RA week 9

Question 1

Answer 1

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Question 2

Bones of the pectoral girdle + glenohumeral joint?

Answer 2

scapula, clavicle + humerus

Question 3

Bony projections of the scapula?
Angles, borders + fossae?

Answer 3

bony projections = spine, coracoid process + acromion
angles, borders + fossae = sites of muscle attachment for muscles that move the scapula + humerus

Question 4

Answer 4

Some muscles originate from the scapula and insert into the humerus e.g. rotator cuff muscles – subscapularis originates from the anterior surface. Infraspinatus, supraspinatus and teres minor from the posterior surface
Some muscles originate from the ribs + vertebrae and then insert into the scapula e.g. at the medial border – the anterior surface is the insertion point for serratus anterior, the posterior surface is the insertion point for the rhomboid muscles and levator scapulae

Question 5

to act on a joint…

Answer 5

a muscle or its tendon must pass over the surface of that joint

Question 6

If the muscle or its tendon crosses the anterior surface of the joint…
if it crosses the posterior surface…
if it crosses the medial (inner) surface…
if it crosses the lateral (outer) surface…

Answer 6

If the muscle or its tendon crosses the anterior surface of the joint it will flex the joint
if it crosses the posterior surface it will extend it
if it crosses the medial (inner) surface it will adduct it
if it crosses the lateral (outer) surface it will abduct it

Question 7

bony features of humerus? + function?

Answer 7

tubercles = sites of muscle attachment
bicipital groove is created by the tendon of the long head of biceps brachii

The muscle attachment areas are also shown – e.g., you can see that the rotator cuff muscles all insert onto the greater tubercle except subscapularis which inserts into the lesser tubercle

Question 8

Answer 8

clavicle provides attachment sites for some large muscles that move the scapula, arm, head and neck

Question 9

clavicle function?

Answer 9

The clavicle acts a bony prop that holds the upper limb away from the body wall, allowing it to move freely and perform a wide range of movements. Although it is relatively small compared to the scapula and humerus it provides attachment sites for some large muscles that move the scapula, arm, head and neck

Question 10

glenoumeral joint surrounded by?
Reinforced by?
What are these?

Answer 10

glenohumeral joint is synovial ball+socket joint so is surrounded by a capsule
capsule reinforced by ligaments:

• glenohumeral ligaments (superior, middle + inferior) = from lesser tubercle → glenoid cavity
• coracohumeral liagemnt = from greater tubercle → coracoid process of scapula
• Bursae = around proximal part of long head of biceps as it passes thru bicipital groove
• Transverse humeral ligament = (between greater + lesser tubercles) holds biceps tendon in the bicipital groove

Question 11

bony link between body wall and upper limb?

ligaments?

Answer 11

clavicle passes between the sternum and the scapula and is the only bony link between the body wall and the upper limb

Question 12

…

what is the blood supply to the scapula + proximal humerus?

Answer 12

There is an anastomosis around the scapula that supplies the scapula and the muscles around it

Blood supply is from branches of the subclavian artery

The right subclavian artery is a branch of the brachiocephalic trunk and the left subclavian is a direct branch of the arch of the aorta

The subclavian artery forms many branches that supply structures in the thorax, neck and upper limb

The terminal branches of some of these vessels can supply structures far from the subclavian artery itself – for example the vertebral arteries unite to form the basilar artery that supplies the brain and the internal thoracic artery terminates in a superior epigastric artery that supplies part of the abdominal wall

The subclavian artery itself becomes the axillary artery as it emerges from beneath the clavicle and passes over the surface of the first rib.

Branches from the thyrocervical trunk and the axillary artery supply the scapula and the proximal humerus

Question 13

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Blood supply to scapula?

Answer 13

Dorsal scapular artery (deep branch of the transverse cervical artery from the thyrocervical trunk) = passes down the medial border of the scapula and anastomoses with branches from the suprascapular artery and subscapular artery

Suprascapular artery (from thyrocervical trunk)

Subscapular artery (from axillary artery) also forms the thoracodorsal artery that supplies muscles at the lateral border of the scapula

Question 14

“spaces” associated with muscles on posterior surface of scapula + proximal humerus?

why are they significant?

Answer 14

There are two anatomical ‘spaces’ associated with the muscles attached to the posterior surface of the scapula and the proximal humerus:

Quadrangular space = lies between teres minor (sup. border), teres major (inf. border), long head of triceps brachii (medial border) and humerus (lateral border)

• axillary nerve that supplies deltoid and teres minor passes through this space to reach posterior surface of arm from the axilla
• posterior circumflex humeral artery runs alongside axillary nerve

Triangular space = lies between teres major (sup. border), long head of triceps brachii (medial border) + the humerus (lateral border)

• radial nerve passes through this space to leave the axilla and enter the posterior compartment of the arm to supply triceps brachii
• deep brachial or ‘profunda brachii’ artery runs with the radial nerve

Question 15

“spaces” associated with muscles on posterior surface of scapula + proximal humerus?

why are they significant?

Answer 15

There are two anatomical ‘spaces’ associated with the muscles attached to the posterior surface of the scapula and the proximal humerus:

• Quadrangular space = lies between teres minor (sup. border), teres major (inf. border), long head of triceps brachii (medial border) and humerus (lateral border)
  *

Question 16

pectoralis major attachments?

function?

Innervation?

Answer 16

Clavicle, costal cartilage ribs 1-6 + sternum to → outer lip of bicipital groove of the humerus

function = flexion and adduction of the arm, medial rotation of the humerus

innervation = medial (C8, T1) + lat (C5, C6, C7) pectoral nerves from medial + lateral cords of the brachial plexus

Question 17

pectoralis minor attachments?

function?

innervation?

Answer 17

3^rd, 4^th, 5^thribs to coracoid process of scapula

function = pulls shoulder anterior and inferior, or can elevate ribs if shoulder is fixed

innervation = medial pectoral nerve (C8,T1) from medial cord of brachial plexus

(unlike pec major, it does not cross the glenohumeral joint so cannot act upon it)

Question 18

Serratus anterior attachments?

Function?

Innervation?

Answer 18

Outer surface upper 8 ribs to medial border of the scapula

function = protraction of the scapula e.g. when throwing a punch during boxing

innervation = long thoracic nerve (C5, 6, 7) of the brachial plexus

Question 19

Trapezius attachments?

Innervation?

Function?

Answer 19

attachments = superior nuchal line, nuchal ligament spinous processes C7-T12 to → lateral ⅓ clavicle, acromion and spine of scapula

Innervation = spinal accessory nerve (CN XI, motor), cervical plexus C3,C4 (pain)

ascending part (A) = depress scapula

transverse part (B) = retracts scapula

descending part (C) = elevate scapula, rotate glenoid cavity (allows arm to move above head e.g. when brushing hair)

Question 20

Latissimus dorsi attachments?

Function?

Innervation?

Answer 20

Attachments = ilium, thoracolumbar fascia, spinous process of lower 6 thoracic vertebrae to → floor of bicipital groove of humerus

Function = extension, medial rotation and adduction of arm

climbing, chin-ups

(passes over posterior surface of the glenohumeral joint and attaches to humerus so will extend the arm)

Innervation = Thoracodorsal nerve, post. cord brachial plexus, C6-8

Question 21

Levator scapulae attachments?

function?

innervation?

Answer 21

attachments = transverse processes of atlas and axis, 3^rdand 4^thC vertebrae to → medial scapular border between superior angle and medial end of scapular spine

Function = help control scapular position, elevate shoulder (with trapezius), shoulder fixed can laterally flex neck to same side

Innervation = Direct C3, 4 and C5 via dorsal scapular nerve

Question 22

Rhomboid major and minor attachments?

Function?

Innervation?

Answer 22

major = from 2-5 thoracic spines to → medial border of scapula (spine to inferior angle)

minor = from nuchal ligament and c7-T1 thoracic spines to → medial end of spine of scapula

Function = retraction of scapula

innervation = dorsal scalpular nerve C4-5

Answer 23

major = from 2-5 thoracic spines to → medial border of scapula (spine to inferior angle)

minor = from nuchal ligament and c7-T1 thoracic spines to → medial end of spine of scapula

Function = retraction of scapula

innervation = dorsal scalpular nerve C4-5

Question 24

deltoid attachments?

function?

innervation?

Answer 24

Lateral 13 clavicle, acromion, spine of scapula to → deltoid tuberosity of humerus

function = abduction of the arm from 10* (supraspinatus) to 110* mostly middle fibres, extension and lateral rotation of arm from posterior fibres, flexion and medial rotation of arm from anterior fibres

innervation = axillary nerve (C5, 6) from posterior cord of brachial plexus

Answer 25

Lateral 13 clavicle, acromion, spine of scapula to → deltoid tuberosity of humerus function = abduction of the arm from 10\* (supraspinatus) to 110\* mostly middle fibres, extension and lateral rotation of arm from posterior fibres, flexion and medial rotation of arm from anterior fibres innervation = axillary nerve (C5, 6) from posterior cord of brachial plexus

Question 26

what lies in the delto-pectoral groove? function?

Answer 26

cephalic vein It drains blood from the skin and superficial fascia from the lateral side of the dorsum of the hand, the forearm, and the medial side of the arm, before piercing the clavipectoral fascia to enter the axilla and join the axillary vein

Question 27

Teres major attachments? Function? Innervation? Rotator cuff?

Answer 27

Attachments = lateral border of scapula (lower ⅓ posterior) to medial lip of bicipital groove of humerus Function = adduction and medial rotation of the arm innervation = subscapular branch of posterior cord of brachial plexus (lower C5-6) Teres means ‘cord-like’ as this muscle looks like a cord when cut. ‘Major’ tells you there is another, smaller muscle with a similar name elsewhere in the upper limb. This is teres minor and will be discussed later with the other rotator cuff muscles. Teres major is **not** part of the rotator cuff and attaches to the scapula inferior to teres minor. It acts to draw the arm closer to the body and to assist in medial rotation of the humerus.

Question 28

Subclavius attachments? Functions? Innervation?

Answer 28

Attachments = sternal end of 1st rib to middle ⅓ of underside of clavicle Function = draws clavicle down and slightly forwards during abduction Innervation = nerve to subclavius C5, 6

Question 29

rotator cuff? function? most common direction?

Answer 29

—Group of four muscles that help to keep the head of the humerus in the glenoid cavity of the scapula ## Footnote Prevent dislocation from very shallow joint The most common direction to dislocate the shoulder is towards this gap in an antero-inferior direction

Question 30

Which muscles make up the rotator cuff?

Answer 30

subscapularis supraspinatus infraspinatus teres minor

Question 31

subscapularis attachments? function? Innervation?

Answer 31

odd one out - lies on anterior surface of the scapula + attaches to lesser tuberlce (the others are posterior and attach to greater tubercle + laterally rotate the arm) attachments = subscapular fossa (anterior scapula) to → lesser tubercle of humerus function = medially rotate arm innervation = upper and lower subscapular nerves (C5, 6, 7) from posterior cord of brachial plexus

Question 32

supraspinatus attachments? function? innervation?

Answer 32

attachments = supraspinous fossa to → greater tubercle of humerus (upper facet) function = abducts arm first 10-15\* innervation = suprascapular nerve (C5, 6) from superior trunk of brachial plexus

Question 33

infraspinatus attachments? function? innervation?

Answer 33

infraspinous fossa of scapula to → greater tubercle of humerus (middle facet) function = lateral rotation of arm Innervation = suprascapular nerve (C5, 6) from superior trunk of brachial plexus

Question 34

Teres minor attachments? Function? Innervation?

Answer 34

Attachments = upper ⅔ lateral border of scapula to → greater tubercle of humerus (lower facet) Function = lateral rotation of arm innervation = axillary nerve (C5, 6) branch of posterior cord of the brachial plexus (

Question 35

…

Answer 35

The slide demonstrates the way the muscles form a cuff around the joint. Most of the scapula has been removed and the bone of the glenoid fossa has been lifted away from the joint to show the ring of muscle and connective tissue associated with the rotator cuff. The head of the humerus can be seen surrounded by muscle. The same image is shown in the diagram but the glenoid fossa is shown instead of the humeral side of the joint. This concludes the pectoral girdle and shoulder joint presentations. The next presentation describes the structures of the axilla.

Question 36

clavipectoral fascia? which structures pierce the clavipectoral fascia?

Answer 36

* Encloses subclavius and pectoralis minor * Suspensory ligament to fascial floor of axilla fascia pierced by 3 structures = cephalic vein as it enters axilla to join axillary vein, thoracoacromial artery as it leaves the axilla to supply the body wall, and lateral pectoral nerve that leaves axilla to supply pectoralis major with motor innervation

Question 37

boundaries of the axilla?

Answer 37

* Anterior wall = pect. major and minor, subclavius, fascia * Floor = skin that extends into arm * Roof = rib 1, clavicle, scapula * Posterior wall = subscapularis, teres major, latissimus dorsi, long head of triceps brachii * Lateral wall = humerus * Medial wall = serratus anterior and wall of thorax

Question 38

Contents of the axilla?

Answer 38

* Vessels, nerves, lymphatics for upper limb * Short head of biceps and coracobrachialis * Lymph nodes that drain both the upper limb and mammary tissue * Adipose tissue

Question 39

Axillary vein formed from? what does this do? where is axillary vein located? what other veins drain into axillary?

Answer 39

mainly formed from basillic vein - once it crosses inferior margin of teres major basilic vein drains postero-medial surface of hand + forearm axillary vein anterior to axillary artery in axilla and becomes subclavian vein at lat. border rib 1 cephalic and brachial veins also drain into axillary (medial brachial vein may join basilic vein)

Question 40

what does cephalic vein drain? drains to?

Answer 40

The cephalic vein drains the superficial tissues of the lateral side of the forearm and hand and runs through the deltopectoral groove to reach the clavipectoral fascia. It pierces this fascia to enter the axilla, where it will drain into the axillary vein

Question 41

axillary artery lies inferior to? spans? pathway? function?

Answer 41

lies inferior to axillary vein * spans from subclavian (lat. margin rib 1) to brachial (inf. margin teres major) divided into 3 parts in relation to their position relative to pect. minor: * 1st part (1 branch) = proximal (medial) to pect. minor = **superior thoracic artery** * 2nd part (2 branches) = posterior to pect.minor = **thoracoacromial** and **lateral thoraic arteries** * 3rd part (3 branches) = distal to pect. minor = **subscapular, anterior + posterior circumflex humeral arteries** These arteries supply blood to the muscles of anterior body wall + humerus and form anastomoses around the scapula with branches of the subclavian artery. This anastomosis compensates for any brief occlusion of the axillary artery that may be caused by movements of the upper limb, maintaining blood flow to the upper limb regardless of the position of the arm

Question 42

…

Answer 42

The slide shows some of the branches of the axillary artery Note that pectoralis minor has been reflected so that the branches of the second part of the artery can be seen

Question 43

Axillary lymph nodes drain

Answer 43

upper limb, lateral breast tissue, upper back + shoulder, lower neck Tail of breast tissue into axilla creates pathway

Question 44

axillary node groups?

Answer 44

20-30 axillary nodes - 5 groups * **Humeral** - posterior to axillary vein = upper limb * **pectoral** - inferior margin of pectoralis minor = thorax and mammary * **subscapular** - posterior axillary wall = back, shoulder, neck * **Central** - axillary fat = communicate with other nodes * **Apical** - superior margin of pectoralis minor = drain other nodes and mammary tissue lymph drains to central nodes deep in the axillary before draining to apical nodes at apex of axilla

Question 45

…

Answer 45

The lateral parts of the breast tissue will also drain lymph into axillary nodes. This is facilitated by the presence of a tail of breast tissue that passes along the thoracic wall towards the axilla. Lymph from the more medial tissues of the breast will drain into internal thoracic nodes.

Question 46

brachial plexus nerve roots?

Answer 46

brachial plexus lies in axilla but nerves originate from C5-T1 nerve roots in the neck (upper thorax for T1)

Question 47

axillary nerve roots? damage?

Answer 47

the axillary nerve contains fibres from C5 and C6 This means that if one root is damaged the nerve fibres from the other root will still allow some function in the nerve if C5 was damaged then C6 fibres would still allow some innervation of deltoid muscle – abduction of the arm would be weaker but still possible.

Question 48

where do C5-T1 nerve roots lie? what do they carry? Trunks? Pathway?

Answer 48

The roots lie in the posterior triangle of the neck and pass between the anterior and middle scalene muscles —Roots receive grey rami communicantesso carry post-ganglionic sympathetic fibres * —Superior trunk = C5 & C6— * Middle trunk = C7— * Inferior trunk = C8 & T1 pass over rib 1 and enter the axilla

Question 49

branches of roots and trunks of brachial plexus?

Answer 49

* C5 root - **phrenic nerve** (diaphragm), **dorsal scapular nerve** (rhomboid major + minor) * C5-7 - **long thoracic nerve** (serratus anterior) ONLY superior trunk * C5, 6 to **suprascapular nerve** (infraspinatus and supraspinatus) and **nerve to subclavius** (subclavius muscle)

Question 50

trunks divide into? what nerves?

Answer 50

—Each trunk divides into an anterior and posterior division ## Footnote —3 anterior divisions - divisions from superior and middle trunks form **lateral cord** and anterior devision from inferior trunk will form **medial cord** (fibres associated with anterior compartments of the arm and forearm—) 3 posterior divisions - form **posterior cord** of plexus (nerves associated with posterior compartments of the arm and forearm—) No peripheral nerves direct from divisions Anterior divisions will form the **musculocutaneous, median and ulnar nerves** as part of its terminal ranches - associated with anterior compartments of arm + forearm Posterior division will form **radial nerve** as one of its terminal branches - posterior compartment of arm and forearm

Question 51

cords named in relation to? what are they?

Answer 51

cords named in relation to axillary artery lateral cord lies closer to humerus, medial lies closer to body wall and posterior cord lies behind artery * **lateral** - unites anterior divisions of upper and middle trunks therefore C5-C7 fibres present - also origin of **lateral pectoral nerve** * **posterior** - unites all posterior divisions therefore C5-T1 fibres present = origins of **subscapular** and **thoracodorsal nerves** * **medial** - continuation of anterior division therefore C8-T1 fibres present = origin of **medial pectoral** and **cutaneous nerves**

Question 52

terminal nerve branches of cords?

Answer 52

Lateral cord = (lateral pectoral), terminal branches are **musculucutaneous nerve** and lateral root of **median** nerve posterior cord = (subscapular nerves, thoracodorsal), terminal branches are **axillary, radial** nerve Medial cord = (medial pectoral, medial cutaneous arm + forearm), **ulnar** nerve, medial root of **median** nerve

Question 53

…

Answer 53

Although for the last slide I described the motor supplies of the terminal branches, each terminal branch also carries sensory fibres. For example, the axillary nerve supplies motor innervation to teres minor and deltoid muscles but also supplies sensory innervation to the skin of the upper lateral arm – called the ‘badge-patch’ area as this is where you might have an insignia badge on your uniform in the army. In the diagram on this slide look closely at the area highlighted by a small plastic rod – the nerves in this area appear to form an ‘M’ shape.

Question 54

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Answer 54

The photographs also show this ‘M’ shape. This is the easiest way to start to identify the components of the plexus. Use the axillary artery to locate the lateral and medial cords. Then follow the lateral cord as it divides into a nerve that disappears into coracobrachialis – this is the musculocutaneous nerve – and a branch that goes to the midline to join with part of the medial cord to form the median nerve – this is the lateral root of the median nerve. Follow the medial root of the median nerve back to the medial cord and confirm the other large terminal branch of the medial cord – the ulnar nerve. Therefore, finding the ‘M’ shape allows you to identify the main terminal branches of the lateral and medial cords

Question 55

…

Answer 55

The lateral and medial cords innervate muscles in the anterior compartments of the arm, forearm and the palmar aspect of the hand. The anterior compartments of the arm and forearm are often called ‘flexor compartments’ as they contain muscles that flex the elbow, wrist and digits. The musculocutaneous nerve will usually pierce coracobrachialis muscle in the arm and can be identified using this landmark. The median nerve forms from the lateral and medial cords in the ‘M’ shape and descends the anterior compartment of the arm to pass through the cubital fossa and later also the carpal tunnel at the wrist to pass into the hand. The ulnar nerve lies medially in the arm before passing behind the medial epicondyle of the humerus to lie in the medial side of the forearm and then pass into the hand.

Question 56

….

Answer 56

The posterior cord lying behind the axillary artery and forming its terminal branches deep to the ‘M’ shape formed by the other nerves. The axillary nerve wraps around the neck of the humerus to pass through the quadrangular space to enter deltoid and teres minor – **it is close to the joint and may be damaged during the classic antero-inferior dislocation of the glenohumeral joint**. The radial nerve passes deep in the arm before leaving the anterior surface of the humerus and passing through the triangular hiatus to reach the posterior compartment of the arm. It then travels at the lateral side of the cubital fossa to reach the posterior compartment of the forearm. The posterior compartments of the arm and forearm are often called the ‘extensor compartments’ as they contain muscles that extend the elbow, wrist and digits. The radial nerve courses around the humerus in the arm creating a spiral groove. The lateral and medial heads of triceps brachii attach to the humerus either side of this groove. As the radial nerve is close to the bone here, **it can be damaged by a mid-shaft fracture of the humerus.**

Question 57

function of anterior compartment of the arm? muscles? Innervation?

Answer 57

flexors of arm and elbow biceps brachii, coracobrachialis, brachialis innervation = musculocutaneous nerve

Question 58

Most anterior muscle in anterior compartment? origin and insertion? function? innervation?

Answer 58

biceps brachii origins * long head = supraglenoid tubercle of scapula (forms tendon that creates groove at proximal end of humerus) * short head = coracoid process of scapula insert into radial tuberosity functions = supination (most powerful supinator of the forearm) + flexion of the elbow (also weak flexion of arm), long head prevents head of humerus moving superiorly, short head resists dislocation innervation = musculocutaneous nerve (C5, 6)

Question 59

coracobrachialis origin? Insertion function? innervation? landmark?

Answer 59

Coracobrachialis is a small muscle, its name tells you it attaches to the coracoid process of the scapula inserts medial mid-shaft humerus crosses anterior surface of glenohumeral joint so flexes arm (also adduction) innervation = musculocutaneous nerve (C5-7) musculocutaneous nerve acts as a landmark for this muscle - as the musculocutaneous nerve divides from the lateral cord, it usually pierces coracobrachialis (Coracobrachialis does not cross the elbow joint, so cannot act on this joint)

Question 60

brachialis origin? Insertion? located? function? Innervation?

Answer 60

distal half of anterior surface of humerus inserts on ulnar tuberosity and coronoid process located under biceps brachii function = flexion of the elbow Innervation = musculocutaneous nerve (C5, 6) (+ small component of lateral fibres from radial nerve C7) (It attaches to the ulna, so is not involved in pronation and supination of the forearm. It is the most powerful flexor of the elbow joint and it mainly innervated by the musculocutaneous nerve)

Question 61

posterior compartment of the arm? origin? Insertion? Function? Innervation?

Answer 61

posterior compartment of the arm is filled by triceps brachii Origin * long head from infraglenoid tubercle of the scapula * medial head from posterior surface of shaft of humerus (inf. to radial groove) * lateral head from humerus (superior to radial groove) inserts into olecranonon of the ulna function = extends elbow joint, long head resists dislocation innervation = **radial nerve (C6-8)** (It attaches to the ulna, so is not involved in pronation or supination, but crosses the posterior surface of the elbow joint so is an extensor of that joint) (the medial and lateral heads originate from the humerus but the long head attaches to the infraglenoidtubercle of the scapula)

Question 62

brachial artery? function? branches?

Answer 62

continuation of axillary artery once it has crossed inferior border of teres major brachial artery supplies arm via its branches * deep brachial artery (profunda brachii) = forms radial collateral artery + sup. and inf. ulnar collateral branches * radial and ulnar collateral arteries form anastamosis around elbow joint * Terminal branches of brachial artery = radial + ulnar arteries in cubital fossa

Question 63

…

Answer 63

The slide shows the arterial anastomosis around the elbow joint. Note that the collateral branches from the brachial and profunda brachii arteries join with recurrent arteries from the radial and ulnar arteries. The ulnar artery then goes onto to form a common interosseous branch that forms anterior and posterior interosseous branches to supply the deep structures of the forearm.

Question 64

how do these structures reach the area they supply?

Answer 64

The brachial artery and median nerve cross the anterior surface of the humerusto enter the cubital fossa. The musculocutaneous nerve lies under biceps brachii and divides to supply the anterior compartment of the arm. The radial and ulnar nerves must pass through the lateral and medial intermuscular septa respectively to reach the forearm.

Question 65

…

Answer 65

This cross section also shows the basilic and cephalic veins in the arm. Note how the basilic vein has passed to a deeper position in the arm (it is the main tributary of the axillary vein) but the cephalic vein remains very superficial as it passes towards the delto-pectoral groove.

Question 66

distal humerus provides attachment for? medial epicondyle? lateral epicondyle?

Answer 66

distal humerus provides attachment for muscles of the arm (brachialis and coracobrachialis) and forearm (brachioradialis and extensor carpi radialis longus etc) medial epicondyle provides attachment for muscles of the anterior compartment of the forearm i.e. **common flexor origin** lateral epicondyle provides attachment for extensors of wrist and digits i.e. **common extensor origin**

Question 67

articulation of the elbow joint?

Answer 67

is between the rounded capitulum of the humerusand the head of the radius and with the trochlea of the humeruswith the ulna

Question 68

posterior surface distal humerus provides attachment for? function of …?

Answer 68

posterior surface distal humerus provides attachment for triceps brachii and anconeus Anconeusextends the elbow and is innervated by the radial nerve

Question 69

boundaries of the cubital fossa?

Answer 69

* Lateral = brachioradialis * Medial = pronator teres * Roof = skin, fascia and bicipital aponeurosis * Floor = brachialis

Question 70

where are veins in cubital fossa found? Which veins? pathways?

Answer 70

superficial veins of cubital fossa lie in superficial fascia above bicipital aponeurosis cephalic and basilic veins comunicate via madian cubital vein (altough there is variation) The cephalic vein drains the lateral side of the dorsum of the hand, passes along the roof of the anatomical snuffbox, then runs up the lateral side of the forearm to reach the cubital fossa. The basilic vein drains the medial side of the dorsum of the hand and the medial forearm before reaching the cubital fossa

Question 71

medial cutaneous nerve of forearm derived from? lateral cutaneous nerve of forearm?

Answer 71

Medial cutaneous nerve of the forearm = derived directly from the medial cord of the brachial plexus Lateral cutaneous nerve of the forearm = the terminal branch of the musculocutaneous nerve (a branch of the lateral cord of the brachial plexus)

Question 72

contents of cubital fossa?

Answer 72

from medial to lateral = median nerve, bifurcation of brachial artery into ulnar + radial, tendon of biceps, (radial nerve) deep veins accompanying the arteries are also present (radial nerve not within the fossa but skirts its lateral boundary as it lies under brachioradialis) (brachial artery usually accompanied by several brachial veins)

Question 73

…

Answer 73

The arteries around the elbow joint form an anastomosis The slides show the inferior ulnar collateral branch of the brachial artery, the radial recurrent branch of the radial artery and the ulnar recurrent branch of the ulnar artery

Question 74

elbow joint? why is movement restricted to flexion + extension? what surrounds the joint? other movement that takes place at elbow joint?

Answer 74

The elbow is a synovial hinge joint between the humerus, radius and ulna The shape of the bones + collateral ligaments restrict movement to flexion and extension * medial + lateral collateral ligaments prevent abduction/adduction A capsule surrounds the joint = crossed by brachialis anteriorly (with the median nerve and brachial artery) and crossed medially by the ulnar nerve as it passes around the posterior surface of the **medial** epicondyle of the humerus Pronation + suppination * THead of the radius moves against the rounded capitulum of the humerus * An annular ligament wraps around the neck of the radius to facilitate this movement

Question 75

synovium of elbow joint? what passes around medial epicondyl? Lateral epicondyle?

Answer 75

The synovium of the joint extends to form bursae = there is a bursa associated with the subcutaneous tissue at the **posterior** surface of the elbow The ulnar nerve passes around medial epicondyle to reach the anterior compartment of the forearm Radial nerve wraps around the lateral epicondyle to reach the posterior compartment of the forearm (also supplies cutaneous innervation)

Question 76

bursae of elbow joint?

Answer 76

subcutaneous olecranon bursa subtendinous bursa of triceps brachii

Question 77

medial and lateral collateral ligament function? what is lateral collateral formed from?

Answer 77

The medial and lateral collateral ligaments prevent abduction and adduction at the elbow Lateral collateral ligament (radial collateral ligament) is formed from one band that communicates with the annular ligament around the neck of the radius

Question 78

parts of lateral collateral ligament? Medial collateral ligament?

Answer 78

lateral collateral ligament is formed from one band that communicates with annular ligament around the neck of the radius medial collateral ligament has 3 parts: * anterior, posterior + oblique part * (more complicated shape helps to support the deeper bony cavity on the medial side of the elbow joint between the humerus and ulna)

Question 79

How can you tell which is medial side? function?

Answer 79

sharper interosseous border on the medial edge of the shaft of each bone This forms the attachment site of the interosseous membrane that lies between and supports the radius and ulna The subcutaneous border of each bone is smooth and can be felt if you run your fingers down your forearm, as can the styloid processes of each bone at the wrist.

Question 80

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Answer 80

The slide shows the origins and insertions of muscles to the radius and ulna. Some of the deeper muscles of the forearm also gain attachment from the interosseous membrane between the bones

Question 81

Answer 81

Pectoralis major, and beneath it, pectoralis minor lie on the anterior wall of the thorax, pectoralis major inserts into the outer lip of the bicipital groove and so crosses the anterior surface of the glenohumeral joint – this allows it to flex the arm at this joint. Pectoralis minor does not cross the glenohumeral joint but attaches to the coracoid process of the scapula allowing it to tilt the scapula forwards and downwards.

Question 82

Answer 82

Latissimus dorsi is a large flat muscle that passes from the posterior wall of the thorax and abdomen, wraps around the lateral wall and then inserts into floor of the bicipital groove. It crosses the posterior surface of the glenohumeral joint, so can extend it. It attaches to the larger/heavier body wall and passes laterally to the smaller, lighter humerus, so when it contracts it can drag the humerus towards the body wall – adduction. This is a characteristic it shares with pectoralis major. Photograph A shows latissimus dorsi as it passes across the body wall and photograph B shows the tendon of latissimus dorsi as it passes to insert on the humerus.

Question 83

Answer 83

Serratus anterior attaches laterally to the upper 8 ribs and inserts into the medial border of the scapula. To do this it passes between the scapula and the body wall. Photograph A shows serratus anterior on the lateral wall of the thorax. Photograph B shows serratus anterior passing towards the scapula on the posterior body wall and photograph C shows serratus anterior attaching to the medial border of the scapula. Photograph C shows a view you do not normally see during dissection, as the entire upper limb has been detached from the body wall, so that the anterior surface of the scapula can be observed. Not all of the muscle is visible as it had to be sectioned to remove the scapula from the body – only the remnants of the muscle are outlined by the dotted white line. Serratus anterior acts to protract the scapula.

Question 84

Answer 84

Trapezius is one of the superficial muscle layer of the back (as is latissimus dorsi). It has fibres that run in different directions and pass between the head and neck, the scapula, clavicle and spinous processes of the vertebrae. This allows trapezius to elevate, depress, retract and rotate the scapula on the body wall. Photograph A shows part of trapezius but the upper attachments of the muscle are still hidden beneath the skin of the neck. Photograph B shows the muscles that lie immediately inferior to trapezius – rhomboid major and minor. They pass from the spinous processes of the thoracic vertebra to the medial border of the scapula and act to drag the scapula towards the midline – retraction of the scapula.

Question 85

Answer 85

Deltoid forms a muscular cap over the lateral side of the glenohumeral joint. Photograph A shows the anterior fibres of deltoid that attach to the clavicle. They cross the anterior surface of the joint and can flex the joint. The small piece of blue paper lies under the cephalic vein that runs in a groove between pectoralis major and deltoid before piercing the clavipectoral fascia and gaining entry into the axilla to drain into the axillary vein. Photograph B shows a posterior view of the scapula. The main bulk of deltoid passes across the lateral (or outer) surface of the joint and therefore acts to abduct the glenohumeral joint. Photograph B shows these fibres and also shows the posterior fibres of deltoid that pass to the spine of the scapula. They cross the posterior surface of the joint and can extend the joint. Deltoid is innervated by the axillary nerve, which is shown by the red plastic strip in photograph C. Deltoid has been partially reflected in this image to show the axillary nerve and the posterior circumflex humeral artery as they emerge from the quadrangular space.

Question 86

Answer 86

Photograph A shows a posterior view of the scapula of the left upper limb and photograph B shows the same view but of the right upper limb. Teres major muscle is labelled in both images (B has a red plastic strip under the muscle). The name teres major tells you it is cord-like structure in cross section and that there is a cord-like smaller ‘minor’ muscle elsewhere in the upper limb. Teres major passes from the lateral border of the scapula and inserts into the medial border of the bicipital groove. It acts to pull the humerus closer to the scapula – adduction.

Question 87

Answer 87

Photograph A shows the anterior surface of the scapula – you have already seen serratus anterior passing under the scapula to attach to the medial border earlier in this presentation. If serratus anterior is reflected then the muscle shown in photograph B is revealed. The name subscapularis tells you it lies under the scapula – it attaches to the anterior surface of the scapula that lies against the posterior body wall. Subscapularis is part of the rotator cuff muscles that pass from the scapula to the humerus and help hold the head of the humerus against the shallow glenoid fossa of the scapula, they help to prevent dislocation of the joint. Subscapularis is the odd one out of the rotator cuff – it lies on the anterior surface of the scapula (the rest are posterior), it attaches to the lesser tubercle of the humerus (the rest insert on the greater tubercle) and it acts to medially rotate the humerus (the others abduct or laterally rotate).

Question 88

Answer 88

The next rotator cuff muscle is supraspinatus. It is also difficult to see during dissection, as it lies under trapezius. Photograph A shows a posterior view of the scapula with the cut ends of trapezius still attached to the spine of the scapula. Photograph B shows the same posterior view but with trapezius reflected to reveal supraspinatus lying in the supraspinous fossa of the scapula. Supraspinatus inserts onto the upper facet of the greater tubercle of the humerus so crosses over the joint to attach to the lateral side of the humerus – allowing supraspinatus to abduct the humerus. Compare the size of this muscle to deltoid – deltoid is much larger, stronger and performs the majority of abduction of the arm. Supraspinatus initiates abduction – starting the first 10-15 degrees or so of the movement.

Question 89

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Answer 89

The next member of the rotator cuff is infraspinatus. It lies in the infraspinous fossa of the scapula and passes to insert onto the middle facet of the greater tubercle of the humerus. It is a small lateral rotator of the arm. Photograph A is a posterior view of the left scapula and shows the thick layer of fascia that overlies infraspinatus. Photograph B shows the same view but of the right scapula. The fascia has been removed to reveal infraspinatus (shown by the red plastic strip).

Question 90

Answer 90

The final muscle of the rotator cuff is teres minor. It attaches to the lateral border of the scapula and inserts into the lower facet of the greater tubercle of the humerus. It also acts to laterally rotate the arm. It is shown in photograph A by the red plastic strip. Try to remember that teres minor is part of the rotator cuff but teres major is not. Teres major inserts further down the humerus so cannot support the humerus in the same fashion as teres minor. Photograph B is a posterior view of the left scapula showing many of the muscles described in this presentation.

Question 91

Answer 91

The axilla is an anatomical space that lies between the lateral thoracic wall and the humerus. The pectoral muscles form part of the anterior boundary and must be reflected to show the structures that lie within the axilla. Photograph A shows pectoralis major in-situ, with the skin of the floor of the axilla removed to reveal the fat that supports the neurovascular structures beneath. Photograph B shows pectoralis minor reflected to give a better view of the axilla and photograph C shows the axilla after the removal of some of the fat and fascia. The axillary vein is the most superficial structure in the axilla and it is just becoming visible in photograph C.

Question 92

Answer 92

Although the axillary artery receives more attention during your dissection classes, the axillary vein is also an important vessel. It is a continuation of the basilic vein and receives blood from the brachial veins of the arm and from the cephalic vein. It begins at the inferior border of teres major and becomes the subclavian vein at the lateral border of the first rib. Its tributaries are named in a similar fashion to the branches of the axillary artery, though you will not be expected to identify them, just the main axillary vein. Photograph A and B show the axillary vein and smaller veins draining into it.

Question 93

Answer 93

The axillary artery lies inferior to the axillary vein. The red plastic strips and the scissors have been placed under the artery in this photograph. The axillary artery is a continuation of the subclavian artery at the lateral border of rib 1 and becomes the brachial artery at the inferior border of teres major. Pectoralis minor overlies the artery (in this photograph it is reflected to allow you to see the artery) and divides it into 3 parts. In this photograph you can also see parts of the brachial plexus surrounding the artery.

Question 94

Answer 94

The first part of the axillary artery lies proximal to pectoralis minor. It has one branch – the superior thoracic artery (shown in photograph A). The second part of the axillary artery lies posterior to pectoralis minor and has 2 branches – the thoracoacromialand lateral thoracic arteries (shown in photograph B).

Question 95

Answer 95

The third part of the axillary artery lies distal to pectoralis minor and has three branches. – the anterior and posterior circumflex humeral arteries and the subscapular artery.

Question 96

Answer 96

The brachial plexus of nerves lies in the axilla and supplies motor and sensory innervation to the upper limb. The roots lie in the neck and will be visible during deep dissection of the triangles of the neck. The trunks pass under the clavicle and it is the cords and their terminal branches that are easier to identify during dissection of the axilla. The cords are named in relation to the axillary artery – a lateral cord and a medial cord (shown in photograph A) and a cord that lies posterior to the artery. The medial and lateral cords form the musculocutaneous nerve, the ulnar nerve and the median nerve as their terminal branches, this creates the ‘M’ shape seen in photograph B.

Question 97

Answer 97

Photograph A shows the large terminal branches of the lateral cord – the musculocutaneous nerve and the lateral part of the median nerve. Prior to forming these nerves the lateral cord also forms the lateral pectoral nerve. The musculocutaneous nerve is usually easy to identify as it passes from the ‘M’ shape to pierce coracobrachialis. Photograph B shows the large terminal branches of the medial cord – the ulnar nerve and the medial part of the median nerve. Prior to forming these nerves it also forms the medial pectoral nerve and the cutaneous nerves of the arm and forearm.

Question 98

Answer 98

Photograph A shows the large terminal branches of the lateral cord – the musculocutaneous nerve and the lateral part of the median nerve. Prior to forming these nerves the lateral cord also forms the lateral pectoral nerve. The musculocutaneous nerve is usually easy to identify as it passes from the ‘M’ shape to pierce coracobrachialis. Photograph B shows the large terminal branches of the medial cord – the ulnar nerve and the medial part of the median nerve. Prior to forming these nerves it also forms the medial pectoral nerve and the cutaneous nerves of the arm and forearm.

Question 99

Answer 99

The axillary artery and the lateral cord have been gently reflected in photograph A, to show the posterior cord and one of its large terminal branches – the radial nerve. Photograph B shows another terminal branch of the posterior cord - the axillary nerve, this lies deep in the axilla and wraps around the humerus close to the joint capsule. The posterior cord will also form the upper and lower subscapular nerves and the thoracodorsal nerve. The thoracodorsal nerve is shown in photograph C.

Question 100

Answer 100

The terminal branches of the posterior cord supply motor and sensory fibres to the posterior compartments of the arm and forearm. To do this, they must leave the anterior surface of the body and pass into the posterior aspect of the arm. The axillary nerve passes through the quadrangular space (photograph A) and the radial nerve passes through the triangular space/hiatus (photograph B). This will be shown in greater detail in the arm and cubital fossa dissection presentation.

Question 101

Answer 101

In anatomical terminology the ‘arm’ lies between the shoulder and the elbow. The anterior compartment of the arm contains flexors of the arm and elbow that are innervated by the musculocutaneous nerve. Photograph A shows the anterior compartment of the arm still covered in skin. In some individuals it is possible to see the superficial veins through the skin, especially the cephalic vein. Photograph B shows the same arm with the skin removed and the cephalic vein preserved. The vein runs from the lateral side of the dorsum of the hand, along the lateral side of the forearm, communicates with the basilic vein at the cubital fossa and then passes superiorly to run in the deltopectoral groove before piercing the clavipectoral fascia to join the axillary vein. Photograph C shows the cutaneous nerves that lie in the superficial fascia with the cephalic vein. You may have already seen the medial cutaneous nerve of the arm as it originated from the medial cord of the brachial plexus.

Question 102

Answer 102

The most superficial muscle of the anterior or flexor compartment of the arm is biceps brachii. Its name tells you it has two heads and runs along the brachium (or arm). The more medially placed short head attaches to the coracoid process, the long head forms a tendon that creates the bicipital groove on the humerus before crossing the joint to attach to the supraglenoid tubercle of the scapula. Biceps brachii tendon inserts onto the radius and biceps brachii also forms an aponeurosis at the cubital fossa. Biceps brachii is a powerful supinator of the forearm and can flex the elbow.

Question 103

Answer 103

Also attaching to the coracoid process of the scapula is coracobrachialis (visible in photograph A). Coracobrachialis crosses the anterior surface of the glenohumeral joint so can flex the arm. It inserts onto the humerus, so cannot flex the elbow. You have now seen 3 muscles that attach to the coracoid process of the scapula – biceps brachii (short head), coracobrachialis and pectoralis minor. Photograph B shows brachialis, it originates from the humerus just below deltoid and crosses the anterior surface of the elbow joint to attach onto the ulna. It is the most powerful flexor of the elbow joint. All of the muscles of the anterior compartment of the arm are innervated by the musculocutaneous nerve.

Question 104

Answer 104

The posterior compartment of the arm contains the main extensor of the elbow joint – triceps brachii (shown in photograph A). Its name tells you it has 3 heads – a medial, lateral and long head. The medial and lateral heads attach to the humerus either side of the spiral groove and the long head passes to the infraglenoidtubercle of the scapula. Distally, triceps brachii crosses the posterior surface of the elbow joint to insert into the ulna. It acts to extend the elbow joint and is innervated by the radial nerve. The long head of triceps brachii forms the medial boundary of the quadrangular and triangular spaces. Photograph B shows the quadrangular space – the humerus forms the lateral boundary, teres minor forms the superior boundary and teres major the inferior boundary. Photograph C shows a closer view of the contents of the quadrangular space – the axillary nerve and the posterior circumflex humeral artery (and vein).

Question 105

Answer 105

The long head of triceps brachii forms the medial boundary of the triangular space. This ‘space’ is also called the triangular hiatus or interval. The humerus forms the lateral boundary of the triangle and teres major the base (shown in photograph A). Photograph B shows a closer view of the contents of the triangular space – profunda brachii artery and the radial nerve.

Question 106

Answer 106

The brachial artery supplies blood to the arm. It is a continuation of the axillary artery at the inferior border of teres major and passes through the anterior compartment of the arm to divide into its terminal branches of the radial and ulnar arteries at, or near, the cubital fossa. This is shown in photograph A. The brachial artery forms several branches in the arm, the superior and inferior ulnar collateral arteries and muscular branches. It also forms the deep brachial artery – usually called profunda brachii that passes through the triangular space with the radial nerve. Photograph B shows some of these branches. The ulnar collateral arteries (with a radial collateral branch from profunda brachii) contribute to the arterial anastomosis around the elbow joint.

Question 107

Answer 107

The cubital fossa is an anatomical space that lies anterior to the elbow joint. The roof is made of skin and the bicipital aponeurosis. Superficial veins and nerves run in the superficial fascia of the roof. Photograph A shows the cephalic vein, which usually communicates with the basilic vein somewhere in or near the fossa. In many texts they will describe a ‘median cubital vein’ between the two vessels. It is very common not to find this pattern and some individuals (as shown in photograph A) have a long vein that communicates with the cephalic vein instead. Photograph B shows pronator teres forming the medial boundary of the cubital fossa and brachioradialis forming the lateral boundary. The contents of the cubital fossa, from medial to lateral are: the median nerve, the brachial artery and the tendon of biceps brachii.

Question 108

Answer 108

Photograph A shows a deeper dissection of the cubital fossa. The tendon of biceps brachii can be seen, as can the division of the brachial artery into radial and ulnar arteries. It is also possible to see brachialis forming the muscular floor of the cubital fossa as it crosses the anterior surface of the elbow joint. Photograph B shows a closer view of the ulnar and radial arteries. It shows the small anterior ulnar recurrent artery as it branches from the ulnar artery. It contributes to the arterial anastomosis around the elbow joint. The ulnar artery will then form a common interosseous branch that divides to form anterior and posterior interosseous branches – these vessels will be described further in the forearm presentations