B) Anterior belly of the digastric muscle

Explanation: The anterior belly of the digastric muscle forms the sides of the submental triangle, contributing to its anatomical boundaries.

C) The anterior border of the sternomastoid

Explanation: The posterior boundary of the anterior triangle is formed by the anterior border of the sternomastoid muscle, which is a key landmark in the neck.

C) It houses important muscles and vessels related to the jaw and neck

Explanation: The Digastric (Submandibular) Triangle is significant as it contains important muscles like the mylohyoid and hyoglossus, as well as vessels that are crucial for functions related to the jaw and neck.

C) Posterior belly of digastric

Explanation: The posterior belly of the digastric muscle forms the boundary below and behind the digastric (submandibular) triangle, which is essential for understanding its anatomical structure.

C) Platysma

Explanation: The platysma is a superficial muscle in the neck that contributes to facial expressions, particularly those associated with sadness or surprise.

B) Body of the hyoid bone

Explanation: The base of the submental triangle is formed by the body of the hyoid bone, which is a key anatomical landmark in this region.

C) Anterior belly of digastric

Explanation: The anterior belly of the digastric muscle forms the boundary below and in front of the digastric (submandibular) triangle, highlighting its role in the triangle's anatomy.

A) Superficial and deep layers

Explanation: The infrahyoid muscles are organized into two distinct layers: a superficial layer and a deep layer, which helps in understanding their anatomical arrangement.

B) Changes in facial symmetry and wedge-shaped cervical vertebrae

Explanation: If congenital torticollis is left untreated, asymmetrical growth changes can occur in the face, and the cervical vertebrae may become wedge-shaped, leading to further complications.

D) Sternocleidomastoid

Explanation: The sternocleidomastoid muscle is not part of the floor of the Digastric (Submandibular) Triangle; instead, the floor is formed by the mylohyoid, hyoglossus, and superior constrictor of the pharynx.

B) Hemorrhage into the sternocleidomastoid muscle

Explanation: Hemorrhage into the sternocleidomastoid muscle can be detected as a small, rounded 'tumor' during the early weeks after birth in cases of congenital torticollis.

B) Anterior triangle

Explanation: The anterior triangle is the area located in front of the sternocleidomastoid muscle, highlighting its role in dividing the neck into distinct anatomical regions.

B) Submental triangle, Digastric triangle, Carotid triangle, and Muscular triangle

Explanation: The anterior triangle is subdivided into four smaller triangles: the Submental triangle, Digastric (submandibular) triangle, Carotid triangle, and Muscular triangle, which are important for anatomical and clinical understanding.

B) Mylohyoid, hyoglossus, and superior constrictor of the pharynx

Explanation: The floor of the Digastric (Submandibular) Triangle is formed by the mylohyoid muscle, hyoglossus muscle, and the superior constrictor of the pharynx, which are key anatomical structures in this region.

B) Anterior and Posterior triangles

Explanation: The sternocleidomastoid muscle divides the side of the neck into the anterior triangle in front of the muscle and the posterior triangle behind it, which are key anatomical features of the neck.

B) Facial artery

Explanation: The facial artery is noted as being present in the digastric (submandibular) triangle, indicating its role in supplying blood to this area.

C) Lower border of the mandible

Explanation: The upper boundary of the digastric (submandibular) triangle is defined by the lower border of the mandible, which is crucial for understanding its anatomical location.

C) Assist in breathing

Explanation: The scalene muscles play a significant role in respiration by elevating the first and second ribs during inhalation.

B) Protects the vocal cords

Explanation: The thyroid cartilage is a prominent structure in the neck that serves to protect the vocal cords, playing a crucial role in the respiratory and vocal systems.

A) Midline of the neck, superior belly of omohyoid muscle, sternocleidomastoid muscle

Explanation: The muscular triangle is defined by the midline of the neck, the superior belly of the omohyoid muscle, and the sternocleidomastoid muscle, which are its specific anatomical boundaries.

C) Superior belly of the omohyoid muscle

Explanation: The superior belly of the omohyoid muscle is positioned in front and below the carotid triangle, contributing to its lower boundary.

A) Skin and superficial fascia

Explanation: The roof of the anterior triangle consists of skin, superficial fascia containing the platysma muscle, and deep fascia, which together form the outer layer of this anatomical region.

B) Section of the spinal part of the accessory nerve

Explanation: In severe cases of spasmodic torticollis, sectioning of the spinal part of the accessory nerve may be necessary to alleviate the symptoms caused by muscle contractions.

C) Mastoid process of the temporal bone and lateral half of the superior nuchal line

Explanation: The insertion of the Sternocleidomastoid muscle is at the mastoid process of the temporal bone and the lateral half of the superior nuchal line, which allows for its functional actions.

C) Posterior belly of the digastric muscle

Explanation: The posterior belly of the digastric muscle forms the boundary in front and above the carotid triangle, helping to delineate its upper limit.

B) Repeated chronic contractions of muscles

Explanation: Spasmodic torticollis is primarily caused by repeated chronic contractions of the sternocleidomastoid and trapezius muscles, leading to abnormal neck positioning.

C) Assist in breathing

Explanation: The scalene muscles play a significant role in respiration by elevating the first two ribs, thus assisting in breathing.

E) Nerve to mylohyoid

Explanation: The nerve to mylohyoid is specifically mentioned as innervating the mylohyoid muscle, which is important for its function in the digastric (submandibular) triangle.

A) Anterior border of the sternomastoid muscle

Explanation: The posterior boundary of the carotid triangle is defined by the anterior border of the sternomastoid muscle, which is crucial for identifying the triangle's anatomical limits.

B) Excessive stretching of the sternocleidomastoid muscle during difficult labor

Explanation: Most cases of congenital torticollis result from excessive stretching of the sternocleidomastoid muscle during difficult labor, leading to complications such as hemorrhage into the muscle.

B) Submental veins

Explanation: The submental veins are specifically located in the submental region and are involved in draining venous blood from that area.

B) Sternocleidomastoid

Explanation: The sternocleidomastoid muscle is crucial for head rotation and flexion, making it a key muscle in neck movement.

B) Digastric and superior belly of omohyoid

Explanation: The anterior triangle is subdivided by the digastric muscle and the superior belly of the omohyoid muscle, which helps to define the smaller triangles within the anterior triangle.

B) Tilts the head to the same side and rotates the face to the opposite side

Explanation: When the Sternocleidomastoid muscle acts on one side, it tilts the head to the same side while rotating the face to the opposite side, demonstrating its role in head movement.

C) Mylohyoid muscles with their median raphe

Explanation: The floor of the submental triangle is formed by the two mylohyoid muscles along with their median raphe, which is crucial for the structural integrity of this area.

B) Filter lymph from the chin and lower lip

Explanation: The submental lymph nodes are responsible for filtering lymphatic fluid from the chin and lower lip, playing a crucial role in the immune response.

C) Sternohyoid

Explanation: The sternohyoid muscle is located in the superficial layer of the infrahyoid muscles, positioned medially alongside the superior belly of the omohyoid laterally.

C) Flex and stabilize the cervical spine

Explanation: The longus colli muscle is important for flexing and stabilizing the cervical spine, contributing to neck posture and movement.

B) Repeated chronic contractions

Explanation: Spasmodic torticollis is characterized by repeated chronic contractions of specific neck muscles, leading to abnormal postures and discomfort.

B) Sternocleidomastoid

Explanation: The sternocleidomastoid muscle is crucial for head rotation and neck flexion, making it a key muscle in neck movement.

B) Omohyoid

Explanation: The superior belly of the omohyoid muscle is one of the defining boundaries of the muscular triangle, highlighting its anatomical significance in the neck region.

C) The lower border of the mandible

Explanation: The superior boundary of the anterior triangle is defined by the lower border of the mandible, which is an important anatomical landmark.

B) Psychogenic

Explanation: Spasmodic torticollis is usually psychogenic in origin, indicating that psychological factors may contribute to the muscle contractions.

C) Thyrohyoid

Explanation: The thyrohyoid muscle is part of the deep layer of the infrahyoid muscles, positioned above the sternothyroid muscle, which is below.

B) Suprahyoid muscles

Explanation: The suprahyoid muscles are essential for the swallowing process as they elevate the hyoid bone and assist in the movement of the larynx.

B) Suprahyoid muscles

Explanation: The suprahyoid muscles are responsible for elevating the hyoid bone during swallowing and speaking, playing a vital role in these functions.

C) X, XI, XII

Explanation: The last three cranial nerves are X (Vagus), XI (Accessory), and XII (Hypoglossal), which have important functions in the neck and throat.

B) Hyoglossus and thyrohyoid muscles

Explanation: The anterior part of the floor of the carotid triangle is formed by the hyoglossus and thyrohyoid muscles, which are important for various functions including swallowing and speech.

B) The midline of the neck

Explanation: The anterior boundary of the anterior triangle is defined by the midline of the neck, which serves as a central reference point for this anatomical region.

B) Sternocleidomastoid

Explanation: The sternocleidomastoid muscle is crucial for head rotation and neck flexion, making it a key muscle in neck movements.

B) Submental branch of facial artery

Explanation: The submental branch of the facial artery provides blood supply to the submental region, highlighting its importance in vascular anatomy.

C) Smaller triangular spaces

Explanation: Each of the anterior and posterior triangles contains smaller triangular spaces, which are significant for various anatomical and clinical considerations.

B) Muscular Triangle

Explanation: The infrahyoid muscles are primarily located within the muscular triangle, which is an important area in the anatomy of the neck.

C) Assisting in respiration

Explanation: The scalene muscles play a significant role in respiration by elevating the first and second ribs during inhalation.

B) Middle and inferior constrictor muscles of the pharynx

Explanation: The posterior part of the floor of the carotid triangle is made up of the middle and inferior constrictor muscles of the pharynx, which play a crucial role in the swallowing process.

B) Sternocleidomastoid

Explanation: The sternocleidomastoid muscle is crucial for head rotation and neck flexion, making it a key muscle in neck movement.

C) It contracts and shortens due to fibrous tissue invasion

Explanation: If congenital torticollis is left untreated, the hemorrhage in the muscle becomes invaded by fibrous tissue, which contracts and shortens the sternocleidomastoid muscle.

B) Manubrium sterni and medial third of the clavicle

Explanation: The Sternocleidomastoid muscle originates from the manubrium sterni and the medial third of the clavicle, which are key anatomical landmarks for this muscle.

B) Below

Explanation: The sternothyroid muscle is located below the thyrohyoid muscle, which is an important aspect of their anatomical arrangement in the deep layer of the infrahyoid muscles.

B) Internal jugular vein, common carotid artery, and vagus nerve

Explanation: The carotid sheath contains the internal jugular vein, common carotid artery, and vagus nerve, which are crucial structures in the neck's vascular and nervous systems.

B) They drain lymph from the head and neck

Explanation: The upper and lower deep cervical lymph nodes are responsible for draining lymphatic fluid from the head and neck, playing a crucial role in the immune system.

D) Scalene

Explanation: The scalene muscles are not mentioned as boundaries of the muscular triangle; instead, the boundaries include the midline of the neck, the superior belly of the omohyoid muscle, and the sternocleidomastoid muscle.

E) All of the above

Explanation: All listed structures, including the mylohyoid raphe, body of hyoid bone, cricoid cartilage, and suprasternal notch, are located in the midline of the neck, highlighting the anatomical significance of this region.

B) Scalenes

Explanation: The scalene muscles are primarily responsible for lateral flexion of the neck, allowing for side-to-side movement.

C) Nerve to mylohyoid

Explanation: The nerve to mylohyoid is responsible for innervating the mylohyoid muscle, which plays a role in elevating the floor of the mouth.

B) Spinal part of accessory nerve and C2, C3

Explanation: The Sternocleidomastoid muscle is primarily supplied by the spinal part of the accessory nerve and cervical nerves C2 and C3, which are crucial for its motor and proprioceptive functions.

B) They flex the neck forwards

Explanation: When both Sternocleidomastoid muscles act together, they flex the neck forwards, which is an important action for various movements of the head and neck.

C) Submandibular salivary gland

Explanation: The submandibular salivary gland is specifically mentioned as being located within the digastric (submandibular) triangle, highlighting its anatomical significance in this region.

C) Posterior triangle

Explanation: The posterior triangle is the area located behind the sternocleidomastoid muscle, which is important for understanding the anatomy of the neck.

C) Digastric

Explanation: The digastric muscle, which has anterior and posterior bellies, is classified as a suprahyoid muscle, located superior to the hyoid bone.

B) Drain lymph from the submandibular region

Explanation: The submandibular lymph nodes are responsible for draining lymph from the submandibular region, playing a crucial role in the immune response.

B) Platysma

Explanation: The platysma is a superficial muscle in the neck that contributes to facial expressions, particularly those associated with sadness or surprise.

A) Cricoid cartilage

Explanation: The cricoid cartilage is located just above the trachea and is an important structure in the airway, providing support and maintaining the patency of the airway.

C) Assist in breathing

Explanation: The scalene muscles play a significant role in respiration by elevating the first and second ribs, thus aiding in inhalation.

B) Depress the hyoid bone

Explanation: The infrahyoid muscles primarily function to depress the hyoid bone and stabilize it during swallowing and speaking.

A) Stylohyoid

Explanation: The stylohyoid muscle is part of the suprahyoid muscles, which are located above the hyoid bone, while the others listed are infrahyoid muscles.

C) Platysma

Explanation: The platysma is a superficial muscle in the neck that contributes to facial expressions, particularly in lowering the jaw and tensing the skin of the neck.

D) Thyroid gland

Explanation: The thyroid gland is not located in the digastric (submandibular) triangle, while the other structures listed are associated with this anatomical region.

C) Geniohyoid

Explanation: The geniohyoid muscle is one of the suprahyoid muscles, which are located above the hyoid bone, while the others listed are infrahyoid muscles.

B) To elevate the hyoid bone

Explanation: The suprahyoid muscles are primarily responsible for elevating the hyoid bone during swallowing and speaking.

C) Sternocleidomastoid and trapezius

Explanation: The sternocleidomastoid and trapezius muscles are the primary muscles involved in spasmodic torticollis, as their chronic contractions lead to the condition.

B) Platysma

Explanation: The platysma is a superficial muscle in the neck that contributes to facial expressions, particularly those associated with sadness or surprise.

B) Depress the hyoid bone

Explanation: The infrahyoid muscles primarily function to depress the hyoid bone and stabilize it during swallowing and speaking.

A) It connects the two lobes of the thyroid gland

Explanation: The isthmus of the thyroid gland is significant as it connects the two lobes of the thyroid, playing a vital role in endocrine function.

C) Mylohyoid

Explanation: The mylohyoid muscle is classified as a suprahyoid muscle, while the omohyoid, sternothyroid, sternohyoid, and thyrohyoid are all infrahyoid muscles located inferior to the hyoid bone.

B) Depress the hyoid bone

Explanation: The primary function of the infrahyoid muscles is to depress the hyoid bone, which is essential for various functions including swallowing and speech.

C) Submental triangle

Explanation: The submental triangle is defined by the presence of submental lymph nodes, veins, and the submental branch of the facial artery, making it a distinct anatomical area.

A) They help in identifying blood vessels and nerves

Explanation: The subdivisions of the anterior triangle are significant in anatomy and clinical practice as they assist in identifying important blood vessels and nerves that run through these areas.

B) Suprasternal notch

Explanation: The suprasternal notch is located at the base of the neck, just above the sternum, and serves as an important anatomical landmark.

A) Facial artery

Explanation: The lower part of the external carotid artery gives rise to several branches, including the facial artery, which supplies blood to the face.

B) It provides motor innervation to infrahyoid muscles

Explanation: The ansa cervicalis is a loop of nerves that provides motor innervation to the infrahyoid muscles, which are important for swallowing and speech.

E) Lateral triangle

Explanation: The lateral triangle is not a subdivision of the anterior triangle; the subdivisions include the Submental triangle, Digastric triangle, Carotid triangle, and Muscular triangle.

D) It is part of the autonomic nervous system

Explanation: The sympathetic trunk is a component of the autonomic nervous system, playing a role in the regulation of involuntary bodily functions.

A) Infrahyoid muscles

Explanation: The infrahyoid muscles are responsible for the movement of the hyoid bone and play a role in swallowing and speech.