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What movement occurs when the chin is turned to the opposite shoulder?
What movement occurs when the chin is turned to the opposite shoulder?
What is the primary action of the muscles when acting together?
What is the primary action of the muscles when acting together?
In the case of the 40-year-old woman with neck issues, what neck position indicates abnormality?
In the case of the 40-year-old woman with neck issues, what neck position indicates abnormality?
Which muscle action is common in both clinical cases described?
Which muscle action is common in both clinical cases described?
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What structure would likely be affected in both the 40-year-old woman and the baby with torticollis?
What structure would likely be affected in both the 40-year-old woman and the baby with torticollis?
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What is one of the primary actions of the trapezius muscle?
What is one of the primary actions of the trapezius muscle?
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Which cranial nerve is responsible for the nerve supply to the trapezius muscle?
Which cranial nerve is responsible for the nerve supply to the trapezius muscle?
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A common clinical symptom of damage to the accessory nerve may include which of the following?
A common clinical symptom of damage to the accessory nerve may include which of the following?
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Where does the accessory nerve emerge from the sternocleidomastoid muscle?
Where does the accessory nerve emerge from the sternocleidomastoid muscle?
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What is a key step in testing the function of the accessory nerve?
What is a key step in testing the function of the accessory nerve?
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What injury is characterized by a drooping shoulder due to lesion of a specific nerve?
What injury is characterized by a drooping shoulder due to lesion of a specific nerve?
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Which structure travels anterior to the anterior scalene?
Which structure travels anterior to the anterior scalene?
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What condition may arise from an injury to the cervical pleura?
What condition may arise from an injury to the cervical pleura?
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Which of the following arteries arises from the thyrocervical trunk?
Which of the following arteries arises from the thyrocervical trunk?
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What result may occur from an injury to the upper trunk of the brachial plexus?
What result may occur from an injury to the upper trunk of the brachial plexus?
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What is included in the contents of the superficial cervical fascia?
What is included in the contents of the superficial cervical fascia?
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Which layer of the deep cervical fascia surrounds the carotid sheath?
Which layer of the deep cervical fascia surrounds the carotid sheath?
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What muscle forms part of the boundaries of the posterior triangle of the neck?
What muscle forms part of the boundaries of the posterior triangle of the neck?
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Which area is innervated by the accessory nerve?
Which area is innervated by the accessory nerve?
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Which vein is NOT part of the superficial cervical fascia contents?
Which vein is NOT part of the superficial cervical fascia contents?
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What structure is found in the roof of the posterior triangle of the neck?
What structure is found in the roof of the posterior triangle of the neck?
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What does the cervical plexus primarily innervate?
What does the cervical plexus primarily innervate?
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Which of the following correctly outlines a boundary of the posterior triangle?
Which of the following correctly outlines a boundary of the posterior triangle?
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What muscular structure is involved with superficial cervical fascia?
What muscular structure is involved with superficial cervical fascia?
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What content of the posterior triangle is essential for providing sensory information to the skin of the neck?
What content of the posterior triangle is essential for providing sensory information to the skin of the neck?
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Which muscles are located in the posterior triangle of the neck?
Which muscles are located in the posterior triangle of the neck?
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What structure extends into the posterior triangle from the chest cavity?
What structure extends into the posterior triangle from the chest cavity?
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Which nerve supplies the diaphragm?
Which nerve supplies the diaphragm?
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What is the main artery that passes through the posterior triangle?
What is the main artery that passes through the posterior triangle?
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Which branch contributes to the skin over the shoulder?
Which branch contributes to the skin over the shoulder?
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Which lymph nodes are located in the posterior triangle of the neck?
Which lymph nodes are located in the posterior triangle of the neck?
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What structure does the anterior scalene muscle directly relate to?
What structure does the anterior scalene muscle directly relate to?
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Which of the following best describes the division of the posterior triangle?
Which of the following best describes the division of the posterior triangle?
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What vein crosses the base of the posterior triangle before joining the subclavian vein?
What vein crosses the base of the posterior triangle before joining the subclavian vein?
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Which of the following nerves is not a branch of the cervical plexus?
Which of the following nerves is not a branch of the cervical plexus?
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Which movement is primarily associated with contralateral head rotation?
Which movement is primarily associated with contralateral head rotation?
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In cases of torticollis, which direction does the head typically tilt?
In cases of torticollis, which direction does the head typically tilt?
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What is likely revealed in both cases of the 40-year-old woman and the infant presented with neck issues?
What is likely revealed in both cases of the 40-year-old woman and the infant presented with neck issues?
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Which position indicates an abnormal neck posture commonly seen in neck issues?
Which position indicates an abnormal neck posture commonly seen in neck issues?
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Which side of the neck is typically affected in torticollis cases?
Which side of the neck is typically affected in torticollis cases?
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What is the primary function of the trapezius muscle during shoulder movement?
What is the primary function of the trapezius muscle during shoulder movement?
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What nerve injury would most likely lead to an inability to shrug the shoulder?
What nerve injury would most likely lead to an inability to shrug the shoulder?
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Where does the accessory nerve typically emerge in relation to the sternocleidomastoid muscle?
Where does the accessory nerve typically emerge in relation to the sternocleidomastoid muscle?
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Which of the following structures does the accessory nerve pass deep to as it descends?
Which of the following structures does the accessory nerve pass deep to as it descends?
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In clinical testing, which action would signal proper function of the accessory nerve?
In clinical testing, which action would signal proper function of the accessory nerve?
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What clinical condition is characterized by shoulder drooping due to a lesion?
What clinical condition is characterized by shoulder drooping due to a lesion?
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Which artery is NOT mentioned as being associated with the thyrocervical trunk?
Which artery is NOT mentioned as being associated with the thyrocervical trunk?
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Injury to which structure may lead to a hemothorax?
Injury to which structure may lead to a hemothorax?
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Which nerve is primarily responsible for the innervation of the diaphragm?
Which nerve is primarily responsible for the innervation of the diaphragm?
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What upper trunk injury can lead to Erb Duchenne Palsy?
What upper trunk injury can lead to Erb Duchenne Palsy?
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Which of the following structures primarily contributes to the formation of the superficial cervical fascia?
Which of the following structures primarily contributes to the formation of the superficial cervical fascia?
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What is the location of the brachial plexus in relation to the posterior triangle?
What is the location of the brachial plexus in relation to the posterior triangle?
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Which layer of deep cervical fascia surrounds the structures in the posterior triangle?
Which layer of deep cervical fascia surrounds the structures in the posterior triangle?
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Which cranial nerve is primarily responsible for motor innervation in the posterior triangle?
Which cranial nerve is primarily responsible for motor innervation in the posterior triangle?
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What anatomical structure can be found at the boundary of the posterior triangle of the neck?
What anatomical structure can be found at the boundary of the posterior triangle of the neck?
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Which surface structure is often used as a landmark for locating the accessory nerve?
Which surface structure is often used as a landmark for locating the accessory nerve?
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Which structure runs posterior to the anterior scalene muscle in the neck?
Which structure runs posterior to the anterior scalene muscle in the neck?
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What is contained within the carotid sheath as part of its contents?
What is contained within the carotid sheath as part of its contents?
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Which of the following veins is responsible for draining the face and superficial neck?
Which of the following veins is responsible for draining the face and superficial neck?
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Which lymphatic structure is typically associated with the posterior triangle?
Which lymphatic structure is typically associated with the posterior triangle?
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Which components are primarily responsible for the passage of the brachial plexus and subclavian artery in the posterior triangle of the neck?
Which components are primarily responsible for the passage of the brachial plexus and subclavian artery in the posterior triangle of the neck?
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Which muscle innervated by the cervical plexus is primarily responsible for diaphragm movement?
Which muscle innervated by the cervical plexus is primarily responsible for diaphragm movement?
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Which of the following arteries is specifically mentioned as being present in the posterior triangle of the neck?
Which of the following arteries is specifically mentioned as being present in the posterior triangle of the neck?
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What anatomical structure crosses the base of the posterior triangle before joining the subclavian vein?
What anatomical structure crosses the base of the posterior triangle before joining the subclavian vein?
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What is the primary role of the lesser occipital nerve?
What is the primary role of the lesser occipital nerve?
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Which lymph nodes are specifically identified as being within the posterior triangle of the neck?
Which lymph nodes are specifically identified as being within the posterior triangle of the neck?
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What muscle acts as a divider in the posterior triangle by separating the occipital triangle from the omoclavicular triangle?
What muscle acts as a divider in the posterior triangle by separating the occipital triangle from the omoclavicular triangle?
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Which of the following muscles is NOT typically found in the posterior triangle of the neck?
Which of the following muscles is NOT typically found in the posterior triangle of the neck?
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Which of the following structures extends into the posterior triangle from the chest cavity?
Which of the following structures extends into the posterior triangle from the chest cavity?
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Study Notes
Posterior Triangle of the Neck
- The posterior triangle is a region in the neck that contains various anatomical structures, including vessels, nerves, and muscles.
- The posterior triangle is bounded by the trapezius muscle, the sternocleidomastoid, and the middle third of the clavicle.
- The roof of the posterior triangle is formed by the superficial cervical fascia, which contains the platysma muscle, external jugular vein, and superficial lymph nodes.
- The floor of the posterior triangle is formed by the muscles of the neck, such as the splenius capitis, levator scapulae, and scalenus muscles.
- The posterior triangle is divided into two parts: the occipital triangle (upper) and the supraclavicular triangle (lower).
- The inferior belly of the omohyoid muscle separates the occipital triangle from the supraclavicular triangle.
The Accessory Nerve (CN XI)
- The accessory nerve (CN XI) supplies the sternocleidomastoid and trapezius muscles.
- The accessory nerve is a mixed nerve (motor and sensory).
- The accessory nerve emerges from the posterior border of the sternocleidomastoid muscle at the junction of the superior and middle thirds.
- The accessory nerve descends and enters the posterior triangle before entering the trapezius muscle.
- The accessory nerve can be tested by having the patient shrug their shoulders or rotate their head against resistance.
Structures within the Posterior Triangle
- The posterior triangle contains the following structures:
- Accessory Nerve (CN XI)
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Cervical Plexus:
- Cutaneous Branches: Lesser occipital, Great auricular, Transverse cervical, and Supraclavicular nerves.
- Muscular Branches: Ansa cervicalis and Phrenic nerve.
- Brachial Plexus: Upper trunk (C5 and C6 roots) passes through the space between the anterior and middle scalene muscles.
- Scalene Muscles: Anterior, middle, and posterior scalene muscles.
- Subclavian Artery: The third part of the subclavian artery emerges from the space between the anterior and middle scalene muscles.
- Subclavian Vein: Passes anterior to the anterior scalene muscle.
- Subclavian Artery Branches: Suprascapular and transverse cervical arteries.
- Apex of the Lung: Extends up to just inferior to the subclavian vessels.
- Occipital Lymph Nodes
- Supraclavicular Lymph Nodes
Clinical Applications of the Posterior Triangle
- Torticollis: A condition where the head is tilted to one side, often due to a shortening or tightening of the sternocleidomastoid muscle.
- Accessory Nerve (CN XI) Lesions: Can cause drooping of the shoulder and weakness in turning the head to the opposite side.
- Cervical Plexus Block: An anesthetic procedure used to block pain in the neck and shoulder.
- Phrenic Nerve Injury: Can cause difficulty breathing.
- Cervical Pleura Injury: Can lead to pneumothorax (collapsed lung) or hemothorax (blood in the chest cavity).
- Subclavian Vessel Injuries: Can result in bleeding.
- Brachial Plexus Injury: Can lead to Erb-Duchenne palsy, which affects the shoulder and arm.
Posterior Triangle of the Neck
- The posterior triangle of the neck is a region of the neck located behind the sternocleidomastoid muscle and in front of the trapezius muscle.
- Its boundaries are:
- Superior: Inferior border of the occipital bone
- Inferior: Middle third of the clavicle
- Anterior: Posterior border of the sternocleidomastoid
- Posterior: Anterior border of the trapezius
- The posterior triangle is further divided into two sub-triangles by the inferior belly of the omohyoid muscle:
- Occipital triangle: Larger, superior portion
- Supraclavicular triangle: Smaller, inferior portion
- The roof of the posterior triangle is formed by the investing layer of the deep cervical fascia and the skin.
- The floor of the posterior triangle is formed by:
- Splenius capitis
- Levator scapulae
- Scalenus posterior
- Scalenus medius
- Scalenus anterior
- The contents of the posterior triangle include:
- Accessory Nerve (CN XI): Runs deep to the sternocleidomastoid muscle, emerges at the junction of superior and middle thirds of the posterior border, passes deep to the investing fascia, descends into the posterior triangle, and enters the lower third of the anterior border of the trapezius.
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Cervical Plexus: Located in the posterior triangle, its branches contribute to sensory and motor functions of the head, neck, and shoulder.
- Cutaneous branches: Include the lesser occipital, great auricular, transverse cervical, and supraclavicular nerves which provide sensation to various regions of the head, neck, and shoulder.
- Muscular branches: Include the ansa cervicalis, which supplies the strap muscles (infrahyoid muscles), and the phrenic nerve, which supplies the diaphragm.
- Brachial Plexus: The upper trunk of the brachial plexus (C5 and C6 roots) passes through the scalene space between the anterior and middle scalene muscles.
- Subclavian Artery (3rd Part): Emerges from the space between the anterior and middle scalene muscles, flanking the brachial plexus roots.
- Suprascapular and Transverse Cervical Arteries: Branch off from the thyrocervical trunk, which is a branch of the first part of the subclavian artery.
- Subclavian Vein: Passes anterior to the anterior scalene muscle.
- Apex of the Lung with Pleural Space: Extends up to the inferior aspect of the subclavian vessels.
- Occipital and Supraclavicular Lymph Nodes: Located within the posterior triangle.
- The clinical relevance of the posterior triangle includes:
- Torticollis: A condition characterized by a twisted neck due to tight or shortened muscles, often affecting the sternocleidomastoid muscle.
- Lesions of the Spinal Accessory Nerve (CN XI): Lead to drooping of the shoulder.
- Cervical Plexus Block: A nerve block procedure targeting the cervical plexus, used for pain relief in the neck, head, and shoulder.
- Injury to the Phrenic Nerve: Can affect diaphragmatic function, leading to breathing difficulties.
- Injury to the Cervical Pleura: May result in pneumothorax (collapsed lung).
- Injury to the Subclavian Vessels: Can lead to heamothorax (blood in the chest cavity).
- Upper Trunk of the Brachial Plexus Injury: May cause Erb-Duchenne palsy, characterized by weakness and paralysis of the shoulder and arm muscles.
Sternocleidomastoid Muscle
- It is a large, strap-like muscle located on the side of the neck.
- Its origin is at the manubrium of the sternum and the medial third of the clavicle.
- It inserts at the mastoid process of the temporal bone and the superior nuchal line of the occipital bone.
-
Action:
- Individually: Turns the chin towards the opposite shoulder (contralateral head rotation).
- Together: Flexes the head.
Trapezius Muscle
- A large, flat, triangular muscle that covers the back of the neck and shoulder.
- It originates from the occipital bone, the ligamentum nuchae, and the spinous processes of the seventh cervical and all thoracic vertebrae.
- It inserts at the lateral third of the clavicle, the acromion process of the scapula, and the spine of the scapula.
-
Action:
- Rotates and elevates the scapula.
- Shrugs the shoulders.
- Nerve Supply: Accessory Nerve (CN XI)
Anatomical Structures in the Scalene Space
- Scalene Space is the space between the anterior and middle scalene muscles and the first rib.
-
Structures that pass through the scalene space:
- Brachial Plexus: The roots of the brachial plexus (C5-T1) pass through the scalene space, along with the subclavian artery.
- Subclavian Artery (3rd part): Passes through the scalene space.
-
Structures that pass anterior to the anterior scalene muscle:
- Subclavian Vein: Passes anterior to the anterior scalene muscle.
- Phrenic Nerve: Travels along the anterior scalene muscle and does not pass through the scalene space.
Jugular Veins
- The external jugular vein is a major surface vein of the neck. It originates at the angle of the mandible and descends along the lateral border of the sternocleidomastoid muscle. It pierces through the investing layer of the deep cervical fascia, joining the subclavian vein approximately 3 cm above the middle third of the clavicle.
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Description
Explore the posterior triangle of the neck, a crucial anatomical region that encompasses vital structures such as muscles, vessels, and nerves. Learn about its boundaries, composition, and the role of the accessory nerve in supplying essential muscles. This quiz will enhance your understanding of neck anatomy.
