (C5-7)
What is the major function of serratus anterior?
Protraction os scapula, as well as anchoring the thoracic wall.
What is the origin, insertion and innervation of rhomboid major?
Originates from spinous processes of T2-T5.
Inserts onto medial border of spine of scapula
Innervation by dorsal scapular nerve C4-5
What is the origin, insertion and innervation of rhomboid minor?
Originate from the spinous processes of C7 and T1
Inserts onto the smooth triangular area at medial end of spine of scapula
What is the major function of the rhomboids?
Retracts scapula
Rotates to depresses the glenoid cavity
What is the origin, insertion and innervation of levator scapulae?
Originates from transverse processes of C1-C4
Inserts onto medial border of scapula (superior to spine)
Innervated by dorsal scapular nerve
What is the origin, insertion and innervation of teres major?
Originate from the inferior angle of the scapula
Inserts onto medial lip of the inter tubercular groove of humerus
Innervated by lower sub scapular nerve (C5-C6)
What is the major function of teres major?
Adduction of humerus, and medial rotation.
What is the primary function of the rotator cuff?
Securing the humeral head into the glenoid fossa
Where do the SIT muscles attach onto?
Greater tubercle of humerus
In anti-clockwise manner, starting superiorly, what are the muscles of the rotator cuff (think SITS)?
Supraspinatus - Superior facet
Infraspinatus - Middle facet
Teres minor - Inferior facet
Subscapularis - Lesser tubercle of humerus
Which rotator cuff muscles laterally rotate vs medially rotate?
Lateral = Infraspinatus and teres minor
Medial = subscapularis
What nerve supplies supraspinatus and Infraspinatus?
Suprascapular nerve C4-C6
What nerve supplies teres minor?
Axillary nerve
How many muscles link the scapula to the humerus?
6!
Rotator cuff muscles + deltoid and teres major
What is the origin, insertion and innervation of biceps brachii?
Originates from two heads: 1. Short head = tip of coracoid process, 2. Long head = supraglenoid tubercle
Insertion onto the tuberosity of radius and fascia of forearm onto bicipital aponeurosis
Innervated by the musculocutaneous nerve C5-C7
What is the origin, insertion and innervation of coracobrachialis?
Originates from tip of coracoid
Inserts onto middle third of humerus
Innervated by musculocutaneous nerve C5-C7
What is the origin, insertion and innervation of brachialis?
Originates from distal half of anterior humerus, and
inserts onto the coronoid process of ulna
Innervated by musculocutaneous nerve C5-C7
What is the combined actions of biceps, brachialis and coracobrachialis? What is the additional action of biceps brachii?
Flexion of the arm at the elbow
Biceps also acts to supinate the forearm when in a pronated position.
What is the origin, insertion and innervation of triceps brachii?
3 heads from which it originates:
- Long head = infraglenoid tubercle
- Lateral head = posterior surface of humerus, superior to radial groover
- Medial head = posterior surface of humerus
Insertion of triceps = proximal end of olecranon of ulna and fascia of forearm
Innervated by radial nerve
What is the origin, insertion and innervation of anconeus?
Originates from lateral epicondyle of humerus
Inserts onto lateral surface of olecranon
Innervated by radial nerve
What are the most superficial flexor muscles in forearm? There are 4!
Origins and insertions?
- Flexor Carpi Radialis: medial epicondyle to base of 2nd metacarpal
- Palmaris longus: Medial epicondyle to flexor retinaculum
- Flexor carpi ulnas: Medial epicondyle + olecranon of ulna to pisiform, hook of hamate, and 5th metacarpal
- Pronator teres: 2 heads: coronoid process of ulna, medial epicondyle humerus to lateral surface of radius
What nerve supplies the flexor compartment?
What are the exceptions?
Median nerve
Except for FCU, and Flexor digitorum profundus which is innervated by ulnar nerve
What muscle is in ‘the intermediate layer’ of the forearm flexor compartment? Origin and insertion?
Flexor digitorum superficialis
Humeroulnar head: medial epicondyle and radial head to shafts of middle phalanges of medial 4 digits (i.e. not thumb)
What muscles comprise the deep layer of flexor compartment? Origin and insertion? (there are 3)
- Flexor digitorum profundus: Proximal radius and ulna anterior surface + interosseous membrane to base of DISTAL phalanges of digits 2 to 5 (medial and lateral parts)
- Flexor polices longus: anterior surface of radius and IOM to base of distal phalanx of thumb
- Pronator quadratus: distal anterior surface or ulna to distal anterior surface of radius
What is the difference in function between FDS versus FDP?
FDS terminates at middle phalanges, FDP terminates at distal phalanges.
FDS = PIP and MCP flexion
FDP = DIP flexion
What are the superficial muscles of the posterior/extensor compartment? - 6 muscles
From lateral to medial:
- Brachioradialis: from lateral supracondylar ridge down to distal radius, doesn’t cross the wrist. Weak flexion when arm mid-pronated
- Extensor carpi radialis longus: Lateral epicondyle to dorsal aspect base of 2nd metacarpal
- Extensor carpi radialis brevis: lateral epicondyle to dorsal aspect of base of 3rd metacarpal
- Extensor digitorum: lateral epicondyle to extensor expansion of medial 4 digits
- Extensor digit minimi: lateral epicondyle to extensor expansion 5th digit
- Extensor carpi ulnaris: lateral epicondyle to dorsal aspect of base of 5th metacarpal
What are the deep muscles of the extensor compartment of the forearm? There are 5: lateral to medial
- Supinator: Lateral epicondyle + annular ligament to lateral, posterior and anterior surfaces of proximal third of radius
- Extensor indicis: posterior surface IOM and distal ulna to extensor expansion of 2nd digit
- Abductor pollicis longus: from IOM to base of 1st metacarpal
- Extensor pollicis longus: Posterior ulnar and IOM to dorsal aspect of base of distal phalanx of thumb
- Extensor pollicis brevis: posterior surface distal third ulna and IOM to dorsal aspect of base of proximal phalanx of thumb
What spinal nerves form the brachial plexus?
C5-T1
Which rami of the spinal nerves contribute to brachial plexus?
Anterior rami
What area do the roots of the of the brachial plexus pass through before uniting into trunks?
Between anterior and middle scalene muscles (alongside the subclavian artery)
What roots merge to form the superior trunk?
C5 and C6
What root/s form the middle trunk?
Continuation of C7
What roots merge to form inferior trunk?
C8 and T1
What is significant about the divisions and the muscles they supply?
Anterior divisions supply flexor compartment
Posterior divisions supply extensor compartment
What is significant about cords and how they are named?
Named relative to position to axillary artery
I.e. posterior cord = posterior to axillary artery, medial cord = medial and lateral cord = lateral to axillary artery
What divisions contribute to the lateral cord?
Anterior divisions of superior and middle trunk
What divisions contribute to the medial cord?
Anterior division of inferior trunk
What divisions contribute to the posterior cord?
Posterior divisions of all three trunks
What are the terminal branches of the brachial plexus from lateral to medial (think MARMU)?
M: musculocutaneous
A: Axillary
R: Radial
M: Median
U: Ulnar
What branches arise from the medial cord prior to it continuing on to become the ulnar nerve?
Medial pectoral nerve
Medial cutaneous nerve of arm
Medial cutaneous nerve of forearm
Where do the divisions of the brachial plexus form?
Behind the clavicle, and then form the cords BEFORE entering the axilla (i.e. divisions of the BP do not enter the axilla)
Where does the axillary artery begin and end?
Lateral border of 1st rib as continuation of the subclavian artery, and ends at inferior border of trees major (becoming the brachial artery)
How are the branches of the axillary artery remembered?
By dividing into 3 parts:
1 branch in 1st part
2 branches in 2nd part
3 branches in 3rd part
What is the first part of the axillary artery, and what is the associated branch?
From lateral border of 1st rib to medial border of pectoralis minor.
Branch = superior thoracic artery
What is the second part of the axillary artery, and what are the associated branches?
Posterior to pectoralis minor
Two branches = acromial and lateral thoracic arteries
What is the third part of the axillary artery, and what are the associated branches?
Third part = lateral border of pectoralis minor to inferior border of teres major
Three branches are sub scapular artery, anterior circumflex humeral artery and posterior circumflex humeral artery
What is the origin of the radial nerve?
Terminal branch of the posterior cord of the brachial plexus (C5-T1)
Describe the course of the radial nerve after coming off from brachial plexus?
Exits axilla posteriorly, laying on tendon of latissimus dorsi and passing posteriorly to humerus in radial groove.
Passes between lateral and medial heads of triceps, perforating inter muscular septum and enters ACF.
Following this, divides into superficial (cutaneous) and deep (motor) radial nerves.
What is the origin of the median nerve?
Lateral root of the lateral cord of BP
Medial root of medial cord of BP
(C6-T1)
Describe the course of the median nerve throughout upper limb?
After branching from lateral and medial cords of BP, unites lateral to axillary and brachial artery, running in medial aspect of arm to pass into most medial aspect of ACF.
Passes anteriorly in forearm to enter the carpal tunnel.
What is the origin of the ulna nerve?
Terminal branch of the medial cord of BP, C7-T1
Describe the course of the ulna nerve throughout the upper limb?
After exiting the axilla, travels alsongside brachial artery on lateral aspect, and Descends along medial aspect of arm, and passes POSTERIOR to medial epicondyle (i.e. not via ACF) and descends along ulnar aspect of forearm to hand. Passes over superiorly to flexor retinaculum
Describe blood supply to the upper limb?
From arch of aorta:
- R brachiocephalic artery –> right arm
- L subclavian artery from arch directly –> left arm
Subclavian artery passes underneath clavicle and heads laterally, and posterior to anterior scalene muscle. **Gives off vertebral artery branch here
When passing over the top of first rib, then becomes axillary artery. Axillary artery passes behind pectoralis minor, and when passing inferior border of teres major, becomes brachial artery.
Brachial artery runs between biceps and triceps, and then enters cubital fossa and divides into radial and ulna artery. Radial artery runs down the radial side of arm, through anatomic snuff box and interdigital space to meet the ulna artery via arcade in the hand. (Ulna travels via Guyon’s canal over the flexor retinaculum)
Describe superficial venous drainage of the upper limb?
Dorsal venous network in hand drains into two major superficial veins:
**Named due to embryological origin in limb bud
1) Cephalic - runs along lateral aspect of arm up to ACF, passing over biceps brachii
2) Basilic - runs along medial aspect of arm up towards ACF, passing between biceps and triceps
Basilic vein merges with brachial veins to form the axillary vein
Cephalic vein penetrates clavipectoral fascia and joins terminal part of axillary vein to form subclavian vein.
Describe deep venous drainage of upper limb?
Deep veins tend to be paired, and following course of arteries of upper limb.
I.e. radial veins, ulnar veins –> merging in ACF to form 2 brachial veins which become axillary vein (where superficial veins will drain into also) –> subclavian vein –> brachiocephalic vein –> SVC
What are the boundaries of the anterior cubital fossa?
Superior = imaginary line between medial and lateral epicondyles of humerus
Medial = Pronator teres
Lateral = Brachioradialis
Roof = ante brachial fascia
What are the contents of the cubital fossa from lateral to medial?
“Really need beer to be at my nicest”
Radial nerve
Biceps tendon
Brachial artery
Median nerve
**Median cubital vein in room anterior to brachial artery also
What muscles does the median nerve innervate?
All of the flexor compartment of the forearm aside from FCU and half of FDP.
Also innervates LOAF:
Lumbricals (lateral 2)
Opponens
Abductor pollicis brevis
Flexor pollicis brevis
What muscles does the ulnar nerve innervate?
Flexor carpi ulnaris
Medial half of flexor digitorum profundus
Most of the intrinsic muscles of the hand except for lateral 2 lumbricals
What is the carrying angle of the elbow?
5-15 degrees - formed by the acute angle made by median axis of the arm and forearm in full extension
What is the axis of rotation for pronation/supination?
140 degrees
What are the bony articulations of the elbow?
Humero-ulnar
Humero-radial
Radio-ulnar
From lateral to medial, what are the proximal row of carpal bones?
Scaphoid
Lunate
Triquetrium
Pisiform
What bones does the scaphoid articulate with?
Trapezium
Lunate
Capitate
Trapezoid
What is the distal row of carpal bones from lateral to medial?
Trapezium
Trapezoid
Capitate
Hamate
What are the borders of the carpal tunnel?
Lateral = scaphoid proximally, trapezium distally
Medial = Triquetrum proximally, hamate distally
Floor = scaphoid, lunate proximally, hamate and capitate distally
Roof = flexor retinaculum
What are the contents of the carpal tunnel?
Median nerve
Flexor pollicis longus - has its own sheath
4 tendons of FDS - both FD share a common sheath
4 tendons of FDP
What is more medial, ulnar artery or nerve?
Ulnar nerve
What are the 3 intrinsic muscles of the thenar compartment? (‘OAF’)
Opponens Pollicis - deep to abductor pollicis
Abductor pollicis brevis - most lateral, attaches from scaphoid to base of proximal phalanx
Flexor pollicis brevis - medial to abductor pollicis brevis
**All innervated by recurrent branch of median nerve
What muscle exists in the adductor compartment of the hand?
Adductor pollicis brevis
From base of 2nd and 3 MC tendon attaching to proximal phalanx of thumb
Innervated by deep branch of ulnar nerve
What are the three muscles of the hypothenar compartment?
Abductor digiti minimi, most lateral in compartment, from pisiform to base of proximal phalanx
Flexor digiti minimi brevis: hook of hamate to proximal phalanx
Opponens digiti minimi: most medially, hook of hamate to proximal phalanx
What is the attachment of the lumbricals?
Tendons of flexor digitorum profundus to lateral sides of extensor expansions of digits
Causes flexion MCP and extension of interphalangeal joints (‘bye bye’ motion)
How many dorsal versus how many palmar Interossei?
4 x dorsal
3 x palmar
What is the site of attachment for the dorsal Interossei?
What is function?
Adjacent sides of metacarpals (bipinnate muscles) and inserting onto the bases of proximal phalanges/extensor hoods
DAB = abduction of the fingers from axial line
What is the site of attachment of the palmar Interossei?
Function?
Palmar surfaces of 2nd, 4th and 5th metacarpals (unipennate muscles) to the bases of proximal phalanges/extensor hoods.
PAD = adduction of fingers towards axial line, as well as assisting in flexion of MCP and extension of IP
What is the purpose of the quadrangular space?
Transmission of axillary nerve and posterior circumflex humeral artery and vein.
What are the borders of the quadrangular space?
Superior = Teres minor
Inferior = Teres major
Medially = long head of triceps brachii
Laterally = surgical neck of humerus
What is the purpose of the triangular space?
Allows passage of the circumflex scapular artery from axilla into posterior arm and scapula
What are the borders of the triangular space?
Skinny triangle!
Superiorly = teres minor
Inferiorly = teres major
Medially = lateral border of long head triceps brachii
What is the purpose of the triangular interval?
It transmits the profunda brachii and the radial nerve into the posterior compartment of the arm
What are the borders of the triangular interval?
Superiorly = teres major
Lateral = lateral border lateral head triceps
Medial = lateral border of medial head triceps
What are the borders of the axilla?
Anteriorly = pectoralis major and minor
Medially = serrates anterior and thoracic wall
Laterally = humerus neck
Posteriorly = Subscapularis, Latissimus dorsi, teres major
What are the borders of the clavipectoral triangle?
It’s in the name!
Pectoralis major
Clavicle
Deltoid laterally
