Superficial Back Muscles
This large triangular muscle is innervated by the spinal accessory nerve (CN XI).
What is the trapezius?
Unilateral contraction of the erector spinae group primarily produces this movement.
What is lateral flexion of the vertebral column?
The obliquus capitis inferior muscle acts primarily to perform this head motion.
What is ipsilateral rotation of the atlas (C1) on the axis (C2)?
This nerve provides cutaneous innervation over the back of the head, just superior to the suboccipital region.
What is the greater occipital nerve?
An injury to this nerve can result in inability to elevate the shoulder.
What is the spinal accessory nerve (CN XI)?
This muscle elevates the scapula and is innervated by the dorsal scapular nerve.
What is the levator scapulae?
All intrinsic (deep) back muscles, including the erector spinae group, are innervated by branches of this division of spinal nerves.
What are the dorsal (posterior) rami?
This artery courses through the suboccipital triangle.
What is the vertebral artery?
This nerve emerges in the suboccipital triangle and innervates the suboccipital muscles.
What is the suboccipital nerve?
After posterior spine surgery, a patient has difficulty extending the trunk and shows a flattened lumbar curve. Which muscle group is most likely affected?
What is the erector spinae group?
What is the primary action of the latissimus dorsi at the shoulder joint?
What is extension, adduction, and internal (medial) rotation of the humerus?
This deep back muscle lies directly deep to the trapezius and spans from the transverse processes of C7–T4 to the mastoid process, assisting in head extension and rotation.
What is the splenius capitis?
One of the borders of the suboccipital triangle, this muscle extends and rotates the head.
What is the rectus capitis posterior major?
The erector spinae muscles are innervated by this division of the spinal nerves.
What are the dorsal (posterior) rami?
Paralysis of the trapezius muscle can result in this physical exam finding due to unopposed pull of the levator scapulae.
What is shoulder droop?
These paired muscles retract the scapula and share innervation from the dorsal scapular nerve.
What are the rhomboid major and minor?
The primary function of the erector spinae muscles.
What is extension of the spine and maintenance of posture?
This muscle forms the superolateral border of the suboccipital triangle.
What is the obliquus capitis superior?
This nerve arises from the C5 spinal nerve and innervates the rhomboids and levator scapulae.
What is the dorsal scapular nerve?
Damage to the dorsal scapular nerve could result in weakness in these muscles responsible for scapular retraction.
What are the rhomboid major and minor?
Weakness or injury to this nerve can cause a winged scapula due to loss of serratus anterior function.
What is the long thoracic nerve?
This deep back muscle, most prominent in the lumbar region, helps stabilize individual vertebrae and is implicated in core stability.
What is multifidus?
This muscle forms the inferolateral border of the suboccipital triangle.
What is the obliquus capitis inferior?
The medial and lateral pectoral nerves innervate this large anterior chest muscle that contributes to adduction and internal rotation.
What is the pectoralis major?
A patient recovering from a cervical spine injury has difficulty rotating their head to the same side and extending the neck. Injury to which deep back muscle is most likely involved?
What is the splenius capitis?