48 Neurovasculature

STUDYAIMS

At the end of your study, you should be able to:

Describe the arterial supplyof the arm, forearm, and hand, distinguishing the arteries supplying each of the compartments Know the locations of the brachial, radial, and ulnar pulses

Describe the venous drainage of the hand, forearm, and arm Describe the lymphatic drainage of the upper limb Understand the organization of the brachial plexus

Know the innervation to the compartments of the arm and forearm Recognize the course of the major nerves of the upper limb

Understand the dermatome map of the upper limb and its cutaneous innervation

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GUIDE

Upper Limb: Neurovasculature

Vascular Supply to the Upper Limb

[Plate 421, Brachial Artery in Situ]

Arterial Supply to the Arm

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Axillaryartery

Begins at lateral border of first rib and ends at inferior border of teres major

Divided into three descriptive parts bypectoralis minor muscle

First part

First rib to medial border of pectoralis minor

Is enclosed in axillarysheath

One branch-superior thoracic arterysupplying serratus anterior

Second part

Posterior to pectoralis minor

Two branches

Thoracoacromial artery

Lateral thoracic artery

Both supplythe pectoral muscles and breast

Third part

Lateral border of pectoralis minor to inferior border of teres major

Three branches

Subscapular artery

Largest branch

Divides into circumflexscapular and thoracodorsal arteries

Supplies serratus anterior, teres major, subscapularis, and latissimus dorsi muscles

Anterior and posterior circumflexhumeral arteries

Brachial artery

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Continuation of the axillaryartery, ends in cubital fossa

Lies anterior to triceps and brachialis throughout its course

Accompanied bymedian nerve, which crosses anterior to arteryand lies mediallyin cubital fossa

Divides into ulnar and radial arteries under bicipital aponeurosis

Branches

Manymuscular branches

Profunda brachii arteryfrom medial aspect

Superior and inferior ulnar collateral branches

Profunda brachii (deep arteryof the arm)

Accompanies radial arteryin radial groove

Divides into anterior and posterior descending branches to elbow

Arterial Supply to the Forearm

Ulnar artery

Larger of two terminal branches of brachial artery

Begins medial to biceps tendon and descends through anterior compartment deep to pronator teres

Branches

Anterior ulnar recurrent

Posterior ulnar recurrent

Common interosseus, which branches into

Anterior interosseus artery

Posterior interosseus artery

Muscular branches to muscles of medial side of forearm

Branches to the hand

Radial artery

Begins in cubital fossa at neck of radius

Passes distallydeep to brachioradialis muscle

Palpable throughout lateral forearm (best felt at the wrist)

Branches

Supplies flexor and extensor muscles on lateral side of forearm

Radial recurrent artery

Branches to the hand

Arterial Supply to the Hand

Branches from the ulnar artery

Palmar carpal branch

Runs across anterior wrist deep to tendons of flexor digitorum profundus (FDP)

Anastomoses with palmar carpal branch of radial arteryto form palmar carpal arch

Dorsal carpal branch

Arises proximal to pisiform

Crosses dorsal to wrist

Anastomoses with dorsal carpal branch of radial arteryto form dorsal carpal arch

Superficial branch of ulnar arteryin hand-continues into palm as superficial palmar arch

Deep (palmar) branch of ulnar arteryin the hand

Anastomoses with radial artery

Forms deep palmar arch

Venous Drainage of Hand and Forearm

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Veins of hand

Superficial and deep palmar venous arches

Dorsal venous network (arch)

Both drain to cephalic and basilic veins

Superficial veins of forearm

Basilic vein ascends posteromediallyon forearm

Cephalic vein ascends on lateral border of forearm

Median cubital vein connects cephalic and basilic over cubital fossa

Deep veins of forearm

Paired radial and ulnar veins and interosseus veins accompanyarteries of same name

All communicate with superficial veins and median cubital vein

Venous Drainage of Arm

Superficial veins (drain into axillaryvein)

Cephalic vein

On anterolateral surface

Enters groove between deltoid and pectoralis major (deltopectoral groove)

Then deltopectoral triangle

Empties into termination of axillaryvein

Basilic vein

Medial side, inferior arm

Pierces deep fascia at junction of inferior and middle third of arm

Runs superiorlyto axillaryvein

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Deep veins

Paired, accompanybrachial artery(venae comitantes)

Form at elbow from radial and ulnar veins

Have valves

Merge with basilic vein to form axillaryvein

Lymphatics

All lymph from the arm drains to the axillarynodes

Lymph from breasts and thoraxalso drains to the nodes

Nerve Supply to Upper Limb

Brachial Plexus [C5-T1]

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Composed of

Roots (5)

Trunks (3)

Divisions (6)

Cords (3)

Branches (13+4 from roots)

Roots

Ventral rami of spinal nerves C5-T1

Give rise to

Dorsal scapular nerve (C5, possible contribution from C4)

Long thoracic nerve (C5-C7) to serratus anterior muscle

Trunks

Superior from ventral rami of C5 and 6

Branches

a.Nerve to subclavius muscle

b.Suprascapular nerve to supraand infraspinatus, shoulder joint

Middle from ventral ramus of C7

Inferior from ventral rami of C8 and T1 Divisions

Anterior divisions of superior and middle trunks form lateral cord

Anterior division of inferior trunk continues as medial cord

Posterior divisions of all three trunks for posterior cord Cords

Named byrelationship to axillaryartery, which theysurround

Lateral

Medial

Posterior

Branches

Branches from lateral cord

Lateral pectoral nerve (C5-C7) to pectoralis major and minor muscles

Musculocutaneous (C5-C7)

Lateral root of median nerve (C6-C7)

Branches from medial cord

Medial pectoral nerve (C8-T1) to pectoralis minor and major

Ulnar nerve (C8-T1)

Medial brachial cutaneous nerve (C8-T1) supplies skin over medial surface of arm and proximal surface of forearm

Medial antebrachial cutaneous nerve (C8-T1) to skin over medial forearm

Median root of median nerve (C8-T1)

Branches from the posterior cord

Upper subscapular nerve (C5-C6) to subscapularis

Lower subscapular nerve (C5-C6) to teres major and subscapularis

Thoracodorsal nerve (C6-C8) to latissimus dorsi

Axillarynerve (C5-C6) to teres minor and deltoid (ends as the upper lateral brachial cutaneous nerve)

Radial nerve (C5-T1) supplies all extensors of the upper limb and sensation to skin overlying extensor region, including hand

Other facts

Anterior divisions supplythe flexor parts of the upper limb

Posterior divisions supplythe extensor parts of the upper limb

Each cord divides into two main terminal branches

Posterior→axillaryand radial

Lateral→musculocutaneous and median

Medial→Median and ulnar

Supraclavicular part of plexus

Arises from roots and trunks

Approachable through posterior triangle of the neck

Dorsal scapular nerve

Nerve to subclavius

Suprascapular nerve

Long thoracic nerve

Infraclavicular part (cords and their branches) is in the axilla Arise from cords

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Approachable through axilla

All the rest of the nerve branches from brachial plexus

Ulnar nerve supplies

Flexor carpi ulnaris

Medial half of FDP

Hypothenar muscles

Third and fourth lumbricals

All interossei muscles

Skin over the medial hand and 1½ digits

Median nerve supplies

Forearm flexors (except flexor carpi ulnaris and the lateral half of flexor digitorum profundus)

Thenar muscles and first and second lumbricals

Skin over the lateral hand and 3½ digits

Musculocutaneous nerve supplies

Flexor muscles of arm (anterior compartment)

Skin over lateral aspect of forearm (lateral antebrachial cutaneous)

Radial nerve supplies

Triceps

Anconeus

Extensor muscles of forearm

Skin over posterior arm and forearm

Axillarynerve supplies

Teres minor

Deltoid

Shoulder joint

Skin over inferior deltoid

Dermatomes and Cutaneous Innervation of the Upper Limb

[Plate 401, Dermatomes of Upper Limb]

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[Plate 402, Cutaneous Innervation of Upper Limb]

Dermatomes

Band-like areas of skin

Each supplied bya single spinal nerve through dorsal and ventral rami

Arranged in segmental fashion

Cutaneous innervation of the upper limb

Follows segmental arrangement of spinal nerve contributions to the brachial plexus

No representation of C7 on anterior aspect of arm and forearm

No representation of T1 on palmar or dorsal surface of hand

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