SKULL Lab (+ sinuses)

* redo these slides

Axial skeleton

• total: 80 bones

• skull: 28 bones

• vertebral column: 26 bones

• thoracic cage: 25 bones

• hyoid bone: 1 bone

Skull (cranium) (28)

• skeletal structure of the head that supports the face and protects the brain

• includes:

  • cranial bones (8)

  • facial bones (14)

  • middle earbones (6)

Cranial bones (8)

• frontal (1)

• parietal (2)

• occipital (1)

• temporal (2)

• spheniod (1) - joins with 7 cranial bones

• ethmoid (1) - deepest bone of skull

Facial bones (14)

• nasal (2)

• lacrimal (2) - most medial bone of orbit

• zygomatic (2)

• maxilla/maxillae (2)

• palatine (2)

• inferior nasal concha (2)

• vomer (1)

• mandible (1) - only movable bone in skull

Auditory Ossicles

• 3 auditory ossicles in each ear

Hyoid Bone

• located in the anterior cervical region and is the only bone that does not form an articulation (joint)

Suture

an immobile joint between adjacent bones of the skull

Cranial Sutures

• Coronal suture

• Sagittal suture

• Squamous suture

• Lambdoid suture

Coronal suture

• runs from side to side across the skull, within the coronal plane of section

• joins the frontal bone to the right and left parietal bones

Sagittal suture

• extends posteriorly from the coronal suture, running along the midline at the top of the skull in the sagittal plane of section

• unites the right and left parietal bones

Squamous suture

• located on the lateral skull

• unites the squamous portion of the temporal bone with the parietal bone

Lambdoid suture

• extends downward and laterally to either side away from its junction with the sagittal suture

• joins the occipital bone to the right and left parietal and temporal bones

Frontal Bone

a single bone that forms the forehead

• Supraorbital foramen (notch)

Supraorbital foramen (notch)

Located near the midpoint of the supraorbital margin is a small opening

Occipital Bone

a single bone that forms the posterior skull and posterior base of the cranial cavity

• External occipital protuberance

• Foramen magnum

• Condyle

External occipital protuberance

serves as an attachment site for a ligament of the posterior neck

Foramen magnum

allows for passage of the spinal cord as it exits the skull

Condyle

on either side of the foramen magnum, form joints with the first cervical vertebra and thus support the skull on top of the vertebral column

Temporal Bone

forms the lower lateral side of the skull

• Zygomatic process

• Zygomatic arch

• External auditory (acoustic) meatus

• Mastoid process

• Styloid process

• Mandibular fossa

Zygomatic process

a longer posterior portion, extending forward from the temporal bone

Zygomatic arch

bony arch on the side of skull that spans from the area of the cheek to just above the ear canal

External auditory/acoustic meatus (ear canal)

large opening on the lateral side of the skull that is associated with the ear

Mastoid process

serves as a muscle attachment site; on the side of the head just behind your earlobe

Styloid process

posterior to the mandibular fossa on the external base of the skull is an elongated, downward bony projection; serves as an attachment site for several small muscles and for a ligament that supports the hyoid bone of the neck

Mandibular fossa (lower jaw)

joins with the skull at this site as part of the temporomandibular joint, which allows for movements of the mandible during opening and closing of the mouth

Ethmoid

a single, midline bone that forms the roof and lateral walls of the upper nasal cavity, the upper portion of the nasal septum, and contributes to the medial wall of the orbit; on the interior of the skull, the ethmoid also forms a portion of the floor of the anterior cranial cavity

• Crista galli

• Cribriform plate

• Perpendicular Plate

• Middle nasal conchae

Crista galli

a small upward bony projection located at the midline; functions as an anterior attachment point for one of the covering layers of the brain

Cribriform plate

a small, flattened area with numerous small openings termed olfactory foramina to either side of the crista galli; small nerve branches from the olfactory areas of the nasal cavity pass through these openings to enter the brain

Perpendicular Plate

forms the upper portion of the nasal septum

Middle nasal conchae

curved bones that project from the lateral walls of the nasal cavity

Sphenoid

a single, complex bone of the central skull; joins with almost every other bone of the skull

• Lesser wing

• Greater wing

• Sella turcica

• Hypophyseal Fossa

• Optic foramen (canal)

• Superior orbital fissure - between greater and lesser wing of sphenoid bone

Lesser wing

resemble the wings of a flying bird, form the lip of a prominent ridge that marks the boundary between the anterior and middle cranial fossae

Greater wing

extend laterally to either side away from the sella turcica, where they form the anterior floor of the middle cranial fossa

Sella turcia

located at the midline of the middle cranial fossa

Hypophyseal fossa

rounded depression in the floor of the sella turcica which houses the pea-sized pituitary (hypophyseal) gland

Optic foramen (canal)

allows for passage of the optic nerve from the retina to the brain

Superior orbital fissure

located on the anterior wall of the middle cranial fossa, lateral to the optic canal and under the projecting margin of the lesser wing of the sphenoid bone; nerves to the eyeball and associated muscles, and sensory nerves to the forehead pass through this opening

Zygomatic Bone (cheekbone)

forms much of the lateral wall of the orbit and the lateral-inferior margins of the anterior orbital opening

• Temporal process

• Inferior orbital fissure - between maxilla, sphenoid and zygomatic

• Zygomatic arch

Maxilla

one of a pair that together form the upper jaw, much of the hard palate, the medial floor of the orbit, and the lateral base of the nose

• Infraorbital foramen

• Alveolar process

• Hard palate

Palastine Bone

each maxillary bone can be seen joining together at the midline to form the anterior three-quarters of the hard palate

• Hard palate

Mandible

forms the lower jaw and is the only moveable bone of the skull

• Alveolar process

• Mental foramen

• Body

• Angle

• Ramus

• Condylar process

• Coronoid process

Hyoid Bone

an independent bone that does not contact any other bone and thus is not part of the skull

• Greater horn (cornu)

• Lesser horn (cornu)

• Body

Sinuses

hollow air-filled spaces located within certain bones of the skull, communicate with the nasal cavity and are lined with nasal mucosa

• Frontal sinus

• Sphenoidal sinus

• Maxillary sinus (only in lab manual)

• Ethmoidal sinus/air cells