Head, Neck and Early embryonic development

Learning & Test Objectives

*This is a combined test of two separated learning units!

Head and Neck

  1. Skull and cervical vertebrae- Tempromandibular joint, spaces and foramina.
  2. Fasciae and compartmentation.
  3. Arrangement of muscles within their functional groups.
  4. Origin and insertion, innervation, and function of muscles, vessels and nerves of the head and neck. 
  5. Topographical spaces of the head and neck.
  6. Identifying and drawing structures observed on cross-sections.

Early Development

1. Early embryo – blastocyst, bilaminar germ disk, trilaminar germ disc, description of these structures and their layers

2. Gastrulation – overview of the process, role of the primitive streak

3. Muscle, bone and limb development – somite (description, significance, derivatives), groups of muscles, embryological basis of muscle innervation, types of ossification, morphogenesis of the limbs


Description of the test

The test is held by the general rules of written tests (see Continuous Testing – Organization).

The test covers bones, joints, muscles, vessels, and nerves of the head and neck. As well as the also the early embryonic development and development of bones, muscles and limbs including developmental defects of all aforementioned structures. Concerning the skull, it is required to recognize its foramina, their content and the topographical regions of the skull. For the mimetic muscles it is necessary to know their names, functions and their locations. It is not necessary to know their precise origins and insertions, with the exception of the buccinator. It is not necessary to know the which branches of the facial nerve innervate which mimetic muscles and which branches of the mandibular nerve innervate which muscles of mastication. It is necessary to know the suboccipital and deep neck muscles exact origins and innervations. The test may also contain questions on general myology, the fascia of the head and neck, and radiological images. It is necessary to describe germ layers and name their derivatives, including components of mesoderm. It is necessary to describe two types of ossification as well as the histology of the epiphyseal plate.


Clinical notes

The masseter muscle may be overloaded with frequent use of chewing gum. Overload can also occur in people under stress, during which they cannot bite something. The patient does not complain of pain in the muscle, but of toothache (upper or lower stools), in the ear or above the orbit.

Trigger points in the medial and lateral pterygoid muscles  must be considered in the differential diagnosis of ear pain. The muscles are palpated in the oral cavity and the trigger points are tender upon palpation.

The danger triangle of the face (trigonum mortis) is an area richly supplied with blood, located between the angles of the mouth and root of the nose. Venous blood from this area drains into the intracranial venous sinuses, thus there is a risk of a pathological process spreading to the intracranial space from this area.

Torticollis is a shortening of the sternocleidomastoid muscle with the head tilted to the affected side and rotated to the opposite side.

Brachial plexus and subclavian artery compression may occur at the fissura scalenorum. It is one of the manifestations of thoracic outlet syndrome (TOS) or thoracic outlet syndrome (TOS)

Ectopic pregnancy is when the embryo is implanted outside the uterus, most often in the fallopian tube. The embryo usually dies in the 2nd gestational month. The mother may be at risk of bleeding, so this is a critical condition that require medical attention.

The all-or-nothing phenomenon is a theoretical model describing early embryonic damage - the embryo either dies or survives without damage (teratogenic effects). Although this model is controversial among some experts, its use in clinical practice is rationalized also calls fo psychological support (reassurance of a pregnant women).


Other interesting notes

Modiolus anguli oris is a nodal point in the corners of the mouth that serves as an attach point for mimic muscles, creating the "motor center" of the face.

The subgaleal layer consists of loose connective tissue is the site of weakest resistance and allows mobility of the scalp against the skull, including the galea aponeurotica, to be detached from the cranial vault.

The musculi scaleni function mainly as a deep stabilization system of the cervical spine. They have respiratory function and contract during significant respiratory effort.

In the early period of development, the right-left axis of the embryo is determined. When this process is disrupted, e.g. by dysfunction of the nodal cilia in patients with primary ciliary dyskinesia, the thoracic and abdominal organs may be inverted.

Situs viscerum inversus refers to the mirror-inverted positioning of all internal organs. Situs ambiguus (heterotaxy) denotes a disorder of laterality in only some organs, e.g. dextrocardia. In contrast, situs solitus refers to the normal position of the organs.

Teratomas are tumors containing derivatives of all germ layers. The sacrococcygeal teratoma, which is thought to originate in the remnants of the primitive streak, is the most common tumor of newborns (incidence approximately 1 : 30 000 births).


Pictures to draw


  • Transverse section of the neck at the C6 level 

Histology & Embryology 

  • Section of the embryo at the 9th day of development
  • Differentiation of intraembryonic mesoderm with mapping of prospective epiblast regions during gastrulation
  • Epiphyseal plate ossification

Examples of pictures are e.g. Memorix histology in the chapter Connective tissue, and Langman’s medical embryology in chapters 4 and 5.


Radiographical images

Radiolographs of the bone and joints of the axial skeleton

Created: 2. 2. 2021 / Modified: / Responsible person: MUDr. Azzat Al-Redouan