Questions and Answers
The platysma muscle is a thick, strap-like muscle located in the neck.
False
The sternocleidomastoid muscle assists in forced inspiration.
True
The action of the platysma includes tensing the skin of the neck.
True
The platysma muscle originates from the manubrium of the sternum.
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Weakness of the sternocleidomastoid muscle can lead to torticollis.
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The platysma is innervated by the spinal accessory nerve.
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Study Notes
Superficial Muscles of the Neck
Platysma
- A thin, quadrilateral muscle that lies in the subcutaneous tissue of the neck
- Origin: fascia of the chest and shoulder
- Insertion: lower border of the mandible and skin of the neck
- Action: depresses the mandible, tenses the skin of the neck, and assists in facial expressions
- Innervation: cervical branch of the facial nerve (CN VII)
Sternocleidomastoid Muscle (SCM)
- A thick, strap-like muscle that runs from the sternum and clavicle to the mastoid process
- Origin: manubrium of the sternum and medial portion of the clavicle
- Insertion: mastoid process of the temporal bone
- Action: rotates the head, flexes the neck, and assists in forced inspiration
- Innervation: spinal accessory nerve (CN XI) and C2-C3 spinal nerves
Clinical Relevance
- The platysma muscle is often used in neck lift surgeries to improve the appearance of the neck and jawline.
- The SCM muscle is a common site for muscle strain and may cause pain and stiffness in the neck and shoulder region.
- Weakness or paralysis of the SCM muscle can result in torticollis, a condition characterized by abnormal twisting or tilting of the head.
Superficial Muscles of the Neck
Platysma
- Thin, quadrilateral muscle located in the subcutaneous layer of the neck.
- Originates from the fascia surrounding the chest and shoulder areas.
- Inserts at the lower border of the mandible and the skin of the neck.
- Functions include depressing the mandible, tensing the neck skin, and aiding in facial expressions.
- Innervated by the cervical branch of the facial nerve (Cranial Nerve VII).
Sternocleidomastoid Muscle (SCM)
- Thick, strap-like muscle extending from the sternum and clavicle to the mastoid process of the skull.
- Originates from the manubrium of the sternum and the medial portion of the clavicle.
- Inserts at the mastoid process of the temporal bone of the skull.
- Responsible for head rotation, neck flexion, and supporting forced inspiration.
- Innervated by the spinal accessory nerve (Cranial Nerve XI) and cervical spinal nerves C2-C3.
Clinical Relevance
- The platysma plays a crucial role in neck lift surgeries for enhancing neck and jawline appearance.
- The SCM is frequently affected by muscle strain, leading to neck and shoulder pain and stiffness.
- Weakness or paralysis of the SCM can lead to torticollis, resulting in abnormal head twisting or tilting.
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Description
This quiz covers the platysma and sternocleidomastoid muscles, including their origins, insertions, actions, and innervations.
