ANA 111

• The skull consists of 22 bones and 3 pairs of ossicles
• Divisions of the skull

  • Neurocranium (bones that make up the back of the skull)
  • Viscerocranium (bones that make up the facial bones)
• Paranasal sinuses


  • Maxillary sinuses
  • Frontal sinuses
  • Ethmoid sinuses
  • Sphenoid sinuses
• Functions of the paranasal sinuses

  • Producing mucus to trap dust and bacteria
  • Aiding in resonance and sound production
  • Warming and humidifying the air
• Respiratory muscles


  • Diaphragm
  • External intercostal muscles
  • Internal intercostal muscles
  • Scalene muscles
• Pinna (auricle)


  The cartilaginous, curved structure that protrudes from the head
• Ear canal (external auditory meatus)


  The tube that connects the pinna to the eardrum
• Parts of the external ear

  • Tragus
  • Antitragus
  • Helix
  • Lobule
• Functions of the external ear


  • Collecting sound waves
  • Directing sound waves into the ear canal
  • Protecting the ear canal from dust, dirt, and other small objects
• Tympanic membrane


  A thin, translucent layer of tissue that separates the external ear canal from the middle ear
• Functions of the tympanic membrane

  • Transmitting sound energy to the middle ear bones (ossicles)
  • Separating the outer ear from the middle ear, protecting the inner ear from external noise
  • Helping to regulate air pressure in the middle ear
• Structure of the tympanic membrane

  • Composed of a thin layer of epithelial tissue, supported by a ring of fibrous tissue (annulus)
  • Attached to the malleus (hammer) bone in the middle ear
  • Approximately 10 mm in diameter
• Trachea


  A tube that connects the throat (pharynx) to the lungs, allowing air to pass through
• Vertebral heights of the trachea

  • Cervical spine (neck): C6 - trachea begins, just below the larynx, C7 - trachea descends, passing in front of the vertebral bodies
  • Thoracic spine (upper back): T1-T4 - trachea continues its descent, gradually shifting to the right side, T5 - trachea bifurcates (divides) into the right and left main bronchi, which enter the lungs
• Accessory muscles of respiration

  • Sternocleidomastoid muscle (SCM)
  • Scalene muscles (anterior, middle, and posterior)
  • Pectoralis muscles (major and minor)
  • Rhomboid muscles (major and minor)
  • Latissimus dorsi muscle
  • Trapezius muscle
  • Serratus anterior muscle
  • Levator scapulae muscle
• Primary and accessory muscles of respiration

  • Primary muscles: Diaphragm, External intercostal muscles, Internal intercostal muscles

  Accessory muscles: Sternocleidomastoid muscle (SCM), Scalene muscles, Serratus anterior muscle, Levator scapulae muscle
• Thoracic inlet


  The upper boundary of the thoracic cavity (chest cavity)
• Boundaries of the thoracic inlet

  • Anterior (front): Manubrium of the sternum

  Posterior (back): First thoracic vertebra (T1)

  Lateral (sides): First ribs and costal cartilages
• Structures passing through the thoracic inlet

  • Trachea (windpipe)

  Esophagus (food pipe)

  Major blood vessels (arteries and veins)

  Nerves (e.g., vagus nerve, phrenic nerve)
• Functions of the thoracic inlet

  Respiration (breathing)

  Digestion (swallowing)

  Circulation (blood flow)

  Nerve function (communication between the brain and thoracic organs)
• Third ribs


  Ribs located lower in the chest cage, below the first and second ribs, and generally smaller and less curved than the first ribs
• First ribs


  Topmost ribs in the chest cage with a longer and more curved shape and a tubercle on their superior surface for scalene muscle attachment
• Thoracic inlet: Lateral boundaries


  First ribs and costal cartilages
• Thoracic inlet: Posterior boundary

  First thoracic vertebra (T1)
• Thoracic inlet: Anterior boundary


  Manubrium of the sternum
• Superior mediastinum


  The area behind the manubrium of the sternum
• Borders of the superior mediastinum

  • Anterior: manubrium of the sternum
  • Posterior: vertebral bodies of T1-4
  • Superior: superior thoracic aperture
  • Inferior: imaginary plane @ T4/5
  • Laterally: mediastinal part of parietal pleura
• Contents of the superior mediastinum

  • Sternohyoid muscle
  • Thymus
  • Trachea
  • Oesophagus
• Arteries in the superior mediastinum

  • Aortic arch
  • Left subclavian
• Veins and lymphatic vessels in the superior mediastinum

  • Thoracic duct
  • Brachiocephalic veins
• Nerves in the superior mediastinum

  • Vagus nerve
  • Cardiac nerve
  • Phrenic nerve
• Apex of the lungs

  Projects upwards, 2.5 cm above clavicle (transverse process of T1)
• Anterior border of the right lung

  • Extends from apex to sternoclavicular joint, to midline of sternal angle, downwards to xiphisternal joint
• Anterior border of the left lung

  • Extends from apex to sternoclavicular joint, to midline of sternal angle, turns back to reach 6th costal cartilage
• Inferior border of the lungs

  • Midclavicular line_ 6th rib
  • Midaxillary line_ 8th rib
  • Scapular line_ 10th rib
  • Adjacent to vertebral column _ 10th rib
• Posterior border of the lungs

  • Lines between C7 and T10
  • Oblique fissure_ from root of spine of scapula, spinous process T2, joins the 6th rib
  • Horizontal fissure_ right lung, midsternal line, 4th costal cartilage to oblique fissure
• Hilum


  Gateway to the lungs
• Structures entering the lungs at the root

  • Primary bronchus
  • 1 pulmonary artery
  • Bronchial artery and nerves
• Structures exiting the lungs at the root

  • 2 pulmonary veins
  • Bronchial veins
  • Lymphatic vessels
• Relationships of the root of the lung

  • Situated at T5-T7
  • Anterior_ phrenic nerve
  • Posterior_ vagus nerve
  • Inferior_ empty pulmonary ligament