Lesson 4 BSC2085 LAB

Axial Skeleton

Composed of three main parts: Skull, Vertebral column, and Bony Thorax.

Cranium

The upper part of the skull that houses the brain.

Two major areas of Cranium

- cranial vault

- cranial floor

Cranial Vault

The superior, lateral, and posterior walls of the skull.

Cranial Floor

Contains three concavities: anterior, middle, and posterior cranial fossae.

Fossae

The plural of fossa, referring to the concave depressions in the cranial floor.

Coronal Suture

Connects the frontal bone to the parietal bone.

Lambdoid Suture

Connects the parietal bone to the occipital bone.

Sagittal Suture

Connects the left and right parietal bones.

Squamous Suture

Connects the parietal bone to the temporal bone.

Frontal Bone

The bone forming the forehead and upper part of the eye sockets.

Frontal bone components

Glabella and Supraorbital foramen (notch)

Glabella

Located between the orbital cavities.

Supraorbital Foramen (Notch)

Opening above each orbit, serving as a passageway for blood vessels and nerves.

Parietal Bone

Forms the sides and roof of the cranium.

Temporal Bone

Bone located at the sides and base of the skull.

Regions of the temporal bone

Squamous region, tympanic region, mastoid region, petrous region

Squamous region contains

Zygomatic process

Tympanic region contains

External acoustic meatus- ear canal

Styloid process- ligament attachment site

Mastoid region contains

Mastoid process- a muscle attachment site located on the temporal bone.

Petrous region contains

Jugular foramen- passage for jugular vein and cranial nerves IX, X, and XI

Carotid canal- passage for internal carotid artery

Internal acoustic meatus- passage for cranial nerves VII and VIII

Occipital associated structures

Foramen magnum

Occipital condyles

Hypoglossal canal

Foramen magnum

Where the spinal cord enters the cranium to connect to the brain

Occipital Condyles

Articulation site with the 1st cervical vertebra (atlas).

Hypoglossal Canal

Passage for cranial nerve XII (hypoglossal nerve).

Sphenoid bone associated structures

Greater wings- part of orbital cavity

Sella turcica- midline of sphenoid bone

Lesser wings- anchors dura mater

Optic canals- opening at base of lesser wings for cranial nerve II

Hypophyseal fossa

Houses the pituitary gland; part of sella turcica

Optic canals

Openings at base of lesser wings for cranial nerve II (optic nerve)

Ethmoid bone

Crista galli and Cribriform plate

Crista galli

Anchors dura mater (leathery connective tissue membrane that surrounds and protects the brain and spinal cord)

Cribriform plate

Allows olfactory fibers (cranial nerve I) from nasal mucosa to enter the brain

Facial bones

Mandible, Maxilla, Palatine, Zygomatic, Lacrimal, Nasal, Vomer, Inferior nasal conchae

Mandible

Body of mandible, Mandibular ramus, Mandibular angle, Coronoid process, Mandibular notch, Condylar process

Maxilla

Palatine process - anterior part of the hard palate

Hard palate

Composed of BOTH the palatine process of the maxilla AND the palatine bone

Hyoid bone

Serves as a point of attachment for many tongue and neck muscles

Paranasal Sinuses

Four skull bones (maxillary, sphenoid, ethmoid, frontal) contain sinuses (mucosa-lined air cavities)

They lighten the skull and act as resonance chambers for speech

Sinusitis

Inflammation of sinuses (from bacterial infection or allergy)

Fetal Skull

Contains areas of fibrous membranes (fontanelles) that allow the skull to compress slightly during birth

Craniosynostosis

Birth defect that causes one or more of the sutures on a baby's head to close earlier than usual. No fontanelles

Fontanelles

Areas of fibrous membranes in the fetal skull that allow for brain growth during late fetal life. Completely ossify by 1.5-2 years old