Notes: Long Bones, Skeletal Functions, and Skull Structures

Shape Designation: Long bones typically feature a long axis in relation to their other parts. This category includes bones such as the metacarpals.
Regional Designations: Long bones have specific regional designations:
- Epiphysis: These are the ends of the long bones, found on both sides. For example, in the femur, the epiphyses are the ends with all the knobs and articulation points. These external features correlate with internal bone structures.
- Internal Structure of Epiphyses: Internally, the epiphyses are predominantly composed of spongy bone (also known as trabecular bone). This is the site where red marrow is found.

Purpose for Lab vs. Lecture: In lab sessions, the focus was primarily on learning the names of bones and their substructures (e.g., condyles). In contrast, the lecture's purpose is to understand what these bony substructures actually do and what they are for, adding additional functional aspects to the anatomical knowledge.
Tissue Types: The skeletal system encompasses multiple tissue types, not just the osseous tissue of the bones themselves. It also includes cartilage tissue and other supportive connective tissues.

Communication (Sound Production):
- Many senses are localized in the head and supported by bony structures of the axial skeleton.
- The axial skeleton also facilitates sound production and communication.
- Mandible: Moving the mouth for talking involves the mandible, a bone of the axial skeleton, essential for audible communication and making noise.
- Larynx Support: The axial skeleton supports structures of the larynx (the voice box).
Respiration (Breathing Mechanics):
- When taking a deep breath:
  - The diaphragm, the primary respiratory muscle separating the thoracic cavity from the abdominal cavity, contracts.
  - The external intercostal muscles of the rib cage also contract.
  - Contraction of the diaphragm and external intercostals moves the rib cage upwards and outwards.
- Thoracic Column: The thoracic column is divided into $24$ vertebrae in total:
  - $7$ cervical vertebrae (bones of the neck).
  - $12$ thoracic vertebrae (bones of the thoracic cage), which are the posterior articulations for the rib cage.
Hyoid Bone Specifics:
- The hyoid bone is unique in that it does not articulate with any other bones directly.
- While it appears attached to the cervical vertebrae in skeletal models in labs, this is only to hold it in place; it actually sits off and away from them.

Ossification Differences:
- Intramembranous Ossification vs. Endochondral Ossification: A main difference between these two processes lies in the starting material used to build the bones.
Calcification vs. Ossification (Clinical Relevance):
- Calcification: Technically, this is the deposition of calcium into a tissue.
- Ossification: This refers to the formation of bone tissue.
- Abnormal Calcification: Any tissue can undergo calcification. However, if soft tissues that are not supposed to form bone become calcified and turn into bone tissue abnormally, it is considered pathological. A variety of diseases can result in this abnormal calcification process.

Divisions of Nasal and Oral Cavities:
- Nasal Septum: Divides the nasal cavity into left and right sides.
- Hard Palate: Divides the nasal cavity from the oral cavity. It is formed by the coming together of two structures: the maxillae and the palatine bones.
- Soft Palate: Located posterior to the hard palate. When soft tissues are overlaid onto the axial skeleton, the soft palate is added. It is crucial for controlling processes like breathing and swallowing.
  - Uvula: The small, dangling structure at the back of the throat is part of the soft palate. Its function includes preventing food from entering the nasal cavity during swallowing.