WINDSOR UNIVERSITY SCHOOL OF MEDICINE St.Kitts DEPARTMENT OF ANATOMY UPPER LIMB Dr. SREEKANTH THOTA

Upper Limb The upper limb is divided into the shoulder (junction of the trunk with the arm), arm, elbow, forearm, wrist, and hand.

How to study upper limb? 1. Bones of the Upper Limb 2. Brachial Plexus 3. Muscles of the Upper Limb a. Shoulder b. Arm c. Forearm d. Hand 4. Blood vessels of upper limb 5. Lymphatics of upper limb 6. Joints of upper limb

Bones of the Upper Limb Best way to learn bones of upper limb is during the anatomy lab, looking at Netter and follow your instructor.

Brachial Plexus The brachial plexus is a somatic plexus formed by the anterior rami of C5 to C8, and most of the anterior ramus of T1. It originates in the neck, passes laterally and inferiorly over rib I, and enters the axilla.

Brachial Plexus All major nerves that innervate the upper limb originate from the brachial plexus, mostly from the cords. The parts of the brachial plexus, from medial to lateral, are roots, trunks, divisions, and cords.

Brachial Plexus Injuries Injuries to the brachial plexus affect movements and cutaneous sensations in the upper limb. Signs and symptoms depend on the part of the plexus involved. Injuries to the brachial plexus result in paralysis and anesthesia.

Branches of the Brachial Plexus Roots: The roots of the brachial plexus are the anterior rami of C5 to C8, and most of T1. 1. Dorsal scapular nerve (C5) 2. Long thoracic nerve (C5, 6, and 7)

Trunks In the inferior part of the neck, the roots of the brachial plexus unite to form three trunks 1. Superior trunk, from the union of the C5 and C6 roots. 2. Middle trunk, which is a continuation of the C7 root. 3. Inferior trunk, from the union of the C8 and T1 roots. The inferior trunk lies on rib I posterior to the subclavian artery; the middle and superior trunks are more superior in position.

Branches of the trunks The only branches from the trunks of the brachial plexus are two nerves that originate from the superior trunk (upper trunk): 1.Suprascapular nerve (C5 and 6) 2.Nerve to the subclavius muscle (C5 and 6)

Divisions Each of the three trunks of the brachial plexus divides into an anterior and a posterior division. No peripheral nerves originate directly from the divisions of the brachial plexus.

Cords The three cords of the brachial plexus originate from the divisions and are related to the second part of the axillary artery. The anterior divisions of the upper and middle trunks unite to form the lateral cord, the anterior division of the lower trunk continues as the medial cord, and the posterior divisions of all three trunks join to form the posterior cord.

Cords

Brachial plexus

Relationships to the axillary artery.

Branches of the lateral cord 1.Lateral pectoral nerve(C5, 6, 7) 2.Musculocutaneous nerve(C5, 6, 7) 3.Lateral root of median nerve(C5, 6, 7)

Branches of the brachial plexus

Branches of the medial cord 1.Medial pectoral nerve(C8; T1) 2.Medial cutaneous nerve of arm (C8; T1) 3.Medial cutaneous nerve of forearm(C8; T1) 4.Ulnar nerve(C8; T1) 5.Medial root of median nerve(C5, 6, 7, 8; T1)

Branches of the posterior cord 1.Upper subscapular nerve(C5, 6) 2.lower subscapular nerve(C5, 6) 3.Thoracodorsal nerve(C6, 7, 8) 4.Axillary nerve(C5, 6) 5.Radial nerve(C5, 6, 7, 8; T1)

Relations Roots and trunks lie in the neck- Supraclavicular part Cords and branches lie in the axilla- Infraclavicular part

Branches of the Brachial Plexus and Their Distribution

1. Dorsal scapular nerve (C5) Rhomboid minor, rhomboid major, levator scapulae muscles

2. Long thoracic nerve (C5, 6, 7) Serratus anterior muscle

3. Suprascapular nerve (C5, 6) Supraspinatus and infraspinatus muscles

4. Nerve to subclavius (C5, 6)

5. Lateral pectoral nerve (C5, 6, 7) Pectoralis major muscle

6.Musculocutaneous nerve (C5, 6, 7) Coracobrachialis, biceps brachii, brachialis muscles

7. Median nerve(C5, 6, 7, 8; T1) All muscles in the anterior compartment of the forearm (except flexor carpi ulnaris and medial half of flexor digitorum profundus), three thenar muscles of the thumb and two lateral lumbrical muscles

8. Medial pectoral nerve (C8; T1) Pectoralis major and minor muscles

9. Medial cutaneous nerve of arm(C8; T1) Skin of medial side of arm

10. Medial cutaneous nerve of forearm (C8; T1) Skin of medial side of forearm

11.Ulnar nerve (C8; T1) All intrinsic muscles of the hand (except three thenar muscles and two lateral lumbricals); also flexor carpi ulnaris and the medial half of flexor digitorum profundus in the forearm

12. Upper subscapular nerve (C5, 6) Subscapularis muscle

13. Lower subscapular nerve (C5, 6) Subscapularis and teres major muscles

14. Thoracodorsal nerve (C6, 7, 8) Latissimus dorsi muscle

15. Radial nerve (C5, 6, 7, 8; T1) All muscles in the posterior compartments of arm and forearm

16. Axillary nerve (C5, 6) Deltoid, teres minor

Brachial plexus lesions

Injury to C5-6 at Erb’s point Muscles paralysed – Deltoid, Erb-Duchenne’s Palsy Injury to C5-6 at Erb’s point Muscles paralysed – Deltoid, biceps, brachialis, barachioradialis Posture – waiter’s tip deformity Mechanism of injury : fall on shoulder or excessive pulling of head of new born during delivery

Klumpke’s palsy Injury to C8-T1 Muscles paralyzed – small muscles of hand Deformity Claw hand Mechanism : Sudden superior pull

Clawed hand due to loss of innervation of Intrinsic muscle of the hand Symptoms: Clawed hand due to loss of innervation of Intrinsic muscle of the hand

Radial nerve

wrist-drop The characteristic clinical sign of radial nerve injury is wrist-drop.

Fracture of the Humeral Shaft A midhumeral fracture may injure the radial nerve in the radial groove in the humeral shaft. Fracture is not likely to paralyze the triceps because of the high origin of the nerves to two of its three heads.

Main Effect: Radial Nerve Injury in Axilla: Mechanism: SATURDAY NIGHT PALSY Radial Nerve Injury in Axilla: Mechanism: Crutches pressing in axilla Saturday night palsy! Main Effect: WRIST DROP

Axillary nerve

Note the left deltoid muscle atrophy.

Musculocutaneous nerve

Median nerve

Radial and ulanar arteries and median nerve Radial and ulanar arteries and median nerve. Three nerves could be involved ???

Carpal Tunnel syndrome Common in computer professionals. Due to constant dorsiflexion of wrist while typing the keyboard

Ulnar nerve

Cutaneous Nerves of upper limb