Study Notes for Anatomy and Physiology I - Skeletal System

Anatomy and Physiology I - Skeletal System Notes

Axial Skeleton: 80 bones
- Comprises bones of the head, neck, and torso.
- Includes:
- 74 bones forming the upright axis of the body.
- 6 tiny middle ear bones.
Appendicular Skeleton: 126 bones
- Comprises bones of the upper and lower extremities.

Axial Skeleton:
- Cranial Bones:
- Frontal Bone
- Parietal Bones
- Occipital Bone
- Temporal Bones
- Sphenoid Bone
- Ethmoid Bone
- Facial Bones:
- Nasal Bones
- Maxilla
- Zygomatic Bones
- Mandible
- Lacrimal Bones
- Palatine Bones
- Inferior Nasal Conchae
- Vomer
- Other structures: Crest of the ilium, sacrum, coccyx.

Frontal Bone
- Forms the forehead and anterior part of the top of the cranium.
- Contains frontal sinuses, forms the upper portion of the orbits, and forms the coronal suture with the parietal bones.
Parietal Bones
- Form the bulging top of the cranium.
- Form several sutures:
  - Lambdoid Suture with the occipital bone.
  - Squamous Suture with the temporal bone.
  - Coronal Suture with the frontal bone.
Temporal Bones
- Form part of the side and base of the skull.
- Articulate with the parietal bone and sphenoid bone.
- Contains several features:
  - External Acoustic Meatus
  - Mastoid Process
  - Styloid Process
Occipital Bone
- Forms the lower, posterior part of the skull.
- Articulates with three other cranial bones and the first cervical vertebra (atlas).
Sphenoid Bone
- Bat-shaped bone located centrally in the cranial floor.
- Anchors various bones and contains the sphenoid sinuses.
Ethmoid Bone
- Lies anterior to the sphenoid and contributes to the medial walls of the orbit and the nasal cavity.
- Contains cribriform plate for olfactory nerves and forms part of the anterior cranial floor.

Maxilla (Upper Jaw):
- Two maxillae form the keystone of the face.
- Articulate with several other facial bones and contain maxillary sinuses.
Mandible (Lower Jaw):
- Largest and strongest bone of the face.
- Forms the only movable joint of the skull with the temporal bone.
Zygomatic Bone:
- Forms the cheek and the outer margin of the orbit.
Nasal Bone:
- Forms the upper part of the bridge of the nose.
- Articulates with frontal bone, maxillae, and other nasal bones.

A U-shaped bone located above the larynx, suspended from the styloid processes of the temporal bones.
Unique because it does not articulate with any other bone, serving as an attachment point for tongue and neck muscles.

Overview: Serves as the flexible longitudinal axis of the skeleton.
- Consists of 24 vertebrae, plus the sacrum and coccyx.
Types of Vertebrae:
- Cervical (7): C1 (Atlas) allows nodding, C2 (Axis) allows rotation.
- Thoracic (12): Articulate with ribs.
- Lumbar (5): Support the lower back.

Dagger-shaped bone in the anterior chest wall, comprising three parts:
1. Manubrium: Upper handle
2. Body: Middle blade
3. Xiphoid Process: Cartilaginous lower tip, ossifies in adulthood.
Ribs: 12 pairs, articulating with the vertebrae and sternum.
- Floating Ribs: Ribs 11-12, do not attach to the sternum.

Unique features such as fontanels (soft spots) allow molding during birth and rapid brain growth.
At birth, the face constitutes a smaller proportion of the total cranium compared to maturity.

The eight bones of the cranium must be identified and their articulations must be understood.
The 14 bones of the face and their connections are critical for understanding craniofacial anatomy.
The hyoid bone's unique property of articulating with no other bones is essential to note.