Lab 24 Pre-Lab Exercise
There are several steps in this lab that benefit from pre-lab preparation using bones and models. Please review this material before lab. Also feel free to return to this during lab as needed. The following is organized by which in-lab task the material helps you prepare:
To prepare to separate the head from the neck, please do the following:
1. Refer to a skeleton and loose vertebral material to identifying the following:
- Atlas (C1): Anterior arch, superior articular facet, transverse process, posterior arch, facet for dens.
- Axis (C2): Dens
2. Examine a skull and identify the following structures on the occipital bone:
- Occipital condyle
- Pharyngeal tubercle
- Foramen magnum
3. Examine the atlanto-occipital joint between the occipital condyle and the superior articular facet of the atlas. Examine the way the atlas (C1) fits on the skull, and the way the axis (C2) articulates with the atlas. Use the images provided here to understand the transverse ligament of the atlas. It holds the dens to the anterior surface of the atlas, while allowing the atlas to rotate.
To prepare for the dissection of the larynx
Go to the model room and examine a model of the larynx. The skeleton of the larynx is responsible for maintaining a patent airway. It consists of a series of articulating cartilages that are united by membranes. Use an illustration and a model to study the cartilages and membranes:
- Thyroid cartilage– formed by two laminae (a lamina is a thin, flat plate) joined in the anterior midline to form the laryngeal prominence.
- The superior horn of the thyroid cartilage projects superiorly.
- The inferior horn of the thyroid cartilage articulates with the cricoid cartilage through the cricothyroid joint.
- Epiglottic cartilage – an unpaired, heart-shaped cartilage that lies posterior to the tongue and hyoid bone. The stalk of the epiglottic cartilage is attached within the angle formed by the thyroid laminae.
- Cricoid cartilage- shaped like a ring (from krikos, Greek, meaning ring). Its lamina is a broad, flat area that is positioned posteriorly, and its arch is located anteriorly.
- Arytenoid cartilages - situated on the superior border of the lamina of the cricoid cartilage. Each arytenoid cartilage is pyramid-shaped and articulates with the cricoid cartilage through a synovial joint. Each arytenoid cartilage has a muscular process for attachment of intrinsic laryngeal muscles and a vocal process for attachment of the vocal ligament. Thyrohyoid membrane - connects the superior border of the thyroid cartilage to the hyoid bone. When the suprahyoid and infrahyoid muscles move the hyoid bone, the larynx also moves.
- Vocal ligaments - the posterior end of each vocal ligament is attached to the vocal process of an arytenoid cartilage. The anterior end of each vocal ligament is attached to the inner surface of the thyroid cartilage, at the angle formed by the laminae.