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Answer Guide for the Back and Upper Limb Essay Examination - October 2, 2009

Note. The following is a guide to answering the questions and is not the "answer."

Vertebral Column and Spinal Canal

Review the anatomy of the vertebral column and spinal canal. Include bones, articulations, ligaments, spaces, contents, muscles, movements and limitations of movement, vasculature and lymphatic drainage, innervation, and relationships. Include mention of the fascial layers penetrated during lumbar puncture and a brief account of saddle anesthesia. (12 pts)

General Comment

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


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


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

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 terminalis internal and external - coccyx


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


  • Deep intrinsic muscles - dorsal rami
  • Intermediate muscles - ventral rami,
  • Superficial muscles - brachial plexus, spinal accessory, and cervical plexus
  • Zygapophyseal branches


  • Flexion
  • Extension
  • Lateral flexion
  • Rotation

Ligaments and Limitation of Movements

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


  • Radicular arteries
  • Augment anterior and posterior spinal arteries
  • Artery of Adamkewitz
  • Anterior and posterior internal vertebral venous plexuses
  • Valveless - spread of infection
  • Epidural fat


  • Vertebral foramen
  • 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

Lymphatic drainage

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

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
  11. pia mater
  12. spinal cord or cauda equina

Saddle anesthesia

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


Elbow Region and Cubital Fossa

Review the anatomy of the elbow region and cubital fossa. Include bones, articular surfaces, cavities, capsules, ligaments, contents, boundaries, muscles, movements and limitations of movement, vasculature, innervation, relationships to surrounding structures, and lymphatic drainage. (12 pts).

General comment

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

Bones, Articular Surfaces, and Synovial Cavity

  • 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

Capsules and Ligaments

  • 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

Boundaries and Contents of Cubital Fossa

  • Boundaries
    • Superior: line across humeral epicondyles
    • Inferior: crossing of pronator teres and brachioradialis
    • Anterior: bicipital aponeurosis
    • Posterior: brachialis, supinator, and tendon of the biceps
    • Lateral: brachioradialis
    • Medial: pronator teres
  • Contents - medial to lateral
    1. inferior ulnar collateral artery
    2. anterior recurrent ulnar artery
    3. median nerve
    4. brachial artery splitting to ulnar and radial arteries
    5. tendon of the biceps
    6. lateral cutaneous nerve of forearm
    7. radial nerve, superficial and deep branches
    8. radial collateral artery
    9. radial recurrent artery

Muscles, Movements, and Limitations of Movement

  • Flexion
    • 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
    • Posterior compartment of arm - triceps and anconeus
    • Flexor origin from medial humeral epicondyle
    • Olecranon and olecranon fossa - stability on extension

Vasculature and Innervation

  • elbow anastomosis- relationships to epicondyles and to adjacent muscles
  • Hilton's law - musculocutaneous, median, ulnar, and radial nerves
  • Cutaneous nerves
    • Lower lateral cutaneous of arm, posterior cutaneous nerve of arm
    • posterior cutaneous nerve of forearm
    • Medial and lateral cutaneous nerves of the forearm


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

Lymphatic Drainage

  • Supratrochlear nodes, axillary etc.


Ulnar Nerve

Review the origins, relationships, and distributions of the ulnar nerve. Discuss ulnar nerve injury and its effects on muscles, joints, and sensory distributions. (12 pts)


  • lower roots of the brachial plexus (C8,T1)
  • terminal branch of medial cord


  • axilla - medial and anterior to axillary artery
  • arm - crosses anterior surface of teres major and lattissimus dorsi, then crosses posterior to medial intermuscular septum, posterior to brachial artery, medial to triceps (long head)
  • elbow - passes in ulnar groove of the humerus at the medial epicondyle, site of injury or entrapment
  • elbow - enters forearm by passing between humeral and ulnar heads of flexor carpi ulnaris, site of injury or entrapment
  • forearm - passes between flexor carpi ulnaris and flexor digitorum profundus
  • wrist - crosses anterior to flexor retinaculum, lateral to pisiform, medial to hook of hamate, Guyon's tunnel
  • hand - superficial branch to 1.5 digits cutaneous, deep branch to all muscles of hand less "2LOAF"
    • flexor pollicis brevis is dually innervated
    • deep branch enters deep palm by passing deep to abductor digiti minimi.


  • axilla
  • arm
  • elbow
  • forearm - flexor carpi ulnaris, ulnar half of flexor digitorum profundus
  • wrist - dorsal ulnar nerve
  • hand
    • wrist - dorsal ulnar nerve, palmar branch *superficial (palmar) branch to 1.5 digits cutaneous and palmaris brevis
    • deep branch to all muscles of hand less "2LOAF"
    • flexor pollicis brevis is dually innervated

Ulnar Nerve Injury

  • axilla
  • arm
  • elbow - weakened flexion
  • forearm
  • wrist - weakened adduction and flexion
  • hand - loss IP extension concurrent with MP flexion
    • claw hand - hyerextended MP joints with IP joints tethered in flexion, less clawing on the radial side due to intact radial two lumbricals.

Additional Comments

  • 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





-- LorenEvey - 04 Oct 2009

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Topic revision: r1 - 16 Oct 2009, UnknownUser
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