Podcast
Questions and Answers
Which of the following is the primary function of the back?
Which of the following is the primary function of the back?
- Providing musculoskeletal support for the trunk (correct)
- Filtering blood
- Synthesizing vitamin D
- Facilitating digestion
Which of the following is NOT a bony element of the back?
Which of the following is NOT a bony element of the back?
- Distal elements of the ribs (correct)
- Vertebrae
- Superior aspects of the pelvic bones
- Posterior regions of the skull
Which nerve type is primarily responsible for innervating the extrinsic muscles of the back?
Which nerve type is primarily responsible for innervating the extrinsic muscles of the back?
- Cranial nerves
- Anterior rami of spinal nerves (correct)
- Posterior rami of spinal nerves
- Autonomic nerves
Which group of back muscles is directly involved in the movements of the vertebral column and head?
Which group of back muscles is directly involved in the movements of the vertebral column and head?
Which muscle is NOT part of the first layer of the superficial back muscles?
Which muscle is NOT part of the first layer of the superficial back muscles?
What is the shape of the trapezius muscle described as?
What is the shape of the trapezius muscle described as?
Where does the base of the trapezius muscle's triangle lie?
Where does the base of the trapezius muscle's triangle lie?
From where does the trapezius muscle originate, in a top-down order?
From where does the trapezius muscle originate, in a top-down order?
Which of the following is the insertion point of the upper fibers (descending part) of the trapezius muscle?
Which of the following is the insertion point of the upper fibers (descending part) of the trapezius muscle?
Which nerve provides motor innervation to the trapezius muscle?
Which nerve provides motor innervation to the trapezius muscle?
What is the main action of the trapezius muscle when the whole muscle is considered?
What is the main action of the trapezius muscle when the whole muscle is considered?
Which movement is primarily associated with the upper fibers of the trapezius muscle?
Which movement is primarily associated with the upper fibers of the trapezius muscle?
In which direction do the lower fibers of the trapezius muscle move the shoulder blade?
In which direction do the lower fibers of the trapezius muscle move the shoulder blade?
What other muscle does the trapezius work with to rotate the scapula?
What other muscle does the trapezius work with to rotate the scapula?
Which of the following best describes the latissimus dorsi muscle?
Which of the following best describes the latissimus dorsi muscle?
Though anatomically in the back, how is the latissimus dorsi functionally classified?
Though anatomically in the back, how is the latissimus dorsi functionally classified?
Which anatomical structure serves as the insertion point for the latissimus dorsi muscle?
Which anatomical structure serves as the insertion point for the latissimus dorsi muscle?
Which nerve innervates the latissimus dorsi muscle?
Which nerve innervates the latissimus dorsi muscle?
Which of the following actions is a primary function of the latissimus dorsi muscle?
Which of the following actions is a primary function of the latissimus dorsi muscle?
Besides adduction and medial rotation, what other movement does the latissimus dorsi assist?
Besides adduction and medial rotation, what other movement does the latissimus dorsi assist?
In movements like climbing or gymnastics, what action does the latissimus dorsi facilitate?
In movements like climbing or gymnastics, what action does the latissimus dorsi facilitate?
What is the primary clinical significance of the auscultation triangle?
What is the primary clinical significance of the auscultation triangle?
Which of the following muscles does NOT contribute to the boundaries of the auscultation triangle?
Which of the following muscles does NOT contribute to the boundaries of the auscultation triangle?
In relation to the lumbar triangle, where is the hernia most likely to occur?
In relation to the lumbar triangle, where is the hernia most likely to occur?
Which of these muscles forms the floor of the lumbar triangle?
Which of these muscles forms the floor of the lumbar triangle?
Where does the levator scapulae insert?
Where does the levator scapulae insert?
What are the nerve roots that supply the levator scapulae?
What are the nerve roots that supply the levator scapulae?
What action does downward rotation of the scapula accomplish?
What action does downward rotation of the scapula accomplish?
Where does the rhomboideus minor insert?
Where does the rhomboideus minor insert?
From which vertebrae do the rhomboid major muscles originate?
From which vertebrae do the rhomboid major muscles originate?
What is the key action of both rhomboid muscles?
What is the key action of both rhomboid muscles?
Apart from elevating the scapula, what other secondary action do the rhomboids perform?
Apart from elevating the scapula, what other secondary action do the rhomboids perform?
A patient presents with an inability to retract their scapula. Which nerve is MOST likely affected?
A patient presents with an inability to retract their scapula. Which nerve is MOST likely affected?
During a physical exam, a medical student notes difficulty auscultating lung sounds through the auscultation triangle. Assuming no underlying pulmonary pathology, what anatomical variant in the patient is MOST likely the cause?
During a physical exam, a medical student notes difficulty auscultating lung sounds through the auscultation triangle. Assuming no underlying pulmonary pathology, what anatomical variant in the patient is MOST likely the cause?
Which muscle pair is most directly responsible for both elevating the rib cage to aid in inspiration, and depressing the rib cage to aid in expiration?
Which muscle pair is most directly responsible for both elevating the rib cage to aid in inspiration, and depressing the rib cage to aid in expiration?
A surgeon is performing a novel reconstructive surgery involving a muscle transfer. They need a flat, triangular muscle that has both spinal accessory nerve and cervical nerve innervation, inserts onto the clavicle and scapula, and whose upper fibers raise the shoulder. Which muscle BEST fits these criteria?
A surgeon is performing a novel reconstructive surgery involving a muscle transfer. They need a flat, triangular muscle that has both spinal accessory nerve and cervical nerve innervation, inserts onto the clavicle and scapula, and whose upper fibers raise the shoulder. Which muscle BEST fits these criteria?
A 35 year-old male presents with shoulder pain and limited range of motion following a weightlifting injury. Imaging reveals damage to a structure responsible for both adduction and medial rotation of the arm, and also assists in pulling the trunk upwards towards the arms. Furthermore, nerve conduction studies indicate involvement of the posterior cord of the brachial plexus, specifically affecting the thoracodorsal nerve. Which ONE of the following muscles is MOST consistent with the patient's presentation?
A 35 year-old male presents with shoulder pain and limited range of motion following a weightlifting injury. Imaging reveals damage to a structure responsible for both adduction and medial rotation of the arm, and also assists in pulling the trunk upwards towards the arms. Furthermore, nerve conduction studies indicate involvement of the posterior cord of the brachial plexus, specifically affecting the thoracodorsal nerve. Which ONE of the following muscles is MOST consistent with the patient's presentation?
Flashcards
What is the back?
What is the back?
Posterior aspect of the body; provides musculoskeletal support for the trunk.
Bony elements of the back
Bony elements of the back
Vertebrae, ribs, pelvic bones, and posterior skull regions.
Muscle groups of the back
Muscle groups of the back
Superficial, Intermediate, and Deep groups.
Extrinsic back muscles
Extrinsic back muscles
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Innervation of extrinsic muscles
Innervation of extrinsic muscles
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Function of the superficial group
Function of the superficial group
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The Intermediate Group
The Intermediate Group
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Intrinsic muscles
Intrinsic muscles
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Innervation of intrinsic muscles
Innervation of intrinsic muscles
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First layer back muscles
First layer back muscles
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Second layer back muscles
Second layer back muscles
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Trapezius Muscle
Trapezius Muscle
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Inferior Trapezius Origin
Inferior Trapezius Origin
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Trapezius Action
Trapezius Action
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Trapezius Nerve Supply
Trapezius Nerve Supply
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Latissimus Dorsi
Latissimus Dorsi
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Latissimus Dorsi Origin
Latissimus Dorsi Origin
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Latissimus Dorsi Insertion
Latissimus Dorsi Insertion
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Latissimus Dorsi nerve supply
Latissimus Dorsi nerve supply
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Auscultation Triangle
Auscultation Triangle
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Boundaries of Auscultation Triangle
Boundaries of Auscultation Triangle
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Boundaries of Lumbar Triangle
Boundaries of Lumbar Triangle
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Levator Scapulae Origin
Levator Scapulae Origin
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Levator Scapulae Action
Levator Scapulae Action
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Levator Scapulae Nerve Supply
Levator Scapulae Nerve Supply
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Rhomboideus Minor Origin
Rhomboideus Minor Origin
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Rhomboideus Minor Insertion
Rhomboideus Minor Insertion
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Rhomboideus Major Origin
Rhomboideus Major Origin
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Rhomboideus Major Insertion
Rhomboideus Major Insertion
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Rhomboideus Nerve Supply
Rhomboideus Nerve Supply
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Rhomboideus Action
Rhomboideus Action
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Study Notes
- The lecture focuses on the muscles of the back.
- The lecture objective is to identify the structures forming the back.
- The lecture will clarify the layers of the muscles in the back.
- The lecture will describe the origin, insertion, nerve supply, and action of the superficial layer of the back.
- The lecture will define and describe the boundaries and functions of triangles related to the latissimus dorsi muscle (Auscultation and lumbar triangles).
Introduction to the Back
- The back comprises the posterior aspect of the body and offers the musculoskeletal support for the trunk.
- Bony parts of the back include vertebrae, proximal elements of the ribs, superior aspects of the pelvic bones, and posterior basal regions of the skull.
- Muscles interconnect vertebrae and ribs, connecting them to the pelvis and skull.
- The back contains the spinal cord and proximal spinal nerves for information transit to and from the body.
Organization of Back Muscles
- Back muscles are organized into superficial, intermediate, and deep groups.
- Muscles of the superficial and intermediate groups are extrinsic, originating from outside the back during embryological development.
- Extrinsic muscles are supplied by anterior rami of spinal nerves.
- The superficial group consists of muscles involved in movements of the upper limb.
- The intermediate group includes muscles attached to the ribs, aiding respiratory function.
- The deep group consists of intrinsic muscles, developing within the back, and are innervated by posterior rami of spinal nerves; they are directly related to the movements of the vertebral column and head.
- Intrinsic muscles include extensors and rotators of the head (splenius capitis and cervicis), extensors, rotators of the vertebral column (erector spinae), and short segmental muscles (interspinales and intertransversarii).
Superficial Group Muscles
- Muscles of the superficial group lie immediately deep to the skin and superficial fascia.
- First layer includes the trapezius and latissimus dorsi muscles.
- Second layer includes the levator scapulae, rhomboideus minor, and rhomboideus major.
Trapezius
- Originates from the back of the skull to the back of the thoracic wall.
- Each muscle is flat, triangular, with its base along the vertebral column (origin) and apex pointing to the shoulder tip (insertion).
- The muscles on both sides form a trapezoid shape together.
- It originates from the medial third of the superior nuchal line, external occipital protuberance, ligamentum nuchae, the spine of the 7th cervical vertebra, spines of all thoracic vertebrae, and supraspinous ligaments.
- Upper fibers insert into the posterior border of the lateral third of the clavicle.
- Middle fibers insert into the medial border of the acromial process and the crest of the spine of the scapula.
- Lower fibers insert into the medial part and upper border of the crest of the spine of the scapula.
- Supplied by the spinal part of the accessory nerve (motor) and dorsal rami of C3, C4 nerves (proprioception).
Trapezius Actions
- Contraction retracts the scapula (whole muscle).
- Upper fibers raise the shoulder.
- Lower fibers depress the shoulder.
- Working with the serratus anterior (lower 5 digitations), it rotates the scapula when raising the arm above the head.
Latissimus Dorsi
- It is a large, flat triangular muscle beginning in the lower back, tapering to a narrow tendon attaching to the humerus.
- From an anatomical view it is a muscle of the back, but is functionally part of the upper limb.
- The origin is by aponeurosis from the posterior part of the outer lip of the iliac crest, lumbar fascia, lower six thoracic spines, lower 3 or 4 ribs, and the back of the inferior angle of the scapula.
- The insertion is by a flat tendon into the floor of the inter-tubercular (bicipital) groove.
- It is innervated by the thoracodorsal nerve (posterior cord of the brachial plexus from C6, 7, 8).
- It primarily adducts and medially rotates the arm.
- It assists in the extension of the shoulder joint.
- It depresses the shoulder, preventing upward movement.
- It pulls the trunk upward towards the arms for climbing and gymnastics.
- This muscle assists in swimming and rowing.
Triangles Related to Latissimus Dorsi
- Triangles related to latissimus dorsi are used for auscultation.
Auscultation Triangle:
- Is a triangular space in the musculature of the back, near the inferior angle of the scapula.
- Boundaries:
- Posteriorly: lower fibers of trapezius muscle.
- Anteriorly: medial border of scapula.
- Below: upper border of latissimus dorsi muscle.
- Floor: rhomboideus major muscle.
Lumbar Triangle:
- Is a triangular area on the lower back.
- Boundaries:
- Anteriorly: posterior border of external oblique muscle.
- Posteriorly: latissimus dorsi muscle.
- Below: iliac crest.
- Floor: internal oblique muscle.
Functions of the Triangles:
- AUSCULTATION TRIANGLE: Region for auscultation of the posterior lung segments.
- LUMBAR TRIANGLE: Rare location for a lumbar hernia to occur.
Second Layer
- The muscles of this layer are levator scapulae, rhomboideus minor, and rhomboideus major.
Levator Scapulae
- Origin: Transverse processes of upper 4 cervical vertebrae.
- Insertion: Medial border of scapula at the superior angle.
- Nerve Supply: Dorsal scapular nerve (C4, 5) from roots of brachial plexus and directly from 3rd and 4th spinal nerves.
- Action: Elevates the scapula, rotates it downward (tilting the glenoid cavity inferiorly), and helps in lateral flexion of the neck.
Rhomboideus Minor
- Origin: Lower part of ligamentum nuchae, and Spines of C7 and T1 vertebra.
- Insertion: Medial border of the scapula opposite its spine.
Rhomboideus Major
- Origin: Spines of the T2, 3, 4, and 5 vertebrae.
- Insertion: Medial border of the scapula between the spine and inferior angle.
- Nerve Supply and Action of Rhomboideus Muscles:
- Nerve Supply: Dorsal scapular nerve (C4, 5) from roots of brachial plexus.
- Action: Retracts (adducts) the shoulder, elevates the scapula and helps in downward rotation of scapula (tilting the glenoid cavity inferiorly).
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