Mylohyoid muscle
This muscle (m. mylohyoideus) is one of the most important structures forming the muscular basis of the floor of the oral cavity.
Attachment points:
- Origin (Origo): muscle bundles originate from the mylohyoid line of the same name, located on the inner surface of the mandible.
- Insertion (Insertio): fibers run toward the body of the hyoid bone and also weave into a specific tendinous structure — the median raphe (raphe mylohyoidea).
Biomechanics and functions: The action of the muscle depends directly on which bone structure is fixed at the moment:
- When the hyoid bone is mobile, it pulls it upward while simultaneously elevating the floor of the oral cavity.
- If the hyoid bone is securely fixed by other muscles, contraction of m. mylohyoideus results in depression of the mandible.
Blood supply and innervation: The muscle tissue is supplied by branches of the lingual and submental arteries (aa. sublingualis, submentalis). Motor impulses are supplied via the mylohyoid nerve (n. mylohyoideus), which is a branch of the trigeminal nerve (n. trigeminus).
Smallest scalene muscle
The smallest scalene muscle (m. scalenus minimus) belongs to inconstant (variable) anatomical structures of the neck region.
Its anatomical features are as follows:
- Origin: muscle bundles start from the transverse processes of the sixth and seventh cervical vertebrae (C6–C7).
- Insertion: fibers descend, reaching the dome of the pleura and the first rib.
- Function: due to its location and fixation points, this muscle performs an important task — it tensions and strengthens the dome of the pleura, ensuring its stability.
Topographic anatomy: omotracheal triangle
For precise orientation in the neck, specific topographic zones are distinguished. One of them is the omotracheal, or muscular, triangle — trigonum omotracheale (musculare).
Boundaries of the triangle:
- Laterally, the space is bounded by the anterior margin of the sternocleidomastoid muscle (m. sternocleidomastoideus).
- Superiorly and laterally, the boundary is formed by the inferior belly of the omohyoid muscle (m. omohyoideus).
- The medial boundary is the conventional median line of the neck.
Contents: Vital organs of the neck are projected within the omotracheal triangle. The thyroid gland, larynx, and cervical trachea are located here.
Briefly: answers to topical questions
Which muscles belong to the suprahyoid group of neck muscles?
The suprahyoid group of neck muscles includes muscles located above the hyoid bone that form the floor of the oral cavity. This group includes:
- Mylohyoid muscle (m. mylohyoideus).
- Geniohyoid muscle (m. geniohyoideus).
- Digastric muscle (m. digastricus).
- Stylohyoid muscle (m. stylohyoideus).
These muscles participate in the act of chewing by depressing the mandible, and in swallowing by elevating the hyoid bone.
Which muscles form the infrahyoid group of neck muscles?
The infrahyoid group is formed by the neck muscles located below the hyoid bone. They include:
- Sternohyoid muscle (m. sternohyoideus).
- Sternothyroid muscle (m. sternothyroideus).
- Thyrohyoid muscle (m. thyrohyoideus).
- Omohyoid muscle (m. omohyoideus).
These muscles fix the position of the hyoid bone and pull it downward, participating in the act of swallowing. They can also function as accessory respiratory muscles.
Which neck muscles participate in depressing the mandible?
The suprahyoid neck muscles participate in depressing the mandible (opening the mouth). They include:
- Mylohyoid muscle (m. mylohyoideus) — depresses the jaw when the hyoid bone is fixed.
- Digastric muscle (m. digastricus) — anterior and posterior bellies participate.
- Geniohyoid muscle (m. geniohyoideus).
- Stylohyoid muscle (m. stylohyoideus).
An important biomechanical condition for their effective action is the rigid fixation of the hyoid bone by the musculature located below it.
To remember the function of the mylohyoid muscle, picture it as a "seesaw" between the mandible and the hyoid bone: if one end (bone) is fixed, the other (jaw) is depressed, and vice versa.
Class and exam questions
What main groups is the middle musculature of the neck divided into?
The middle group is classified into two main subgroups: suprahyoid and infrahyoid muscles.
To which bone does the mylohyoid muscle attach?
It attaches to the body of the hyoid bone as well as to the median raphe (raphe mylohyoidea).
Where does the smallest scalene muscle originate from?
This variable muscle originates from the transverse processes of the lower cervical vertebrae, specifically C6 and C7.
What organs are located in the omotracheal triangle?
Within this triangle (trigonum omotracheale), the thyroid gland, larynx, and trachea lie.
What else to study on this topic
- Functional anatomy of other suprahyoid muscles
- Full composition of the infrahyoid muscle group
- Variant anatomy of the muscular system of the neck
- Topography of all triangles of the anterior neck region
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