Ganglion - collection of cells outside of the CNS

Nucleus - collection of cells in the CNS

No

But they can in the PNS if cell bosy remains intact and myelinating Schwann cells remain active

Begins at foramen magnum

Ends at vertebral L1-L2 level

How many pairs of cranial nerves are there?

How about spinal nerves? 

12 pairs of  cranial nerves

31 pairs of spinal nerves (8C, 12T, 5L, 5S, 1CC)

C1 - between skull and atlas (above C1 vertebra)

C2-C7 - above the corresponding vertebrae

C8 - below C7 vertebra

all the others - below corresponding vertebrae

What makes up a spinal nerve?

What does a spinal nerve split into?

Dorsal root (sensory) + ventral root (motor)

Spinal nerves are very short; after 1 cm they divide into dorsal primary ramus and ventral primary ramus (both of those are mixed nerves - motor and sensory)

Key dermatomes:

C6

C8

C5-T2

T4

T10

C6 - thumb

C8 - little finger

C5-T2 - upper limb

T4 - nipple

T10 - umbilicus

S2 - ends as a blind sac

Dural filum terminale (a.k.a. coccygeal ligament) is attached to the coccyx

Epidural space

Subdural space

Subarachnoid space

Epidural - between skull and dura

Subdural - potential space above arachnoid

Subarachnoid - between arachnoid and pia; filled with CSF

between L3 and L4 or between L4 and L5

Use highest points of iliac crests as a landmark to get into the subarachnoid space

What spinal neurons does polio virus affect?

How about Herpes zoster?

How about herniated intervertebral disk - what does it compress?

Polio - ventral horn motor neurons

Herpes zoster - dorsal root ganglia

Herniated disk - nucleus pulposus compresses the spinal nerve (both sensory and motor)-generally one associated with lower vertebra(L4-L5 disk --> L5 nerve root)

Kyphosis

Lordosis

Scoliosis

Kyphosis - posterior convex (thoracic)

Lordosis - lumbar (anterior curvature)

Scoliosis - lateral curvature

Spinalis, longissimus, iliocostalis

Innervated by dorsal rami of spinal nerves

Laterally bend and extend the back

Preganglionic - in lateral horn in T1-L2; axons leave in ventral roots and enter T1-L2 spinal nerves; leave nerves in white rami communicans (myelinated) and enter sympathetic chain ganglia; synapse and re-enter spinal nerves as gray rami communicans. Some pass through ganglia without synapsing and leave ganglia as thoracic and lumbar splanchnic nerves on the way to abdominal and pelvic ganglia.

The ones from above and below T1 and L2 travel in sympathetic chain until they reach cervical, lower lumbar and sacral ganglia; no white rami at these levels.

Thus there are 14 white rami communicans and 31 gray rami communicans  

Preganglionic neurons are in brain stem (CN 3,7,9,10) and in S2-S4 spinal segments (travel in spinal nerves S2-S4 nerves and branch off as pelvic splanchnic nerves)

Brainstem ganglia are - ciliary, pterygopalatine, submandibular and otic; there also are thoracic and abdominal ganglia (receive fibers from CN X) and pelvic ganglia (pelvic splanchnic nerves)

Ptosis, miosis (constricted pupil) and anhydrosis (lack of sweating in the face)

SNS issue - cervical sympathetic chain

Are pectoral and pelvic girdles a part of axial skeleton?

A rounded part of a bone that forms part of a joint

(i.e. capitulum [radius] and trochlea [ulna] for the humerus)

Surrounded by tough outer fibrous capsule and thin inner lining that keeps small amount of synovial fluid between the articulating surfaces

Includes ball and socket joint and hinge joint

Muscles that flex shoulder and/or elbow

Innervated by musculocutaneous nerve

Muscles extend shoulder and/or elbow

Innervated by radial nerve

Primary flexor of the elbow

Supinates the forearm

Crosses 3 joints - elbow, glenohumeral, proximal radioulnar)

Innervated by musculocutaneous nerve

Long head originates from sup. glenoid fossa;

short head - from coracoid process of scapula

Both heads insert onto radial tuberosity 

Dermatomes of the upper limb:

C6, C7, C8

C6 - lateral forearm and thumb

C7 - posterior forearm and middle finger

C8 - medial forearm and little finger

O: medial clavicle, sternum, costal cartilages

I: humerus

Innervation - medial and lateral pectoral nerves

Action - aDDucts and medially rotates humerus

O: ribs 3-5

I: coracoid process of scapula

Innervation - medial pectoral nerve

Action - stabilize and medially rotate scapula, accessory muscle of respiration

O: ribs 1-8

I: anterior surface of medial scapular border

Innervation - long thoracic nerve (runs superficial to the muscle)

Action - lateral rotation of scapula to permit abduction of scapula above the horizontal plane

Injury --> "winged scapula"

O: clavicle, acromion, scapular spine

I: deltoid tuberosity of humerus

Innervation - axillary nerve

Action - everything except ADDuction

SITS

Supraspinatus

Infraspinatus

Teres minor

Subscapularis

O: supraspinous fossa of scapula

I: greater tubercle of humerus

Innervation - suprascapular nerve

Action - stabilizes joint; assists onset of aBduction

O: infraspinous fossa of scapula

I: greater tubercle of humerus

Innervation - suprascapular nerve

Action - laterally rotate arm, stabilize joint

O: lateral border of scapula

I: greater tubercle of humerus

Innervation - axillary nerve

Action - lateral rotation of arm, joint stabilization

O: subscapular fossa

I: lesser tubercle of humerus

Innervation - upper and lower subscapular nerves

Action - medially rotate humerus; joint stabilization

O: inferior angle of scapula

I: shart of humerus

Inervation - lower subscapular nerve

Action - aDDucts and medially rotates arm

Screw the lawyers, save a patient

1 - superior thoracic artery

2 - thoracoacromial artery, lateral thoracic artery

3 - posterior and anterior humeral circumflex arteries, subscapular artery(this one later divides into thoracodorsal and circumflex scapular)

Richard Tucker Drinks Cold Beer

R - rami (C6-T1)

T - trunks (upper [C5,C6], middle [C7], lower [C8,T1])

D - divisions (anterior and posterior)

C - cords (lateral, posterior, medial)

B - branches(axillary, radial, musculocutaneous, median, ulnar)

C5 and C6

Travels through quadrangular space

Innervates deltoid and teres minor

Becomes superior lateral cutaneous nerve of the arm (supplies small patch of skin over the shoulder)

C5-C8

Wraps around the shaft of humerus (frequently injured here)

Sensation on skin over posterior arm, forearm,  dorsum of hand 

Innervates extensors of arm and forearm

Superficial branch suppiles dorsum of radial side if hand; until wrist travels deep to brachioradialis

Deep branch supplies extensor carpi radialis brevis and supinator Posterior interosseous nerve after comes out of the supinator

Injury results in wrist drop

Mostly C5 and C6

Thravels through coracobrachialis muscle (can get compressed here)

Innervates anterior compartment of the arm

Continues as lateral cutaneous nerve of the forearm to the lateral forearm

C6-T1

Innervates anterior compartment of the forearm and thenar compartment

(Rule of anterior compartment of the forearm - median nerve innervates muscles that flex the fingrs and pronate the forearm - exception is flexor carpi ulnaris)

Supplies most of the palm and index and middle fingers with sensation

C8 and T1

Innervates some forearm muscles

Primary nerve to small muscles of the hand

Supplies skin on the ulnar side of the hand, little finger and ulnar side of the ring finger with sensation

Passes posterior to middle epicondyle of humerus

C5, C6, C7

Innervates serratus anterior

Runs superficial to the muscle - easily injured here

Comes from ventral ramus of C5

Innervates rhomboids and levator scapulae

From upper trunk (C6 and C7)

Innervates suprasinatus and infraspinatus

Medial - from medial cord; innervates pectoralis major and minor

Lateral - from lateral cord; innervates pectoralis major

From posterior cord

Innervates subscapularis

Middle subscapular nerve

(a.k.a nerve to latisimus dorsi)

(a.k.a. thoracodorsal nerve)

From posterior cord

Innervates latissimus dorsi

From posterior cord

Innervates subscapularis and teres major

From medial cord

Supply skin on medial arm and forearm

O: coracoid process of scapula

I: shaft of humerus

Innervation - musculocutaneous nerve (C6)

Action - flexes and aDDucts arm

O: shaft of humerus

I: ulna

Innervation - musculocutaneous nerve

Action - flexes forearm

O: long head of scapula

I: olecranon

Innervation - radial nerve (esp. C7)

Action - extends forearm

Long head crosses glenohumeral joint

Clinical correlate:

muscles of anterior compartment are innervated primarily by C6

Muscles of posterior compartment are innervated mainly by C7

 So C7 injury will affect primarily posterior compartment and anterior should be ok

Radial nerve.

 Lose extensors and so wrist remians flexed

Flexor carpi radialis - median n. (flex, aBducts)

Palmaris longus - median n.

Flexor carpi radialis - ulnar n. (flex, aDDucts)

Pronator teres - median n. [C7] (also flexes forearm)

Medial epicondyle

Injury results in "golfer's elbow"

Flexor digitorum superficialis - median n.

Flexes MP and PIP joints

 Flexor digitorum profundis - 1/2 median nerve, 1/2 ulnar nerve

Flexor pollicis longus - median n.

Pronator quadratus - median n.

Can get injured between 2 heads of pronator teres (pronator syndrome) or in carpal tunnel

Severely limited movement of thumb and wasting of thenar eminence

Loss of cutaneous sensation in hand and fingers - test tip of index finger

Lose fine motor control of index finger

Bishop's hand - if injury higher up

Some Lovers Try Positions That They Can't Handle (proximal to distal row, radial to ulnar)

Scaphoid

Lunate (can compress median nerve)

Triquetrum

Pisiform (sesamoid - in tendon of flexor carpi ulnaris)

 Trapezium ("base of thumb")

 Trapezoid

Capitate

Hamate (with hook)

Covered by flexor retinaculum

9 tendons and 1 nerve

[Flexor digitorum superficialis and profundus and flexor pollicis longus

Median nerve]

No major vessels pass through carpal tunnel

Innervated by recurrent branch of median nerve (C8)

Abductor pollicis brevis

Flexor pollicis brevis

Opponens pollicis

Deep branch of ulnar nerve (T1)

Abductor digiti minimi

Flexor digiti minimi

Opponens digiti minimi

"Bye-bye muscles" - flex MP, extend IP

Lumbricals - from tendons of flexor digitorum profundus to extensor expansion; innervated by median nerve and deep branch of ulnar n.

Palmar interossei (PAD) - deep branch of ulnar nerve

Dorsal interossei (DAB) - deep branch of ulnar nerve

Test - by ability to adduct/abduct fingers (T1)

Adductor pollicis - deep branch of ulnar nerve

Ulnar - tip of little finger

Median - tip of index finger

Radial (superficial branch) - skin on dorsal webbing of thumb

C6 - dorsum of thumb

C7 - tip of middle finger

C8 - tip of little finger

Injured at medial epicondyle or in canal of Guyon at the wrist

Impaired abduction/adduction of fingers

Uncoordinated fingers

Claw hand - 4th and 5th MPs hyperextended at rest

Paresthesia in ulnar palm and little finger - test little finger

All innervated by radial nerve

Brachioradialis - C6; flexes forearm

 Extensor carpi radialis longus - C6 and C7

Extensor carpi radialis brevis

Extensor digitorum (mainly MP joints, weak IP)

Extensor digiti minimi

Extensor carpi ulnaris

All but ECRL and brachioradialis come from common extensor origin - lateral epicondyle

Lateral epicondyle

Posterior forearm except for brachioradialis (which is a flexor, so no worries) and extensor carpi radialis longus

Injury = tennis elbow

All innervated by radial nerve

Supinator

Extensor indicis

3 outcropper muscles - extensor pollicis longus and brevis and abductor pollicis longus

Between the tendons of the outcropper muscles - extensor pollicis longus and brevis and abductor pollicis longus

Indicates fractured scaphoid bone

Palpate pulse of the radial artery here

Trauma to upper trunk of brachial plexus - lose C5 and C6

Radial - lose C6 muscles - brachioradialis and ECRL

Lose most of musculocutaneous - flexors of arm

Lose lateral pectoral n., upper and lower subscapular n., suprascapular nerve

 Result - lose aBduction and lateral rotation; see upper limb aDducted and medially rotated, elbow extended and pronated at rest; flexed wrist - "head waiter's tip hand"