The arm
- Short description
- from the front there is bicecps brachia and brachialis under the biceps , specially on the lower half of the arm
- on the lateral side above the elbow joint , there is brachioradialis
- notice that : these muscles name refer to the origin of them … like :
*coracobracilis which is origin is ( corocoid process ) and it’s insetions is ( brachial )
*and oppiste to it is brachioradialis which origin is lateral supracondyler ridge of humerus and inserted into
styloiad process of radius …
- anconeus muscle , is located behind the elbow joint .. and it’s function is ( extension )
- for the arm , it’s enclosed in sheath of deep fascia ( we first locate the skin then superficial fascia and then deep
fascia enclosed in the muscle , and with the muscle we locate nerves and blood vessels )
- in the arm we have to facial septa , one in the medial side and the other on the lateral side and the facial septa
is attached to the medial and lateral sypracondyler ridge .. so they are located in the lower half of the arm… and
these two septa are the one which separate the anterior compartment from the posterior compartment …
- the anterior compartment contains the flexor muscles , and the postioer compartments contain the extensor
muscle to the elbow joint…
- so we have two septa divide the upper arm into anterior and posterior facial compartement .. each having it’s
own muscles and nerves and blood vessels…
- Anterior compartment of the upper Arm :
Muscles :
- we have the biceps brachii ( it’s named to distinguish it from other muscles that also have two heads such as:
biceps femoris in the back of the thigh )
- coracobrachialis , it’s located in the anterior compartment and medialy
-brachialis , under the bicesps
Blood supply :
all these muscles take blood supply from “ Brachial artery “
Nerve supply : musculocutaneous nerve , a branch from the lateral cord of brachial plexus…
* in the anterior compartement , we will study the musculocutaneous nerve , the median nerve , the ulnar nerve
, radial nerve , the brachial artery , basilica vein , and the muscles …
First : the muscles ( we have 3 muscles in the anterior compartment )
1 - The biceps :
Origin : it has two heads , long and short
* short head : from the corocoid process
*long head : it cross in the bicipital grove , and under a ligament called “ transverse humeral ligament “ which
keep and save the tendon of the bicips , then cross through the upper part of the shoulder joint towards it’s origin
in the supragelnoid tubercle above gelnoid cavity
Insertion : radial tuberosity , and bicipital aponeurosis ( which is a fascia covering the cubital fossa )
nerve supply : musclocutenous nerve ( after piercing the coracobrachilis , it cross between the bicepis and
brachialis .. then goes to the lateral side , and above the elbow it comes superficial and ends as lateral cutanous
nerve of the forearm .. which supply the skin on the lateral side of the forearm
Action : flexion in the elbow joint , and supination during flexion and this action is called “ screwing “
( it works in the elbow joint because the tendons of it cross through the elbow joint )
* there is another muscle is called “ supinator “ and it also make supination , but in the extension of the elbow
joint….
2 - Coracobrachilis :
Origin : Coracoid process
Insertion : medial aspect of the shaft of the humerus in the middle …. And this inseriotn because it’s in the
middle side of the humerus , it’s considered as a land mark in the anatomical changes in this level … for example :
* opposite to the insertion of coracobrachilis , we have the insertion of the deltoid which is on the lateral side
* medin nerve crossing the brachil artery at the level of the insertion of coracobrahiclis ( it’s coming from lateral
and crossing to become medial )
And these changes is so important …
Nerve supply : musclocutenous
Action : flexion of the arm , and weak adductor of the arm…
3 -Brachilis : it lies under the bicips
Origin : from the lower half of the anterior surface of the humerus
Insertion : coronoid process of ulna ( or ulnar tuborosity )
Nerve supply : it has two innervations ,
* medial half from musclocuteneous
* lateral half from radial
And this is sooo important to know for questions !
Eg : Q : all of the following have dual innervations ( or double innervations ) except :
And till now , we have take the following muscles as a double innervation muscles :
- brachialis ( musclocutenous & radial )
- pectoralis major ( lateral and medial pectoral nerve )
- subscapularis ( upper & lowe subscapulaer nerve )
Action : flexor of elbow joint
- Brachial artery :
- teres major lies unders pectoralis major …
- when we want to talk about brachial artery , we should know the main things such as : beginning , end ,
branches , relation ( ‫(للي بدو يتخصص جرااحة‬
- Brachial artery begins at the lower border of teres major as continuation of axillary artery .
(( subclavin artery >>> axillary artery >>> brachial artery ))
- median nerver in the beginning it’s lateral to the artery ... and at the level of insertion for coracobracialis , the
median nerve cross in the front of the artery and comes to the medial side of the artery …until it reach the cubital
fussa it still medial !
- ulnar nerve : in the lower part , it’s in the medial side of the artery and it pierce the inermusculor septum
towards the posterior compartment … and at the level of insertion of coracobracialis , it pierces the medial
intermuscular septum and moves from the anterior compartment to the posterior compartement … and when it
goes to the forearm it cross behind the medial epicondyle
- the median and the ulanr give “””no “”” branches in the arm
- the brachial artery is the main supply to provide the muscles and bones in the arm , and its terminates at the
neck of the raidus into radial & ulnar arteries which supplies the forearm.
Relations :
Anteriorly : the vessels is superfacial and it’s overlapped from lateral side by coracobrachilis and biceps…and we
can feel the pulsation of it if we put our fingers in the skin because it’s superfacil… and the medial cutaneous nerve
of the forearm lies in the front of the upper part .. the median nerve crosses it’s upper part .. and in the lower part
we find the bicipital aponerosis crosses it’s lower part ( crosses means that it’s in the roof of the cubital fossa ,
making a cover to the brachial artery )
Posterily : the artery lies above in the triceps … and also it’s posterior to the insertion of coracobrachils and
brachilis …
Medialy : ulnar nerve , and basilica vein >> in the upper part of the arm
And in the lower part of the arm , the median nerve lies on it’s medial side…( here the ulnar nerve goes to the
posterior compartment of the arm )
Laterally : the median nerve and coracobrachilis and bicips muscle >> above
And the tendon of bicips >> lower
* in the cubital fossa the bicips tendon is lateral , brachial artery is medial and most medial is median nerve … so
the arrangement in the cubital fossa from medial to lateral :
Median nerve / brachial artery / biceps tendon /
And this point clinically is so important , because when we measure the blood pressure , we put ( ‫(ملف قياس الضغط‬
and bloat we block the brachial artery and we put the headset on the cubital fossa over the brachial artery to hear
the pulsation of artery ….. And the people who know anatomy put their fingers medially to biceps tendon on
brachial artery and hear the pulsation …. And if you put the headset lateral to tendon you will never ever hear the
pulsation …
•
Triple relation between the median nerve and the artery :
- It runs downward on the lateral side of the brachial artery , Halfway down the upper arm, it crosses the brachial
artery and continues downward on its medial side
- Q : What are the branches of brachial artery ??
The doctor said that we mention its beginning and its termination and its relations and its branches ..
Axillary artery : the branches of first part : superior thoracic artery , second give two branches :
thoracoacromial and lateral thoracic(to the breast) arteries , third : subscapular on medial side and anterior and
posterior circumflex on lateral side around surgical neck of humerus ….
Then the brachial artery start at the lower border of teres major muscle and ends at the neck of radius and
terminate into radial and ulnar arteries in the forearm and their ends give blood supply to all of the hand so that
they make ( we will see that later on ) superficial and deep palmar archs … and these archs give didital arteries to
fingers …
Branches of brachial artery :
1. Profunda brachii artery : it starts near to the beginning of br.artery and follows the radial nerve in the
spiral groove on the middle of the back of the humerus from medial to lateral … and the profunda brachii
give one ascending and two descending branches which take part in the anastomosis around the elbow
joint ..
2. On the medial side the brachial artery gives superior and inferior ulnar collateral arteries …collateral
means : ‫ مرافق‬they follow the ulnar nerve more specific the superior .. it follow the ulnar nerve till the
ulnar nerve arrive the elbow joint and take part in the anastomosis around that joint …
3. Muscular branches to the muscles of the anterior compartment of the arm
4. The nutrient artery to the humerus (in any bone we find foramen … and there is an artery enter this
foramen and supply the bone) ..
•
•
•
•
•
- Then the doctor read from the slides :
Muscular branches to the anterior compartment of the upper arm
The nutrient artery to the humerus
The profunda artery arises near the beginning of the brachial artery and follows the radial nerve into the
spiral groove of the humerus
The superior ulnar collateral artery arises near the middle of the upper arm and follows the ulnar nerve
The inferior ulnar collateral artery arises near the termination of the artery and takes part in the
anastomosis around the elbow joint
And at the level of the neck of the radius the Br . artery terminate into ulnar and radial arteries ..
Musculocutaneous Nerve :
It is a branch of the lateral cord of brachial plexus and it pierces the coracobrachialis muscle then passes
between biceps and brachialis and gives muscular branches to the previous three muscles ( except the lateral
half of brachialis which supplied from radial nerve ) .. and ends as lateral cutaneous nerve of the forearm on
the lateral side before the end of biceps and give the skin over the lateral side of the forearm …
•
It runs downward and laterally, pierces the coracobrachialis muscle
•
and then passes downward between the biceps and brachialis muscles
•
It appears at the lateral margin of the biceps tendon and pierces the deep fascia just above the elbow
•
It runs down the lateral aspect of the forearm as the lateral cutaneous nerve of the forearm
General principle : any nerve cross on any joint , it gives innervations to the joint ..
Then the ulnar and median nerves give innervations to elbow joint too …
The radial nerve after being in the spiral groove , it pierces the lateral intermuscular septum from posterior to
anterior compartment … not on the level of coracobrachialis , but lower to it … and then the radial nerve runs
down to the forearm anterior to the lateral epicondyle …
The radial nerve is the most lateral in the cubital fossa …
 Posterior compartment of the arm :
There is the triceps muscle having three heads and one insertion ..
•
Nerve supply to the muscle: Radial nerve
•
Blood supply: Profunda brachii and ulnar collateral arteries
•
Structures passing through the compartment: Radial nerve from its beginning and ulnar nerve in the
lower half after pierces the intermuscular septum …
The triceps muscle :
Origin :
*Long head : from Infraglenoid tubercle of scapula beneath glenoid cavity
*Lateral head : from Upper half of posterior surface of shaft of humerus ( above the spiral groove)
*Medial head Lower half of posterior surface of shaft of humerus (below the spiral groove )
Then the three heads go and have one Insertion: Olecranon process of ulna
Innervation: Radial nerve and C6, 7, 8
And the profunda brachii artery follow the radial nerve in the spiral groove and supply the triceps
Action : Extensor of elbow joint
The medial head is below the lateral head
 Radial nerve :
It is a branch of the posterior cord of brachial plexus
This nerve Winds around the back of the arm in the spiral groove with the profunda artery between the heads of
triceps
It pierces the lateral fascial compartment above the elbow and continues downward into the cubital fossa in
front of the elbow, between the brachialis and the brachioradialis muscles
Again the radial nerve is the most lateral in the cubital fossa between two muscles : brachialis and the
Brachioradialis muscle .
In the spiral groove, the nerve is accompanied by the profunda vessels, and it lies directly in contact with the
shaft of the humerus .
The branches of the radial nerve :
It gives many types of branches : muscular , cutaneous and articular branches
In the axilla, branches are given to the long and medial heads of the triceps, and the posterior cutaneous
nerve of the arm is given off.
In the spiral groove branches are given to the lateral and medial heads of the triceps and to the anconeus ( the
anconeus: A small muscle behind the elbow joint and its function : the extension of the elbow joint )
The lower lateral cutaneous nerve of the arm supplies the skin over the lateral and anterior aspects of the
lower part of the arm ( inferior to the deltoid , it gives the lower lateral cutaneous nerve of the arm )
The posterior cutaneous nerve of the forearm runs down the middle of the back of the forearm as far as the
wrist.
In the anterior compartment of the arm, after the nerve has pierced the lateral fascial septum, it gives
branches to the brachialis.
And finally gives articular branches to the elbow joint .
The ulnar nerve :
Having pierced the medial intermuscular septum halfway down the upper arm (at the level of the insertion of
coracobrachialis muscle) , the ulnar nerve descends behind the septum, covered posteriorly by the medial
head of the triceps ..
The nerve is accompanied by the superior ulnar collateral vessels. At the elbow, it lies behind the medial
epicondyle of the humerus .. this means that the ulnar have no branches in the arm !.
Profunda Brachii Artery :
The profunda brachii artery arises from the brachial artery near its origin .
It accompanies the radial nerve through the spiral groove.
supplies the triceps muscle, and takes part in the anastomosis around the elbow joint.
It gives ascending and two descending branches .
Superior and Inferior Ulnar Collateral Arteries :
The superior and inferior ulnar collateral arteries arise from the brachial artery and take part in the
anastomosis around the elbow joint
Sensation over the shoulder , arm and the forearm :
We said that the radial nerve give posterior cutaneous nerves to the arm and the forearm .. and the lower
lateral of the arm .
And we said that the musculocutaneous nerve give the lateral cutaneous nerve of the forearm ..and from the
medial cord of BR. Plexus , there is the medial cutaneous nerves of the arm and the forearm ….
The picture on the left called anterior view and on the right calle posterior view ..
First : we have the supraclavicular nerve from c3 and c4 ..
(C3 and c4 means : the anterior rami of the third and fourth cervical nerves )
supraclavicular nerve : above the clavicle and give the skin beneath the clavicle and over the upper part of
deltoid ..
the upper lateral cutaneous nerve of the arm ( from axillary nerve and the lower lateral cutaneous nerve of
the arm from radial nerve) : the lower half of the deltoid is supplied by it .
the lateral cutaneous nerve of the forearm : from musclocutaneous nerve ..
The medial side :
We have intercostobrachial nerves (T2) . intercostals (between ribs ) it runs on the medial upper part of the
arm … the we have the medial cutaneous nerves of the arm and the forearm from the medial cord of the BR .
plexus ..
And we have the posterior cutaneous nerves of the arm and the forearm from the radial nerve … and now we
know all of the cutaneous nerves to the upper limb .
Then the doctor read from slides :
•
The sensory nerve supply to the skin over the point of the shoulder to halfway down the deltoid muscle is
from the supraclavicular nerves (C3 and 4).
•
the lower half of the deltoid is supplied by the upper lateral cutaneous nerve of the arm, a branch of the
axillary nerve (C5 and 6).
•
The skin over the lateral surface of the arm below the deltoid is supplied by the lower lateral cutaneous
nerve of the arm, a branch of the radial nerve (C5 and 6).
•
The skin of the armpit and the medial side of the arm is supplied by the medial cutaneous nerve of the
arm (T1) and the intercostobrachial nerves (T2).
•
The skin of the back of the arm is supplied by the posterior cutaneous nerve of the arm, a branch of the
radial nerve (C8).
..
Dermatomes and Cutaneous Nerves :
Dermatomes means : we connect between the nerve and skin which supplied by this nerve
)‫(نربط بين العصب ووين بروح على الجلد‬
To the upper limbs : at the lateral side of the neck , we find T2 and below T3 … thus T2 and T3 to the neck ..
C3 and C4 : the supraclavicular which supply deltoid as we mention ..
Then we find c5 and below it there is C6 … to the thumb …this means that the upper limb from the root of the
neck to the wrist joint supplied by nerves come from C3 ,4.5 and 6 and T1 and T2
The middle of the hand (index and middle finger ) supplied by C7 ..
The medial side supplied by C8
The medial side of the arm : supplied by T1 and T2
‫ فقط من الساليد إحفظ كل جزء ملون‬... ‫عشان تريح نفسك كل ما سبق هو كالم بتأشير الدكتور على الصورة السفلية‬
‫ طبعا الصورة موجودة بالساليد ملونة وسهلة للحفظ‬... ‫وشو بياخذ‬
The superficial veins :
- The veins of the upper limb can be divided into groups: superficial, deep and intercommunicating (connect
between superficial and deep veins ) veins .
- The deep veins also called the venae comitantes, which accompany all the large arteries, usually in pairs ..
- The veins is opposite to branches of the arteries called tributaries
- Each artery has two veins one on the right and the other on the left and called : venae comitantes …
- We have three major superficial veins :
1- Cephalic vein : on the lateral side and starts from the thumb dorsally and ascends on the lateral side
and pierces the deltopectoral space and drains in the axillary vein
2 - Basilic vein : starts from dorsum from the root of the little finger and becomes anterior in the elbow
joint and then pierces the deep fascia and joins the venae comitantes and make the axillary vein
- Thus the axillary vein made up of the unite of the venae comitantes of the brachial artery with the basilic vein at
the lower border of the teres major muscle and ends at the outer border of the first rib and complete as
subclavian vein
- And we have the median cubital vein between the cephalic and basilic veins in the roof of the cubital fossa and
this is the place of injection of intravenous
‫المالحظة التالية هي مالحظة إضافية من الدكتور ولكن ليست مهمة على اإلطالق كما ذكر‬
We maybe find many forms of that vein for example : ( median basilic and median cephalic ) or (other vein make a
complication like anterior median vein of the forearm ) but the major form (median cubital vein) is the must common
Then the doctor read from the slides :
•
The basilic vein ascends in the superficial fascia on the medial side of the biceps
•
Halfway up the arm, it pierces the deep fascia and at the lower border of the teres major joins the venae comitantes
of the brachial artery to form the axillary vein
The end
Please remember : no pain …. No gain