Dr. Mujahid Khan. The scalenus anterior muscle is a key muscle in understanding the root of the...
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Transcript of Dr. Mujahid Khan. The scalenus anterior muscle is a key muscle in understanding the root of the...
Dr. Mujahid Khan
The scalenus anterior muscle is a key muscle in understanding the root of the neck
It is deeply placed
It descends almost vertically from the vertebral column to the first rib
Related to the carotid arteries, the vagus nerve, the internal jugular vein, and the deep cervical lymph nodes
The transverse cervical and suprascapular arteries and the prevertebral layer of deep cervical fascia bind the phrenic nerve to the muscle
Related to the pleura, the origin of the brachial plexus, and the second part of the subclavian artery
The scalenus medius muscle lies behind the scalenus anterior muscle
Related to the vertebral artery and vein and the sympathetic trunk
On the left side, the medial border is related to the thoracic duct
Related to the emerging branches of the cervical plexus, the roots of the brachial plexus, and the third part of the subclavian artery
Origin: Transverse processes of third, fourth,
fifth, and sixth cervical vertebrae
Insertion: First rib
Action: Elevates first rib, laterally flexes and
rotates cervical part of vertebral column
It lies behind the scalenus anterior
It extends from the transverse process of the atlas and the transverse processes of the next five cervical vertebrae
Inserted into the upper surface of the first rib behind the groove for the subclavian artery
The muscle lies behind the roots of the brachial plexus and the subclavian artery
Origin: Transverse processes of lower cervical
vertebrae
Insertion: Second rib
Action: Elevates second rib, laterally flexes and
rotates cervical part of vertebral column
Origin: Anterior tubercle of C1, bodies of C1 to C3 and
transverse processes of C3 to C6 vertebrae
Insertion: Bodies of C5 to T3 vertebrae, transverse
processes of C3 to C5 vertebrae
Action: Flexes neck with rotation to opposite side
Origin: Basilar part of occipital bone
Insertion: Anterior tubercles of C3 to C6 transverse
processes
Action: Flexes the head
Origin: Base of the skull, just anterior to the
occipital condyle
Insertion: Anterior surface of lateral mass of atlas
Action: Flexes the head
Origin: Jugular process of occipital bone
Insertion: Transverse process of atlas
Action: Flexes head and helps stabilize it
The cervical plexus is formed by the anterior rami of the first four cervical nerves
The rami are joined by connecting branches, which form loops that lie in front of the origins of the levator scapulae and the scalenus medius muscles
The plexus is covered in front by the prevertebral layer of deep cervical fascia
Is related to the internal jugular vein within the carotid sheath
The cervical plexus supplies the skin and the muscles of the head, the neck, and the shoulders
The lesser occipital nerve (C2): Supplies the back of the scalp and the
auricle
The greater auricular nerve (C2 and3): Supplies the skin over the angle of the
mandible
The transverse cervical nerve (C2 and 3): Supplies the skin over the front of the neck
The supraclavicular nerves (C3 and 4) The medial, intermediate, and lateral
branches supply the skin over the shoulder region
These nerves are important clinically, because pain may be referred along them from the phrenic nerve (gallbladder disease)
Prevertebral muscles, sternocleidomastoid (proprioceptive, C2 and 3), levator scapulae (C3 and 4), and trapezius (proprioceptive, C3 and 4)
A branch from C1 joins the hypoglossal nerve
Some of these C1 fibers later leave the hypoglossal as the descending branch, which unites with the descending cervical nerve (C2 and 3), to form the ansa cervicalis
The first, second, and third cervical nerve fibers within the ansa cervicalis supply the omohyoid, sternohyoid, and sternothyroid muscles
Other C1 fibers within the hypoglossal nerve leave it as the nerve to the thyrohyoid and geniohyoid
It arises in the neck from the third, fourth, and fifth cervical nerves of the cervical plexus
It runs vertically downward across the front of the scalenus anterior muscle
Enters the thorax by passing in front of the subclavian artery
The phrenic nerve is the only motor nerve supply to the diaphragm
It also sends sensory branches to the pericardium, the mediastinal parietal pleura, and the pleura and peritoneum covering the upper and lower surfaces of the central part of the diaphragm