anat:lect note upper limb-shoulder

8/8/2019 ANAT:Lect Note Upper Limb-shoulder

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THE UPPER LIMB: SHOULDER

Divisions of the upper limb, if you remember, we talked about skeletal system (in the introduction), we

said appendicular skeleton and axial. The appendicular, we mean by upper and lower limbs. Each limb,

in order to be attached to the axial skeleton, we have a special structure called girdle.

For the upper limb, we have pectoral girdle, for lower limb we have pelvic girdle. Before I start talking

about pectoral girdle, just a view of different regions, this part refers to the pectoral girdle, specifically 2

bones:

1) clavicle-anterior border2) scapula-posteriorly

The region from the shoulder to the elbow joint, we call it the arm. And the bone in this region is the

humerus. From the elbow joint to the wrist, we call it the forearm made of 2 bones, because we have

muscles, nerves, arteries, veins. Were just trying to call it from different regions and distal to it, we have

the hand, carpal bones, metacarpal bones and phalanges.

So, the pectoral girdle, again, for having strut structure is like for same reason we have a strut in a car.

Without bone, if it bumps on the road, to be immediately tilted by the body of the car. So, we have a

joint, a strut, that will absorb the shock and smoothly transfer it to the body. Same principle in our body.

SPECIAL THANKS TO:

NUR NUHA ADALIA AIN

FARAH HANISAH SITI FATIMAH

NAJWA AIMAN ABU BAKAR

AINAA NADIA WAN MUHAMMAD NAJIB

MARYAM JAMEELAH NORFARAHIN

AMIRAH LABIBAH NUR LIYANA


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the bone will withstand more and more forces without fracture. And the importance of clavicle as Ive

just told you, its a shock absorber. This is the main job.

It absorbs shock from the upper limb if you punch someone, if you receive a trauma to your hand, it will

be transmitted, smoothened by this pectoral girdle plus it has protective function to protect the blood

vessels and structures that lie posterior and anterior to it. Just 1 thing about clavicle that makes it proneto fractures. It is subcutaneous through its entire limb.

So, its just covered by the skin and superficial fascia. There is no muscle on top, usually there is no fat.

If you put your finger, you will feel the bone immediately. So, iftheres a trauma in this region, there is

no cushion to protect the clavicle. This is why the clavicle fractures is common. Why? Because it is

subcutaneous through its entire limb. This is what happens when the fracture occurs, usually it will

affect medial and lateral third. The lateral third force the cavity connected to the shoulder will go down

and the medial will go up.

This site, we call it the shoulder drop, as it will be accompanied by medial rotation of the humerus. So

far, in addition to the powerpoint presentation, we said that clavicle is a shock absorber. 2nd,its

subcutaneous, which make it prone to fractures.

Now, well talk about the scapula. The scapula is the 2nd part of the pectoral girdle. This bone is a flat

bone, triangular in shape. So, triangular, it will have 3 angles, right?

We have superior angle, inferior angle, plus the lateral angle is transformed into a structure we call

glenoid cavity. So,the shape, concave surface that consume the humerus for the articulation with

humerus. It has 2 surfaces. The surface that lies against the thoracic cage, we call it costal and it is the

limb of the surface from the 2nd to 7th ribs. The posterior surface, it has a spinous process in the middle,

so its divided into 2 parts. The posterior surface of the scapula is divided into two parts by its spinousprocess.

Somebody asked Q, and the dr said: oh sorry. This right in the middle is the spinous process. It will

continue and become what? The Acromion Process. So the spinous process and the acromion process

are continuous with each other.

What these spinous process does? It divides the posterior surface into two fossa. The Supraspinous

fossa and the Infraspinous fossa. While the anterior surface has one fossa, we call it Subscapular fossa.

[slide 9]

This is different view of scapula, an anterior view, posterior view, and a lateral view where you can see

there is a depression cavity; which is the Glenoid Cavity for articulation. And there is one thing about the

cavity. It is not deep. So the articulation will not be stable by itself. Meaning, to strengthen this

articulation. And you will see how in a minute. And the function of the pectoral girdle is to attach the

upper limb. Which part of the upper limb? The arm. What is the bone of the arm? The humerus.


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And you must make two articulations. At the shoulder joint and at the elbow joint. Here it articulate

with the scapula, and at the elbow joint,it articulate with two bones. The radius and the ulna. The detail

information that you see here [slide 10], about the names of the different regions, the articulation

surfaces and the depression of the arm, I will cover them when we talk about the arm.

Ok, at first we talk about the joint and articulations here, and I told you wherever the bones cometogether, we need to have a joint. There are 3 main joints in the shoulder region. [slide 12]

The sterno-clavicular, between the sternum and the clavicle.

The acromio-clavicular, between the acromion process and the clavicle.

The shoulder joint or we call the Gleno-humeral joint between the glenoid cavity of scapula and the

humerus.

[slide 13] And this is the questions which you have to answer about the joints,the type of joints. Which

surfaces make its articulation? What are the supporting ligaments? What kind of movements is

available? And the special structures for that joint.

[slide 14] Lets start with the sterno-clavicular joint. It is synovial (double plane). It has an articular disk

in the middle that is what we are talking about 2 joints. Two plane joints. The movement; we have the

anterior and posterior movement, where it take place in the medial compartment. The superior and

inferior movement is placed in the lateral compartment. So we have two compartments for the joint;

lateral and medial. Each is responsible for 2 movements.

Medial compartment: anterior-posterior movement / backward-forward movement

And the lateral compartment, at the features there is the articulation disk that will cause the shock

absorber.

[slide 15] The other joint that is the Gleno-humeral (shoulder) joint I think when we talk about the ball &

socket joint, we mentioned to you about the shoulder joint articulations you already know that the head

of the humerus and the glenoid cavity of scapule. And this joint is not fixed by itself. It fit together

because the humerus is not a complete bone. Its just one-third of a bone.(its not a complete

sphere.Just one-third of a bone)

So the articulation is not like this. It is like very shallow. So this will strengthen this joint. How? We have

ligaments. So by synovial joint, we have covering capsule which covers the structure. The bones, the

articular disk, etc.

[slide 16] If we cut the capsule, remove the head of the humerus this is what we will see (lateral view).

Inside the capsule we have 3 ligaments attaching the head of the humerus to the scapular. We call them

Gleno-humeral ligaments.

In addition to that, we have a ligament called transverse humeral ligament which extend between the

lesser tubercle and the greater tubercle of the humerus. Are these the only means which stabilize this


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joints? No. Write these down, to increase stability as we have a shallow hole or shallow cavity. You want

to make it deep. How? We build *not sure what doctor Ayman said]. So, what is done here is we have

cartilaginous margin called the glenoid labrum. This cartilaginous margin, increases the depth of the

glenoid cavity. The bone cavity is shallow, so on the margin we put another cartilaginous margin to

increase the depth of the glenoid cavity and this is called glenoid labrum.

[slide 18]Movement of shoulder joint,it is one of freely movable joint, there is a kind of movement

called circumduction which is composed of flexion, extension, abduction and adduction. The

characteristic of this joint, the fibrous capsule is weak inferiorly because as I told you in the abdominal

wall, if there is an opening in a wall this is a weakness. And this capsule has an opening to allow the long

head of triceps to pass through. So, this is the picture of triceps muscle of the arm, it has long head of

muscle to pass through the capsule. So, we have an opening then it is the part of weakness. Another

reason why the capsule is weak. The joint is surrounded by muscle and strengthen by muscle from 3

direction. Anterior, superior, posterior but not inferior. There is no muscle at the inferior surface. The

muscle that surround this joint we called it Rotator Cuff muscle.

[slide 19] The acromio-clavicular joint, synovial plane. It lies at acromion process and clavicle. It is

present by a ligament called acromio-clavicular ligament, superior and inferior. This is the joint Im

talking about, but the ligament is not apparent in this picture.


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Now, lets talk about muscle of the shoulder. Im talking about the the general muscle here so dont be

confused with the Rotator Cuff Muscle that just surround the shoulder joint. So, the muscle that

present at the shoulder region, we called Thoraco-appendicular Muscles, extend from the thoracic cage

and the upper limb which upper appendicular and Scapulo-humeral Muscles which extend from the

scapula to the humerus. So, two groups.

[slide 21] We have 4 muscles at the anterior Thoraco-appendicular Muscles, Pectoralis Major and Minor

(Muscles of the chest). The large muscle here is the pectoralis major. If we cut this muscle and we move

it, we will see the pectoralis minor and we can also see a small muscle inferior to the clavicle we call it

subclavius. And we have lateral here is the serratus anterior which filled up the space at the lateral part.

*slide 22+ Lets talk about the origin and insertion of each one plus the action. This muscle (pectoralis

major) innervated by medial and lateral pectoral nerves. This muscle will adduct the humerus. Beneath

this muscle we have pectoralis minor which is only innervated by medial pectoral nerve.


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And, Im gonna talk about something funny here. There is two nerve, medial pectoral nerve and lateral

pectoral nerve. If you look at the cadaver, the medial pectoral nerve is actually lateral. But why we

called it medial? Because its origin is medial to the origin of the lateral.

[slide 24] this picture I want you to know that the pectoralis minor is beneath the pectoralis major or

pectoralis major is superficial to pectoralis minor.

The serratus anterior muscle, why we called it serratus because the margin is serrated, supplied by long

thoracic nerve. And this long thoracic nerve is not supply ___ although it does not give motor

innervation to other muscles. . [not sure about the meaning of this sentence]. So, the action of serratus

muscle is actually the action of long thoracic nerve.

What this muscle does is keep the scapula in close contact with thoracic cage. It always in close contact.

Why? Because of this long thoracic nerve. So, the action of thoracic anterior muscle or the long thoracic

nerve is to keep the scapula in close contact with the thoracic cage. Mainly this function is done by longthoracic nerve. So, what will happen if you cut the long thoracic nerve or you damage the muscle? The

scapula will hang away from thoracic cage and there will be like harm in your back, we called it winged

scapula.

If the long thoracic nerve or the muscle is damaged, it will push the skin posteriorly. We called it winged

scapula. As you see, this is the cross-section that the scapula should be in close contact with the ribs.

Why? Because either the nerve or the muscle will damage. This is how it looks like. So, when you

bending your back, the scapula will be much much much more pronounced in the case of winged

scapula. Subclavius is just a small muscle, lying anterior to clavicle. Innervation, simple nerve to

subclavius.

Now we talk about the posterior thoracoappendicular muscle, or sometimes we called them extruded

muscle of the back. Why? Because they are surface in the back, have attachment to the back, but its

function is to move the upper limb.


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So, let's start with the large muscle. Most superficial we called it trapezius, trapezoid in shape. Beneath

this muscle, not beneath, I mean also in superficial we called it latissimus dorsi, triangular in shape. We

cut the trapezius out, to see two muscles here, rhomboidus major and rhomboidus minor connecting

the scapula to transverse process of vertebrae. And a muscle going down from superior angle, we called

it levator scapulae muscle.

The scapulo-humeral muscles, we have infraspinatous muscle, supraspinatous muscle. If we flip the

scapula, we can have subscapular and the muscle lies here is subscapularis. We also have two muscles

going from scapula to the humerus, one inserted posteriorly the other inserted anteriorly we called

them as teres minor and teres major.(not sure) Teres minor is inserted posteriorly, teres major is

inserted anteriorly to the humerus. And deltoid is like a cap muscle that surround the lateral

margin,anteroposterior lateral margin towards shoulder.

Now, we talk about rotator cuff muscles. What are the rotator cuff muscles? Cuff means, y3ni I have one

sheet surrounding my arm like this. So the shoulder joint have a cuff, a muscle coat made of four

muscles. And these four muscles surround the joint from only three directions. As we said, ___. So,

superior to the joint we have supraspinatous, anterior we have subscapularis while posterior we have

infraspinatous and teres minor.

Look at this picture, in anterior view, you see the part subscapularis. Superiorly, we have supraspinatous

that cover the joint. Posteriorly, we have two muscles, infraspinatous and teres minor. Teres major is

not part of rotator cuff muscles.

(First part of lecture ended here)

(2nd

lecture)

The last lecture we start talking about the upper limb and the last thing in the upper limb that we cover

is the pectoral girdle, which is the structure that connects the upper limb to the axial skeletal.

We talk about the skeletal part, the muscle andjoints that form the pectoral girdle, the next topic well

be talking about something that is also related to pectoral girdle.

So, this arrangement that having a girdle that connects the upper limb to the axial skeletal, it create

spaces in the shoulder region. Now,the reason Im going to tell you about triangular spaces that is

located in posterior aspect of the shoulder is because it is a landmark for me to know the certain

structures.

So as the name applies,its triangular in shape, of course,its a space so it has boundaries.The superior

boundary;Im talking about this small space here,triangular in shape. You see,there is an artery coming

out from this space. The superior boundary of this space is the teres minor muscle. The inferior

boundary is the teres major,and the lateral boundary is long head of triceps. Triceps is the muscle of the

posterior compartment of the arm. U will learn about it when we talk about the arm. So if I dissect that

region I will see an artery coming out,which is circumflex scapular artery.When I see the structure,Im

gonna tell u about it.


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The second space Im gonna tell u about is quadraangular space. Quadraangular space has 4 limbs. 5.30

It is lateral to triangular space. The superior boundary is teres minor, inferior boundary is teres major.

Medial boundary is long head of triceps. Lateral boundary is the surgical neck of humerus. Do u

remember? The structure that connects the shaft to the rest of the bone we call it surgical neck,ok?

And at that region,if I cut the connective tissue, we can see a nerve,which is the axillary nerve,and anartery which is the posterior circumflex humeral artery.It supply teres minor muscle,and it also supplies

the deltoid muscle.Those are 2 small spaces.

Now,Ill talk about large spaces,created by the anatomy of the shoulder girdle,which is the axillar. The

axillar is pyramidal in shape, the apex of that pyramid is directed toward the root of neck.And this space

is very important. Why?because it cointains the neurovascular bundle of the upper limb, which is the

nerve,veins and artery which supply the upper limb,they all pass through this space. Also it has which

is the lymph node,called the axillary lymph node. It is important because in metastasize of

cancer,especially in females breast cancer,u know,the most tricky region that is usually undiagnosed is

the axillary tail of breast which lie in the axillar.

And since its a pyramid,it has apex,base,and 4 walls.ok?Lets starts with the apex,as we said its directed

toward the root of the neck. It is bounded by..and lets do this together..(-lets determine the boundary

together-lets do it!) Posteriorly we have upper border of scapula, anteriorly we have the clavicle and

medially we have the first ribs. The base is actually formed by the skin that encloses the space.and this

skin extends from the arm to the thorax which is lateral aspect of the thorax.This is in the lateral-medial

direction.

What about the anterior-posterior direction? If u remember,we had talked about anterior axillary fold

and posterior axillary fold.They are the front and the posterior boundaries of your axilla,respectively.

The anterior axillary fold is made by the margin of the pectoralis major.

The posterior axillary fold is made by the margin of the lattisimus dorsi muscle.(ma hada bidduh haza

recorder?wa la akhuzuh?

(lecturer is asking,curious about a recorder that is recording his lecture without sohib.anyway u

shouldnt do this; recording the lecture without attending is really impolite-there will be no

barakah.Hopefully ALLAH give us maghfirah to be impolite,and the dr. forgive us.)

Anyway,i just would like to say sth. If u think to be absent with lame excuses, think it again and again.

Do the dr has an option to be absent like us? While the dr is very tired giving the lecture and before

that,think about the works behind the lecture itself-preparing themselves,the slides,etc- and we?we

choose to be absent just like that? Please be rational.lets improve.

The base of the pyramid,its gonna be rectangle. Ops sorry a square, because it has 4 limb. We have

basically the skin that extend from the arm to the lateral thorax and this is the lateral medial direction.

What about from back or the anterior posterior boundaries? It is made by the axillary fold. The anterior

axillary fold and the posterior axillary fold. This skin fold is usually ... with the ulnary muscle


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I cant hear this part. Sorry! Please check from the slide and book.

The anteriorly we have pectoralis major. Posteriorly we have the lattisimus dorsi muscle. We have talked

about the apex and the base.

Now ,moving to the anterior wall. This is the superior view. This is the humerus. this is the rib of the

thoracic cage. Scapula posteriorly and anteriorly is the anterior wall of the axilla.

As you see the muscular wall is made up of pectoralis major, pectoralis minor, and supperiorly

subclavius. Pectoralis minor is not (in here) just hide in space. It has fascia covering it and connecting it

to the clavicle and to the pectoral region we called it clavipectoral fascia. What is clavipectoral fascia?

The definition is there for you. A fascia is a layer that encased (cover) the pectoralis minor and extend to

encased the clavicle.

The posterior wall. In this picture if we move pectoralis major and if we remove pectoralis minor and we

remove...

(12.30) i cant hear anything. Sorry.

But some this is some info from the intenet about the posterior wall of the axilla: -

Three muscle that involve. The subscapularis muscle. The teres major and the latissimus dorsi. Inferior to

the subscapularis is the teres major muscle, which combines with the latissimus dorsi to form the

posterior axillary fold.

So,these are the 3 muscle that making the wall of posterior wall of the axilla. (teres major, latisimus

dorsi and subscapularis muscle.)

(please check from the book )

Now the medial wall. This is the medial wall, its made of the ribs, the first 4 ribs. And what lies on top of

this ribs? Laterally it is the serratus anterior muscle. This is the medial wall.

The lateral wall. you know, it just the part of the humerus part. This part, mainly the intertubercle

groove. and this intertubercle groove contain, houses the, long head of biceps

So this is for the boundary of the axilla

Now, the contents of the axilla is four structure. Which are the axillary artery, the axillary vein, the

axillary lymph nodes and the brachial plexus.

We start with the axillary artery. The axillary artery is the continuation of the subclavian artery so the

subclavian artery will crosses the first rib on the outer boundary, I stop say it subclavian. Now it is called

axillary artery. I continue calling it axillary artery until the lower border of the teres major muscle. So this

is the length(?) of the axillary artery. From the outer border of the first rib to the lower border of the

teres major muscle. Are we cool so far?~cool~
http://download.videohelp.com/vitualis/med/mmp-b-s.htm#Teres_major_musclehttp://download.videohelp.com/vitualis/med/mmp-b-s.htm#Latissimus_dorsi_musclehttp://download.videohelp.com/vitualis/med/mmp-b-s.htm#Latissimus_dorsi_musclehttp://download.videohelp.com/vitualis/med/mmp-b-s.htm#Teres_major_muscle


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Now this axillary, and what does it become? It become the brachial artery after that.

Now lets talk about the axillary artery. Its divided by the pectoralis minor muscle into three division. So

the first part; It extend from the outer border of the first rib until the medial border of the pectoralis

minor muscle.

The second part of the artery lies beneath or underneath the pectoralis minor muscle. The third part

extends from the lateral border of the pectoralis minor until the lower border of the teres major muscle.

Straight forward right?-inshaALLAH-

Now we gonna talk about the branches that comes from each part. The first part we have only one

branch, which is the highest thoracic artery or we called it superior thoracic artery. Do you still

remember, the thorax we said that the first two intercostals spaces have intercostals artery emanating

from the aorta but rather we have an artery called superior thoracic artery that supplies both. This is the

superior thoracic artery that we talked about.

What about the second part of the axillary artery? We have 2 branches;The thorachoacromion artery

and the lateral thoracic artery. These are two branches from the second part.

What about the third part? It has also , u may consider2 or 3 branches. The first branch we have the

subscapular artery and the second is the anterior and posterior circumflex humeral artery. They hold the

surgical neck and they anastomoses with each other. So we can consider this is one or two(because it

anastomose wth each other)

So between these branches, which is the largest branch?We like this in anatomy. Which is the largets

brach..the smallest brach..It is the subscapular artery. So the subscapularis artery is the largest branch

of the axillary artery,ok?

And notice, the vein is located, medial or lateral to the artery? Medial.So the axillary vein lies medial to

the artery.

[Refer to slide 44 for better understanding about the location of axillary vein].

Scapular Anastomoses

Before jumping to the vein, we can talk about important structure or important phenomena in the

shoulder called scapular anastomoses. I defined what anastomoses means in the introduction.

Anastomoses = when difference branches or difference arteries that supplying difference things meet

together. (anastomoses with each other)

Scapular anastomoses refer to anastomoses between branches of subclavian and branches of axillary

artery. Why do u think Allah made this anastomoses in our body? We think Its because of the prime

mobility in the shoulder that sometimes, these movement,difference positions might lead to kinking or


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building(?) of the axillary artery. And this is serious. The blood supply to the upper limb will be shortage.

So we need the blood to be continuously flow. So if there is something wrong happen to the axillary

artery, we need a bypass/a collateral circulation from the subclavian to be able to reach the upper limb.

*notes from the book pg 458 the extreme mobility of the shoulder joint may result in kinking of the

axillary artery and a temporary occlusion of its lumen. To compensate for this, an important arterialanastomosis exist between the branches of the subclavian artery and the axillary artery, thus ensuring

that an adequate blood flow takes place into the upper limb irrespective of the position of the arm.

Refer to slide 46 because the dr is explaining the blood flow. - This is what we have here. We have the

superficial cervical artery and suprascapular artery which is the branches of subclavian artery. They

anastomoses with the subscapular artery of axillary. Usually the flow of blood is flow down from the

subclavian artery and flow down from axillary. But what happen if there is a blockage whether it is

because of thrombus or kinking of the artery, the blood will have reverse flow. The blood will flow from

subclavian as normal but it will continue to go up to subscapular artery to supply the upper limb. Is that

clear?

Id like u to know,which artery involved in this anastomoses.

Clinical importance,Whether it is because of kinking, due to hyper movement of the shoulder joint or

whether it is because of thrombus when we have atherosclerosis, these anastomoses will rescue the

upper limb. It will make sure the blood is flowing.

Axillary Vein

When we talk about vein we start from distal and going proximal. Axillary vein is form by union of the

basilic vein and brachial vein. Basilic is superficial. Brachial is deep and becomes superficial in the last

part. They unite together to make axillary vein. Axillary vein later will unite with the cephalic vein to

form subclavian vein. So, its made of the brachial basilic vein ,it will contribute to the formation of

subclavian vein. And axillary vein is medial to the axillary artery. Axillary veins started and end at:-

Start :- at lower border of teres major (by union of: brachial veins + basilic vein)

Ends:- Lateral border of 1st

rib to become subclavian vein.

Axillary Lymph Node

We will talk about the axillary lymph node. We have 5 groups. Lymph node are defense system in

general . Usually its collapsed in cadaver. So its hard to identify the location of each component. So the

theory will be not that enough for us. We have 5 groups:-

1. Pectoral (anterior)2. Subscapular (posterior)3. Humeral (lateral)


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4. Central5. Apical

All of the 1st three points will drain to the central. The central will collect the lymph and drain to the

apical group. The apical group will contribute to the formation of subclavian trunk. The afferent vessels,

we talk about lymphatic, we have upper; carrying the lymph to the lymph node and efferent carryng thelymph from the lymph node. [The lymph vessels that carry lymph to a lymph node are referred to as

afferent vessel; those that transport it away from a node are efferent vessels].

Its medial to axillary vein. So we can talk about the arrangement:- axillary artery medial to it axillary

vein and medial to it is the apical axillary lymph node. [From lateral to medial; axillary artery axillary vein axillary lymph node]

When there is problem with the lymph node, it will be manifested by an enlargement of the lymph

nodes or suddenly u will able to feel nodules underneath your skin. This is an inflamed lymph node and

could be tender. *Not painful but tender which mean its only painful when we touch it]. This could be a

very simple inflammation due to infection or could be a very serious condition like metastases of cancer.

Brachial Plexus

Now the last component of the axilla that we gonna talk about and focus on both theory and practical

exam is the brachial plexus. Remember when we discussed about spinal nerve, we said that spinal nerve

is formed by the union of anterior and posterior roots. Spinal nerve is very short because its almost

immediately splits into anterior and posterior rami. The posterior rami, they like to be separated. They

dont fuse with upper and lower posterior rami.

The anterior one, they tend to make plexus. So they fuse with each other to make a complex network of

nerve. Usually it occurs when supply the structures like upper limb or lower limb. So brachial plexus is a

complex network made by the union of the anterior rami of the C5, C6, C7, C8 and T1 spinal nerves. And

this network will end up supplying the upper limb including the pectoral girdle. So, the anterior rami will

merge together to form what we called trunks. So the 5 roots will end up forming 3 trunks. Each trunk

contains anterior and posterior division. At this division again will fuse with each other forming cords.

And the cords will have terminal branches.

So the 5 roots will end up forming 3 trunks. These trunks will make divisions; anterior and

posterior.These divisons,again, will fuse with each other forming cords. And the cords will have terminal

branches. Notice that the roots,trunks,and divisions all are located in the posterior triangle of the neck.

The only part of brachial plexus that is located in the axillar actually is the cords and the terminal

branches. Of course, the specific location of the trunks for example, as u can see is above the clavicle,the

divisions,they lie posterior to the clavicle.But still,they are in the posterior triangle of the neck.

This picture is just summarizing the location of different parts ya3ni when u study something, u starts

with something simple then move to more complex. Ya3ni u will memory every single branch of the

brachial plexus but in the exam, u will forget that it has 5 roots.(u wont forget enshaALLAH if u


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follow the what doctor said.) So start build information step by step. So this is the brachial plexus with

all the branches. This is the number here, we have 5 roots,3 trunks, 6 divisions,3 cords and 16 nerves.

How many roots do we have ? 1,2,3,4,5(doctor is counting cutely) And these will merge to form 3

trunks. Each trunk will get 2 divisions, so the total is 6 divisions and these divisions will unite to form 3

cords within the internal branches,in addition different branches originating from different parts.

Lets starts with the roots. How many branches coming from the roots? We have only 2 branches. 2

nerves.The long thoracic nerves which supply the serratus anterior and the dorsal scapular nerve which

supply the rhomboid major and minor plus the levator scapulae muscle. So we have only 2 branches

coming from the roots.

What about the trunks? Only 2 branches also. Nerve of subclavius which supply the subclavius muscle

and the suprascapular nerve which supply the supra and infraspinatous muscle.

Now the divisons we have anterior and posterior divisons. Notice that all the posterior divisons make

the posterior cords. The anterior divisons of the first 2 trunks, they make the lateral cords. The anterior

divisions or the medialthis is lateral cord,posterior, and this is medial cords. The divisons, this is

anterior,this is posterior, this is anterior,this is posterior,this is posterior and this is anterior.

I didnt show u this from the beginning because it has 2 mistakes in them. 1st mistake:, they call the

nerve, subclavius nerve,sometimes we have different terminologies in the different text book.2nd

mistake: The medial pectoral nerve,they make it comes from the divisions,but actually it comes from the

medial cords. So this should make things easier, regarding the trunks and the divisions.

Lets continues discussing different nerve alright. Lateral pectoral nerve comes from lateral cord. it

supplies the pectoralis major muscle. Medial pectoral nerve, it comes from medial cord,it supplies

pectoralis major and minor. And I mentioned funny thing in the last lecture that actually when we makedissection , the lateral pectoral is located medial to the medial pectoral. The name we just call them

lateral and medial referring to their origin; lateral cord and medial cord. From the posterior cord we

have 3 branches, lets start with the upper subscapular nerve,it supplies the subscapularis muscle.

Coracodorsal nerve, it supplies the latisimus dorsi muscle. We have lower subscapular nerve, it supplies

teres major and part of the subscapularis. When u hear the name cutaneous, it means its sensory to the

skin in different regions of the arm and forearm. Axillary nerve, I told u that it supplies the deltoid and

teres minor muscle.

The terminal branches, brachial, ulnar, musculocutaneous will be discussed when we talk about the arm

and forearm, but I like u to know like for example the medial nerve has 2 roots; 1 coming from the

lateral cord, and 1 coming from medial cord and I like u to know that the radial nerve is the continuation

of the posterior cord,same thing with the musculocutaneous nerve. So please understand the image,

dont memorize because I can flip it, this is the right brachial plexus.In the exam u might see the left

brachial plexus. So start to draw or make charts of the left brachial plexus.

(the 2nd

lecture ended here)


15/21

(The last part of upper limbs lecture)

(Doctor was talking about second exam)

I think I should not mention about the 2nd exam because we have already finished it.

Now we focus on the final material...

Last lecture we talked about the brachial plexus. As you notice, the brachial plexus, we

have one picture or two picture that we talked. It is important topic to understand. Just to

complete what i was talking about, we said we have part of the brachial plexus that lies in the

axilla is the cord. The medial cord, lateral cord and the posterior cord.

The relationship between the brachial plexus and the axillary artery is important. Thefisrt part of the axillary artery, as you notice in the picture below is medial to all the cords of the

brachial plexus. This is the first part. The second part lies in the middle. So, the posterior cord is

posterior to the second part of the axillary artery. The medial cord is medial to the second part

of the axillary artery. And the lateral cord is lateral to the second part of the axillary artery.

What about the third part of axillary artery? We dont have cord any more. This is now the

terminal branches. Okay?


16/21

THE ARM

Now we continue our talk about the upper limb. We start with the arm, and we define

the area of the arm as the part between the shoulder joint and the elbow joint. So, the bone

that make the arm, there is only one bone which is the humerus. They articulate with the

glenoid fossa which is in scapula superiorly, and articulate inferiorly with the bones of forearm

which is ulna and radius. Arm and forearm, which one do you think is longer? Forearm? No! Its

the ARM.. the arm is longer because the humerus is the longest bone in the upper limb. So, the

arm is longer.

Now, lets talk about different part of the humerus. The first part of the upper part, is the

head which looks like one third of the sphere. It will fit into the glenoid fossa of scapula. Around

the head we have constriction called it the anatomical head. Beyond that, we have two round

process we called it the lesser and greater tubercle. They are site of articulation or attachment

of various muscle, shoulder joint and the arm. We have lesser tubercle which is medial, and wehave greater tubercle which is lateral. Between both lesser and greater tubercle, we have

groove we called it intertubecular groove. Along this groove, we have long head of biceps

tendon, it is originated from supraglenoid tubercle of scapula and pass through along this

groove. Next, the surgical neck which is often expose to fracture, between the proximal end of

humerus and the shaft. We have a constriction we called it surgical neck. We go a little down

the humerus, we see roughness on the shaft of humerus, we called it deltoid tuberosity.

Why??? Because it is the site of attachment for deltoid muscle. Just beneath deltoid tuberosity,

we found a groove that we called spiral groove. This spiral groove is for the radial nerve. The

radial nerve pass through that groove.


17/21

Now we talk about the proximal end.Proximal close to the ... (cant hear). So, we have

talked about the proximal end of the humerus, now, we will talk about the distal end. This is the

anterior aspect. You notice that, we have two processes. One medial and one lateral, medial is

larger we called it medial epicondyle. And the smaller one is the lateral one, we called it lateral

epicondyle. What about the articular surfaces that will articulate with the ulna and radius of theforearm. We have two regions. One of those we called it trochlea(number 4), trochlea is pulley-

shaped. Ulna will fit on this pulley-shaped (trochlea). So, trochlea for articulation with the ulna

and capitulum for articulation with radius. Radius and ulna are the bones of the forearm. On

top of the trochlea, we have a depression or fossa we called it coronoid fossa. Why? Because

the coronoid process of ulna will fit there. Lateral to the coronoid fossa, we called have radial

fossa because radial nerve will fit to that area. This is what gonna happen during flexion. You

will understand more when you see the ulna and radius in the next lecture.

Let's look at the posterior surface, we still can recognize large medial epicondyle or small

lateral epicondyle. You see we have only one fossa here on the posterior aspect, called

olecranon fossa. Why? Because it articulates with olecranon process of ulna. When is it going to

happen? During extension. When you flex, the olecranon will move away from its fossa. But

when you extend, it move towards its fossa back.

This medial and lateral epicondyle are site for insertion of extensor and flexor of the forearm.

This is just a posterior and anterior view. You can see that we have several attachment for

muscles and humerus which is at lesser tuberosity, greater tuberosity and surgical neck.

So, this picture shows you why do we have all these processes that we have muscles in

humerus that need sites of attachments. Humerus is a long bone and vulnerable to fractures.

Usually, fractures statistic occur at specific location. One of the hot spot for fractures is surgical

neck. Mostly people who suffer osteoporosis have little amount of bone, less amount of


18/21

matrix, and less amount of minerals. Why do we scared off by the fractures? Because

remember in this area when we studied in quadrangular spaces which blood vessels and nerves

pass through close to surgical neck? The axillary nerve and posterior circumflex humeral artery.

So the fractures will have sharp edges which might injure these structure. So, depending on

location of fractures, it might injure the nerve and artery.

Let's talk about tranverse fracture of humerus. In this area we have spiral groove where the

radial nerve will pass. So when you fracture the area you might injure the radial nerve.

Of course the displacement of bone will depends on whether this fracture occur distal or

promixal to deltoid attachment. The main action of deltoid is to abduct the shoulder joint. So

the fracture is below apart. Above the fracture will be both lateral. And the part below the

fracture will goes superiorly because the triceps will pull it up.

In supracondylar region fracture, most likely nerve to be affected is median nerve. Refer to atlas

to get a clear picture of it.

Fracture of medial epicondyle is a such big process that more likely to be fractured than the

lateral one. The nerve (ulnar nerve) which run behind the area (medial epicondyle process) will

likely to be injured.

In English, they refer ulna as funny bone which is on the medial side. Why? When it hits table or

anything, there will be tingling sensation. Why? Because there will be a direct trauma to the

ulnar nerve and it is most superficial in that area.

Now we are going to talk about muscular and neurovascular bundle that involved in the area. Inlayer of body, we have skin, beneath it, subcutaneous tissue or superficial fascia. It connects the

skin to the underlying deep fascia.

Fascia as a deep fascia, is tough layer which has muscle. In the arm, this deep fascia will get

intramuscular septum, lateral and medial. This green line will go from deep fascia to humerus

sheath. And what is the result from this? The arm is divided into two compartments ( flexor and

extensor). This is regarding function and area which is located either anterior compartment or

posterior compartment.

Now we talk about muscles in each compartments. For the anterior compartment we have 3

muscles. Biceps brachii, brachialis muscles and coracobrachialis muscle. Brachii is important to

distinguish this (biceps brachii) from biceps humerus in lower limb.

The posterior compartment, we have only one muscle but 3 heads. And this is why we call it as

triceps. We have long, lateral, and medial heads.


19/21

Let's talk about anterior compartment first. The biceps brachii muscle is the most superficial

muscle. If we remove the skin, the first thing you will see is the biceps brachii. Will you see the

brachiallis? No. Because it is covered . Triceps is in posterior aspect.

Slide 67-68

Coracobrachialis, maybe you see the upper part. Ok? So we have two heads as you can see

from this picture. One head which is the short head is originated from the coracoid process

from scapula,and the lateral or long head is inserted in the supraglenoid tubercle of scapula.

What about the insertion? Part of the tendon will go to the radius, the second part will end up

as a structure we call it bicipital aponeurosis. It will cover the cortical process. The story will

become more sensible as we go to the rest, about limb lectures. The action of this muscle, is

the flexor and lower point supinator. So, if you are screwing or unscrewing a nail of something

due to this by.....(the Dr. didnt finished his sentence). You are doing this by the action of biceps

brachii. This is just to show you the supraglenoid tubercle, where the long head is inserted.

Slide 69

The BRACHIALIS muscle, it is deep to biceps brachii, as i just mention to you .Origin, from the

lower hand of the humerus shaft and it is inserted into the ulna. Which part of the ulna? The

coronoid process. Also, the function is the flexion of the elbow joint or the forearm, the same

thing. In the exam, when you see the flexion of the forearm or the flexion of the elbow joint, it

means the same thing.

Slide 70

CORACOBRACHIALIS muscle , is small muscle, in the superior part, as I just told you, it will be

covered by the biceps brachii , the same thing ,it just sketched to you be able to see without

removing the biceps brachii muscle. It is weak flexor and adductor of the arm. What about the

innervations of the anterior compartment of the arm? The innervation is from

musculocutaneous nerve. Do we have exception? YES! Small part of the brachialis is located

posteriorly, so it will be innervated by radial nerve. Part from the second exam, the anterior

compartment is innervated by the musculocutaneous nerve. OK?

Slide 71

Now, lets talk about the posterior compartment of the arm (TRICEPS MUSCLE) . Only one

muscle , but has three heads. LATERAL , MEDIAL, and LONG heads. Which one do you think this

is? Lateral is the medial head and this is the long head (while pointing to the slide). And the

three heads are inserted into the olecranon process of the ulna. The long head, the origin of the

long head is from the inferior glenoid tubercle . The innervation, the posterior compartment of


20/21

the arm and the forearm is innervated by the radial nerve. So, we have a ( ) for their insertion

(Im not sure about this), as we say the nerve in the posterior aspect will innervate the posterior

aspect and the nerve in anterior aspect will innervate to the anterior aspect. What is the

action? Extension of the forearm, or extension of the elbow joint.

Slide 72

Now, lets talk about the nerves of the arm. The same nerves forming with more branches, will

be discussed when we talk about the forearm. For the sake of this lecture, we gonna mention

their course in the arm. We said, we have 5 roots for the brachial plexuses, 3 trunks, 3 cords,

and 16 nerves. The ones that go to the upper limb, with terminal branches are only four. The

rest are for the innervation of the humerus scapula muscles and ( ) muscle, and etc.

Slide 73-74

Lets talk about the MUSCULOCUTANEOUS nerve. The musculocutaneous nerve , we are talkingabout this branch, small branch, it will go through the coracobrachialis muscle. And actually

this is one (.................) parts for me to know the nerve. And well see which nerve pass through

the coracobrachialis, as you can see its going in inferolateral direction, and where it is located?

Between biceps brachii and brachialis muscle. So this is the coracobrachialis and it will stay in

between the biceps and the brachialis. So it will supply the three muscles of the anterior

compartment. Does we have a sensory part, cutaneous part? YES. It will continue distally as the

lateral cutaneous nerve of the forearm . (slide 74) So, this is what we talking about, we cut

the biceps, and all what we see now are the musculocutaneous passing between the cut biceps

and brachialis.

Slide 75

The MEDIAN nerve, and if you remember which cords of the medial nerve? We said the medial

has two roots, it will come from two cords which was the lateral and the medial because we

said the posterior will continue as the radial. It will elongated in the bicipital groove. What is the

bicipital groove? We have a well-developed muscle in your upper limb tries to flex your biceps,

you will note there is a groove between the biceps and the remaining of your arm.This is the

bicipital groove. Lets look at the median nerve. This is the median nerve, so in the upper hand,

it is lateral to what? To the brachial artery. As we go down, it will pass to the medial tobrachial artery and it will enter the cubital fossa, behind to the tendon of biceps brachii.

This is what we are talking about. This area is the cubital fossa and this tendon is cut to show

you the continuation of the nerve. And this is the bicipital groove.


21/21

The ulnar nerve,it originates from the medial cord, as you can see, it will pass behind the medial

epicondyle and also while Im seeking the upper limb, this is the good location to go and look

for the ulnar nerve. Know that, this ulnar nerve does not supply muscles within the arm, it only

gives branches to the forearm and hand. Well talk about this branches when we talk about the

forearm.

So, what we need to know now that also .. in bicipital groove,it is medial to brachial artery and

pass posterior to the medial humeral epicondyle. This superficial location of the nerve give rise

to the term funny elbow or funny bone when you have injury here because we move the funny

bone. This back.. well go through them in detail when we talk about the forearm especially for

the ulna and the radius. Here the musculotenous nerve, it shows you the roots. Specific roots

that comes from and the branches in the axilla,upper arm and the rest. You can see that it does

not have motor innervations in the forearm (musculotenous). Motor innervation is limited to

the upper arm which is the anterior compartment of the arm. The median nerve, it only

supplies the brachial artery within the arm.it does not give innervations to any muscle or any

cutaneous..

The ulnar nerve as well no innervation within the arm and radial nerve. Now, its easier to study

this nerve because it supplies the posterior compartment of both the arm and forearm,it will

pass posteriorly and it will bind them to the spiral groove to be located anteriorly as it will pass

anterior to the lateral epicondyle. Also,this is a good location to look for radial nerve. ..to the

triceps and will have cutaneous branches (cant hear)

Cutaneous branches we have the lower lateral cutaneous nerve of the arm,and posterior

cutaneous nerve of the forearm. These are the branches within the arm,okey?

(Then, the lecture ends and we dont have the recording for the rest of the lecture which is

brachial artery until the end. Please refer to the books or slides so that you wont get any wrong

informations.)

-END-

SPECIAL THANKS TO THOSE WHO INVOLVE IN THE MAKING OF THIS LECTURE NOTE.

MAY ALL OF YOU THAT READ THIS NOTE PRAY FOR THEIR SUCCESS NOW AND

HEREAFTER.

(SORRY FOR ANY MISTAKES.)

anat:lect note upper limb-shoulder

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