Skeletal System: Skull Learning Target #4

Cranial Bones: 8 large, flat bones make up the cranium, which encloses and protects the brain. All are single bones with the exception of the parietals and the temporals. Frontal (1), parietal (2), temporal (2), occipital (1), sphenoid (1), ethmoid (1)

Cranial Bones: Parietal bone Frontal bone Sphenoid bone Ethmoid bone Occipital bone Temporal bone

Cranial Bones: Frontal Ethmoid Sphenoid Temporal Parietal Occipital

Associated Structures of the Skull Foramen magnum = opening in the occipital bone that the spinal cord passes through Occipital condyles (2) = articular surfaces of the occipital bone Form the joint between the occipital bone and the first cervical vertebrae Occipital condyles Foramen magnum

Associated Structures of the Skull Sutures = “seam” or “stitch;” immoveable joint found between the bones of the skull Coronal  between frontal and parietal bones Lambdoid  between parietal and occipital bones Sagittal  between parietal bones Squamous  between parietal and temporal bones Coronal Sagittal Lambdoid Squamous

Associated Structures of the Skull Sella turcica = depression in the superior surface of the sphenoid bone Surrounds and protects the pituitary gland Sella turcica

Associated Structures of the Skull External auditory meatus (2) = ear canal, located in the temporal bone, contains 3 additional bones: Malleus (hammer) Incus (anvil) Stapes (stirrup) External auditory meatus

Associated Structures of the Skull Mastoid process (2) = projection of the temporal bone behind the ear Site of attachment for muscles of the neck Styloid process (2) = projection of the temporal bone inferior to the ear Site of attachment for tongue muscle Mastoid process Styloid process

Associated Structures of the Skull Fontanels = soft spots; fibrous membranes between the bones of the fetal skull Allow the skull to compress slightly during childbirth and allow for brain growth during late fetal life. These areas ossify as the infant ages, completing the process by age 20-22 months.

Facial Bones: These bones form the base for the muscles of the face, which allows us to chew our food and show emotion/expressions. All are paired except the mandible and the vomer. Maxilla (2), mandible (1), lacrimal (2), nasal (2), zygomatic (2), palatine (2), and vomer (1)

Facial Bones: Nasal Zygomatic Lacrimal Maxilla Vomer Mandible

Facial Bones: Nasal Lacrimal Zygomatic Mandible Maxilla

Facial Bones: Zygomatic Maxilla Vomer Palatine

Associated Structures of the Skull Paranasal sinuses = cavities lined with mucus membranes found in 4 skull bones. Lighten the skull Act as resonance chambers for speech

Hyoid Bone Only bone that does not articulate with the rest of the skeleton. Not classified as a facial or cranial bone. Suspended from the styloid processes of the temporal bone. Supports the tongue and serves as an attachment point for neck muscles moving the larynx.

Disorders of the Skull Sinusitis- inflammation of the sinuses Deviated septum- air flow is restricted to one nostril or the other; can be partial or complete

Disorders of the Skull Cleft palate = palatine process of the maxilla fails to unite with the palatine bone Leaves a hole in the roof of the mouth. Can be surgically corrected by closing the tissue gap