Syste Matic Anatomy

Syste matic Anatomy

Anatomy Department of WHU

Ⅲ. Brachial Plexus （Ⅰ ） Position & formation Position: posterosuperior to subclavian artery. Formation: the union of the anterior branches of

root trunk division

C5

C6

C5 - C8 & most part of

C7

the anterior branch of

C8

T1.

T1

roots C4 C5 C6 divisions

C7 C8 T1

cords

roots

trunks

anterior division posterior division

trunks

root trunk division

C5

C6 C7 C8 T1

Trunk Division Anterior division Posterior

Superior trunk

Middle trunk ( C7 ramus )

(anterior rami of C5 and C6)

Lateral cord

Inferior trunk

(central rami of C8 and T1 )

Medial cord

(anterior division of the upper and (anterior division of the lower trunk middle trunk) )

Posterior cord

（Ⅱ） Branches of brachial plexus

1. Branches of supraclavicular group: most of them are short muscular branches. levator scapulae and rhomboideus Dorsal scapular nerve Major long Suprascapular nerve supraspinatus and the infraspinatus branches: Long thoracic nerve serratus anterior

The damage of the long thoracic nerve results in paralysis of the serratus anterior and shows the symptom of “winging of scapula”

2. Branches of infraclavicular group: Most of them are long branches. They innervate the shoulder, the chest, the brachia, the forearm and hands . Major branches: median nerve, ulnar nerve, musculocutaneous nerve, radial nerve, axillary nerve, thoracodorsal nerve, lateral & medial pectoral nerves.

Median Nerve 1. Roots

Lateral cord

Medial cord 2. No branches in the arm. 3. Innervation: in the forearm, distributes to most muscles in the flexor compartment of the forearm except the brachioradialis, the flexor carpi ulnaris & the medial half of the flexor digitorum profundus.

root trunk division

C5 C6 C7 C8 T1

3. Palmar cutaneous branch: innervates the skin of the thenar & central part of the palm. 4. Recurrent branch: innervates the thenar muscles except the adductor pollicis. 5. Common palmar digital nerves & proper palmar digital nerves: control the 1st & 2nd lumbrical muscles, innervate the skin of the palmar aspect of the lateral 3 & ½ fingers, as well the skin on the dorsum of their terminal phalanges.

Ulnar Nerve 1. 2. 3.

Arises from the medial cord of the brachial plexus. Has no branch in the arm. In the forearm it innervates the flexor carpi ulnaris & the medial half of the flexor digitorum profundus.

4. Dorsal branch: to the skin on the ulnar ½ of the dorsum & the posterior surface of the ulnar 1 & ½ fingers. 5. Superficial palmar branch: to the skin of the hypothenar & the anterior surface of the ulnar 1 and ½ fingers. 6. Deep palmar branch: to the hypothenar muscles, the adductor pollicis, the 3rd & the 4th lumbricals, & the interossei.

Superficial branch

Skin of the hypothenar Skin of the anterior surface of the ulnar 1 & ½ fingers

Palmar branches Deep branch

Hypothenar muscles Adductor pollicis Interossei 3rd & 4th lumbricals

Musculocuteneous nerve

Lateral antebrachial cutaneous nerve

1. Arises from the lateral cord of the brachial plexus. 2. Its muscular branches distribute to the coracobrachialis, the biceps brachii & brachialis. 3. The lateral antebrachial cutaneous nerve distributes to the skin on the lateral side of the forearm.

Muscular Musculo- branch

cutaneous Cutaneous n. branch

Brachialis Muscles in Biceps brachii the arm Coracobrachialis Skin of the lateral side of the forearm

lateral antebrachial cutaneous n.

Radial Nerve 1. Arises from the posterior cord of the brachial plexus. 2. Its branches in the arm: 1) Muscular branches: innervate the triceps brachii. 2) Cutaneous branches: supply the skin on the dorsum of the arm.

3. At the level of the lateral epicondyle of the humerus, it is divided into deep & superificial branches: 1) Deep branch: contributes to the brachioradialis & the posterior group muscles of the forearm. 2) Superficial branch: contributes to the skin of the radial side of the dorsum of the hand & of the proximal digits of the radial 2 & ½ fingers.

Axillary Nerve 1. Arises from the posterior cord of the brachial plexus. It passes through the quadrangular space with the posterior circumflex humeral vessels. 2. Muscular branches: supply the deltoid & teres minor. 3. Cutaneous branch: supplies the skin over the deltoid.

Thoracodorsal nerve--- latissimus dorsi Lateral pectoral nerve & medial pectoral nerve--pectoralis minor and pectoralis major

Distribution of Cutaneous Nerves to Hand

Median n.

Ulnar n.

Radial n.

Ulnar n.

Median n.

Ulnar n.

Radial n.

Ulnar n.

The radial 2/3 skin of the palm. Skin of the palmar part of the radial 3 & ½ Median n. finger, as well as the skin of their dorsal part of distal & middle phalanges.

Median n.

Ulnar n.

Radial n.

Ulnar n.

Skin of the hypothenar & the palmar surface of the ulnar 1 & ½ fingers. Ulnar n. Skin on the ulnar ½ of the dorsum & the posterior surface of the ulnar 1 & ½ fingers.

Median n.

Ulnar n.

Radial n.

Ulnar n.

Skin on the radial side of the dorsum of the hand Radial n. Skin of the dorsum of the proximal digits of the raidal 2 & ½ fingers

Highlights The formation, position & distribution of 5 major branches of the brachial plexus: axillary nerve musculocutaneous nerve radial nerve median nerve ulnar nerve Distribution of Cutaneous Nerves to Hand

Assignments

P466 Fig. Ⅵ-5-11