Human Anatomy: Skull and Nasal Cavity

Skull (Anterior View)

• Most prominent structures: Frontal bone, zygomatic bone, maxillae, mandible
• Most prominent openings: Orbits/eye sockets (cone-shaped fossae, provide protection for the eyes, attachment points for eye muscles), Nasal cavity (divided by nasal septum)
• Other openings: Superior and inferior orbital fissures, Optic foramen, Nasolacrimal canal

Nasal Cavity

• Divided into right and left halves by the nasal septum
• Nasal septum formed by two structures: Vomer bone, Perpendicular plate of the ethmoid bone
• Lateral wall of the nasal cavity contains three bony shelves called nasal conchae: Inferior nasal concha, Middle nasal concha, Superior nasal concha

Paranasal Sinuses

• Frontal, maxillary, ethmoidal, and sphenoidal sinuses

Mastoid Air Cells

• Small air-filled cavities within the mastoid process of the temporal bone.

Skull (Interior View of the Cranial Cavity)

• Floor of the cranial cavity can be divided into three cranial fossae: Anterior, middle, and posterior
• Bones forming the floor: Frontal, Ethmoid, Sphenoid (central region - sella turcica), Temporal, Occipital
• Foramina in the floor of the middle fossa: Foramen rotundum, Foramen ovale, Foramen spinosum, Jugular foramen
• Foramina at the posterior fossa: Foramen magnum

Frontal Bone

• Flat bone
• Makes up the forehead and upper portion of the eye sockets

Parietal Bones

• Pair of flat bones located on either side of the head behind the frontal bone

Temporal Bones

• Pair of irregular bones located under the parietal bones

Occipital Bone

• Flat bone at the back of the skull
• Contains the foramen magnum (opening connecting the spinal cord to the brain)

Sphenoid Bone

• Irregular bone located below the frontal bone

Ethmoid Bone

• Irregular bone located in front of the sphenoid bone
• Forms part of the nasal cavity

Viscerocranium/Facial Bones

• Maxilla: Jawbone, forms the upper jaw, contains the superior teeth
• Zygomatic bone: Cheekbone, anterior to the sphenoid bone; contributes to the zygomatic arch (formed by processes of temporal and zygomatic bones, bridge across the side of the face, provides attachment for mandible-moving muscles)
• Palatine: Roof of oral cavity, separates nasal cavity and nasopharynx from the mouth; aids in chewing and breathing simultaneously
  • Hard Palate: Forms the roof of the mouth and floor of the nasal cavity
  • Soft Palate: Made of connective tissue and muscles, extends posteriorly from the hard palate
• Nasal bones: Form the bridge of the nose
• Lacrimal bones: Form part of the medial walls of the orbits
• Inferior nasal conchae: Small, scroll-shaped bones within the nasal cavity
• Mandible: Forms the lower jaw, contains the inferior teeth, articulates with the temporal bone at the mandibular fossa
• Vomer: Forms the inferior half of the nasal septum

Skull (Lateral View)

• Parietal and temporal bones: Form a large portion of the side of the head, join at the squamous suture
• Parietal bone joins to the:
  • Frontal bone via the coronal suture
  • Occipital bone via the lambdoid suture
• Prominent features of the temporal bone:
  • External auditory canal
  • Mastoid process: Prominent projection behind the ear, attachment point for neck muscles involved in head rotation
  • Sphenoid bone: Resembles a butterfly, part of it can be seen anterior to the temporal bone
  • Zygomatic bone (cheekbone)
  • Zygomatic arch
  • Maxilla
  • Mandible

Lumbar Vertebrae

• Large, thick bodies
• Heavy rectangular transverse and spinous processes
• Superior articular facets face medially, inferior articular facets face laterally
• Adds strength, limits rotation

Sacrum and Coccyx

• Sacrum:
  • Alae: Superior lateral parts of fused transverse processes
  • Auricular surface: Articulates with pelvic bone
  • Median sacral crest: Partially fused spinous processes
  • Sacral hiatus: Site of anesthesia injection
  • Sacral foramina: Intervertebral foramina
  • Sacral promontory: Anterior edge of the body of the first vertebra, marks separation of the abdominal and pelvic cavities
• Coccyx: Tailbone, 3-5 semi-fused vertebrae

Thoracic Cage

• Functions: Protects vital organs, forms a semi-rigid chamber for respiration
• Parts:
  • Thoracic vertebrae
  • Ribs (12 pairs):
    • True ribs (superior seven): Attach directly to the sternum via costal cartilages
    • False ribs (inferior five): Ribs 8 to 10 are joined by common cartilage to the costal cartilage of rib 7 and then to the sternum.
    • Floating ribs (11 to 12): Do not attach to the sternum
  • Sternum

Sternum

• Manubrium: Articulates with the first rib and clavicle, contains the jugular notch (superiorly), joins the body at the sternal angle (where the second rib articulates)
• Body: Third through seventh ribs articulate, also called the gladiolus
• Xiphoid process: Inferior tip

Appendicular Skeleton

• Girdles: Pectoral, Pelvic
• Upper Limbs: Arm, Forearm, Wrist, Hand
• Lower Limbs: Thigh, Leg, Foot

Pectoral Girdle: Scapula and Clavicle

• Scapula:
  • Acromion process: Forms protective cover, attachment for clavicle, attachment for muscles

Pelvic Girdle: Hip Bones and Sacrum

• Hip bones and sacrum form a ring
• Pelvis: Pelvic girdle and coccyx
• Coxal bones: Right and Left
  • Ilium: Iliac crest, anterior/posterior superior iliac spines, greater sciatic notch, auricular surface, sacroiliac joint, iliac fossa
  • Ischium: Ischial tuberosity, lesser sciatic notch, ischial spine, ischial ramus
  • Pubis: Pubic crest, superior/inferior pubic rami, symphysis pubis (pubic symphysis)
• Acetabulum: Articulates with the head of the femur
• Obturator foramen
• Sacrum

Pelvis

• Pelvic brim: Separates the false (greater) pelvis (superior to the brim) from the true pelvis (inferior to the brim)
• Pelvic inlet: Opening superior to the true pelvis
• Pelvic outlet: Opening inferior to the true pelvis

This quiz focuses on the anatomical structures of the skull, including both anterior and interior views, as well as the nasal cavity and its components. Test your knowledge on the prominent bones, openings, and sinuses associated with these essential parts of the human head.