Lecture 7 Skull and Features - Summer 2023 PDF

Musculoskeletal Anatomy The bones of the skull and features Appendicular Skeleton Axial Skeleton  Terms: Tubercle – a small rounded projection Tuberosity – a protuberance in a bone Malleolus – a bony projection...

Musculoskeletal Anatomy The bones of the skull and features Appendicular Skeleton Axial Skeleton  Terms: Tubercle – a small rounded projection Tuberosity – a protuberance in a bone Malleolus – a bony projection Styloid process – a slender projection Facet – two joints coming together (vertebrae) Condyle – a rounded protuberance Sulcus – a groove Fossa – a shallow depression or smoothened area Meatus – a passage through Foramen – an opening or a hole What to focus on: -Be able to identify the bones and features on the skull. -Review all the cartoon images with real bone images found in lab 8 Cranial bones and 14 Facial bones Mnemonic The ethmoid bone is obscured by other bones, so to see it you need a sagittal view of the skull to understand its shape and location. You can see the ethmoid bone shown in green and yellow on the 2 images. The ethmoid bone sits at the roof of the nose between the 2 orbits or eye sockets. Ethmoid Bone  The Ethmoid bone 5 Features: Crista galli, perpendicular plate, ethmoid sinus, cribiform plate and olfactory foramina Perpendicular plate: Forms part of the nasal septum  Ethmoid Bone The cribriform plate is where the olfactory nerves travel through. Specifically, through the olfactory foramina. The olfactory nerves are involved in smell and travel through the ethmoid bone  Ethmoid Bone The crista galli is a sail-like projection located at the top/superior portion of the ethmoid bone. It essentially serves as an anchor point for the brain and prevents the brain from moving around in the skull Ethmoid Bone Ethmoid sinus: Numerous little cavities in the nasal cavity to help keep the nose from drying out  The Occipital bone 8 Features: Foramen magnum, occipital condyles, jugular foramen, superior nuchal line, inferior nuchal line, external occipital protuberance, posterior cranial fossae, hypoglossal canal The occipital bone is located at the back of the skull and protects the underlying cerebellum, brainstem, and occipital lobe of the cerebrum.  The Occipital bone The external occipital protuberance is the “bump” you can feel at the back of your skull, and it serves as an attachment point for some of the neck muscles. Superior and inferior nuchal lines are sites of muscle and ligament attachments to help stabilize the head  The Occipital bone The occipital condyles are protuberances located at the base of the occipital bone, and they articulate with the 1st cervical vertebrae (C1) or the atlas.  The Occipital bone Superior view, internal surface Jugular foramen and Hypoglossal canal are passageways for nerves and or arteries and veins The foramen magnum is a large hole at the base of the occipital bone where the brain stem travels through.  The Occipital bone The Posterior cranial fossa houses the cerebellum and brainstem There are 2 parietal bones, one located on either side of the skull, shown in blue. No features to memorize! Frontal Bone 6 Features  Frontal Bone 6 Features: Glabella, superciliary arch, supraorbital margin, supraorbital foramen, frontal sinus, anterior cranial fossae Glabella: the smooth part of the forehead above and between the eyebrows Supercilliary arch: Bony ridge above the eye sockets Supraorbital margin: Below the superciliary arch, upper boundary of the eye orbit Supraorbital foramen: passageway for nerves/arteries/veins  The Frontal bone The anterior cranial fossa houses the frontal lobes of the brain The Frontal bone  Temporal Bone 5 Features: External acoustic meatus, styloid process, carotid canal, zygomatic process and mastoid process The zygomatic process forms the zygomatic arch which is the cheek bone (zygomatic bone is part of the facial bones) The external and internal auditory meatus is a canal that travels through the temporal bone and connects to the inner ear. The mastoid process serves as an attachment point for some of the neck muscles. The styloid process is a projection where some of the tongue and larynx muscles attach.  The Temporal bone The carotid canal is the passageway for the carotid artery The sphenoid bone is difficult to see from the side but the sections of the skull show the sphenoid bone in yellow. It is shaped like a butterfly as shown in the bottom right.  The Sphenoid Bone 9 Features: sella turcica, greater and lesser wings, optic canal, foramen ovale, foramen rotundum, foramen spinosum, superior orbital fissure, medial and lateral ptyerygoid process, sphenoid sinus  The Sphenoid bone Superior view The optic canal is the passageway for the optic nerve Foramen rotundum, ovale and spinosum are all passageways for nerves Pterygoid process (medial and lateral plates) are attachment sites for the pterygoid muscles which are involved in chewing  The Sphenoid bone The sphenoid bone has a depression called the sella turcica where the pituitary gland sits. The Sphenoid bone  Maxilla 4 Features: infraorbital foramina, palatine process, maxillary sinus and alveolar margin  Maxilla Passage of infraorbital vein, artery and nerve  Maxilla Largest of the paranasal sinuses Maxilla Palatine process (shown in green) forms the nasal cavity floor as well as ¾ of the hard palate. The other ¼ being the palatine bones Palatine bones: not included in the palatine process Maxilla Alveolar margin: the ridge line between the maxilla and the teeth. This feature will also be on the mandible  Mandible 7 Features: Coronoid process, mandibular notch, mandibular condyle, mental foramen, ramus, mandibular angle and alveolar margin Mandible Mental foramina: passageway for nerves, arteries and veins Alveolar margin: ridge before the teeth Ramus: 2 vertical processes on each side of the mandible Coronoid process: projection off of the ramus and serves as an attachment for muscles Mandibular condyle: projection off the ramus which serves as a joint for the jaw to open and close Mandibular notch: a curved depression on the upper border of the lower jaw Mandibular angle The next pair of facial bones are the nasal conchae They are best seen in a sagittal view of the nose, as they are located within the nasal cavity. The nasal conchae serve to allow for rapid warming and humidification of air. The nasal bones are next shown in beige/tan below. There are no significant features to know about the nasal bones. Just remember that most of the nose is made up of cartilage, and the only bony part of the nose is the bridge of the nose where the nasal bones are located. Next is the vomer bone shown in pink below. It is located in the midline of the nasal cavity and can best be seen in a sagittal view of the nose. The vomer bone forms the inferior portion of the nasal septum, which is what divides the right and left nasal passages The next pair of facial bones are the lacrimal bones. They are shown in pink in one of the images below and highlighted in yellow in the other. The lacrimal bones are the smallest bones in the skull and make up part of the medial aspect of each orbit. The word “lacrima” means tears in latin, and this will help you remember the function of the lacrimal bones. The next pair of facial bones are the zygomatic bones shown in orange below. The zygomatic bones form part of each orbit as well as the cheekbone that can be felt on either side of the face. The final pair of facial bones are the palatine bones. They are deeper in the skull and are shown below in blue. 2 features listed in the lab manual: skip those, just be able to locate the bones  Hyoid Bone- 3 Features Involved in speech and swallowing  Sutures of the skull Sagittal suture: Between the parietal bones Coronal suture: Between the frontal and parietal bones Squamous suture: Between the parietal and temporal bones Lambdoid suture: Between the parietal and occipital