Anatomy

1. Neck: skin, fascia and muscles
Dr. Mohammed Mahmoud Mosaed

2. The Neck
The neck is the region of the body between the head and the trunk
• It lies between the lower margin of the mandible above and the
suprasternal notch and the upper border of the clavicle below.
The neck is strengthened by:
• the cervical part of the vertebral column
• Mass of extensor muscles and group of small flexor muscles in
front .
Contents of the neck
• parts of the respiratory system, the larynx and the trachea,
• parts of the alimentary system, the pharynx and the esophagus.
• Vessels and nerves, carotid arteries, internal jugular veins, the
cranial nerves,
• Thyroid and parathyroid glands and the deep cervical lymph
nodes

3. Cutaneous Nerves of the Neck
• The skin of the neck supplied by the branches of the
cervical nerves from the 2nd to the 5th cervical nerves
• The first cervical nerve has no cutaneous branch.
• The skin on the back of the neck (overlying the trapezius
muscle) and on the back of the scalp as high as the vertex
is supplied segmentally by posterior rami of 2nd to 5th
cervical nerves. The greater occipital nerve which is a
branch of the posterior ramus of the second cervical nerve.
• The skin of the front and sides of the neck is supplied by
anterior rami of cervical nerves 2 to 4 through branches of
the cervical plexus; The branches emerge from beneath the
posterior border of the sternocleidomastoid muscle

4. Branches of the cervical plexus that supply the skin of the neck
• The lesser occipital nerve (C2) ascends along the posterior border of the
sternocleidomastoid muscle to supply the skin over the lateral part of the
occipital region and the medial surface of the auricle .
• The great auricular nerve (C2 and 3) ascends across the sternocleidomastoid
muscle and divides into branches that supply the skin over the angle of the
mandible, the parotid gland, and on both surfaces of the auricle.
• The transverse cutaneous nerve (C2 and 3) passes forward across the
sternocleidomastoid muscle and divides into branches that supply the skin
on the anterior and lateral surfaces of the neck, from the body of the
mandible to the sternum .
• The supraclavicular nerves (C3 and 4) descend across the side of the neck.
They pass onto the chest wall and shoulder region, down to the level of the
second rib .
• The medial supraclavicular nerve crosses the medial end of the clavicle and
supplies the skin as far as the median plane.
• The intermediate supraclavicular nerve crosses the middle of the clavicle and
supplies the skin of the chest wall.
• The lateral supraclavicular nerve crosses the lateral end of the clavicle and
supplies the skin over the shoulder and the upper half of the deltoid muscle;
this nerve also supplies the posterior aspect of the shoulder as far down as
the spine of the scapula.

6. Fascia of the neck
• The fascia of the neck divided into: Superficial fascia
and deep fascia
• The superficial fascia of the neck forms a thin layer
that encloses the platysma muscle. Also embedded in
it are the cutaneous nerves, the superficial veins, and
the superficial lymph nodes.
• Deep Cervical Fascia
• The deep cervical fascia supports the muscles, the
vessels, and the viscera of the neck.
• In certain areas, it is condensed to form well-defined,
fibrous sheets called the investing layer, the
pretracheal layer, and the prevertebral layer.
• It is also condensed to form the carotid sheath

7. Superficial Fascia
• The superficial fascia of the neck forms a thin layer that
encloses the platysma muscle, the cutaneous nerves , the
superficial veins, and the superficial lymph nodes.
• The platysma muscle is a thin but clinically important
muscular sheet embedded in the superficial fascia.
• Origin Deep fascia over pectoralis major and deltoid
• Insertion Body of mandible and angle of mouth
• Nerve supply cervical branch of the facial nerve
• Action Depresses mandible and angle of mouth
• Superficial cervical Lymph Nodes
• Site: lie along the external jugular vein superficial to the
sternocleidomastoid muscle.
• They receive lymph vessels from the occipital and mastoid
lymph nodes and drain into the deep cervical lymph nodes.

9. Deep Cervical Fascia
• The deep cervical fascia supports the muscles, the vessels,
and the viscera of the neck.
• In certain areas, it is condensed to form well-defined,
fibrous sheets called the investing layer, the pretracheal
layer, the prevertebral layer and the carotid sheath
• Investing Layer: The investing layer is a thick layer that
encircles the neck. It splits to enclose the trapezius and the
sternocleidomastoid muscles.
• Pretracheal Layer: The pretracheal layer is a thin layer that
is attached above to the laryngeal cartilages . It surrounds
the thyroid and the parathyroid glands, forming a sheath
for them, and encloses the infrahyoid muscles.

10. • Prevertebral Layer
• The prevertebral layer is a thick layer that passes like a
septum across the neck in front of the prevertebral
muscles and the vertebral column. It forms the fascial
floor of the posterior triangle, and it extends laterally
over the first rib into the axilla to form the axillary
sheath
• Carotid Sheath: The carotid sheath is a local
condensation of the deep fascia that surround the
common and internal carotid arteries, the internal
jugular vein, the vagus nerve and the deep cervical
lymph nodes

12. Cervical Ligaments
• Stylohyoid ligament: Connects the styloid process
to the lesser cornu of the hyoid bone
• Stylomandibular ligament: Connects the styloid
process to the angle of the mandible.
• Sphenomandibular ligament: Connects the spine
of the sphenoid bone to the lingula of the
mandible.
• Pterygomandibular ligament: Connects the
hamular process of the medial pterygoid plate to
the posterior end of the mylohyoid line of the
mandible. It gives attachment to the superior
constrictor and the buccinator muscles

14. Muscles of the Neck
• The muscles of the neck include the following:
• The superficial muscles of the side of the neck:
sternocleidomastoid
• The suprahyoid muscles: Digastric, mylohyoid,
geniohyoid, genioglossus, hyoglossus, styloglossus
and stylohyoid muscles.
• The infrahyoid muscles: Omohyoid, Sternohyoid,
Sternothyroid and Thyrohyoid
• The anterior and lateral vertebral muscles: Scalene
muscles (Anterior, middle and posterior)

15. Sternocleidomastoid Muscle
• It is the key neck muscle. It divides the neck into
anterior and posterior triangles.
• Origin: Manubrium sterni and medial third of clavicle,
• Insertion: Mastoid process of temporal bone and
occipital bone
• Nerve supply: Spinal part of accessory nerve and C2 , 3
• Action:
- Two muscles acting together extend head and flex neck
- one muscle rotates head and face to opposite side

17. Relations of sternocleidomastoid
• Superficial relations: The muscle is covered by
skin, fascia, the platysma muscle, and the external
jugular vein
• Deep relations:
• The anterior border covers the carotid arteries,
the internal jugular vein, and the deep cervical
lymph nodes; it also overlaps the thyroid gland.
• The deep surface of the posterior border is
related to the cervical plexus of nerves, the
phrenic nerve, and the upper part of the brachial
plexus.

18. Digastric Muscle
• Origin:
• Posterior belly from the medial surface of
mastoid process (mastoid notch).
• Anterior belly from lower border of the
body of the mandible (digastric fossa).
• Insertion: to the intermediate tendon
which is held in position by fibrous sling to
the hyoid bone, this tendon pierces the
stylohyoid muscle.
• Nerve supply:
• Posterior belly from facial nerve
• Anterior belly from nerve to mylohyoid
from mandibular nerve
• Action: Depression of mandible and
elevation of the hyoid bone.

20. Mylohyoid Muscle
• Mylohyoid forms a muscular
floor for the oral cavity.
• Origin: the whole length of
the mylohyoid line of the
mandible.
• Insertion: Body of hyoid
bone and fibrous raphe.
• Innervation: by the
mylohyoid branch of the
inferior alveolar nerve.
• Actions: it elevates the
floor of the mouth in the first
stage of deglutition. It may
also elevate the hyoid bone
or depress the mandible.

22. Geniohyoid
• Geniohyoid is a narrow muscle which lies above the
medial part of mylohyoid.
• Origin: It arises from the inferior mental spine (genial
tubercle) on the back of the symphysis menti.
• Insertion: into the anterior surface of the body of the
hyoid bone.
• Innervation
• Geniohyoid is supplied by the first cervical spinal nerve,
through the hypoglossal nerve.
• Actions:
• Geniohyoid elevates the hyoid bone and draws it
forwards. When the hyoid bone is fixed, geniohyoid
depresses the mandible.

24. Stylohyoid muscle
• Origin: It arises by a small tendon from the posterior
surface of the styloid process, near its base.
• Insertion: into the body of the hyoid bone at its junction
with the greater cornu. It is perforated near its insertion by
the intermediate tendon of digastric muscle.
• Innervation:
• by the stylohyoid branch of the facial nerve.
• Actions:
• Stylohyoid elevates the hyoid bone and draws it backwards,
elongating the floor of the mouth.
• The stylohyoid ligament is a fibrous cord extending from the tip of the styloid
process to the lesser cornu of the hyoid bone.
• It gives attachment to the highest fibers of the middle pharyngeal constrictor.
• The ligament is derived from the cartilage of the second branchial arch

26. • Genioglossus, hyoglossus and
styloglossus muscles will be
discussed with the muscles of
the tongue.

27. The infrahyoid muscles
• Omohyoid,
• Sternohyoid,
• Sternothyroid
• Thyrohyoid

28. omohyoid
• Origin:
• Inferior belly from the upper
margin of scapula and
suprascapular ligament
• Superior belly from the lower
border of body of hyoid bone
• Insertion: Intermediate tendon is
held to clavicle and first rib by
fascial sling
• Innervation: Ansa cervicalis; C1,
2, 3
• Action: Depresses hyoid bone

29. • Sternohyoid
• Origin: Manubrium sterni and
clavicle
• Insertion: Body of hyoid bone
• Innervation: Ansa cervicalis; C1, 2,
and 3
• Action: Depresses hyoid bone
• Sternothyroid
• Origin: Manubrium sterni
• Insertion: Oblique line on lamina of
thyroid cartilage
• Innervation: Ansa cervicalis; C1, 2,
and 3
• Action: Depresses larynx

30. Thyrohyoid
• Origin: Oblique line on
lamina of thyroid cartilage
• Insertion: Lower border of
body of hyoid bone
• Innervation: First cervical
nerve
• Action: Depresses hyoid
bone or elevates larynx

31. Scalenus anterior
• Origin: Transverse
processes of 3rd , 4th ,
5th , and 6th cervical
vertebrae.
• Insertion: First rib
• Innervation: C4, 5,
and 6
• Action: Elevates first
rib; laterally flexes
and rotates cervical
part of vertebral
column

32. Scalenus Anterior Muscle
• Important Relations
• Anteriorly: Related to: Vessels: the carotid arteries,
transverse cervical and suprascapular arteries, internal
jugular vein. Nerves: the vagus nerve, phrenic nerve
between the muscle and its fascia, and the deep cervical
lymph nodes.
• Posteriorly: Related to the pleura, the roots of the brachial
plexus, and the second part of the subclavian artery. The
scalenus medius muscle lies behind the scalenus anterior
muscle.
• Medially: Related to the vertebral artery and vein and the
sympathetic trunk. On the left side, the medial border is
related to the thoracic duct.
• Laterally: Related to the emerging branches of the cervical
plexus, the roots of the brachial plexus, and the third part of
the subclavian artery

35. Scalenus medius
• Origin: Transverse processes of upper
six cervical vertebrae
• Insertion: First rib
• Innervation: Anterior rami of cervical
nerves
• Action: Elevates first rib; laterally flexes
and rotates cervical part of vertebral
column

36. Scalenus posterior
• Origin: Transverse processes of lower
cervical vertebrae
• Insertion: Second rib
• Innervation: Anterior rami of cervical nerves
• Action: Elevates second rib; laterally flexes
and rotates cervical part of vertebral column