Skeletal System: The Skull

Axial skeleton

Cmposed of the cranial bones, facial bones, vertebral column, hyoid bone, the sternum, and ribs

Appendicular skeleton

Composed of the upper limbs, lower limbs, pectoral girdle, and the pelvic girdle

Frontal bone

Forms the anterior portion of the cranium; contains the frontal sinuses

Vomer

Forms the inferior portion of the bony nasal septum

Foramen magnum

Found at the base of the occipital bone; a large hole through which the spinal chord passes

Zygomatic process

Found in the squamous region of the temporal bone, it is a projection that forms part of the cheekbone. Maxillae also contain projections to form part of this process.

Name the 8 cranial bones.

Frontal bone, parietal bones (paired bones), temporal bones (paired bones), occipital bone, sphenoid bone, and ethmoid bone

Sutures

Immovable joints that unit several of the cranial bones to form the calvaria

Ethmoid sinuses

Internal cavities formed by the lateral bodies of the ethmoid bone

Calvaria

Known as the "skull cap"; consists of the cranial bones that encase the brain

Sphenoid sinuses

Located on the body of the sphenoid; inferior to the sella turcica

Mandible

Lower jaw bone; consists of a central body and two mandibular rami

Perpendicular plate

Middle portion of the ethmoid bone; forms the superior part of the bony nasal septum

Sagittal suture

Midline of the skull; connection of two parietal bones

Styloid process

Needle-like projections; extends from the base of the tympanic region of the temporal bones

Mastoid region

Of the temporal bone; posterior of the tympanic region; contains the mastoid process

Parietal bones

Paired bones; form the superior and part of the lateral walls of the cranium

Occipital bone

Posterior cranial bone; houses the foramen magnum

Mandibular condyle

Posterior process of the mandibular rami; fits into a depression of the temporal bone to form the temperomandibular joint

Orbit

Refers to the structures of the cranial and facial bones that contribute to form the eye socket

Name the bones of the skull that make up the eye orbit.

SLEPZFM: sphenoid, lacrimal, ethmoid, palantine, zygomatic, frontal, and maxilla

Sella turcica

Saddle-like formation on the superior surface of the sphenoid bone; houses the pituitary gland

Four regions of the temporal bones

Squamous region, tympanic region, mastoid region, and petrous region

Cribriform plate

Superior surface of the ethmoid bone; forms the roof of the nasal cavity; has small holes through which the olfactory nerves pass

Nasal conchae

Superior, middle, and inferior; three lobe-like structures extending medially which increase air turbulence; the superior and middle nasal conchae are formed by the lateral bodies of the ethmoid bone

Lambdoid suture

Suture that arches across the posterior surface of the skull; unites the occipital and parietal bones; shaped like the Greek letter Lambda

Squamous region

Temporal bones' most lateral aspect; contains the zygomatic process

Coronoid process

The anterior process of the mandibular rami

Pelvic girdle

The bones forming the pelvis and hip joint

Pectoral girdle

The bones forming the shoulder joint

The skull is made of what two general types of bone?

The cranial and facial bones

Petrous region

The internal portion of the temporal bones; shaped like a mountain ridge

Tympanic region

The temporal bones' most inferior region; houses the external acoustic meatus and styloid process

Mandibular rami

The two "arms" of the mandible; turn superiorly at the mandibular angle and has two process: the coronoid process and the mandibular condyle

Lacrimal bones

Tiny bones located in the medial part of the eye orbit; they form part of the structure that drains tears produced by lacrimal gland of the eye

Crista galli

Triangular process that projects superiorly from the cribiform plate of the ethmoid bone

Nasal bones

Two bones that form the anterior framework for the bridge of the noise.

Zygomatic bones

Two bones that form the bulk end of the cheek and a significant portion of the cheekbone or zygomatic arch

Palatine bones

Two bones that form the posterior part of the hard palate and the posterolateral walls of the nasal cavity

Pterygoid process

Two bony processes descending from the body of the sphenoid bone; attachment site for muscles of mastication

Maxillae

Two fused bones that make up the upper jaw bones, forming the orbit and anterior portion of the hard palate called the palantine process

Squamous sutures

Unite the parietal and temporal bones on the lateral aspects of the skull

Coronal suture

Unite the parietal bones with the frontal bone

Facial bones

form the framework of the face; provide openings for ventilation and eating; form cavities for the sense organs

Temporal bones

paired bones that form the lateral walls of the cranium; contains four general regions

Sphenoid bone

Posterior to the frontal bone on the interior part of the skull; butterfly shaped; consists of the lesser wings and the greater wings; contains the sella turcica, the sphenoid sinuses, and the pterygoid processes

Mastoid process

Process of the temporal bone behind the ear at the base of the skull; found in the mastoid region

Ethmoid bone

Deepest cranial bone; located anterior to the sphenoid bone and posterior to the nasal bones; includes the cribriform plate, the crista galli, ethmoid sinuses, superior nasal conchae, middle nasal conchae, and the perpendicular plate

Inferior nasal conche

Defined as a facial bone in contrast with the middle and superior nasal conchae, which are considered cranial bones; form part of the lateral walls of the nasal cavity; located inferior to the middle nasal conchae

Name the bones that make up the nasal cavities.

Ethmoid, maxilla, palatine, inferior nasal conchae, sphenoid, and vomer

Name the four sinus cavities.

FSEM: Frontal, sphenoid, ethmoid, and maxillary sinuses

Locations and function of the paranasal sinuses

A group of sinuses that surround the nasal cavity; air from the nasal cavity enters the paranasal sinuses via small openings in the bones; air gets filtered, warmed, and humidified

Frontal sinuses

A part of a group of cavities that surround the nasal cavity

Name the indentations of the cranial bones that serve to accommodate the brain.

Anterior, middle, and posterior cranial fossae

The two divisions of the skeletal system

Axial skeleton and appendicular skeleton

External acoustic meatus

Canal leading to eardrum and middle ear: tympanic region marking of the temporal bone

Maxillary sinuses

Cavities located within the walls of the maxillae bones