Answers to the Three Anatomy Questions

Question 1: Uterine Anomalies - What are these anomalies? Explain the cause.

The Anomalies Shown (Mullerian Duct Anomalies)

Cause / Embryological Basis

• Failure of fusion of the two Mullerian ducts → uterus didelphys or bicornuate uterus
• Failure of septal resorption after fusion → septate uterus (the most common anomaly associated with pregnancy loss)
• Failure of one duct to develop entirely → unicornuate uterus
• Partial fusion defects → arcuate or subseptate forms

• Berek & Novak's Gynecology, p. 2064; Creasy & Resnik's Maternal-Fetal Medicine

Question 2: Cardiac Anomaly - What is it? Name the features.

Diagnosis: Tetralogy of Fallot (ToF)

The Four Features (numbered 1-4 in the diagram):

Cause / Embryology

• Moore's Clinically Oriented Anatomy / The Developing Human, per embryology textbook

Question 3: Clinical Condition - What is it? Explain the reason.

Diagnosis: Hydrocephalus

Definition

1. Obstruction to CSF flow (most common)
2. Overproduction of CSF (rare - choroid plexus tumors)
3. Failure of CSF reabsorption

Normal CSF Pathway (how to explain obstruction)

Why the head enlarges in infants

Common causes in neonates/children

• Congenital aqueductal stenosis (stenosis of the Aqueduct of Sylvius) - most common congenital cause
• Arnold-Chiari malformation with obstruction at the foramina
• Post-hemorrhagic (intraventricular hemorrhage in premature infants)
• Tumors obstructing the ventricular pathway
• Meningitis scarring blocking arachnoid granulations
• Gray's Anatomy for Students; Guyton and Hall Textbook of Medical Physiology

Answers to the Three Anatomy Questions (Pages 10-12/27)

Question 1 (Top of image): Cardiac Anomaly - What is it? Explain the reason.

1. Pulmonary stenosis - obstruction of right ventricular outflow
2. Ventricular Septal Defect (VSD) - opening in the interventricular septum
3. Overriding aorta - aorta straddles the VSD, receiving blood from both ventricles
4. Right ventricular hypertrophy - compensatory thickening due to outflow obstruction

Question 2 (Middle - rotated): Cleft Lip and Cleft Palate

Identification

• Left (Image A): Unilateral cleft lip - a cleft/gap in the upper lip
• Right: Cleft palate - a wide fissure through the hard palate exposing the oral-nasal communication

Cause / Embryological Basis

• One frontonasal process (gives medial and lateral nasal processes)
• Two maxillary processes (paired, from 1st pharyngeal arch)
• Two mandibular processes (paired, from 1st pharyngeal arch)

• Cleft lip alone (primary palate defect)
• Cleft palate alone (secondary palate defect - failure of palatine shelf elevation and fusion)
• Cleft lip + cleft palate (both processes fail; more severe cleft lip increases likelihood of palate involvement)

• Creasy & Resnik's Maternal-Fetal Medicine; Thompson & Thompson Genetics and Genomics in Medicine

Question 3 (Bottom - rotated): Identify the Clinical Condition and Explain the Underlying Cause

Clinical Condition: Congenital Hydrocephalus

• Markedly enlarged, dome-shaped cranium (macrocephaly)
• Prominent, bulging forehead (frontal bossing)
• Stretched, thinned scalp with visible superficial veins
• "Setting-sun sign" - eyes deviated downward with visible sclera above the iris (due to pressure on the superior colliculus / Parinaud's phenomenon)

Underlying Cause

1. Obstruction to CSF flow (most common) - e.g., congenital stenosis of the Aqueduct of Sylvius (most common congenital cause), Arnold-Chiari malformation blocking the foramina of exit
2. Impaired CSF reabsorption - e.g., scarring of arachnoid granulations from hemorrhage or meningitis
3. CSF overproduction - rare; choroid plexus papilloma

UMN vs LMN Facial Palsy Diagram (from the textbook):

• Neuroanatomy through Clinical Cases, 3rd Edition; Gray's Anatomy for Students

Answers to the Four Anatomy Questions (Pages 14-16/27)

Question 1 (Slide 1 - rotated): Splenomegaly

Clinical Condition: Splenomegaly (Enlarged Spleen)

Defensive (Protective) Mechanisms of the Spleen

• Senescent (old >120 days) red blood cells that have lost their plasticity
• Abnormal RBCs with inclusions - Howell-Jolly bodies (nuclear remnants), Heinz bodies (denatured Hb), Pappenheimer bodies (iron granules)
• Abnormally shaped cells (sickle cells, spherocytes, target cells)
• Blood-borne pathogens, parasites, and cellular debris
• The plasma is directed to lymphoid tissue where antigens stimulate antibody production

• The white pulp contains the Periarteriolar Lymphoid Sheath (PALS) - T cells surrounding the central artery - and lymphoid follicles (B cells)
• Responds to blood-borne antigens by producing IgM antibodies (primary immune response)
• Produces opsonins (tuftsin and properdin) that enhance phagocytosis
• This is why asplenic patients are at high risk of overwhelming infections by encapsulated bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis)

• Normally one-third of all platelets are stored in the spleen
• In splenomegaly, up to 80% of platelets can be sequestered → thrombocytopenia

• Between weeks 3-5 of fetal life, the spleen produces red and white blood cells (extramedullary hematopoiesis)
• This function can be reactivated in pathological states (myelodysplasia, thalassemia)

• Sabiston Textbook of Surgery, pp. 1470-1471

Question 2 (Slide 2 - rotated): Paranasal Air Sinuses

Name the Paranasal Air Sinuses

Where They Open in the Lateral Wall of the Nose

• Gray's Anatomy for Students, p. 1218-1219; Sabiston Textbook of Surgery, p. 1338

Question 3 (Slide 3): Identify the Clinical Condition

Clinical Condition: Anencephaly

Underlying Cause

• The forebrain fails to develop (absent cerebral hemispheres)
• The overlying meninges, skull vault (cranial bones), and scalp are all absent
• The brain tissue that does form remains exposed and degenerates

• ~2/3 of affected infants are female
• Incompatible with sustained life - most are stillborn; live-born infants survive only hours
• Associated with polyhydramnios (fetus cannot swallow amniotic fluid normally due to lack of brain control)

1. Folic acid deficiency - the single greatest environmental factor. Maternal serum folate <200 μg/L significantly increases NTD risk. Supplementation with 400-800 μg/day before conception and through the first 2 months reduces NTD incidence by >75%
2. MTHFR gene variant - a common missense variant makes methylenetetrahydrofolate reductase unstable, impairing folate recycling; homozygotes are at doubled risk
3. Teratogens - valproic acid, methotrexate, some anticonvulsants
4. Chromosomal abnormalities and single-gene defects (minority)
5. Hyperthermia, maternal diabetes

• Thompson & Thompson Genetics and Genomics in Medicine, 9th ed.; Medical Physiology

Question 4 (Slide 4): Lumbar Puncture Diagram

What the Diagram Shows

• Patient in lateral decubitus (fetal) position - knees drawn to chest, spine fully flexed to widen the interspinous spaces
• A spinal needle being inserted in the lumbar region (between L3-L4 or L4-L5)
• Zoomed inset showing the needle passing between two vertebrae into the subarachnoid space

Anatomical Basis

• The spinal cord ends at L1-L2 (conus medullaris) in adults
• Below this, only the cauda equina (nerve roots floating in CSF) remains - these move aside rather than being pierced by the needle, making it safe
• The dural sac continues to S2

1. Skin and subcutaneous fat
2. Supraspinous ligament
3. Interspinous ligament
4. Ligamentum flavum
5. Epidural space
6. Dura mater
7. Arachnoid mater
8. Subarachnoid space → CSF is obtained here

• Diagnosis of meningitis, encephalitis, subarachnoid hemorrhage
• Measurement of CSF pressure
• Administration of spinal anaesthesia or intrathecal drugs
• CSF sampling for multiple sclerosis, Guillain-Barré syndrome

Answers to the Hand/Upper Limb Anatomy Questions

Slide 1 (Top): Palmar Thickening with Flexion Contracture

Clinical Condition: Dupuytren's Contracture

• Fibroproliferative disease of the palmar fascia (not a nerve injury)
• Most commonly affects the 4th (ring) and 5th (little) fingers
• Progressive nodules develop first in the palm, then cords form that contract the fingers
• More common in males, those of Northern European descent, diabetics, alcoholics, epileptics

Slide 2: Wrist Drop

1. Clinical Condition: Wrist Drop (Radial Nerve Palsy)

2a. Nerve Involved: Radial Nerve (CN - Brachial Plexus)

• Wrist drop - inability to extend the wrist (extensor carpi radialis longus/brevis, extensor carpi ulnaris are paralysed)
• Loss of extension at all 5 MCP joints
• Loss of extension and abduction of thumb
• At high lesion (spiral groove or above): loss of elbow extension (triceps) too
• Supination weakness

• "Saturday night palsy" - compression in the spiral groove of the humerus (arm draped over a chair while asleep/intoxicated)
• Humeral shaft fracture (mid-shaft, at spiral groove)
• Crutch compression in the axilla (high radial palsy)
• Shoulder dislocation

2b. Cord of Brachial Plexus: Posterior Cord

• Localization in Clinical Neurology, 8th ed.

Slide 3: The Marked Area on the Hand (rotated)

Identify the Marked Area: Anatomical Snuffbox

Which Carpal Bone Injury Can Be Identified in This Area?

• The scaphoid has a retrograde blood supply (enters distally); a fracture at the waist can interrupt blood supply to the proximal pole → avascular necrosis if missed/untreated
• Often missed on initial X-ray; if snuffbox tenderness is present, treat as scaphoid fracture until proven otherwise (CT or MRI)
• Bailey and Love's Short Practice of Surgery; Campbell's Operative Orthopaedics

Slide 4: Claw Hand Deformity

Clinical Condition: Claw Hand (Ulnar Nerve Palsy - Main en Griffe)

• Interossei and medial two lumbricals are paralysed
• Extensor digitorum pulls the MCPs into hyperextension (unopposed)
• Flexor digitorum profundus (still intact) pulls the IPs into flexion (unopposed)
• Result: MCP hyperextension + IP flexion = "clawing"

• Hypothenar wasting and first dorsal interosseous space wasting
• Froment's sign (positive = flexes thumb IP joint when gripping paper - uses FPL to compensate for paralysed adductor pollicis)
• Sensory loss: ulnar 1.5 fingers (little + ulnar half of ring) and ulnar palm

• THIEME Atlas of Anatomy - General Anatomy and Musculoskeletal System

Slide 5 (partially visible): Winged Scapula

Clinical Condition: Winged Scapula

Nerve Involved: Long Thoracic Nerve (C5, C6, C7)

• The medial border "wings" away from the chest wall
• The inferior angle points posteriorly and laterally
• Shoulder abduction above 90° is impossible

1. Axillary lymph node dissection (mastectomy - most common iatrogenic cause; nerve runs down lateral thoracic wall, just deep to skin)
2. Stabbing or direct trauma to the lateral chest wall
3. Neuralgic amyotrophy (Parsonage-Turner syndrome)
4. Carrying heavy loads on the shoulder
5. First rib fracture

• Gray's Anatomy for Students; Fischer's Mastery of Surgery

Answers to the Upper Limb & Lower Limb Anatomy Questions

Image 1 (Top): Posterior Back View with Prominent Scapula

Clinical Condition: Winged Scapula

Nerve Injured: Long Thoracic Nerve (of Bell)

• Arises directly from roots C5, C6, C7 (before they form the trunks of the brachial plexus)
• Runs down the lateral thoracic wall on the external surface of the serratus anterior muscle, just deep to the skin - making it vulnerable to injury in axillary surgery

Muscle Involved: Serratus Anterior

• Origin: outer surfaces of ribs 1-8 (digitations)
• Insertion: medial border (costal surface) of the scapula
• Action: protracts the scapula and holds its medial border against the thoracic wall; essential for elevating the arm above 90°

• Axillary lymph node dissection (mastectomy) - most common iatrogenic cause
• Stab wounds to the lateral chest wall
• Carrying heavy loads on the shoulder
• Neuralgic amyotrophy (Parsonage-Turner syndrome)
• Gray's Anatomy for Students

Image 2: Palpation of the Dorsum of the Foot (rotated)

Arterial Pulsation Shown: Dorsalis Pedis Artery

Other Arteries of the Lower Limb Where Pulsations Can Be Felt:

• Schwartz's Principles of Surgery; S. Das Manual on Clinical Surgery

Image 3: Dropped Foot (rotated)

Clinical Condition: Foot Drop

Nerve Involved: Common Peroneal (Fibular) Nerve

• Tibialis anterior - dorsiflexion of ankle
• Extensor digitorum longus/brevis - toe extension
• Extensor hallucis longus - great toe extension
• Peroneus (fibularis) longus and brevis - eversion of foot

1. Fracture of the neck of fibula - most common
2. Prolonged pressure (crossing legs, plaster cast, prolonged squatting)
3. Knee dislocation
4. Diabetic neuropathy
5. Iatrogenic (knee surgery, hip replacement)

• S. Das Manual on Clinical Surgery

Image 4: Infant with Arm Held at Side in Abnormal Posture

Clinical Condition: Erb-Duchenne Palsy (Erb's Palsy)

• Arm adducted and internally rotated at the shoulder
• Forearm extended and pronated
• Wrist flexed
• Fingers relatively spared

Cause: Upper Brachial Plexus Injury - C5 and C6 nerve roots (upper trunk)

• Internal rotation (subscapularis, pectoralis major - still intact via C5-T1 via median/anterior cord)
• Adduction (pectoralis major, latissimus dorsi)
• Pronation (pronator teres - partially intact)

• Neuroanatomy through Clinical Cases, 3rd Ed.

Image 5: Prominent Tortuous Leg Veins

Clinical Condition: Varicose Veins

Anatomical Basis / Cause: Venous Valve Incompetence

• Deep veins (femoral, popliteal, tibial) drain the majority of blood
• Superficial veins (great saphenous, small saphenous) drain the skin and subcutaneous tissue
• Perforating veins connect the two systems; their valves only allow flow from superficial → deep
• Valves in all veins prevent retrograde flow when the calf muscle pump contracts

1. Valvular incompetence at the sapheno-femoral junction (where the great saphenous vein drains into the femoral vein) is the most common site
2. High pressure from the deep system refluxes back into the superficial system
3. Raised venous pressure → progressive dilation and tortuosity of superficial veins
4. Other incompetent sites: sapheno-popliteal junction (small saphenous) and perforating vein valves

• Sapheno-femoral junction (great saphenous → femoral vein)
• Perforating veins in the mid-thigh
• Sapheno-popliteal junction (small saphenous → popliteal vein)

• Venous eczema (skin breakdown from chronic high pressure)
• Haemosiderin skin pigmentation (brown staining)
• Lipodermatosclerosis
• Venous ulcers (gaiter area, medial malleolus) - most serious complication

• Gray's Anatomy for Students; Pfenninger and Fowler's Procedures for Primary Care

Answers to the Final Two Anatomy Questions (Page 27/27)

Slide 1: Identify the Bone and Name the Nerves Closely Related to It

The Bone: Humerus

• Head - articulates with the glenoid cavity
• Anatomical neck - immediately distal to the head
• Greater tubercle (lateral) - insertions of supraspinatus, infraspinatus, teres minor
• Lesser tubercle (anterior) - insertion of subscapularis
• Intertubercular (bicipital) groove - lodges the tendon of the long head of biceps
• Surgical neck - most common site of fracture; the constriction just below the tubercles

• Deltoid tuberosity (lateral mid-shaft) - attachment of deltoid
• Radial (spiral) groove - runs obliquely across the posterior shaft

• Capitulum (lateral) - articulates with head of radius
• Trochlea (medial) - articulates with trochlear notch of ulna
• Medial epicondyle (prominent)
• Lateral epicondyle
• Olecranon fossa (posterior) - receives olecranon in extension
• Coronoid fossa (anterior) - receives coronoid process in flexion

Nerves Closely Related to the Humerus

• Gray's Anatomy for Students, p. 818

Slide 2: X-ray - Explain the Radiological Finding and Deformity in the Hand

Diagnosis: Colles' Fracture

Radiological Findings (X-ray Analysis)

• Transverse fracture of the distal radius, approximately 2 cm proximal to the radiocarpal joint
• Lateral (radial) displacement of the distal fragment (arrow pointing laterally)
• Radial shortening relative to the ulna
• Often associated with ulnar styloid fracture
• May show intraarticular extension into the radiocarpal or radioulnar joint

• Dorsal displacement of the distal radial fragment (arrow pointing dorsally toward "dorsum of hand")
• Dorsal angulation - loss of the normal volar (palmar) tilt of the distal radial articular surface
• The distal fragment tilts backwards relative to the shaft

Clinical Deformity: "Dinner Fork" Deformity

• A dorsal hump/prominence at the wrist (the dorsally displaced distal fragment)
• A corresponding depression on the volar (palmar) side
• The appearance resembles a dinner fork seen from the side - hence the name

Mechanism of Injury

• Postmenopausal women with osteoporosis (most classic demographic)
• After age 40

Key Displacements in Colles' Fracture (the "DROLL" mnemonic):

• Dorsal displacement of distal fragment
• Radial displacement
• Osteoporosis (common background)
• Loss of volar tilt
• Lengthening lost (radial shortening)

Complications

• Median nerve injury - most common nerve complication (compressed in the carpal tunnel by displaced fragment → acute carpal tunnel syndrome)
• Malunion → persistent deformity
• Extensor pollicis longus tendon rupture (late)
• Complex regional pain syndrome (Sudeck's atrophy)
• Radiocarpal/radioulnar joint stiffness

• Rosen's Emergency Medicine