keeping food and liquid from obstructing the airway; second, the larynx is the area with vocal cords and subsequently functions to produce sound and vocalizations. The larynx contains the following structures, which are important to swallowing and vocalization.
—Cricoid cartilage: A ring-shaped structure providing the transition from larynx to trachea. Provides an attachment point for the cartilage, ligaments, and muscles involved in sound production and the opening and shutting of the airway.
—Epiglottis: An elastic, spoon-shaped flap extending from the posterior tongue to the anterior border of the thyroid cartilage. During swallowing, the epiglottis folds over to cover the opening of the larynx (ie, glottis) to block any food or fluid from entering the airway.
—Thyrohyoid membrane: A fibrous, elastic membrane connecting thyroid cartilage to the hyoid bone by a mucosa bursa that aids the upward movement of the larynx in swallowing.
—Thyroid cartilage: A semicircular structure positioned on the anterior larynx. Consists of a fusion of 2 cartilage plates. The external point of fusion is the laryngeal prominence (ie, Adam’s apple) and is more pronounced in men. The thyroid cartilage supports and protects the upper larynx and anchors the anterior portion of the vocal cords.
—Vocal cords: Situated in the mucous membrane on each side of the larynx opening. As exhaled air moves through the larynx, the vocal cords vibrate and produce sound.
The compressive forces of strangulation may lead to occlusion, fractures, and hemorrhages of the larynx’s cartilaginous framework. It takes approximately 22 pounds of force for airway occlusion at the level of the thyrohyoid membrane, 31.5 pounds of force to fracture the thyroid cartilage, and 41 pounds of force to fracture the cricoid. Laryngeal fractures often allow air to escape into the soft tissues of the neck, producing subcutaneous emphysema (ie, subcutaneous crepitation), which can result in potential airway compromise that can develop into acute asphyxia, and eventually, death. Subsequent hemorrhages and swelling may also play a role in airway compromise as a result of these injuries. If these fractures or hemorrhages go untreated or unrecognized, the victim may survive initially, but over hours, or even days, the victim may develop life-threatening airway complications, leading to a delayed death. Vocal cord injury that leads to swelling or hematoma formation may result in temporary or long-term vocal dysfunction that includes a hoarse voice (ie, dysphonia) or the inability to produce a voice (ie, aphonia).
TRACHEA
The trachea is a hollow tube located along the body’s midline that connects the larynx to the 2 main bronchi of the lungs. Incomplete, highly elastic, C-shaped cartilage rings are located anteriorly along the tracheal wall. The trachea’s primary function is to allow air flow to and from the lungs. It takes approximately 33 pounds of pressure to completely occlude the trachea. Tracheal occlusion inhibits the inhalation of oxygen and the exhalation of carbon dioxide, resulting in multisystem hypoxia and acidosis. The force of the strangulation pressure may also fracture the trachea, causing subcutaneous emphysema and subsequent airway compromise.
ANATOMY OF THE EAR
When documenting injuries on a patient after strangulation, it is important to inspect and photograph both sides of the ears (Figure 4). Initial injury, unless it involves dermal capillary injury, may not be visible but over time may surface, allowing for reassessment and documentation.
—Triangular fossa: A shallow depression in the anterior part of the top of the ear’s auricle between the 2 crura into which the antihelix divides.
—Scaphoid fossa: A shallow oval depression that is situated above the pterygoid fossa on the pterygoid process of the sphenoid bone and that provides attachment for the origin of the tensor veli palatini muscle.
—Helix: The outer rim of the ear that extends from the superior insertion of the ear on the scalp (root) to the termination of the cartilage at the earlobe. The helix can be divided into 3 approximate parts: the ascending helix, which extends vertically from the root; the superior helix, which begins at the top of the ascending portion, extends horizontally, and curves posteriorly to the site of Darwin tubercle; and the descending helix (sometimes called posterior), which begins inferior to Darwin tubercle and extends to the superior border of the earlobe. The lower portion of the posterior part is often noncartilaginous. The border of the helix usually forms a rolled rim, but the helix is highly variable in shape.
Figure 4. Anatomy of the ear.
—Crus of helix: The continuation of the anteroinferior ascending helix, which extends in a posteroinferior direction into the cavity of the concha above the external auditory meatus. The average crus helix extends about one-half to two-thirds the distance across the concha.
—Antihelix: A Y-shaped curved cartilaginous ridge arising from the antitragus and separating the concha, triangular fossa, and scapha. The antihelix represents a folding of the conchal cartilage, and it usually has similar prominence to a well-developed helix. The stem (the part below the bifurcation) of the normal antihelix is gently curved and branches about two-thirds of the way along its course to form the broad fold of the superior (posterior) antihelical crus and the more sharply folded inferior (anterior) crus. The inferior and superior crura of the antihelix can vary both in volume and degree of folding.
—Tragus: A posterior, slightly inferior, protrusion of skin-covered cartilage, anterior to the auditory meatus. The inferoposterior margin of the tragus forms the anterior wall of the incisura.
—Intertragic notch: The space that separates the tragus from the antitragus in the outer ear.
—Antitragus: The anterosuperior cartilaginous protrusion lying between the incisura and the origin of the antihelix. The anterosuperior margin of the antitragus forms the posterior wall of the incisura.
—Concha: The fossa bounded by the tragus, incisura, antitragus, antihelix, inferior crus of the antihelix, and root of the helix, into which opens the external auditory canal. It is usually bisected by the crus helix into the cymba superiorly and cavum inferiorly.
—Cavum concha: The inferior portion of the cavity of the auricle of the ear. It leads to the external acoustic meatus.
—Cymba concha: The narrowest end of the concha.
—Lobe: The soft, fleshy lower part of the external ear.
STRANGULATION-RELATED INJURIES AND CONDITIONS
The learner may find reviewing the following definitions useful in completing the activities within this book. Terminology for indicators of direction when documenting findings in a medical forensic examination include anterior (nearer the front), posterior (nearer the back), inferior (nearer the bottom), superior (nearer the top), medial (to the middle), lateral (to the side), proximal (nearer the center of the body), and distal (away from the center of the body) (Figure 5).
SIGNS AND SYMPTOMS OF STRANGULATION
