General Comment

• Vertebral column forms an osseofibrous canal that protects the spinal cord

Bones

• Seven cervical, 12 thoracic, 5 lumbar, 5 sacral, 4 coccygeal = 33 (9 fused)
• C1 and C2
• Cervical - bifid spines, transverse foramina, and more
• Thoracic - Rib articulations and more
• Lumbar - large bodies and more
• Sacral - fused and more

Boundaries of the Vertebral Foramen

• Vertebral region
  • Anterior - posterior longitudinal ligament, vertebral body
  • Posterior - lamina
  • lateral right and left - pedicle
• Intervertebral region
  • Anterior - intervertebral disk
  • Posterior - ligamentum flavum
  • Lateral right and left - intervertebral foramen, zygapophyseal
• Superior - foramen magnum
• Inferior - Sacral hiatus

Articulations

• Intervertebral disk - nucleus pulposus, annular ligament, anterior and posterior longitudinal ligaments
• Zygapophyseal joint - changes from cervical to lumbar regions and movements
• Costotransverse and costovertebral joints
• Curves - cervical lordosis, thoracic kyphosis, lumbar lordosis, sacral kyphosis, scoliosis

Spaces and Contents

• Epidural space - between bone/ligament and dura mater
  • Internal anterior and posterior vertebral plexuses
  • Epidural fat
• Subdural space - potential space between dura mater and arachnoidea
• Subarachnoid space - between arachnoidea and pia mater
  • Cerebral Spinal Fluid
• Spinal cord - C1 to L2 (conus medullaris)
• Thecal sac (dural sac) - C1 to S2
• Cauda equina
• Filum terminale internal and external - sacral hiatus and coccyx

Stability of the Spinal Cord

• Denticulate ligaments
• Filum terminale internal and external
• Rootlets
• Meninges and cerebral spinal fluid (CSF)
• Cauda equina

Muscles

• Erector Spinae - spinalis, longissimus, and iliocostalis
• Transversospinalis
• Psoas major and quadratus lumborum (optional comment)
• Longissimus cervicis and capitus
• Splenius cervicis and capitus
• Longus colli and capitus (optional comment)

Innervation

• Deep intrinsic muscles - dorsal rami
• Intermediate muscles - ventral rami
• Psoas major and quadratus lumborum - ventral rami
• Superficial muscles of the back - brachial plexus, spinal accessory, and cervical plexus
• Zygapophyseal branches

Movements

• Flexion
• Extension
• Lateral flexion
• Rotation

Ligaments and Limitation of Movements

• Anterior longitudinal ligament - limit extension
• Posterior longitudinal ligament - limit flexion
• Ligamentum flavum - limit flexion, gradual relaxation
• Interspinous - limit flexion
• Supraspinous - limit flexion

Vascularization

• Radicular arteries - essential for blood supply to cord
• Augment anterior and posterior spinal arteries
• Artery of Adamkiewicz - from lower posterior intercostal artery or upper lumbar artery, surgical risk
• Anterior and posterior internal vertebral venous plexuses, valveless and spread of infection or metastatic disease
• Anterior and posterior external vertebral venous plexuses, valveless and spread of infection or metastatic disease
• Valveless - spread of infection
• Epidural fat

Lymphatic drainage

• Paraaortic nodes
• Deep cervical nodes
• Lateral sacral nodes
• Venous plexuses and metastatic disease

Lumbar Puncture an Relationships

1. skin
2. tela subcutanea
3. supraspinous ligament
4. interspinous ligament
5. ligamentum flavum
6. epidural space
7. dura mater
8. subdural space
9. arachnoidea
10. subarachnoid space and cerebral spinal fluid (CSF)
11. pia mater (L2 and above)
12. spinal cord (L2 and above) or cauda equina

Saddle anesthesia - Optional

• L5/S1 anterior displacement
• Lordosis
• Compressed sacral nerves within cauda equina

General comment

• Humeroulnar joint - hinge joint
• Humeroradial joint
• Proximal radioulnar joint
• Synovial joint cavity - synovial membrane continuous with elbow and radioulnar joint

Bones, Ligament, Fasciae, and Compartments

• Humeral trochlea and ulnar trochlear notch - elbow joint
• Capitulum and radial head - humeroradial joint
• Head of radius and radial notch of ulnar - proximal radioulnar joint
• Ulnar collateral ligament - medial epicondyle to olecranon and coronoid process
• triangular, anterior, intermediate, and posterior fibers
• radial collateral ligament - lateral epicondyle to annular ligament and to supinator crest
• Annular ligament - secures radial head to the ulnar notch, blends with radial collateral ligament

Muscles, Movements, and Limitations of Movement

• Flexion at elbow
  • Anterior compartment of arm - biceps, brachialis, and brachioradialis
  • Flexor origin from medial humeral epicondyle
  • Pronator teres
  • Coronoid process and coronoid fossa - stability of flexion
• Extension at elbow
  • Posterior compartment of arm - triceps and anconeus
  • Flexor origin from medial humeral epicondyle
  • Olecranon and olecranon fossa - stability on extension
  • Olecranon and olecranon fossa - stability on extension
• Flexion at wrist
  • Ligaments of the wrist joint
  • Antagonistic muscles - posterior compartment of forearm
• Extension at wrist
  • Ligaments of the wrist joint
  • Antagonistic muscles - anterior compartment of forearm
• Adduction at wrist
  • Styloid process of ulna, articular disc, triquetrum, ulnocarpal ligaments and radiocarpal ligaments
• Abduction at wrist
  • Styloid process of radius, scaphoid, radiocarpal ligaments and ulnocarpal ligaments
• Pronation and supination
  • Interosseus membrane, oblique cord, proximal and distal radioulnar joints, and crossing of radius
  • Antagonistic muscles
• Superficial muscles - origins, insertions, innervations, and relationships
  • PT
  • BR
  • FCR
  • PL
  • FCU
• Intermediate muscles - origins, insertions, innervations, and relationships
  • FDS
• Deep muscles - origins, insertions, innervations, and relationships
  • FDP
  • FPL
  • PQ

Vasculature and Innervation

• elbow anastomosis- relationships to epicondyles and to adjacent muscles
• Medial and lateral cutaneous nerves of the forearm

Notable Relationships

• biceps aponeurosis
• median cubital vein, venipuncture
• elbow (cubital) anastomosis
• lateral cutaneous nerve of forearm
• ulnar groove and nerve

Lymphatic Drainage

• Supratrochlear nodes, axillary etc.

Structure (Roots, Trunks, Divisions, Cords, and Branches)

• • Roots - ventral rami C5 - T1; neck
  • Trunks - upper (C5 - C6), middle (C7), lower (C8 - T1); neck
  • Divisions - anterior (mostly flexors), posterior (mostly extensors); how they combine to form cords; neck
  • Cords - medial, lateral, and posterior named for relationship to axillary artery; axilla
• Dorsal scapular nerve - compensation is optional
  • Rhomboids and levator scapulae
  • Weakened retraction and elevation of the scapula
  • Compensation by trapezius
• Long thoracic nerve - compensation is optional
  • Serratus anterior
  • Lost protraction of the scapula - "winging" of the scapula
  • Pectoralis major and minor may compensate for some loss of stability
• Suprascapular nerve - compensation is optional
  • Supraspinatus
    • Lost first 15 degrees abduction
    • Compensation by "hip bump" and leaning to side of lesion
  • Infraspinatus and teres minor
    • Weakened lateral rotation at glenohumeral joint
    • Compensation by deltoid
• Lateral and medial pectoral nerves - weakened adduction and medial rotation - compensation is optional
  • Pectoralis major
    • Adduction compensation by deltoid, teres major, lattissimus dorsi, coracobrachialis, short head biceps
    • Medial rotation compensated by subscapularis and adductors
• Upper subscapular nerve - weakened medial rotation
  • Subscapularis
    • Medial rotation compensation by subscapularis, deltoid, teres major, lattissimus dorsi, coracobrachialis, short head biceps
• Middle subscapular nerve (thoracodorsal nerve) - weakened extension/flexion, adduction, and medial rotation
  • Latissimus dorsi
    • Extension compensated by deltoid, teres major, pectoralis major, coracobrachialis, short head biceps
    • Medial rotation compensated by deltoid, teres major, pectoralis major, coracobrachialis, short head biceps
  • Superficial epigastric and superficial circumflex iliac arteries and veins
• Lower subscapular nerve
  • Subscapularis
    • See upper subscapular nerve
  • Teres major
    • Medial rotation compensation by subscapularis, deltoid, lattissimus dorsi, coracobrachialis, short head biceps
• Axillary nerve
  • Deltoid
    • Rotation compensation by rotator cuff
    • Abduction from 15 -90 degrees at the glenohumeral joint not compensated
    • Some compensation for lost abduction at the glenohumeral joint by scapular rotation - trapezius and serratus anterior
    • Adduction compensated by pectoralis major, coracobrachialis, and latissimus dorsi
  • Teres minor * Lateral rotation compensated by infraspinatus
• Ulnar nerve - compensation is optional
  • Flexor carpi ulnaris
    • Flexion compensated by long flexors of the forearm
    • Adduction compensated by extensor carpi ulnaris
  • Flexor digitorum profundus
    • No compensation of flexion of distal IP for the the ring and little fingers
    • Compensation for flexion at joints proximal to DIP by long flexors
    • Compensation for flexion at MP joints by intrinsic muscles of the hand
  • Intrinsic muscles of the hand
    • Clinical: claw hand
      • Hyperextension at MP joints and tethering at the IP joints
    • Loss of adduction at the MP joints
      • Minor compensation by lumbricals
    • Loss of abduction at the MP joints
      • Minor compensation by lumbricals
    • Loss of extending IPs while flexing MP
      • No compensation
• Median Nerve - compensation is optional
  • Flexor carpi radialis
    • Abduction compensated by extensor carpi radialis
    • Flexion at wrist compensated by flexor carpi ulnaris
  • Flexor digitorum profundus
    • No compensation of flexion of distal IP for the the index and middle fingers
    • Compensation for flexion at joints proximal to DIP for the ring and little fingers by ulnar part of FDP
    • Compensation for flexion at MP joints by intrinsic muscles of the hand
  • Flexor digitorum superficialis
    • No compensation of flexion of proximal IP for the the index and middle fingers
    • Compensation for flexion at joints proximal to DIP for the ring and little fingers by ulnar part of FDP
    • Compensation for flexion at MP joints by intrinsic muscles of the hand
  • Flexor pollicis brevis
    • No compensation for lost flexion of the thumb
  • Pronator teres
    • Compensation for weakened elbow flexion by muscles of anterior compartment of the arm
  • Intrinsic muscles of the hand
    • Radial two lumbricals compensated for by interossei
    • Flexor pollicis brevis compensated by ulnar head
    • Opponens pollicis not compensated
  • Clinical
    • Ape hand due to atrophy of thenar eminence and loss of opposition (pronation)
• Radial Nerve
  • Brachioradialis
    • Elbow flexion compensated by anterior compartment of arm
    • Pronation compensated by pronator teres and pronator quadratus
    • Supination compensated by supinator and biceps
  • Extensor carpi radialis longus/brevis
    • No compensation for wrist drop (loss of flexion)
    • Abduction compensated by flexor carpi radialis
  • Extensor carpi ulnaris
    • No compensation for wrist drop (loss of flexion)
    • Adduction compensated by flexor carpi ulnaris
  • Extensor digitorum, indicis, and digiti minimi
    • No compensation for loss of extension from the distal IP and joints proximal
  • Extensor policis longus and brevis
    • No compensation
  • Abductor pollicis longus
    • Compensation by abductor pollicis brevis
  • Clinical
    • Wrist drop

Relationships to the Axillary Artery

• The brachial plexus is derived from the ventral rami of spinal nerves C5 - T1. There may be contributions from C4 and T2. The three cords of the brachial plexus are within the axilla. They surround the axillary artery and are named accordingly; the medial, lateral, and posterior cords.

Boundaries of the axilla - optional

• • Superior: clavical and thoracic outlet
  • Inferior: skin of the axilla; teres minor and serratus anterior
  • Anterior: pectoralis major and minor
  • Posterior: latissimus dorsi and teres major
  • Medial: serratus anterior
  • Lateral: humerus

Posterior Cord Injury - Functional Deficits and Compensation

• Upper subscapular nerve - weakened medial rotation
  • Subscapularis
    • Medial rotation compensation by subscapularis, deltoid, teres major, lattissimus dorsi, coracobrachialis, short head biceps
• Middle subscapular nerve (thoracodorsal nerve) - weakened extension/flexion, adduction, and medial rotation
  • Latissimus dorsi
    • Extension compensated by deltoid, teres major, pectoralis major, coracobrachialis, short head biceps
    • Medial rotation compensated by deltoid, teres major, pectoralis major, coracobrachialis, short head biceps
  • Superficial epigastric and superficial circumflex iliac arteries and veins
• Lower subscapular nerve
  • Subscapularis
    • See upper subscapular nerve
  • Teres major
    • Medial rotation compensation by subscapularis, deltoid, lattissimus dorsi, coracobrachialis, short head biceps
• Axillary nerve
  • Deltoid
    • Rotation compensation by rotator cuff
    • Abduction from 15 -90 degrees at the glenohumeral joint not compensated
    • Some compensation for lost abduction at the glenohumeral joint by scapular rotation - trapezius and serratus anterior
    • Adduction compensated by pectoralis major, coracobrachialis, and latissimus dorsi
  • Teres minor * Lateral rotation compensated by infraspinatus
• Radial Nerve
  • Brachioradialis
    • Elbow flexion compensated by anterior compartment of arm
    • Pronation compensated by pronator teres and pronator quadratus
    • Supination compensated by supinator and biceps
  • Extensor carpi radialis longus/brevis
    • No compensation for wrist drop (loss of flexion)
    • Abduction compensated by flexor carpi radialis
  • Extensor carpi ulnaris
    • No compensation for wrist drop (loss of flexion)
    • Adduction compensated by flexor carpi ulnaris
  • Extensor digitorum, indicis, and digiti minimi
    • No compensation for loss of extension from the distal IP and joints proximal
  • Extensor policis longus and brevis
    • No compensation
  • Abductor pollicis longus
    • Compensation by abductor pollicis brevis
  • Clinical
    • Wrist drop

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