Transcript anteriorly - Shabeer Dawar

Myology
Muscles of the
Anterior Neck
1
Muscles of the Neck Overview
• Muscle of neck are divided into two groups:
– Anterior
• Superficial (2)
• Hyoids
– Infrahyoids (4)
– Suprahyoids (4)
• Scalenes (3)
• Deep (4)
– Posterior
• Superficial (4)
• Deep (4)
• Note: Some sources divide neck into anterior, posterior, &
lateral.
2
Muscles of Neck Overview
• Functionality
– Since these muscles cross the joints of the cervical
spine, they can move the neck at the cervical spinal
joints
– If a muscle also crosses the atlanto-occipital joint
(C0/C1) then it can move the head upon the neck.
3
Muscles of Neck Overview
• General Rules:
– If a muscle crosses the neck posteriorly, it can extend the
neck at the cervical spinal joints.
– If a muscle crosses the neck anteriorly, it can flex the neck
at the cervical spinal joints.
– If a muscle crosses the neck laterally, it can laterally flex
the neck at the cervical spinal joints.
– If a muscle wraps around the neck, it can cause rotation of
the neck at the cervical spinal joints.
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Muscles of the Anterior Neck –
Superficial (2)
• Platysma :
– By function it is primarily a muscle of facial expression i.e.
innervated by CN VII.
– Platysma of one side blends with contralateral side and
other facial muscles in lower face.
• Sternocleidomastoid (SCM):
– Since it attaches to sternum, SCM is considered an
accessory muscle of respiration.
5
Platysma
O: Subcutaneous Fascia of
Superior Chest
I: Mandible and subcutaneous
fascia of lower face
A: Draws up the skin of superior
chest and neck, creating ridges
in neck skin.
Assists in drawing the lip
laterally and depresses the
mandible
N: CN VII (Facial nerve)
Palpation: Page 138
6
Sternocleidomastoid (SCM)
O: Sternal Head: manubrium
Clavicular Head: Medial clavicle
I: Mastoid process
Actions: Bilateral contraction:
flexion of the neck. Unilateral
contraction results in Lateral
flexion of neck/head and
Contralateral rotation of neck/head
N: Spinal accessory nerve (CN XI)
Palpation: Page 141
7
Muscles of the Anterior Neck –
Infrahyoids (4)
• All 4 infrahyoid muscles are located below the hyoid bone i.e.
the pull hyoid bone inferiorly when contracted.
• All hyoid muscle are important in moving and/or fixating the
hyoid bone. These functions are necessary for chewing,
swallowing, & speech.
• Sternohyoid:
– “Sterno” refers to sternum
– “hyoid” refers to hyoid bone
• Sternothyroid:
– “thyroid” refers to thyroid cartilage
• Thyrohyoid
• Omohyoid:
– “Omo” refers to the shoulder
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Sternohyoid
O: Posterior aspect of the
manubrium and medial
clavicle
I: Inferior Hyoid
A: Depression of hyoid
N: Ansa cervicalis of the
cervical plexus
Palpation: page 147
9
Sternothyroid
O: Posterior Sternum and 1st
costal cartilage
I: Thyroid Cartilage
A: Depression of thyroid
cartilage
N: Ansa cervicalis of the
cervical plexus
Palpation: page 150
10
Thyrohyoid
O: Thyroid Cartilage
I: Hyoid (inferior aspect)
A: Depression of hyoid and
Elevation of thyroid
cartilage
N: CN XII (Hypoglossal nerve)
Palpation: page 152
11
Omohyoid
O: Inferior Belly: Superior angle
of the scapula
Superior Belly: Clavicle via
the central bound to the clavicle
I: Inferior belly: Clavicle (via the
central bound to the clavicle)
Superior belly: hyoid
A: Depression of hyoid
N: Ansa cervicalis of the cervical
plexus
Palpation: page 155
12
Muscles of the Anterior Neck –
Suprahyoids (4)
• Digastric:
– “Di” means two; “gastric” means belly
– External carotid lies inferior and deep to anterior belly
• Stylohyoid:
– External carotid lies inferior and deep to stylohyoid
• Mylohyoid:
– “mill” refers to molar teeth
• Geniohyoid:
– “genio” refers to chin
13
Digastric
O: Posterior belly: mastoid notch
of temporal bone
Anterior belly: Inner surface
of the mandible
I: Hyoid (via the central tendon)
A: Elevation of hyoid,
depression of the mandible,
and retraction of the
mandible.
N: anterior belly: CN V
(Trigeminal nerve)
posterior belly CN VII (Facial
nerve)
Palpation: page 158
14
Stylohyoid
O: Styloid process of temporal
bone
I: Hyoid
Actions: Elevation of hyoid
N: CN VII (Facial nerve)
Palpation: page 161
15
Mylohyoid
O: Entire inner surface of mandible
(this muscle forms the muscular
floor of the mouth)
I: Hyoid
A: Elevation of hyoid and depresses
the mandible
N: CN V (Trigeminal nerve)
Palpation: page 164
16
Geniohyoid
O: Inner surface of mandible,
deep to the mylohyoid
I: Hyoid
A: Elevation of hyoid
N: CN XII (Hypoglossal nerve)
Palpation: page 167
17
Muscles of the Anterior Neck –
Scalenes (3)
• As a group, they attach superiorly from cervical TP's to
inferiorly on the 1st and 2nd ribs
• As a group, scalenes flex and laterally flex the neck
• Nerve supply , C3- C8
• By reverse muscles action, the scalenes can elevated the 1st
& 2nd rib i.e. they are also considered accessory muscle of
respiration.
• A fourth muscle, the scalenus minimus (Sibson's muscle), is sometimes
present behind the lower portion of the scalenus anterior.
• They originate from the transverse processes of the cervical vertebrae of
C2 to C7 and insert onto the first and second ribs. Thus they are called
the lateral vertebral muscles.
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• The scalene muscles have an important relationship to other
structures in the neck.
• The brachial plexus and subclavian artery pass between the anterior
and middle scalenes.
• The subclavian vein and phrenic nerve pass anteriorly to the
anterior scalene as the muscle crosses over the first rib.
• The phrenic nerve is oriented vertically as it passes in front of the
anterior scalene, while the subclavian vein is oriented horizontally as
it passes in front of the anterior scalene muscle.
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Clinical relevance
• Since the nerves of the brachial plexus pass
through the space between the anterior and
middle scalene muscles, that area is sometimes
targeted with the administration of regional
anesthesia by physicians.
• The nerve block, called an interscalene block,
may be performed prior to arm or shoulder
surgery. They also act as accessory muscles of
respiration when additional effort is required.
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Anterior Scalene
O: Anterior tubercles of the
TP’s of C3 – C6
I: 1st Rib
A: Bilateral contraction: flexion
of the neck. Unilateral
contraction causes lateral
flexion and contralateral
rotation of the neck.
Reversed muscle action
causes Elevation of 1st rib
N: Ventral rami of the cervical
spinal nerves
Palpation: page 173
21
Middle Scalene
O: Posterior tubercles of the
TP’s of C2 to C7
I: 1st Rib
A: Bilateral contraction:
flexion of the neck.
Unilateral contraction causes
lateral flexion of the neck.
Reversed muscle action
causes Elevation of 1st rib
N: Ventral rami of the cervical
spinal nerves 3 and 4
Palpation: page 176
22
Posterior Scalene
O: Posterior tubercles of the TP’s of
cervical spine
I: 2nd Rib
A: Unilateral contraction causes lateral
flexion of the neck.
Reversed muscle action causes
Elevation of 2nd rib
N: Ventral rami of the cervical spinal
nerves 3 and 4.
Palpation: page 179
23
Scalenus minimus
• The Scalenus minimus is an anterior muscle of the neck.
• Anatomical Attachments: According to Travell and Simons, this
muscle is absent in a large percentage of the population. It lies
posterior to the subclavian artery, underneath the inferior aspect of
the Scalenus anterior.
• Origin: Extends from the transverse process of the 7th cervical
vertebrae
• Insertion: Attaches to the fascia supporting the dome of the pleura
and inner border of the 1st rib.
• Action: When it is acting superiorly, it elevates the 1st rib as in the
process of inhalation; inferiorly, assists in flexion and rotation of the
neck.
• Nerve Supply: Cervical nerve 7.
• Vascular supply: Muscular branches of the ascending Cervical
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artery.
The Scalene Group
• Scalenes, as well as
SCM, are often
injured during MVA
called whiplash.
• Also known as
cervical acceleration
deceleration (CAD)
injury
25
Muscles of the Anterior Neck – Deep
Prevertebral Group (4)
• Called prevertebral muscles since they lie directly on
the cervical spine vertebral bodies.
• Important at fixating (stabilizing) and neck/head
while talking, swallowing, coughing, & sneezing
Longus Colli:
– Has 3 parts: superior oblique, inferior oblique, & vertical
– Considered to be a strong neck flexor
• Longus Capitis
• Rectus Capitis Anterior
• Rectus Capitis Lateralis
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Longus Colli
O: Bodies of the C3-T3 vertebrae
I: TP’s and Bodies of the C1-C6
vertebrae
A: Bilateral contraction causes weak
flexion of neck. Unilateral
contraction causes lateral flexion and
contralateral rotation of the neck.
N: Ventral rami of the cervical spinal
nerves
For the purpose of HS 113, this muscle is not
palpable
27
Longus Capitis
O: TP’s of C3 – C5
I: Basilar portion of the occiput
A: Bilateral contraction causes
Flexion of head/neck.
Unilateral contraction causes
Lateral flexion of head/neck
N: Ventral rami of the cervical spinal
nerves
For the purpose of HS 113, this muscle is not
palpable
28
Rectus Capitis Anterior
O: TP of the Atlas (C1)
I: Inferior surface of the basilar
portion of the occiput
A: Flexion of head
N: Ventral rami of the cervical
spinal nerves
For the purpose of HS 113, this muscle is not
palpable
29
Rectus Capitis Lateralis
O: TP of the Atlas (C1)
I: Inferior surface of the Occiput
A: Lateral flexion of head
N: Ventral rami of the cervical
spinal nerves
For the purpose of HS 113, this muscle is not
palpable
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