Skeletal System Lab – Vocabulary Flashcards

Overview and key setup

• Skeleton contains approximately $206\,-\,207$ bones.
• The skeleton is divided into two main divisions: the axial skeleton and the appendicular skeleton (note: the transcript sometimes uses the term “appendicator,” which should be corrected to appendicular).
• Axial skeleton components: cranial bones, facial bones, vertebrae, sternum, ribs, and a small bone in the neck called the hyoid bone (not directly attached to other bones).
• The lab uses Visible Body resources in a “tour of the exoskeleton” format; there is a printout of the skeletal object (posted to Google) to help study.
• In this first pass, the instructor aims to cover the axial skeleton and expects the session to last about an hour.
• Course logistics mentioned in the transcript:
  • Video will be posted to a Box folder for the class; access will be via invitation to your institutional email.
  • Teaching assistant: Caroline Tannis, a senior health science major, will help with lab questions.
  • Reach out to the TA for help; use the provided contact channels.

Cranium and basics of sutures

• The cranium and facial bones are examined first; focus starts with cranial sutures.
• Cranial sutures are immovable joints where skull bones meet; they resemble stitches on the skull in appearance.
• Sutures allow newborn skull plates to move slightly for delivery, then fuse over the first year to form stable joints.
• Major sutures discussed:
  • Sagittal suture: runs down the midline of the skull in the sagittal plane; ends rearward at the lambdoid suture.
  • Lambdoid (lambdoidal) suture: located at the back of the skull.
  • Squamous (squamosal) suture: on the sides, between the temporal and parietal bones (one on each side).
• Aside from the primary sutures, there are other sutures around the skull, but the lecture emphasizes sagittal, lambdoid, and squamous sutures.
• For the printout: the instructor notes that some cranial bone labels include extra information in parentheses; students may rewrite the list in a vertical alignment to aid memorization and emphasize the learning process through repetition.

Key cranial bones and notable features (with corrections to terminology from the transcript)

• Frontal bone
  • Supraorbital margin: ridge above the eye socket.
  • Supraorbital foramen: hole in the supraorbital margin through which neurovascular structures pass.
• Temporal bones (right and left)
  • External auditory meatus: the ear canal opening.
  • Mandibular fossa: indentation where the mandible articulates with the temporal bone; behind it lies the external auditory meatus.
  • Zygomatic process of the temporal bone: connects with the zygomatic (cheek) bone.
  • Squamous portion and other features include the region around the meatus and the zygomatic process.
• Occipital bone
  • Nuchal lines (superior and inferior): ridges at the back of the skull.
  • External occipital protuberance: a raised bump in the midline on the posterior skull.
  • Occipital condyles: rounded knobs that articulate with the first cervical vertebra.
• Sphenoid bone (one bone, bilateral processes)
  • Greater wing (lateral aspect) and lesser wing (inside/medial). The greater wing is the more lateral, wing-like part; the lesser wing lies closer to the orbit.
  • Sella turcica (turkish saddle): a concave surface with ridges at the back and front; houses the pituitary gland in the hypophyseal fossa.
  • Optic foramen (optic canal): passage for the optic nerve.
  • Orbital fissures: superior orbital fissure (above) and inferior orbital fissure (below) for nerves and vessels servicing the eye.
  • Inside view reveals the two wings; the greater wing appears prominently, with the lesser wing just inside.
  • The lecture notes that some naming conventions differ; students should be aware of the presence of the sella turcica with the hypophyseal fossa and the optic foramen.
• Ethmoid bone
  • Orbital plate (of ethmoid): part of the medial wall of the orbit.
  • Perpendicular plate: forms part of the nasal septum, hanging down into the nasal cavity.
  • Cribriform plate: with many small holes (cribriform foramina) for olfactory nerve fibers to pass from the nasal cavity to the brain.
  • Crista galli: a vertical crest (crest of the dura mater attachment) on the cribriform plate; historically mispronounced in the lecture as various terms.
  • The ethmoid connects to the orbit and nasal cavity and contributes to the floor of the anterior cranial fossa.
• Wormian (sutural) bones
  • Small extra bones sometimes present within sutures, particularly around the occipital bone; these are called Wormian bones.
  • Their presence can vary by individual and population; historically thought to be more common in some ethnic groups, though newer literature shows variability.
• Cranial fossae (basal cranial depressions)
  • Anterior cranial fossa: houses parts of the frontal lobes.
  • Middle cranial fossa: houses parts of the temporal lobes.
  • Posterior cranial fossa: houses the cerebellum and brainstem regions.
  • The fossae accommodate different portions of the brain and are separated by bony contours.

Facial bones and associated features

• Maxilla (upper jaw; two maxillae, left and right)
  • Infraorbital foramen: opening below the orbit for infraorbital nerve and vessels.
  • Palatine processes of the maxilla: horizontal plates forming the anterior part of the hard palate.
• Palatine bone
  • Behind the maxilla; has a right and left component contributing to the hard palate and floor of the orbit.
• Zygomatic bones (cheekbones)
  • Temporal process of zygomatic bone: articulates with the temporal bone.
  • Frontal process of zygomatic bone: articulates with the frontal bone.
• Lacrimal bone
  • Lacrimal fossa: indentation near the lacrimal bone that relates to tear duct function.
  • Lacrimal foramen: hole for tear duct passage.
• Nasal bones
  • Two nasal bones sit side by side to form the bridge of the nose.
• Inferior nasal conchae (turbinates)
  • Inferior scroll-like bones inside the nasal cavity that help condition and filter air.
  • Some texts refer to turbinates; there are also superior and middle conchae (part of the ethmoid).
• Ethmoid bone connections (recap)
  • The perpendicular plate (ethmoid) contributes to the nasal septum.
  • The orbital plate contributes to the medial wall of the orbit.
• Vomer and nasal cavity floor structures
  • Vomer (noted by the instructor as “bomber”): a single bone forming part of the nasal septum.
  • The floor of the nasal cavity has structures formed by the palate bones and conchae.
• Inferior nasal conchae and related features
  • The inferior nasal conchae are separate bones; the superior and middle conchae are parts of the ethmoid.
• Mandible (lower jaw)
  • Mental region (chin): mental protuberance is felt in the chin area.
  • Mental foramen: openings on the chin for nerves and vessels.
  • Body: horizontal portion of the mandible.
  • Angle: region where the mandible angles upward toward the ramus.
  • Ramus: vertical part of the mandible extending upward from the body toward the skull.
  • Coronoid process: anterior/medial projection resembling a crown point (named from corona meaning crown).
  • Condylar process: posterior projection that forms the temporomandibular joint with the temporal bone; the knob-like ending is the condyle.
  • The mandible is the only movable bone of the skull (via the temporomandibular joint).

Vertebral column and regional anatomy

• Total vertebrae in the adult: $26$
• In a child: $33$ vertebrae (before fusion during development)
• Regions and counts in adults:
  • Cervical vertebrae: seven (C1–C7)
  • Thoracic vertebrae: twelve (T1–T12)
  • Lumbar vertebrae: five (L1–L5)
  • Sacrum: one sacrum formed by the fusion of five sacral vertebrae (S1–S5) in the adult
  • Coccyx: typically four coccygeal vertebrae fused into a single coccyx in the adult (the transcript notes three fused, which is less common; standard anatomy lists four in most adults).
• Atlas and axis (special cervical vertebrae)
  • C1: Atlas, the first cervical vertebra.
  • C2: Axis, the second cervical vertebra.
  • Other cervical vertebrae: C3, C4, C5, C6, C7 (often with C7 referred to as the vertebra prominens).
• Curvatures (orientation when viewed from the back):
  • Cervical region is concave posteriorly when viewed from the front; the overall curvature patterns contribute to the spine’s S-shape.
  • The thoracic region curves posteriorly; the lumbar region curves anteriorly when viewed from the front.
• Sacrum and coccyx development
  • In a child, the sacrum is formed by five separate sacral vertebrae; in adults, these fuse into a single sacrum.
  • The coccyx forms from four separate coccygeal vertebrae that fuse during development.
• Important foramina and spaces in the vertebrae and skull connection
  • The vertebral column supports the spinal cord and provides passageways for nerves and vessels entering/exiting the skull.

Key named terms and hyperlinks to foundational concepts

• Atlas (C1) and Axis (C2)
  • Atlas supports the skull; axis provides the pivot for head rotation via the dens (odontoid process).
• Sella turcica and hypophyseal fossa
  • Sella turcica: saddle-shaped depression on the sphenoid bone; houses the pituitary gland within the hypophyseal fossa.
• Crista galli and cribriform plate
  • Crista galli: a crest for dura mater attachment on the ethmoid; cribriform plate contains olfactory foramina for CN I.
• Optical structures
  • Optic foramen (optic canal): passage for the optic nerve.
  • Superior orbital fissure: passage for cranial nerves III, IV, V1, and VI and associated vessels.
  • Inferior orbital fissure: lower orbital opening for nerves and vessels.
• Mandible geometry
  • Coronoid process (camel-like projection on the anterior edge of the ramus for muscle attachment).
  • Condylar process: posterior projection forming the temporomandibular joint with the temporal bone.
• Foramina and canals (as named in the transcript and corrected here)
  • Infraorbital foramen (maxilla): below the orbit.
  • Foramen ovale (on the sphenoid bone): oval-shaped opening.
  • Foramen lacrimum (lacrimal-related openings on the lacrimal bone) and lacrimal foramen (opening for tear duct passage).
  • Jugular foramen: located at the junction of the temporal and occipital bones; allows internal jugular vein to pass.
  • Internal carotid passage: the region near the carotid canal that accommodates the internal carotid artery.
  • Foramen magnum: large opening in the occipital bone for the brainstem to pass through.
  • Cribriform foramina: holes in the cribriform plate for olfactory nerves.
• Orbital and nasal region anatomy (summary)
  • Orbital plates (ethmoid) and the medial wall of the orbit.
  • Nasal bones form the bridge of the nose; inferior nasal conchae are separate bones forming the lower scrolls inside the nasal cavity.
  • Vomer: forms part of the nasal septum.

Notes on terminology and teaching tips

• Terminology corrections to align with standard anatomy:
  • Appendicular skeleton replaces the misspelled “appendicator skeleton.”
  • Suture naming should include sagittal, coronal, lambdoid, and squamous (squamosal) sutures; the transcript emphasizes sagittal, lambdoid, and squamous.
  • The sella turcica houses the pituitary gland within the hypophyseal fossa.
  • The cribriform plate contains olfactory foramina (not just a single plate) for CN I.
  • The ethmoid bone has a crista galli (not “crista valley”).
  • Wormian bones refer to extra sutural bones, often found in the occipital region.
  • The internal carotid passage is via the carotid canal, not a generic “carotid foramen.”
• Study strategies mentioned by the instructor (practical implications)
  • Print and printout: use the skeletal object printout to study and annotate.
  • Rewriting and reorganizing terms helps reinforce learning; vertical alignment or reformatting can be beneficial.
  • Start with the cranial sutures, then move to cranial bones, followed by facial bones, for a structured approach.
  • Use the Foramina list (on page two of the notes) to integrate cranial and facial bone foramina with their respective bones.
• Real-world relevance and ethical/philosophical implications
  • Understanding cranial sutures helps in pediatric assessment of skull growth and development.
  • Knowledge of skull foramina and nerve/vessel pathways is crucial for clinical procedures, neurology, and radiology.
  • The variability of Wormian bones across populations illustrates how anatomical variation relates to ethnic and developmental factors; this has historical and educational significance in anatomy education.

A quick recap of numerical references

• Total adult bones: $206\text{ to }207$
• Vertebrae counts by region in adults: Cervical $7$, Thoracic $12$, Lumbar $5$, Sacrum $1$ (formed from $5$ fused vertebrae), Coccyx $4$ (typically fused to form a single coccyx)
• Vertebral counts in a child: $33$ total before fusion
• Crown-point terminology: Coronoid process (from corona = crown)
• Hyoid bone: a unique, independent bone in the neck that does not articulate with other bones but serves as an attachment for tongue and neck muscles.

Optional connections to foundational principles

• The axial skeleton protects the central nervous system (cranium) and thoracic organs (rib cage, sternum) and supports the axial axis of the body.
• The curvatures of the spine (cervical and lumbar lordosis; thoracic and sacral kyphosis) contribute to the spine’s mechanical efficiency and load distribution.
• Sutures allow for skull growth during development and provide a rigid protective casing for the brain after birth.
• The anatomy of the orbit, nasal cavities, and cranial fossae supports sensory organs (eye, smell, taste) and the brain’s structural integration.

End of cranial and vertebral overview

• The lecture will continue with more foramina, then return to cranial bones, before moving on to the vertebral column and associated ligaments, joints, and regional anatomy. Students should review the printable skeletal diagram and the Visible Body tour for a visual reinforcement of these structures.