Head And Neck

Head and Neck Lectured by Bien Eli Nillos, MD

Muscles of the Neck

Anterior Triangle 

The anterior triangle is bounded, in front, by the middle line of the neck; behind, by the anterior margin of the Sternocleidomastoid; its base, directed upward, is formed by the lower border of the body of the mandible, and a line extending from the angle of the mandible to the mastoid process; its apex is below, at the sternum.

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This space is subdivided into four smaller triangles by the Digastricus above, and the superior belly of the Omohyoideus below. These smaller triangles are named the carotid, the submandibular, the submental, and the muscular.

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Muscular Triangle, is bounded, in front, by the median line of the neck from the hyoid bone to the sternum; behind, by the anterior margin of the Sternocleidomastoid; above, by the superior belly of the Omohyoid. It is covered by the integument, superficial fascia, Platysma, and deep fascia

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Contents: common carotid artery, internal jugular vein and vagus nerve, inferior thyroid artery, the recurrent nerve, and the sympathetic trunk , esophagus, the trachea, the thyroid gland, and the lower part of the larynx

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Carotid Triangle, is bounded, behind by the Sternocleidomastoid; below, by the superior belly of the Omohyoid; and above, by the Stylohyoid and the posterior belly of the Digastric. It is covered by the integument, superficial fascia, Platysma and deep fascia

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Contents: upper part of the common carotid artery, internal jugular vein, hypoglossal nerve, vagus nerve, accessory nerve, internal branch of the superior laryngeal nerve, external branch of the superior laryngeal nerve

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Submandibular Triangle corresponds to the region of the neck immediately beneath the body of the mandible. It is bounded, above, by the lower border of the body of the mandible, and a line drawn from its angle to the mastoid process; below, by the posterior belly of the Digastric and the Stylohyoid; in front, by the anterior belly of the Digastric. It is covered by the integument, superficial fascia, Platysma, and deep fascia

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Contents: submaxillary gland, anterior facial vein, external maxillary artery, submental artery, mylohyoid artery and nerve, external carotid artery, internal carotid artery, facial nerve

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Submental Triangle - limited behind by the anterior belly of the Digastricus, in front by the middle line of the neck between the mandible and the hyoid bone; below, by the body of the hyoid bone; its floor is formed by the Mylohyoideus. It contains one or two lymph glands and some small veins; the latter unite to form the anterior jugular vein.

Posterior Triangle 

bounded, in front, by the Sternocleidomastoid; behind, by the anterior margin of the Trapezius; its base is formed by the middle third of the clavicle; its apex, by the occipital bone. The space is crossed, about 2.5 cm. above the clavicle, by the inferior belly of the Omohyoid, which divides it into two triangles, an upper or occipital, and a lower or supraclavicular.

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Occipital Triangle, the larger division of the posterior triangle, is bounded, in front, by the Sternocleidomastoid; behind, by the Trapezius; below, by the Omohyoid. Its floor is formed from above downward by the Splenius capitis, Levator scapulæ, and the Scaleni medius and posterior. It is covered by the skin, the superficial and deep fasciæ, and by the Platysma below.

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Contents: accessory nerve, supraclavicular nerves and the transverse cervical vessels, lymph nodes

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Supraclavicular Triangle, the smaller division of the posterior triangle, is bounded, above, by the inferior belly of the Omohyoid; below, by the clavicle; its base is formed by the posterior border of the Sternocleidomastoid. Its floor is formed by the first rib with the first digitation of the Serratus anterior.

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Contents: third portion of the subclavian artery, subclavian vein, cervical artery, external jugular vein, lymph nodes.

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internal carotid artery - supplies the anterior part of the brain, the eye and its appendages, and sends branches to the forehead and nose four portions: cervical, petrous, cavernous, and cerebral

Cervical Portion 

This portion of the internal carotid begins at the bifurcation of the common carotid, opposite the upper border of the thyroid cartilage, and runs perpendicularly upward, in front of the transverse processes of the upper three cervical vertebræ, to the carotid canal in the petrous portion of the temporal bone.

Petrous Portion 

When the internal carotid artery enters the canal in the petrous portion of the temporal bone, it first ascends a short distance, then curves forward and medialward, and again ascends as it leaves the canal to enter the cavity of the skull between the lingula and petrosal process of the sphenoid.

Cavernous Portion 

In this part of its course, the artery is situated between the layers of the dura mater forming the cavernous sinus, but covered by the lining membrane of the sinus

Cerebral Portion 

Having perforated the dura mater on the medial side of the anterior clinoid process, the internal carotid passes between the optic and oculomotor nerves to the anterior perforated substance at the medial extremity of the lateral cerebral fissure, where it gives off its terminal or cerebral branches.

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external carotid artery begins opposite the upper border of the thyroid cartilage, and, taking a slightly curved course, passes upward and forward, and then inclines backward to the space behind the neck of the mandible, where it divides into the superficial temporal and internal maxillary arteries

The Cervical Vertebrae

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the smallest of the true vertebræ, and can be readily distinguished from those of the thoracic or lumbar regions by the presence of a foramen in each transverse process The first, second, and seventh present exceptional features

 Atlas  Axis  Cervical

Prominens

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The first cervical vertebra is named the atlas because it supports the globe of the head. Its chief peculiarity is that it has no body, and this is due to the fact that the body of the atlas has fused with that of the next vertebra. Its other peculiarities are that it has no spinous process, is ring-like, and consists of an anterior and a posterior arch and two lateral masses.

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The second cervical vertebra is named the epistropheus or axis because it forms the pivot upon which the first vertebra, carrying the head, rotates. The most distinctive characteristic of this bone is the strong odontoid process which rises perpendicularly from the upper surface of the body.

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The Seventh Cervical Vertebra - the most distinctive characteristic of this vertebra is the existence of a long and prominent spinous process, hence the name vertebra prominens. This process is thick, nearly horizontal in direction, not bifurcated, but terminating in a tubercle to which the lower end of the ligamentum nuchæ is attached.

The Skull

Base of the Skull

Lateral View of the Skull

Frontal View of the Skull

The Orbit of the Skull

The Interior Surface of the Skull  The upper surface

of the base of the skull or floor of the cranial cavity presents three fossæ, called the anterior, middle, and posterior cranial fossæ.

Contents of the Foramina of the Skull   

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supraorbital foramen - supraorbital artery, supraorbital vein, supraorbital nerve foramen cecum - emissary veins to superior sagittal sinus anterior ethmoidal foramen - anterior ethmoidal artery anterior ethmoidal vein, anterior ethmoidal nerve posterior ethmoidal foramen - posterior ethmoidal artery, posterior ethmoidal vein, posterior ethmoidal nerve

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optic canal - ophthalmic artery, optic nerve (II) foramina of cribriform plate - olfactory nerve bundles (I) superior orbital fissure - superior ophthalmic vein inferior ophthalmic veinoculomotor nerve (III) trochlear nerve (IV) lacrimal, frontal and nasociliary branches of ophthalmic nerve (V1) abducent nerve (VI) foramen rotundum - maxillary nerve (V2)

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inferior orbital fissure - inferior ophthalmic veins, infraorbital artery, infraorbital veinzygomatic nerve and infraorbital nerve of maxillary nerve (V2) orbital branches of pterygopalatine ganglion infraorbital foramen - infraorbital artery, infraorbital vein, infraorbital nerve

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foramen ovale - accessory meningeal artery, mandibular nerve (V3), lesser petrosal nerve (occasionally) foramen spinosum- middle meningeal artery, meningeal branch of the mandibular nerve (V3) foramen lacerum - internal carotid artery, internal carotid nerve plexus

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jugular foramen - posterior meningeal artery, ascending pharyngeal artery, inferior petrosal sinus, sigmoid sinus, internal jugular vein, glossopharyngeal nerve (IX), vagus nerve (X) accessory nerve (XI) hypoglossal canal - hypoglossal nerve (XII) foramen magnum - vertebral arteries, meningeal branches of vertebral arteries, medulla oblongata spinal roots of accessory nerves

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S – skin C – subCutaneous Tissue A – aponeurosis L – loose connective tissue P – periosteum (pericranium)

Muscles of Mastication

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The Masseter is a thick, somewhat quadrilateral muscle, consisting of two portions, superficial and deep.

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 The Temporalis (Temporal muscle) is a broad, radiating muscle, situated at the side of the head. It arises from the whole of the temporal fossa (except that portion of it which is formed by the zygomatic bone) and from the deep surface of the temporal fascia.

The Ocular Muscle

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Nerves.—The Levator palpebræ superioris, Inferior Oblique, and the Recti superior, inferior, and medialis are supplied by the oculomotor nerve; the Superior Oblique, by the trochlear nerve; the Lateral rectus, by the abducent nerve.

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