Human Structure: Review of Unit 1

Skin, Superficial Back Muscles, Vertebral Canal, and Spinal Cord

Integumentary System

  • Functions: Protection, containment, prevention of dehydration, heat regulation, sensation, synthesis, and storage of vitamin D.
  • Structure:
    1. Epidermis: Protective barrier.
    2. Dermis: Contains nerve endings, sweat glands, oil glands, and hair follicles.
    3. Hypodermis (Subcutaneous): Fat and connective tissue.

  • Components:
    • Hair shaft, root, and follicle
    • Sebaceous glands: Lubricate skin
    • Sweat glands: Eccrine and apocrine
    • Sensory nerve fibers: Meissner's corpuscle, Pacinian corpuscle

Superficial Back Muscles

Trapezius Muscle

  • Innervation: Accessory nerve (CN XI) and ventral rami of C3 and C4
  • Blood Supply: Transverse cervical artery

Latissimus Dorsi Muscle

  • Innervation: Thoracodorsal nerve (posterior cord of brachial plexus)
  • Blood Supply: Thoracodorsal artery
  • Insertion: Floor of the intertubercular sulcus of humerus


Other Back Muscles

  • Levator Scapulae
  • Rhomboid Major
  • Rhomboid Minor


Vertebral Canal and Spinal Cord

Sympathetic Nervous System

  • T4 Sympathetic Ganglion

Spinal Nerve Components

  • Dorsal Root: Sensory or afferent
  • Ventral Root: Motor or efferent
  • Rami Communicantes: Connect spinal nerves to the sympathetic trunk
    • White and gray rami communicantes: Lateral in thoracic region, move anteriorly in the abdomen.

Dermatomes

  • Areas of skin supplied by afferent nerve fibers from a single posterior spinal root.
  • Key dermatomes: C4, C5, T1-T5, T7, T8.


Breast and Pectoral Muscles

Mammary Gland

  • Structures: Areola, nipple, gland lobules, lactiferous ducts, and sinuses
  • Functions: Split into 15-20 lobes, not encapsulated

Lymphatic Drainage

  • Nodes: Subareolar plexus, circumareolar plexus, parasternal nodes
  • Main Paths: Principal axillary lymph path, accessory axillary lymph path

Skeleton of the Pectoral Region

  • Includes: Manubrium, sternum, scapula, clavicle, true ribs (1-7), costal cartilages
  • Axial Skeleton: Head, neck, trunk
  • Appendicular Skeleton: Shoulder girdle, pelvic girdle, extremities

Anterior Thoracic Wall

  • Pectoralis Major Muscle
    • Innervation: Medial and lateral pectoral nerve
    • Blood Supply: Pectoral branch of the thoracoacromial trunk
  • Pectoralis Minor Muscle
    • Innervation: Medial pectoral nerve

Upper Appendicular Skeleton

  • Structures: Clavicle, scapula, humerus


Back and Shoulder Muscles, Vertebral Canal, and Spinal Cord

Superficial Back Muscles

  • Layers:
    1. Superficial Layer: Trapezius, latissimus dorsi (extrinsic muscles)
    2. Intermediate Layer: Serratus posterior superior, inferior
    3. Deep Layer: Splenius, erector spinae, transversospinalis (intrinsic muscles)

Erector Spinae Muscles

  • Muscles: Spinalis, longissimus, iliocostalis
  • Innervation: Branches of the posterior rami

Spinal Cord and Nerve Roots

  • Layers and Spaces:
    1. Epidural Space
    2. Dura Mater
    3. Arachnoid Mater
    4. Subarachnoid Space (with CSF)
    5. Pia Mater

Adult Spinal Cord

  • Ends at: L1/L2 intervertebral disc
  • Dural Sac: Ends at S2 vertebral level
  • Filum Terminale Externum: Attaches to the dorsal coccyx


Upper Limb – Shoulder

Rotator Cuff

  • Muscles: Supraspinatus, infraspinatus, subscapularis, teres minor
  • Function: Stabilizes the glenohumeral joint

Injury

  • Supraspinatus injury: Prevents initiation of abduction
  • Abduction of Upper Limb: Deltoid and supraspinatus muscles


Anatomy of the Arteries

Blood Supply to the Arm and Shoulder

  1. Subclavian Artery
    • Branches: Thyrocervical trunk, suprascapular artery
  2. Axillary Artery
    • Parts:
      1. Superior thoracic artery
      2. Thoracoacromial, lateral thoracic arteries
      3. Subscapular, anterior, posterior circumflex humeral arteries

Thoracic Wall, Pleural Cavity, and Lungs

Thoracic Wall

  • Structures: Subclavian artery, vein, long thoracic nerve, lateral thoracic artery, serratus anterior muscle

Pleura and Pleural Cavity

  • Serous Membrane:
    1. Visceral Pleura
    2. Parietal Pleura (cervical, costal, mediastinal, diaphragmatic parts)

Recesses and Reflections

  • Terms: Costodiaphragmatic recess (important for fluid drainage), costomediastinal recess, sternal junction of costal and mediastinal pleurae, vertebral junction of costal and mediastinal pleurae


Hemothorax and Thoracentesis

  • Hemothorax: Blood in the pleural cavity
  • Thoracentesis: Procedure to remove fluid


Lymphatic Drainage of the Lungs

  • Structures: Paratracheal nodes, bronchomediastinal lymphatic trunk, thoracic duct, bronchopulmonary nodes, pulmonary nodes


*You don't need to memorize the nodes

Pericardium and Heart

Auscultatory Areas

  • Locations:
    • 2nd Intercostal Space: Pulmonary, aortic sounds
    • 5th Intercostal Space: Mitral, tricuspid sounds


Surface Projections of Heart Valves

  • Site of Valves: PAMT (Pulmonary, Aortic, Mitral, Tricuspid)


Coronary Arteries

  • Arteries: Left coronary artery (LCA), right coronary artery (RCA)
  • Branches: Circumflex, marginal branch, etc.


Conducting System of the Heart

  • Components: SA node, AV node, Purkinje fibers
  • Innervation:
    • Sympathetic: Increases heart rate
    • Parasympathetic (Vagus Nerve): Decreases heart rate

Mediastinum

Superior Mediastinum

  • Contains: Thymus, great vessels, vagus & phrenic nerves, trachea, esophagus, thoracic duct

Posterior Mediastinum

  • Structures: Esophagus, thoracic aorta, azygos vein, hemi-azygos vein, thoracic duct, vagus nerves, sympathetic trunk, splanchnic nerves


*They will test you on this content

Upper Limb Anatomy

Brachial Plexus

  • Structure: 5 roots, 3 trunks, 3 anterior divisions, 3 posterior divisions, cords, terminal branches
  • Mnemonic: Real Teachers Drink Cold Beer (Roots, Trunks, Divisions, Cords, Branches)

Important Nerves

  • Nerves: Suprascapular, phrenic, dorsal scapular, long thoracic, etc.

Arm Muscles

Posterior Compartment

  • Triceps Brachii (Long, Lateral, Medial heads): Infraglenoid tuberosity attachment, extends shoulder and elbow
  • Anconeus: Extends elbow


Forearm and Hand

Flexor-Pronator Muscles

  • Origin: Common tendon to medial epicondyle
  • Muscles:
    1. Pronator Teres
    2. Flexor Carpi Radialis
    3. Palmaris Longus
    4. Flexor Carpi Ulnaris (ulnar nerve)
    5. Flexor Digitorum Superficialis (intermediate group)
  • Brachioradialis: Flexor of forearm


Rotators of Radius

  • Pronation: Supinator, pronator teres
  • Supination: Supinator muscle


Brachial Artery

  • Branches: Radial collateral, middle collateral, superior ulna collateral artery

Hand Anatomy

Carpal Tunnel

  • Components: Carpal bones, flexor retinaculum
  • Contents: Flexor tendons, synovial sheaths, median nerve
  • Syndrome: Compression causing diminished sensation, thumb weakness


Movements of the Hand

  • Thumb: Flexion, extension, opposition

Innervation of Hand Muscles

  • Median Nerve: LOAF muscles (Lateral 2 lumbricals, Opponens Pollicis, Abductor Pollicis Brevis, Flexor Pollicis Brevis)
  • Ulnar Nerve: All other intrinsic muscles


Cutaneous Innervation

  • Notable Innervations: Lateral cutaneous nerve of forearm, medial cutaneous nerve of forearm, branches of radial and ulnar nerves


Here's a song to review: