Lecture+6_Skeletal

Lecture Overview

  • Lecture Title: The Skeletal System: The Skull

  • Instructor: Dr. Tara Gaab

  • Course: ANFS240, Spring '25

  • Date: 2/14/25

Class Schedule (Friday 2/14)

  • 08:00-08:25 - LECTURE

  • 08:30-08:55 - QUIZ #1

Bones of the Skull

  • Characteristics:

    • Often paired bones (one on left & right)

    • Fit closely together and are tightly connected

    • Connected via fibrous tissue and cartilage in younger animals

    • Ossify (harden) as the animal grows

    • Visible connections in adult animals: known as "sutures"

Skull Bones Discussion

  • Occipital Bone (#8 - Red)

    • Caudal aspect of the skull and cranium

    • Features the ventral aspect of the foramen magnum

    • Large aperture where the spinal cord exits the skull

  • Parietal Bone (#7 - Light Green)

    • Located at the caudal part of the roof of the cranium

  • Maxillary Bone (#3 - Light Blue)

    • Lateral part of the face

    • Forms part of the hard palate

    • Holds the upper canine and cheek teeth

  • Zygomatic Bone (#10 - Yellow)

    • Positioned caudal to the maxillary bone

    • Contributes to the rostral part of the zygomatic arch

  • Frontal Bone (#6 - Orange)

    • Rostral part of the cranium in most species

    • Forms the entire cranium in pigs and cattle

  • Incisive (Premaxillary) Bone (#2 - Purple)

    • Most rostral bone of the skull

    • Location for attachment of upper incisor teeth

  • Palatine Bone (#11 - Dark Blue)

    • Forms the caudal part of the hard palate

  • Temporal Bone (#9 - Pink)

    • Caudoventral aspect of the skull

    • Caudal component of the zygomatic arch

  • Nasal Bone (#1 - White)

    • Forms the roof of the nasal cavity

Skull Terminology

  • Foramen Magnum (12)

    • Large caudal opening for the spinal cord's passage

  • Occipital Condyles (11)

    • Articulating prominence on the caudal skull aligning with the first spinal vertebra

  • Tympanic Bulla (7)

    • Smooth dome encapsulating the middle ear cavity

    • Plural: "bullae"

Caudal View of the Skull (Ferret)

  • Identified features: foramen magnum, occipital condyles, tympanic bullae

    • Reference: He, Tailun et al. (2002). Anatomy of the ferret skull.

More Skull Terminology

  • Zygomatic Arch

    • Curves laterally from the braincase and passes ventral to the orbit

    • Composed of temporal and zygomatic bones

  • Orbit

    • Space housing the eye and associated structures

    • Complete in herbivores; incomplete in carnivores

  • Temporal Fossa

    • Depression located beneath the zygomatic arch, caudal to the orbit

Additional Terminology

  • Hard Palate

    • Portions of the incisive, palatine, and maxillary bones; separates oral and nasal cavities

  • Nasal Cavity

    • Hollow area dorsal to the hard palate, divided by the nasal septum

    • Includes bony structures called ethmoturbinates

Skull Shapes

  • Dolichocephalic: Long skull shapes (e.g., Borzoi, Greyhound, Saluki)

  • Mesaticephalic: Intermediate skull shapes (e.g., Labrador, Dalmatian, Husky)

  • Brachycephalic: Short and broad skull shapes (e.g., Pug, Pekingese, French Bulldog)

Mandible

  • Definition: Lower jaw bone

  • Characteristics: Only mobile bone of the mammalian skull, housing lower teeth

  • United at the mandibular symphysis, allowing minimal movement

Parts of the Mandible

  • Body

    • Horizontal section where lower teeth attach

  • Ramus

    • Vertical section with no teeth

  • Condyloid (Articular) Process

    • Smooth area articulating with the mandibular fossa of the skull, forming the temporomandibular joint

  • Coronoid Process

    • Prominence at the tip of the ramus where chewing muscles attach