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The prevertebral and paravertebral regions are located anterior and lateral to the cervical vertebral column. These regions contain important muscles, arteries, veins, and nerves that form part of the deep structures of the neck and are covered by the prevertebral fascia.
The prevertebral muscles lie directly in front of the cervical vertebrae and are responsible for flexion of the head and neck.
Longus Colli: Flexes neck and rotates it to opposite side.
Longus Capitis: Flexes head and neck forward.
Rectus Capitis Anterior: Flexes head at the atlanto-occipital joint.
Rectus Capitis Lateralis: Flexes head laterally.
All prevertebral muscles are supplied by ventral rami of cervical spinal nerves.
Origin: Arises from the first part of the subclavian artery.
Course:
Cervical part: Ascends through foramina transversaria of C6–C1 vertebrae.
Atlantic part: Winds around the atlas.
Intracranial part: Pierces dura and arachnoid, enters the foramen magnum to form the basilar artery with its fellow.
Relations: Lies posterior to carotid sheath, accompanied by vertebral vein and sympathetic plexus.
Branches:
Spinal branches
Muscular branches
Posterior meningeal branches
Medullary and cerebellar branches
Termination: Unites with opposite vertebral artery at lower border of pons forming basilar artery.
Expose vertebral artery by reflecting the sternocleidomastoid and longus colli; identify the foramen transversarium of C6 as entry point and note its relation with cervical sympathetic chain and inferior thyroid artery.
Boundaries:
Medial: Longus colli muscle
Lateral: Scalenus anterior
Base: First part of subclavian artery
Contents:
Vertebral artery and vein
Sympathetic trunk
Thoracic duct (on left side)
Inferior thyroid artery and vein
This small but clinically vital space is where aneurysm or catheter insertion complications may affect the vertebral artery or sympathetic chain.
Develops from longitudinal anastomosis between cervical intersegmental arteries.
The proximal part arises from the 7th intersegmental artery (as part of the subclavian artery).
The distal part originates from the cranial connections of upper six intersegmental arteries that later regress.
Clinical relevance:
Anomalies in this development may result in asymmetry or duplication of vertebral arteries.
Vertebrobasilar insufficiency may result from kinking or compression of the artery in cervical spondylosis.
Trachea is a fibrocartilaginous tube that extends from the cricoid cartilage (C6 vertebra) to the level of the sternal angle (T4–T5), where it divides into right and left principal bronchi.
It acts as the air passage between the larynx and bronchi.
Anteriorly:
Isthmus of thyroid gland (2nd–4th tracheal rings)
Inferior thyroid veins
Jugular venous arch
Sternohyoid and sternothyroid muscles
Pretracheal fascia and skin
Posteriorly:
Oesophagus (close contact, allowing tracheoesophageal reflexes)
Laterally:
Lobes of thyroid gland
Common carotid arteries
Composed of 15–20 C-shaped hyaline cartilaginous rings, open posteriorly.
The posterior gap is closed by trachealis muscle (smooth muscle).
Mucous membrane: lined by pseudostratified ciliated columnar epithelium with goblet cells.
Submucosa contains seromucous glands.
Arterial: Inferior thyroid arteries
Venous: Inferior thyroid veins
Lymphatic drainage: Pretracheal and paratracheal nodes
Nerve supply:
Parasympathetic: Recurrent laryngeal nerves
Sympathetic: Cervical sympathetic chain
Tracheostomy: Surgical opening through 2nd–4th tracheal rings to establish airway.
Tracheitis: Inflammation from infection or intubation.
Tracheal deviation: Seen in lung collapse (toward affected side) or pleural effusion (away from affected side).
Foreign body entry: More common into right bronchus due to its vertical alignment.
Compression symptoms: Enlarged thyroid or retrosternal goiter can cause dyspnoea and stridor by pressing trachea.
A muscular tube, about 25 cm long, extending from cricoid cartilage (C6) to cardiac end of stomach (T11).
The cervical part (about 5 cm) lies between the trachea and vertebral column.
Anteriorly: Trachea
Posteriorly: Prevertebral fascia and longus colli
Laterally:
Right recurrent laryngeal nerve (on right side)
Thoracic duct and left recurrent laryngeal nerve (on left side)
Lobes of thyroid gland
Muscle:
Upper 1/3 → striated
Middle 1/3 → mixed
Lower 1/3 → smooth
Epithelium: Non-keratinized stratified squamous
Constricted sites:
Cricoid (C6)
Aortic arch level (T4)
Left bronchus crossing (T5–T6)
Diaphragmatic (T10)
Dysphagia: Difficulty swallowing from stricture or carcinoma.
Oesophageal varices: Portal hypertension leads to dilation of lower oesophageal veins.
Reflux oesophagitis (GERD): Acid regurgitation due to defective lower sphincter.
Tracheo-oesophageal fistula: Congenital defect due to incomplete separation of trachea and oesophagus.
Instrumentation hazard: Cervical oesophagus can be injured during endoscopy due to its proximity to trachea.
Type: Synovial, ellipsoid (biaxial).
Articulating surfaces:
Condyles of occipital bone with superior articular facets of atlas (C1).
Ligaments:
Anterior & posterior atlanto-occipital membranes.
Movements:
Flexion and extension (nodding “yes”).
Lateral flexion (slight).
Nerve supply: C1 spinal nerve via suboccipital nerve.
Three separate articulations between atlas (C1) and axis (C2):
Median joint: Dens of axis with anterior arch of atlas (pivot type).
Two lateral joints: Between articular facets (plane type).
Ligaments:
Transverse ligament of atlas
Alar ligaments
Apical ligament of dens
Cruciform ligament
Tectorial membrane (continuation of posterior longitudinal ligament)
Movements:
Rotation of head (“no” movement).
Occurs around vertical axis through dens.
Type: Plane synovial (between articular processes).
Intervertebral joints: Secondary cartilaginous (between vertebral bodies).
Allow flexion, extension, rotation, and lateral bending of neck.
Atlanto-occipital dislocation: Fatal due to medullary compression.
Atlanto-axial dislocation: Seen in rheumatoid arthritis, trauma, or Down syndrome due to laxity of transverse ligament.
Whiplash injury: Sudden hyperextension → injury to ligaments and muscles.
Fracture of dens (odontoid process): May compress spinal cord or medulla.
Degenerative changes: Osteophytes in uncovertebral joints cause cervical spondylosis, leading to radiculopathy.
Lies lateral to the prevertebral region, containing:
Scalene muscles
Cervical plexus and phrenic nerve
Cervical pleura
There are three main scalene muscles:
Scalenus anterior
Scalenus medius
Scalenus posterior
(A small fourth muscle, scalenus minimus, may be present.)
Scalenus anterior:
Origin: Anterior tubercles of transverse processes of C3–C6
Insertion: Scalene tubercle on 1st rib (between subclavian artery and vein)
Scalenus medius:
Origin: Posterior tubercles of transverse processes of C2–C7
Insertion: Upper surface of 1st rib, behind subclavian artery groove
Scalenus posterior:
Origin: Posterior tubercles of transverse processes of C4–C6
Insertion: Outer surface of 2nd rib
Scalenus minimus (if present):
Origin: Anterior border of C7 transverse process
Insertion: Inner border of 1st rib and dome of cervical pleura
Ventral rami of C3–C8 cervical nerves
Elevate ribs (1st and 2nd) during inspiration
Flex neck laterally and rotate to opposite side
Stabilize neck along with other cervical muscles
Scalenus anterior is a key surgical landmark.
Anterior relations:
Phrenic nerve (covered by prevertebral fascia)
Internal jugular vein
Sternocleidomastoid muscle
Clavicle
Posterior relations:
Brachial plexus
Subclavian artery
Scalenus medius
Cervical pleura (covered by suprapleural membrane)
Dome-shaped part of parietal pleura covering the apex of the lung.
Projects into the root of the neck about 5 cm above the first costal cartilage and 2.5 cm above the medial third of the clavicle.
Strengthened by suprapleural membrane (Sibson’s fascia), derived partly from scalenus minimus.
Anterior: Subclavian artery, scalenus anterior
Posterior: Neck of 1st rib, sympathetic trunk, superior intercostal artery and vein, 1st thoracic nerve
Lateral: Scalenus medius, lower trunk of brachial plexus
Medial: Vertebral bodies, oesophagus, trachea, left recurrent laryngeal nerve, thoracic duct (on left), great vessels of neck
Formed by ventral rami of C1–C4 cervical nerves.
Each ramus divides into ascending and descending branches to form three loops.
Lies deep to sternocleidomastoid and prevertebral fascia, on levator scapulae and scalenus medius.
Cutaneous Branches:
Lesser occipital (C2)
Great auricular (C2, C3)
Transverse cervical (C2, C3)
Supraclavicular (C3, C4)
Muscular Branches:
To infrahyoid muscles (via ansa cervicalis)
To prevertebral muscles
To levator scapulae
Phrenic Nerve:
Chief branch, from C3, C4, C5
Origin: Mainly from C4 with contributions from C3 and C5.
Descends on scalenus anterior, covered by prevertebral fascia.
Enters thorax between subclavian artery and vein.
Right nerve: Passes in front of root of right lung.
Left nerve: Passes in front of root of left lung, crossing aortic arch.
Motor: Diaphragm
Sensory: Central diaphragm, mediastinal pleura, pericardium
Scalene syndrome: Compression of brachial plexus and subclavian artery between scalenus anterior and medius → pain and numbness in upper limb.
Pneumothorax (apical): Penetrating neck injury may tear cervical pleura, collapsing the lung apex.
Phrenic nerve palsy: Paralysis of diaphragm → elevation of hemidiaphragm on X-ray.
Cervical plexus block: Used for regional anesthesia in neck surgeries.
The scalene muscles form an important landmark in the neck —
Subclavian artery passes behind the scalenus anterior.
Subclavian vein passes in front of the scalenus anterior.
Brachial plexus lies between scalenus anterior and medius.
The phrenic nerve lies on the anterior surface of scalenus anterior, deep to prevertebral fascia.
On the right, it crosses the subclavian artery.
On the left, it crosses the first part of the subclavian artery and aortic arch in thorax.
The cervical pleura (cupula) projects 2.5 cm above the medial third of the clavicle.
It is strengthened by Sibson’s fascia (suprapleural membrane) derived partly from scalenus minimus and transverse process of C7.
The cervical plexus lies on levator scapulae and scalenus medius, beneath sternocleidomastoid.
Cutaneous branches emerge around the midpoint of posterior border of sternocleidomastoid (“nerve point of the neck”).
The phrenic nerve carries motor fibers to the diaphragm and sensory fibers from the pericardium, pleura, and peritoneum (central part).
A small muscular slip, scalenus minimus, may be present and is attached to the 1st rib and dome of pleura.
The cervical plexus block is given at the nerve point of neck, useful for anesthesia during neck and thyroid surgeries.
Diagnosis: Scalene (Thoracic Outlet) Syndrome
Explanation:
Caused by compression of the brachial plexus and subclavian artery between scalenus anterior and medius muscles.
Common causes include cervical rib, fibrous band, or hypertrophy of scalene muscles.
Symptoms: numbness, paresthesia, and weakness of upper limb with absent pulse on arm elevation.
Answer: Phrenic nerve (C3, C4, C5)
Explanation:
Injury or block of the phrenic nerve causes paralysis of the diaphragm on the same side.
On imaging, the affected hemidiaphragm appears raised due to loss of tone.
Diagnosis: Cervical (Apical) Pneumothorax
Explanation:
The cervical pleura and apex of the lung extend above the clavicle.
Penetrating wounds or misplaced subclavian vein catheterization may rupture pleura → air enters pleural cavity → lung collapse.
Answer: Phrenic nerve
Explanation:
The phrenic nerve lies close to the lateral lobe of thyroid and may be compressed by tumor, inflammatory enlargement, or during thyroidectomy.
This results in referred pain to shoulder (C4 dermatome) and diaphragmatic paralysis.
Answer: Phrenic nerve.
Explanation:
The phrenic nerve descends on the anterior surface of scalenus anterior, deep to the prevertebral fascia and sternocleidomastoid.
It serves as an important landmark in neck dissections.
Answer: Scalenus anterior, scalenus medius, scalenus posterior, and sometimes scalenus minimus (accessory slip).
Answer:
Elevate first and second ribs during inspiration.
Flex the neck laterally and rotate it to the opposite side.
Help stabilize the cervical spine.
Answer:
Brachial plexus (trunks)
Subclavian artery
This space is called the interscalene (scalene) triangle.
Answer:
Phrenic nerve (on its surface)
Subclavian vein (in front of lower part)
Transverse cervical and suprascapular veins
Sternocleidomastoid muscle
Answer:
Subclavian artery passes behind the muscle.
Subclavian vein passes in front of it.
Answer:
Medially: Longus colli
Laterally: Scalenus anterior
Base: First part of subclavian artery
Contents: Vertebral artery and vein, thoracic duct (left side), sympathetic trunk, inferior thyroid artery.
Answer:
The dome-shaped parietal pleura that covers the apex of the lung and projects into the root of the neck above the first rib.
It is reinforced by Sibson’s fascia (suprapleural membrane).
Answer:
A thickened layer of prevertebral fascia covering the cervical pleura, derived partly from scalenus minimus and the transverse process of C7.
It protects the lung apex from injury in the root of the neck.
Answer:
Formed by ventral rami of C1–C4 spinal nerves, lying deep to sternocleidomastoid on levator scapulae and scalenus medius.
Provides cutaneous and muscular branches to the neck.
Answer:
The midpoint of the posterior border of sternocleidomastoid, where all cutaneous branches of cervical plexus emerge.
It is the site for cervical plexus block in anesthesia.
Answer:
Origin: Mainly from C4, with contributions from C3 and C5.
Course: Descends on scalenus anterior, passes between subclavian artery and vein, and enters thorax to supply the diaphragm.
Answer:
Motor: To diaphragm
Sensory: To pericardium, mediastinal pleura, and diaphragmatic peritoneum
Answer: C3, C4, and C5 — “C3, 4, 5 keeps the diaphragm alive.”
Answer:
Paralysis of the diaphragm on the same side
Elevation of hemidiaphragm on chest X-ray
Dyspnoea and referred pain to shoulder (C4 dermatome)
Answer:
Serve as key landmarks in neck dissections.
Scalene syndrome may compress the brachial plexus and subclavian artery, producing pain, paresthesia, and loss of pulse on arm elevation.
1. The scalenus anterior muscle is innervated by —
A. Dorsal rami of cervical nerves
B. Ventral rami of cervical nerves
C. Accessory nerve
D. Phrenic nerve
✅ Answer: B. Ventral rami of cervical nerves
Explanation: All scalene muscles are supplied by ventral rami of C3–C8.
2. The subclavian artery passes —
A. In front of scalenus anterior
B. Behind scalenus anterior
C. Between scalenus anterior and medius
D. In front of scalenus medius
✅ Answer: B. Behind scalenus anterior
Explanation: The subclavian artery lies posterior to scalenus anterior; the vein lies anterior.
3. The brachial plexus lies between which two muscles?
A. Sternocleidomastoid and trapezius
B. Scalenus anterior and medius
C. Scalenus medius and posterior
D. Longus colli and scalenus anterior
✅ Answer: B. Scalenus anterior and medius
Explanation: The trunks of the brachial plexus occupy the interscalene space.
4. The phrenic nerve descends over which muscle in the neck?
A. Longus colli
B. Scalenus anterior
C. Scalenus medius
D. Sternocleidomastoid
✅ Answer: B. Scalenus anterior
Explanation: The phrenic nerve runs vertically on the anterior surface of scalenus anterior.
5. The root value of the phrenic nerve is —
A. C2, C3, C4
B. C3, C4, C5
C. C4, C5, C6
D. C2, C4, C6
✅ Answer: B. C3, C4, C5
Mnemonic: “C3, 4, 5 keep the diaphragm alive.”
6. The cervical pleura extends above the clavicle by —
A. 1 cm
B. 2.5 cm
C. 5 cm
D. 7 cm
✅ Answer: B. 2.5 cm
Explanation: The cupula projects about 2.5 cm above the medial third of the clavicle.
7. Sibson’s fascia (suprapleural membrane) is derived from —
A. Pretracheal fascia
B. Prevertebral fascia
C. Investing layer of deep cervical fascia
D. Buccopharyngeal fascia
✅ Answer: B. Prevertebral fascia
Explanation: Sibson’s fascia is a thickened extension of prevertebral fascia that strengthens the cervical pleura.
8. Which of the following statements about the phrenic nerve is true?
A. Passes behind subclavian artery
B. Lies anterior to scalenus medius
C. Provides motor supply to diaphragm
D. Crosses behind root of the lung
✅ Answer: C. Provides motor supply to diaphragm
Explanation: The phrenic nerve runs in front of lung root and supplies motor fibers to diaphragm.
9. The cervical plexus is formed by ventral rami of —
A. C1–C3
B. C1–C4
C. C2–C5
D. C3–C6
✅ Answer: B. C1–C4
10. The nerve point of the neck is located —
A. At the posterior border of trapezius
B. At the midpoint of the posterior border of sternocleidomastoid
C. Behind the scalenus anterior
D. Above the clavicle
✅ Answer: B. Midpoint of posterior border of sternocleidomastoid
Explanation: All cutaneous branches of cervical plexus emerge from this point.
11. Injury to the phrenic nerve causes —
A. Vocal cord paralysis
B. Drooping of shoulder
C. Elevation of diaphragm on same side
D. Constriction of pupil
✅ Answer: C. Elevation of diaphragm on same side
Explanation: Paralysis of the diaphragm due to loss of phrenic supply results in raised hemidiaphragm.
12. Which of the following muscles may reinforce the cervical pleura?
A. Scalenus anterior
B. Scalenus medius
C. Scalenus minimus
D. Longus capitis
✅ Answer: C. Scalenus minimus
Explanation: When present, scalenus minimus gives fibers to the suprapleural membrane (Sibson’s fascia).
13. In scalene syndrome, which structures are compressed?
A. Subclavian vein and thoracic duct
B. Subclavian artery and brachial plexus
C. Common carotid artery and vagus nerve
D. Internal jugular vein and phrenic nerve
✅ Answer: B. Subclavian artery and brachial plexus
14. Which nerve lies on the anterior surface of scalenus anterior?
A. Vagus
B. Hypoglossal
C. Phrenic
D. Accessory
✅ Answer: C. Phrenic
15. The cervical plexus lies over which muscles?
A. Longus capitis and longus colli
B. Levator scapulae and scalenus medius
C. Scalenus anterior and medius
D. Splenius capitis and semispinalis capitis
✅ Answer: B. Levator scapulae and scalenus medius
Q1. What are the scalene muscles and where are they located?
They are three paired muscles — scalenus anterior, medius, and posterior — situated on the lateral aspect of the neck, connecting cervical vertebrae to the first two ribs.
Q2. What is the action of the scalene muscles?
They flex the neck laterally, rotate it, and assist in inspiration by elevating the first and second ribs.
Q3. What structures pass between the scalenus anterior and scalenus medius?
The subclavian artery and trunks of the brachial plexus.
Q4. What structure passes in front of the scalenus anterior?
The subclavian vein.
Q5. Which nerve runs on the surface of scalenus anterior?
The phrenic nerve.
Q6. What is the root value of the phrenic nerve?
C3, C4, and C5 — “C3, 4, 5 keeps the diaphragm alive.”
Q7. What is the motor and sensory distribution of the phrenic nerve?
Motor: Diaphragm
Sensory: Central diaphragmatic pleura, pericardium, and diaphragmatic peritoneum
Q8. What happens when the phrenic nerve is injured?
Diaphragmatic paralysis on the same side
Elevation of the hemidiaphragm on X-ray
Dyspnoea (difficulty in breathing) and referred pain to the shoulder (C4 dermatome)
Q9. What is the cervical plexus and where is it situated?
Formed by ventral rami of C1–C4, lying deep to sternocleidomastoid on levator scapulae and scalenus medius.
Q10. Name the cutaneous branches of the cervical plexus.
Lesser occipital (C2)
Great auricular (C2, C3)
Transverse cervical (C2, C3)
Supraclavicular (C3, C4)
Q11. What is the “nerve point of the neck”?
The midpoint of the posterior border of sternocleidomastoid where the cutaneous branches of cervical plexus emerge.
Q12. What is the cervical pleura?
The apical extension of parietal pleura that rises above the first rib into the root of the neck. It covers the apex of the lung.
Q13. How is the cervical pleura strengthened?
By the suprapleural membrane (Sibson’s fascia) derived from prevertebral fascia and partly from scalenus minimus.
Q14. What are the relations of cervical pleura?
Anteriorly: Subclavian artery
Posteriorly: Neck of first rib and sympathetic chain
Medially: Trachea, oesophagus, thoracic duct (on left)
Laterally: Scalenus medius and lower trunk of brachial plexus
Q15. What is scalene (thoracic outlet) syndrome?
Compression of the brachial plexus and subclavian artery between scalenus anterior and medius, leading to pain, numbness, and weakness of the upper limb, and loss of pulse when the arm is elevated.
Q16. Which muscle may give rise to Sibson’s fascia?
Scalenus minimus (when present).
Q17. What is the clinical importance of the nerve point of the neck?
It is used for cervical plexus block in surgical anesthesia during thyroidectomy and other neck surgeries.
Q18. Which structure lies anterior to the cervical pleura and may be injured in subclavian vein puncture?
Subclavian vein. Accidental injury may cause pneumothorax by puncturing the pleura.
Q19. Which side is the thoracic duct related to the cervical pleura?
On the left side, the thoracic duct arches above the pleura to open into the junction of left subclavian and internal jugular veins.
Q20. What is the developmental origin of the diaphragm?
From septum transversum, pleuroperitoneal membranes, dorsal mesentery of oesophagus, and body wall mesoderm.
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