Head and Neck-7 part 1

7/29/2019 Head and Neck-7 part 1

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Muscles and root of the neck

The muscles of cervical region are classified into 3 groups:

1-Superficial muscles

Platysma , SCM , Trapezius

2-Hyoid related muscles

Supra Hyoid Muscle , Infra Hyoid Muscle

3-Cervical vertebral muscles

Ant,Lat,Post.vertebral muscle

Superficial muscles

The Platysma Muscle-Platysma means flat

-Its the muscle of facial expression

-Its Located in the fatty layer

-the origin of platysma is classified inferiorly

All the muscles in the face that are that are related to facial

expression are innervated by the 7th cranial nerve (facial nerve) this

nerve provide motor innervations to all the muscles of facial

expression.


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The platysma is located in the neck ,but it considered part from

muscles of facial expression ,so its innervated by the branch of facial

nerve which called cervical branch

Its Attachment :

Sup. Attachment Inferior border of body of the mandible and the

angle of the mouth

Inf.Attachment Delto pectoral deep fascia

Its Action :

Draws mouth corner inferiorly and draws skin of the neck superiorly

SCM musclehas a sterna and calvicle head and it descend all the way

to lateral surface of mastoid process and o the

lateral part of the superior nuchal lines

Its origin :

Manubrium (sternal head)

Med.1/3 of clavicle (clavicle head)

- The SCM separates the antero-lateral aspect of theneck inti anterior and posterior triangle and it

separate the neck into superficial and deep part . so

(anything outside the SCM is in the superficial andanything deep to the muscle is in the deep part in the

neck )

- The jugular vein outside the SCM is the EJV while theone is deep to SCM is the IJV


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Its insertion :

mastoid processes of temporal bone and lateral part of

the superior nuchal line

Note: the occipital bone posteriorly has two lines , one

sup. And one inf. Nuchal line , these lines arise because

of the muscular attachment . (the sup.nuchal line is

made by the attachment os SCM laterally and the

attachment of trapezius medially )

Its innervations :

Spinal part of 11- The reference muscles (SCM and trapezius) are

innervated by cranial nerve number 11

- For the SCM the innervations is particularly from thespinal branch of accessory nerve

Its Action:

Single turns head super laterally to opposite side

Both flex the neck

Trapezius muscle-its a reference muscle because its located in the

posterior part of the neck ( anything overlyed by this

muscle is part of the trapezius aspect of the neck )

- The trapezius muscle is divided into 3 parts :

1-The middle part : is at the level of scapula when itcontracts it reflects the scapula ,bringing both

scapula together


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2-The superior part : above the scapula and itsfunction to elevates the scapula

3-The inferior part : below the scapula and its functionto depresses the scapula

Its origin :

Med.1/3 of sup.nuchal line

EOP (the prominence of the back of your head)

Nuchal ligament (its in middle of the neck

posteriorly)

Spinous processes (C7-T12)Its insertion :

Lat.1/3 of clavicle

Acromion

Spine of scapula

Its innervation:

Cranial nerve number 11 (accessory nerve)

Hyoid Related Muscles

Suprahyoid muscles1-Geniohyoid muscle : arise from mandible anteriorly

-the mandible in the middle has two genoid

tubercles or also called mental spins (sup. And inf.

Mental spines) from the inferior mental spine there

is a muscle that goes all the way down to the hyoid

bone called geniohyoid muscle


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-from sup.mental spine to the tongue there is a

muscle called genioglusus muscle

-geniohyoid muscle is more in the oral cavity than

in the neck so its not considered a part of muscles

in the neck .

-under the geniohyoid muscle there is a flat muscle

sheat which called mylohyoid muscle .

2- Mylohyoid muscle : floor of the mouth .anything

above the the mylohyiod you are in the oral cavity

and anything below the mylohyoid you are in theneck region .

-mylo refers to the molars teeth

-the mylohyiod extend from the molars on both

sides all the way to the middle where it meets with

the body of the hyoid bone

- inside the mandible there is a linear elevation

called the mylohyiod line which demarcates the

attachment of the mylohyiod muscle

-innervation to the mylohyiod is from the nerve to

mylohyiod and it comes from the inferior dental

nerve (inferior alveolar nerve) before it goes into the

mandible through the mandibular foramen it sends

a small branch to thr mylohyiod muscle so its called

nerve to mylohyiod

3-stylohyiod :is from the styloid process of the

temporal bone all the way down into the hyoid bone


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4-Digastric muscles (2 bellies):the two bellies are

attached to each other by tendon called

intermediate tendon

-the posterior belly is attached to the medial surface

of the mastoid process (on the medial surface of

mastoid process there is the SCM attached)

-the anterior belly arise from the mandible

-the digestive fossa is on the mandible (where the

anterior belly arise from) this is below the mylohyiod

line anteriorly-the intermediate tendon is above the hyoid bone

but not attached to it ,the tendon is attached to the

hyoid bone through a facial sling (part of deep

fascia) this facial sling goes from the body and

greater horn of hyoid bone all the way around the

intermediate tendon and turns back to the hyoid

bone ,by this the tendon is fixed close to the hyoid

bone but not attached to it directly

-when the anterior belly contracts the tendon

moves anteriorly ,when the posterior belly contracts

the tendon moves posteriorly

-depending on the muscle closer to the belly ,this

will determine from where its innervations will be

-when the 4 suprahyiod muscles contracts they help

in in elevating the hyoid bone


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-stylohyiod and post.belly of the digastrics are

innervated by the cervical branch of 7th cranial

nerve (facial nerve) which also innervates the

platysma

-the hyoid bone is attached inferiorly to the larynx

so these 4 muscles also help in elevating the larynx.

Infrahyiod muscles1-sternohyiod 2-sternothyroid 3-omohyiod 4-thyrohyiod

-Infrahyiod muscles are called strap muscles because therun is a strap fasion these 4 muscles are in two layers ,2

superficial and 2 deep .the two anterior ones (the

superficial) are the sternohyiod arising from the

manubrium of the sternum and medial end of the clavicle

all the way up to the body of hyoid bone and the

omohyiod

omohyiod :omo means shoulder

Omohyiod goes to the sup.border of the scapula posteriorly

,it has 2 bodies ,the superior belly which descend down

from the body of the hyoid bone all the way to the

intermediate tendon .another facial loop will come from

the clavicle and cover the tendon and fixes the tendon to

the clavicle through a facial sling .

-the inferior belly arise and goes inferiorly and posteriorly

from the clavicle (to where the facial sling attaches the

intermediate tendon)to the scapula .


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-the omohyiod is lateral to sternohyiod

-the two deep muscles are the sternothyroid ,going from

the sternum all the way to the thyroid cartilage(adams

apple)

-thyroid means shield like

-the thyroid gland is inferior to the thyroid cartilage

-the thyroid cartilage is shielding behind it the larynx and

the thyrohyiod muscle

-when the sternothyriod contracts it pulls the thyroid

cartilage wgich pulls the thyrohyiod muscle and thereforepull thr hyoid muscle inferiorly so these two muscles works

together indirectly

-behind the sternohyiod there is the sternothyriod and

the thyrohyiod muscles .

-the thyrohyiod muscle is the shoretest muscle of all the

these 4 muscles and innervated by C1 via hypoglusal

nerve

-Ansa means loop

-ansa cervical is a loop of nervous fibers formed by

c1,c2,c3 (in the neck) C1 gives a branch that goes and

descend anteriorly this is called anterior branch of ansa

cervical ,c2 and c3 each of them give a branch both join

together to form the posterior part of ansa cervical

-these two parts (anterior and posterior )of ansa cervical

unite together inferiorly forming a loop ,this loop is ansa

cervical .


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-the thyrohyiod muscle innervations comes from c1

directly without getting into the loop

-the ansa cervical innervates the infrahyiod muscles

except thyrohyiod muscle

-Cervical vertebral muscles

The vertebral muscles just you have to know the names of

these vertebral muscles .

Cervical vertebral muscles is classified into 3 groups

around V.C :Anterior , Lateral , Posterior

Anterior cervical vertebral muscles1-Longus Capitis (Capitis means head)

2-Longus Cervicis (Cervicis means attaches to the cervical

vertebrae) , its also called longus colli

It has (longus colli) sup.and inf.oblique and vertical

Lateral Group (Scalene muscles)Scalene means unequal triangle

Scalenous anterior is attached to first rib

Scalenous medius ia attached to first rib

Scalene posterior descends more into the second rib

-when the scalene contracts they bend the neck to the

same side that they contracy (left to the left and rt to the

rt)


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-when scalene anterior attaches to the first rib it forms a

tubercle on the first rib (internal border) which is one of

the reasons why the first rib is a typical

-there is a space located between scalenous anterior and

medius which is called scalene hiatus(hiatus means passage

way) and its inferiorly to the first rib

-the scalene hiatus allow the main blood supply to the

upper limb .subclavian artery from the thoracic to the

upper limb and allows the brachial plexus from the neck

to the upper limb-scalene hiatus boundaries : Ant scalene anterior

Post scalene medius Inf first rib

-anterior structures of scalene anterior are exposed

-relations to Sc.Ant : anterior subclavian vein and phrenic

nerve

Inennervation:cervical spinal nerve

Action : elevatation of ribs , bending cervical spine(neck)

The contents of scalene hiatus : trunks of brachial plexus

and subclavian artery

Posterior cervical vertebral muscles1-levator scapulae (posterolat.corner)

2-splenius capitis and cervicis (splenius means bandage)

3-semispinalis capitis (capitis means attaches to the skull)

(semispinalis passing along the spine )

4-rectus capitis pos.major and minor

5-sup. And inf. Obliques of the head


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- If you cut the semispinalis (the deepest muscle)you willreach into a fossa below the occipital bone forming

triangular area

- Supoccipital region below the occipital bone- The trapezius muscle covers all the posterior group- The rectus capitis posterior minor is from posterior

tubercle of atlas to inferior nuchal line

- The rectus capitis posterior major is from the spineprocess of axis to the inferior nuchal line

- The space between the two nuchal lines there is thespleneous and semispinalis

- The inferior oblique is from the spinous process of axisto the transeverse process of atlas

- The superior oblique from the transverse process of theatlas to the area on occipital bone between sup. And

inf. Nuchal lines

Suboccipital triangle:

Its boundaries :

Medially rectus capitis posterior major

Inf. Inferior oblique

Laterally superior oblique

Its contents :

The vertebral artery ,which passes in the transverse

foramen of the cervical vertebrae then passes through


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foramen magnum to enter the skull ,and the occipital

nerve which innervates the 4 muscles in the occipital

area

-the supoccipital nerve is the posterior branch of c1

-the anterior branch of c1 goes to the thyrohyiod and

the geniohyiod muscles (motor innervations)

The root of the neck :

The area of the neck that lies immediately above the

superior thoracic opening (its the junction between thethorax and the neck)

-the boundaries of the thoracic opening are

manubrium , first rib,andT1

-contents of the root of the neck

1-lower portions of scalene muscles(3 muscles)

2-subclavian artery and vein

3-thoracic duct (lymph vessels extends from thorax to

drain into left brachiocephalis vein)

4-roots and trunks of brachial plexus

5-phrenic nerve (passes anterior to scalene anterior)

from roots of c3,c4,c5 spinal nerves

-thoracic duct is the largest lymph vessel in your body .

,,):

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Head and Neck-7 part 1