D-etre.blogspot.com Organization of the Upper Limb Audrone Biknevicius, Ph.D. Dept. Biomedical...

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Organization of the Upper LimbOrganization of the Upper LimbAudrone Biknevicius, Ph.D.

Dept. Biomedical Sciences, OU HCOM at DublinClinical Anatomy Immersion 2014

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“Anatomical Tool-Kit”

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Week 5

RULE #1Limbs are outgrowths of the ventral body wall that undergo distal growth and differentiation…

Week 7

and rotation

[More detailed limb embryology in MS course]

The upper limbs are innervated by :

A. Dorsal rami of spinal nn.

B. Ventral rami of spinal nn.

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50% 50%

Dorsal rami of spinal nn. Ventral rami of spinal nn.

Developmentally-dorsal limb mm.

Developmentally-ventral limb mm.

Primitive Pectoral Limb

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DEVELOPMENTAL/EVOLUTIONARY BASIS

• 90◦ lateral rotation (forearm mm. undergo incomplete rotation)

• Limb adduction6

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DEVELOPMENTAL/EVOLUTIONARY BASIS

*

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Developmentally-ventral muscles:• Lie anterior to the long bones in anatomical position

Developmentally-dorsal muscles: • Lie posterior to the long bones in anatomical position (* exceptions)

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RULE #2A: Ventral vs. dorsal limb mm.

Anterior

Humerus

Posterior

Radius

Anterior

Posterior

5th metacarpal

Anterior

FOREARM

HAND

ARM

Ulnar

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Upper LimbMuscle

Compartments

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Anterior

Humerus

Posterior

Radius

Anterior

Posterior

5th metacarpal

Anterior

FOREARM

HAND

ARM

Ulnar

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No posterior compartment in the hand

Some posterior compartment mm. are found on the anterolateral aspect of the forearm (*brachioradialis, supinator)

*

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Spinal nerveDorsal primary ramusVentral primary ramus (C5-T1)

Anterior division

Posterior division

limb axis

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RULE #2B: Innervation of anterior vs. posterior compartment mm.

Brachial Plexus(right side; simplified)

Terminal Branches

“Roots of BP” (=ventral rami)

C5

C6

C7

C8

T1

Trunks

U

M

L

Cord

Lat

PostPost

Med

Divisions

Anterior (ventral) division

Posterior (dorsal) division

“Randy Travis Drinks Cold Beer”

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Brachial Plexus(right side; simplified)

Terminal Branches

“Roots of BP” (=ventral rami)

C5

C6

C7

C8

T1

Trunks

U

M

L

Cord

Lat

PostPost

Med

Divisions

Anterior (ventral) division

Posterior (dorsal) division 12

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Radial n.

Musculocutaneous n.

Median n.

Ulnar n.

AnteriorMusculocutaneous n.

Humerus

Radial n.

UlnaRadius

Median n. & Ulnar n.

Radial n.

5th metacarpal

Ulnar n. & Median n.

Anterior

Anterior

Posterior

Posterior

Posterior

MOTOR INNERVATION

Muscle Compartments of the Upper Limb

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Musculocutaneous Nerve (arm)

http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3

All mm. in anterior (flexor) compartment of arm

MRI of arm1.Biceps brachii m. 2.Brachialis m. 3.Brachial a. 4.Humerus. 5.Triceps brachii m.

www.med.umich.edu

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Radial Nerve (arm)

All mm. in posterior (extensor) compartment of arm

http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3

Radial nerve

BB

B

TLongTLat

TMed

The brachialis m. is innervated by which division of the brachial plexus: :

A. Anterior division B. Posterior division

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50%50%

Anterior division Posterior division

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The brachialis m. is innervated by:

A. Median n.B. Musculocutaneous n. C. Radial n.D. Ulnar n.

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25%

25%25%

25%

Median n. Musculocutaneous n. Radial n. Ulnar n.

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The triceps brachii m. is innervated by:A. Musculocutaneous n. B. Radial n.

50%50%

Musculocutaneous n. Radial n.

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Radial Nerve (forearm)

All mm. in posterior (extensor) compartment of forearmAlso * brachioradialis and supinator mm.

http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3

*

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Ulnar Nerve (forearm)

Limited mm. in anterior (flexor) compartment of forearm:-Flexor carpi ulnaris-Flexor digitorum profundus (medial ½)

http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3

Med 1/2

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Median Nerve (forearm)

All anterior (flexor) compartment mm. of forearm except:-Flexor carpi ulnaris m.-Flexor digitorum profundus m. (med ½)

http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3

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RULE #2C

The extensor digitorum m. lies in the posterior compartment, originates on the lateral epicondyle, and is innervated by:A. Median n.B. Musculocutaneous n. C. Radial n.D. Ulnar n.

25%

25%25%

25%

Median n. Musculocutaneous n. Radial n. Ulnar n.

Lateral epicondyle

Extensor digitorum m.

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“Be specific”

The flexor carpi radialis m. is in the anterior compartment, attaches to the medial epicondyle, and is innervated by:

A. Median n.B. Radial n.C. Ulnar n.

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33%

33%

33%

Median n. Radial n. Ulnar n.

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The flexor digitorum profundus m. is the anterior compartment, attaches to the medial epicondyle, and is innervated by:A. Median n.B. Median n. & Ulnar n. C. Ulnar n.

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33%

33%

33%

Median n. Median n. & Ulnar n. Ulnar n.

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The brachioradialis and supinator mm. lie in the anterior aspect of the forearm but attach to the lateral epicondyle of the humerus. They are innervated by:A. Median n.B. Radial n. C. Ulnar n.

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33%

33%

33%

Median n. Radial n. Ulnar n.

www.pelhamrehab.com

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Median Nerve (hand)

Limited hand mm.:-Thenar mm.-Lateral two lumbricals

http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3

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Ulnar Nerve (hand)

All hand mm. not innervated by median n.

http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3

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What about the most proximal muscles of the upper limb?

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*

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Developmentally-dorsal muscles: •Lie posterior to the long bones in anatomical position (* exception = brachioradialis, supinator)

Developmentally-ventral muscles:•Lie anterior to the long bones in anatomical position-or-•Arise from:

– coracoid ossification – sternum and costal cartilages

-or-•Arise from:

– scapular blade ossification– vertebral column

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RULE #2D

Given the attachments of the latissimus dorsi muscle, its innervation will be from which of division of the brachial plexus:

A. Anterior division B. Posterior division

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50% 50%

Anterior division Posterior division

C5

C7

C6

C8

T1

**

*

suprascapular n.supraspinatus & infraspinatus mm.

axillary n.

deltoid & teres minor mm.

upper subscapular n.thoracodorsal n.lower subscapular n.

subscapularis m.latissimus dorsi m.subscapularis & teres major mm.

Brachial Plexus(branches)

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Given the attachments of the pectoralis muscles muscle, its innervation will be from which of division of the brachial plexus:

A. Anterior division B. Posterior division

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Anterior division Posterior division

C5

C7

C6

C8

T1

radial n.

axillary n.

medial n.

musculoskeletal n.

suprascapular n.

upper subscapular n.thoracodorsal n.lower subscapular n.

medial pectoral n.

lateral pectoral n.

long thoracic n.

dorsal scapular n.

**

*

ulnar n.

rhomboid mm.

pectoralis mm.

pectoralis mm.

serratus anterior m.

Brachial Plexus(branches)

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posterior anterior

Upper “roots” of the brachial plexus (C5-6 ventral rami) innervate proximal muscles (shoulder, elbow)

Lower “roots” of the brachial plexus (C8-T1 ventral rami) innervate distal muscles (hand)

RULE #3 Proximal-to-Distal Rule

Somatic motor nerve(GSE, with GSA)

Cutaneous nerves(GSA, GVE, GVA)

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MYOTOME- group of muscles innervated by a single spinal nerve root

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C5

C7

C6

C8

T1

Radial n.

Axillary n.

Medial n.

Musculoskeletal n.

Suprascapular n.

Upper & lower subscapular nn.Thoracodorsal n.

Medial pectoral n.

Lateral pectoral n.

Long thoracic n.

Dorsal scapular n.

**

*

Ulnar n.

Brachial Plexus(all branches)

* Nerve to subclavius** Medial brachial & antebrachial cutaneous nn. 39

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“MIXED FUNCTIONAL MODALITIES”

Most terminal branches of the brachial plexus are mixed fiber nerves:

1.Somatic motor and somatic sensory (prioprioception) to skeletal mm.

2.Then, cutaneous innervation with somatic sensory and sympathetics to skin

posterior anterior

RULE #3

Somatic motor nerve(GSE, with GSA)

Cutaneous nerves(GSA, GVE, GVA)

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Musculocutaneous n.Tank e

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Some purely cutaneous brs. of brachial plexusTank e

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Segmental innervation(C5-T1)

Dermatomes

RULE #5: Dermatome vs. Cutaneous Nerve Distribution

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Foerster (1933) – based on clinical findings (used by neurologists)

Keegan and Garrett (1948) – based on limb development

Segmental (Dermatome) Innervation of Upper LimbM

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Preaxial: C5-C7

Postaxial: C8-T1

Segmental (Dermatome) Innervation of Upper LimbM

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Thumb: C6

3rd Digit: C7

5th Digit: C8

Dermatomes vs. Cutaneous Nerve Distribution

Terminalbranches

Cutaneous nn.

Segmental innervation(C5-T1)

Dermatomes

Anterior Posterior47

Peripheral (Cutaneous ) Innervation of Upper LimbM

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Test for Peripheral Nerve Sensory Function:

Ulnar n. – Tip of 5th digit (little finger)Median n. – Tip of 2nd digit (index finger)

Radial n. – Webbing b/w thumb & index finger (dorsum)

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C6

C7

C8

Stretch Reflex

apbrwww5.apsu.edu/

Reciprocal inhibition of antagonist muscles

Bicipital reflex (C6 cord level) Triceps reflex (C7 cord level)

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Stretch Reflex

IVD Root Sensory Loss Motor WeaknessC4-C5 C5 Shoulder Shoulder weakness

C5-C6 C6 Anterior upper arm, Forearm flexion

Lateral forearm, thumb Biceps reflex

C6-C7 C7 3rd digits Forearm extension Triceps reflex

Wrist extension Hand grip

C7-C8 C8 5th digits Wrist flexionMedial forearm Intrinsic

hand mm.

Source: Devinsky et al. Neurologic Pearls

UPPER LIMB RADICULAR SYNDROMES

Proximal

Distal

Cranial

Caudal