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Upper Limb, part IShoulder, Arm, and Axilla.
Objectives:1. Bones and joints of the shoulder
2. Organization of the shoulder’s muscles
3. Axilla - borders and contents
4. Organization of the brachial plexus
Posterior viewAnterior view
Which joint serves as the only bony attachment of the upper limb to the axial skeleton?
Which of these bones is commonly fractured?
Sternal clavicular joint
clavicle
ORGANIZATION OF THE SHOULDER: MUSCLES AND INNERVATION
}rotator cuff
* Muscles (MM) ATTACH HUMERUS TO AXIAL SKELETON:
1. Latissimus Dorsi ( thoracodorsal n. C6-C8 )
2. Pectoralis Major ( lateral pectoral n. C5-C7, medial pectoral n. C8-Th1 )
- attaches to humerus* MM ATTACH HUMERUS TO THE SCAPULA
1. Supraspinatus, Infraspinatus ( suprascapular n. C5-C6 )
2. Subscapularis ( upper C5 and lower C6 subscapular nn. )
3. Teres Minor ( axillary n. C5-C6 )
4. Teres Major ( lower subscapular n. C6 )
5. Deltoid ( axillary n. C5-C6 )
* MM ATTACH SCAPULA TO AXIAL SKELETON
1. Trapezius ( spinal accesory n. XI )
2. Levator Scapulae, Rhomboids ( dorsal scapular n. C5 )
3. Serratus Anterior ( long thoracic n. C5-C7 )
4. Pectoralis Minor ( medial pectoral n. C8-Th1 )
Supraspinatus .: Assists the deltoid in the initial abduction
Infraspinatus .: Powerful lateral rotator of humerus
Teres minor .: Helps rotate the arm laterally and assists in adduction (like infraspinatus). HOWEVER, it is innervated by the axillary nerve, while the infraspinatus is innervated by the suprascapular nerve
Subscapularis .: It is the primary medial rotator (also adducts it) .: Innervated by the subscapular nerve
The The deltopectoral deltopectoral triangle is also triangle is also known as the known as the “clavicopector“clavicopectoral triangle”. al triangle”. These two These two names tells me names tells me the exact the exact borders. borders.
What’s in the What’s in the triangle? triangle?
The cephalic The cephalic veinvein
Which structures lie in the deltopectoral triangle?
Cephalic vein
The rotator cuff muscles work as a group in holding the head of the humerus in the glenoid cavity. They give protection and stability to the shoulder joint.
Rotator cuff
S I
T
Ssubscapularis
Rotator cuff is formed by the tendons of: Supraspinatus , Infraspinatus, Teres minor and Subscapularis fuses with the joint capsule.
What is the tendonitis of the rotator cuff? inflammation
Axilla (the armpit)
1. Apex – cervicoaxillary canal, the passageway between the neck and the axilla. Lies between the 1st rib, clavicle and upper border of the scapula.
2. Base - formed by the skin, subcutaneous tissue and axillary fascia
3. Four walls: * anterior wall - pectoralis major and minor mm, pectoral and clavicopectoral
fascia.Anterior axillary fold -> pectoralis major!
* posterior wall - scapula , subscapularis m., latissimus dorsi m., teres major m.Posterior axillary fold -> latissimus dorsi and teres major!
* medial wall - thoracic wall and serratus anterior m.
* lateral wall - intertubercular groove of the humerus.Fun note: Axillary fossa = armpit
What passes through the cervico-axillary cannel? .: Arteries, veins, lymphatics and nerves to and from the arm
What mainly forms the posterior wall? .: Scapula
Contents of the axilla:
• axillary artery and its branches
• axillary vein and its tributaries
• brachial plexus
• axillary lymph vessels and lymph nodes
• 3 muscles: long/short head of biceps brachii m. and coracobrachialis m.
The axillary artery and vein, and the cords of brachial plexus(neurovascular bundle) are enveloped in the thin fascial sheath - axillary sheath.
AXILLARY ARTERY
CORDS
ROOTS AND TRUNKS
NEUROVASCULAR BUNDLE
AXILLA
CLAVICLE
Axillary artery – three parts
First part - one branch – superior thoracic a.
Second part - two branches – thoracoacromial a.
– lateral thoracic a.
Third part - three branches – subscapular a.
– anterior circumflex humeral a.
– posterior circumflex humeral a.Screw the lawyer, save the patient
Superior thoracicThoracodorsalLateral thoracicSubscapularAnterior circumflex humeralPosterior circumflex humeral
The thoracoacromial artery will further branch off in 4 directions, named after parts of the body.
Mnemonic: Cadavers Are Dead People
ClavicularAcromialDeltoidPectoral
superior thoracic a.(1st part)
thoracoacromial a.(2nd part)
lateral thoracic a.(2nd part)
anterior circumflexhumeral a. (3rd part)
subscapular a.(3rd part)
thoracodorsal a.
circumflex scapular a.
posterior circumflexhumeral a. (3rd part)
Arterial anastomoses around the scapula
circumflex scapular a.
subscapular a.
axillary a.
thyrocervical trunk
deep branch of transverse cervical a.*(dorsal scapular)
anterior circumflex humeral a.
posterior circumflex humeral a.
profunda brachii a.
Scapular loop:SuprascapularDorsal scapularSubscapular
Humeral loop:anterior circumflex humeral posterior circumflex humeralprofunda brachii
.: Thoracoacromial artery-Cadavers are dead people
-1. clavicular-2. acromial-3. deltoid-4. pectoral
Arterial anastomoses form loops
Think about where the loops are located. That’s where they get the name. The anterior circumflex humeral, posterior circumflex humeral and profunda brachii are all wrapping around in the humerus
The same goes for the scapular loop, which contains the suprascapular, dorsal scapular and subscapular ateries
Axillary lymph nodes
Five principal groups:
1. Pectoral( anterior) nodes receive lymph mainly from anterior thoracic wall and the breast and abdominal wall.
2. Subscapular (posterior) nodes receives lymph from posterior thoracic wall and scapular region.
3. Humeral (lateral) nodesreceive lymph from upper limb.
4. Central nodes (base of axilla)receive lymph from anterior, posterior and lateral nodes.Drain into apical nodes.
5. Apical nodes (apex of axilla)Receive lymph from all the other nodes. Drain into the subclavian trunks.
PLAN OF BRACHIAL PLEXUS = Ventral Rami C5 to T1 ROOTS
(5)
TRUNKS
(3)
DIVISIONS
(3/3)CORDS
(3)TERMINALS
(5)
MEDIAN
ULNAR
MUSCULOCUTANEOUS
RADIAL
AXILLARY
C5
C6
C7
C8
T1
SUPERIOR
MIDDLE
INFERIOR
LATERAL
POSTERIOR
MEDIAL
DIVISIONS = ANTERIOR AND POSTERIOR
Which spinal nerves form the brachial plexus? C5, C6, C7 C8 and T1
A
P
A
Brachial plexus is formed by the union of the anterior (ventral) primary rami of C5 – T1 nerves that constitute roots of brachial plexus.
The roots of brachial plexus unite to form three trunks:* superior trunk (C5-C6)* middle trunk (C7)* inferior trunk (C8-T1)
Each trunk divides into anterior and posterior divisions of brachial plexus.
The divisions of the trunks form three cords of brachial plexus:* posterior cord - posterior divisions of all three trunks* lateral cord – anterior divisions of superior and middle trunk* medial cord – anterior division of the inferior trunk
The cords of brachial plexus give rise to most of the named peripheral nerves (branches) that result from the plexus formation.
5
6
7
8
1
Axillary nerve
Radial nerve
Ulnar nerve
Musculocutaneous nerve
Median nervePosterior cord
Medial cord
Lateral cord
Posterior divisions
Anterior divisions
Basic Anatomy of the Brachial Plexus
Ventral ramior
rootsTrunk
BRACHIAL PLEXUS
Terminal Branches:
Motor Distribution to Arm, Forearm and Hand
Roots, Trunks and Cords:
Motor Distribution to Anterior and Posterior Shoulder
CORDS OF BRACHAL PLEXUS - TERMINAL BRANCHES
I. LATERAL CORD:
1. musculocutaneous n.(C5-C7):
anterior group of arm (muscles of anterior arm are innervated; biceps, brachialis and coracobrachialis)
2. lateral root of median n.(C6-C7) :
anterior group of forearm (except flexor carpi ulnaris, medial half of flexor digitorum profundum)
thenar muscles and first two lumbricals
Musculocutaneous nerve (C5,6,7)
Coracobrachialis muscle
Ulnar nerve
Lateral cord of brachial
plexus
Lateral cutaneous nerve of forearm
Brachialis muscle
Biceps brachii muscleCutaneous innervation
( skin of lateral forearm)
Note the name: musculocutaneous
It innervates the muscles in the arm and the cutaneous layer (skin) of the forearm
What cord does this nerve spring from? The lateral cord.
This is a pretty good way to remember what part of the forearm the musculocutaneous nerve innervates.
Lateral anterior
CORDS OF BRACHAL PLEXUS - TERMINAL BRANCHES
II. MEDIAL CORD:
1. medial root of median n. (C8-T1):
anterior group of forearm (except flexor carpi ulnaris, medial half of flexor digitorum profundum)
thenar muscles and first two lumbricals
2. ulnar n. (C8-T1):
flexor carpi ulnaris
medial half of flexor digitorum profundum
all the small muscles of the hand (except thenar and two first lumbricals)
What did the lateral root of the median nerve innervate? .: thenar muscles, first two lumbricals, and anterior group of forearm except for flexor carpi ulnaris and medial half of flexor digitorum profundum
Does the medial root of the median nerve innervate these exceptions? .: No, in fact it does the same thing as the lateral root (these cords join together to form the median nerve
So what does innervate the flexor carpi ulnaris and the medial half of flexor digitorum profundum? .: ulnar nerve
Anything else? .: All the small muscles of the hand except for the thenar and the first two lumbricals, which is what the median nerve takes care of.
Common & proper digital
nerves
Palmar branch of
median nerve
Median nerve (C5,6,7,8,T1)
Medial cord of brachial plexus
Cutaneous innervation
Lateral cord of brachial plexus
Muscles of hand (thenar group and two first lumbricals)
Flexors of forearm except fl.carp.ulnaris and medial flexor dig. profundus
Muscles of forearm
Note that the median nerve only cutaneously innervates the anterior part of the hand, and the back of the fingertips, not the rest of the back of the hand.
The pimp hand is felt with the radial nerve and the ulnar, I believe.
Flexor carpi ulnaris muscle
Dorsal branch of ulnar nerve
Deep & superficial branch of ulnar nerve
Proper palmar digital nerves
Note: Only muscles innervated by ulnar nerve shown
Medial epicondyle
Cutaneous innervation
Flexor dig. profundus (medial part)
Muscles of the hand
(excluding thenar and
two lumbrical muscles)
Ulnar nerve (C7,8,T1)
CORDS OF BRACHAL PLEXUS - TERMINAL BRANCHES
III. POSTERIOR CORD:
1. axillary n. (C5-C6):
deltoid,
teres minor
2. radial n. (C5-T1):
posterior group of arm and forearm
In what situations the axillary nerve may be damaged (injured)?
Fracture of the surgical neck
Dislocation of the glenohumeral joint
Compression from the incorrect use of crutches
Posterior interosseous nerve (continuation of deep branch of Radial nerve)
Dorsal digital nerves
Superficial branch of radial nerve
a
Superficial and deep branch of radial
nerve
Radial nerve(C5,6,7,8)
C5
C6
C7
C8
T1
ROOTS
BRACHIAL PLEXUS – branches of ROOTS, TRUNKS AND CORDS
DORSAL SCAPULAR C5RHOMBOID MM AND LEVATOR SCAPULE
SUPRASCAPULAR C5,6SUPRASPINATUS MINFRASPINATUS M
LONG THORACIC C5-C7SERRATUS ANTERIOR M
SUBSCAPULAR NN C5,6 SUBSCAPULARIS MTERES MAJOR M
LATERAL PECTORAL C5-C7PECTORAL MM
N. TO SUBCLAVIUS C5,6SUBCLAVIUS
MEDIAL PECTORAL C8,T1PECTORAL MM
THORACODORSAL C6-C8LATISSIMUS DORSI M
ROOTSTRUNKS
CORDS
ARM muscles - action on shoulder and elbow
Flexors (anterior compartment):
* biceps brachii (both joints) - supination and flexion of forearm - flexion of arm * coracobrachialis (shoulder joint) - flexion and add. of arm * brachialis (elbow joint) - flexion of forearm in all position
Extensors (posterior compartment):
* triceps brachii (both joints) - extension of forearm - extension of arm (long h.)
Anterior ( flexor) compartment Posterior (extensors) compartment
Long head of tricep
Important spaces of the shoulder region
Deltopectoral triangle – bounded by the clavicle superiorly, deltoidlaterally and the pectoralis major (clavicular head) medially. Cephalic vein and deltoid branch of thoracoacromial artery.
Quadrangular space – bounded superiorly by the teres minor and subscapularis, inferiorly by the teres major, medially by the long head of the triceps and laterally by the surgical neck of the humerus. Axillary nerve and posterior circumflex humeral artery and vein.
Triangular space – superiorly by the teres minor, inferiorly by the teres major and laterally by the long head of triceps. Circumflex scapular vessels.
Triangular interval - between the two heads of the triceps muscle, inferior to the teres major.Deep brachial artery and radial nerve.
12
3
1 – triangular space, 2 – quadrangular space, 3 – triangular interval
Brachial plexus injuries
Injuries to the brachial plexus affect movements (paralysis) and cutaneous sensation (anesthesia). Signs and symptoms depend on the part of the plexus involved.
Erb-Duchenne palsy is a paralysis of the arm caused by injury to the upper group of thearm's main nerves (specifically, spinal roots C5-C7), almost always occurring during birth. Depending on the nature of the damage, the paralysis can either resolve on its own over a period of months, necessitate physical therapy or require surgery.
Dejerine-Klumpke (Klumpkes) palsy refers to paralysis of the lower brachial plexus.A rare condition where a lower spine lesion causes paralysis of the forearm and hand muscles. The lesion may occur during birth or as a result of infection, tumor or trauma.
Questions of the day!
1. Which muscle is the primary supinator of the forearm? 1. Biceps brachii
2. Which muscle serves as the prime extensor of the forearm?1. Triceps
3. If a tumor grows into the quadrangular space of the axillary region, which structures would be in danger? (Axillary nerve, posterior circumflex humeral)1. Humeral loop2. Brachial plexus
4. ****Which artery may be damaged during the fracture of the shaft of the humerus?1. Posterior circumflex humeral artery