Dr. Zahoor Ahmad PGR, Paediatric surgery, SZMC/H, RYK, Pakistan
Spinal nerves attach toSpinal Nerves the spinal cord via roots Dorsal root Has only sensory neurons Attached to cord via rootlets Dorsal root ganglion ○ Bulge formed by cell bodies of unipolar sensory neurons Ventral root Has only motor neurons No ganglion - all cell bodies of motor neurons found in gray matter of spinal cord 12-2
Spinal Nerves 31 pair each contains thousands of nerve fibers All are mixed nerves have both sensory and motor neurons) Connect to the spinal cord Named for point of issue from the spinal cord 8 pairs of cervical nerves (C1-C8) 12 pairs of thoracic nerves (T1-T12) 5 pairs of lumbar nerves (L1-L5) 5 pairs of sacral nerves (S1-S5) 1 pair of coccygeal nerves (Co1) 12-3
Formation of Rami Rami are lateral branches of a spinal nerve Rami contain both sensory and motor neurons Two major groups Dorsal ramus ○ Neurons innervate the dorsal regions of the body Ventral ramus ○ Larger ○ Neurons innervate the ventral regions of the body ○ Braid together to form plexuses (plexi) 12-4
Dermatomal Map Spinal nerves indicated by capital letter and number Dermatomal map: skin area supplied with sensory innervation by spinal nerves 12-5
Introduction to Nerve Plexuses Nerve plexus A network of ventral rami Ventral rami (except T2-T12) Branch and join with one another Form nerve plexuses ○ In cervical, brachial, lumbar, and sacral regions ○ No plexus formed in thoracic region of s.c. 12-6
Dorsal RamusBranches of Neurons within muscles of trunk and back Ventral Ramus (VR)Spinal Braid together to form plexuses ○ Cervical plexus - VR of C1-C4Nerves ○ Brachial plexus - VR of C5-T1 ○ Lumbar plexus - VR of of L1-L4 ○ Sacral plexus - VR of L4-S4 ○ Coccygeal plexus -VR of S4 and S5 Communicating Rami: communicate with sympathetic chain of ganglia Covered in ANS unit 12-7
Brachial Plexus Formed by ventral rami of spinal nerves C5-T1 Five ventral rami form three trunks that separate into six divisions that then form cords that give rise to nerves Major nerves Axillary Radial Musculocutaneous Ulnar Median 12-8
Brachial Plexus: Radial Nerve Motor components stimulate Posterior muscles of arm, forearm, and hand ○ Triceps, supinator, brachioradialis, extensors ○ Cause extension movements at elbow and wrist, thumb movements Sensory components Skin on posterior surface of arm and forearm, hand 12-10
Brachial Plexus:Musculocutaneous Nerve Motor components stimulate Flexors in anterior upper arm: (biceps brachii, brachialis) ○ Cause flexion movements at shoulder and elbow Sensory: Skin along lateral surface of forearm 12-11
Brachial Plexus: Ulnar Nerve Motor components stimulate Flexor muscles in anterior forearm (FCU, FDP, most intrinsic muscles of hand) Results in wrist and finger flexion Sensory: Skin on medial part of hand 12-12
Brachial Plexus: Median Nerve Motor components stimulate All but one of the flexors of the wrist and fingers, and thenar muscles at base of thumb (Palmaris longus, FCR, FDS, FPL, pronator) Causes flexion of the wrist and fingers and thumb Sensory components Stimulate skin on lateral part of hand 12-13
Etiology traffic accidents birth injuries humerus luxations brachial plexus neuritis stab and bullet wounds tumors (especially lung cancer) cervical rib, fibrous band from C7 (neurogenic thoracic outlet syndrome)
Principles of Localization Certain sites are prone to nerve entrapments/injuries Nerve opposing bone ○ Ulnar nerve at the elbow Closed spaces ○ Carpal tunnel Adjacent structures ○ Median nerve at the elbow, adjacent to the brachial artery
Principles of localization (cont.) Order in which branches arise Movements at specific joints Single nerve ○ Elbow extension Radial Multiple nerves ○ Elbow flexion Musculocutaneous Radial
Brachial Plexus Injuries Upper Lesions of the Brachial Plexus (Erb’s Palsy): resulting from excessive displacement of the head to opposite side and depression of shoulder on the same side.
Thiscauses excessive traction or even tearing of C5 and 6 roots of the plexus. It occurs in infants during a difficult delivery or in adults after a blow to or fall on shoulder.
Effects:Motor: paralysis of the supraspinatus, infraspinatus, subclavius, biceps brachii, part of brachialis, coracobrachialis; deltoid teres minor.Sensroy: sensory loss on the lateral side of the arm.
Deformity: waiter tip postionc. limb will hang by the side,d. medially rotated by sternocostal part of the pectoralis major;e. pronated forearm (biceps paralysis)
Lower Lesions of the Brachial Plexus(Klumpke Palsy) traction injuries by excessive abduction of the arm i.e. occurs if person falling from a height clutching at an object to save himself or herself. Can be caused by cervical rib. T1 is usually torn (ulnar and median nerves)
Motor Effects: paralysis of all the small muscles of the hand.Sensory effects: loss of sensation along the medial side of the arm.deformity: claw hand caused by hyperextension of the metacarpophalangeal joints and flexion of the interphalangeal joints.
Axillary Nerve injuryCauses:crutch pressing upward into thearmpit,Downward shoulder dislocationsfractures of the surgical neck of thehumerus.
Motor effects: Deltoidparalysis teres minor paralysis.Sensory effects: lossof sensation at lower ½ of deltoidDeformity: Wasting of deltoid
Radial Nerve injuryInjury in axilla :crutch pressing up into armpitdrunkard falling asleep with one arm over the back of a chair.fractures of proximal humerus.
Motor effects:paralysis of triceps Anconeus extensors of the wrist Extensors of fingers. Brachioradialis supinator muscle Deformity: Wrist and finger drop
Sensory effects : small area of sansation loss at arm and forearm sensory loss over lateral part of the dorsum of the hand (lat. 3.5 fingers without distal phalynges)
Injuries at Spiral Groove Caused by fracture shaft of humerus. Motor effects: paralysis of extensors of the wrist Extensors of fingers
Deformity: Wrist and finger drop Sensory effects: anesthesia is present over the dorsal surface of the hand (lat. 3.5 fingers)
Median Nerveinjury Motor effects: paralysis of pronator muscles long flexor muscles of the wrist and fingers, Exception:e. flexor carpi ulnarisf. medial half flexor digitorum profundus.
Deformity:apelike hand3.thenar muscles wasted4.thumb is laterally rotated and adducted.5.index and to a lesser extent the middle fingers tend to remain straight on making6.Weakening of lat. 2 fingers
Sensory: Sensory loss on the lat. 3.5 fingers on palmar side Sensory loss over distal phalynges of lat. 4 fingers on dorsal surface
Ulnar nerve injury Motor effects: paralysis of flexor carpi ulnaris medial half of the flexor digitorum profundus All interossei 3-4 lumbricals loss of abduction and adduction of fingers Wasting of hypothenar
Deformity: partial claw handSensory effects : Sensory loss over 1.5 fingers on both surfaces
CARPAL TUNNEL TUNNEL FORMED BETWEEN THE CONCAVITY OF THE CARPAL BONES AND A LIGAMENT THAT COVERS THIS( FLEXOR RETINACULAM) TENDONS OF THE FLEXORS PASS THROUGH MEDIAN NERVE ALSO PASSES THROUGH CROWDED TUNNELCARPAL TUNNEL SYNDROME- CAUSED DUE TO COMPRESSION OF THE NERVE IN THE TUNNEL- CAUSES-- 1. SWELLING OF THE TEDONS( OVERUSE)- 2. PREGNANCY( EDEMA)- 3. ARTHRITISSYMPTOMS- TINGLING OR NUMBNESS-LATERAL PART OF HAND, WEAKNESS IN THUMB MOVEMENTTREATMENT- REST, SPLINTING,ANTI-INFLAMMATORY DRUGS, SURGERY
Diagnosis Relies mainly on clinical examination No specific lab. Studies CT myelography MRI Nerve conduction studies
Treatment Most injuries recover without any Rx Rx is done in very highly specialized centers Surgical optionsd. nerve transferse. nerve graftingf. muscle transfersg. free muscle transfersh. neurolysis of scar around the brachial plexus in incomplete lesions.
Advances in nerve injury Rx Carlstedt obtained promising initial results with the repair of preganglionic lesions by replanting nerve rootlets directly into the spinal cord. This is a dramatic advance because preganglionic lesions were previously thought to be irreparable
End-to-side radial sensory tomedian nerve transfer hasbeen reported to improvesensation and to relieve painin C5 and C6 nerve rootavulsion