Myotomes, Dermatomes, and Muscle Contractions
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Questions and Answers

Which of the following correctly describes the location of the thoracoacromial artery?

  • It is located between the 1st rib and the medial border of the pectoralis minor.
  • It is found behind the pectoralis minor muscle. (correct)
  • It runs along the medial border of the pectoralis minor muscle.
  • It passes through the quadrangular space.

    • What is the primary function of the superior thoracic artery?

  • Supply the serratus anterior and lateral breast.
  • Supply the deltoid muscle and acromion.
  • Provide blood to the scapular anastomosis and latissimus dorsi.
  • Supply the 1st and 2nd intercostal spaces. (correct)

    • Which branch of the axillary artery is the largest and provides branches for the scapular anastomosis and latissimus dorsi?

  • Lateral thoracic artery
  • Thoracoacromial artery
  • Subscapular artery (correct)
  • Anterior circumflex humeral artery

    • Which nerve runs laterally within the cubital fossa, dividing into deep and superficial branches?

    <p>Radial nerve (D)</p> Signup and view all the answers

    What anatomical structure serves as the attachment point for the biceps brachii tendon within the cubital fossa?

    <p>Radial tuberosity (B)</p> Signup and view all the answers

    Which vessel is commonly utilized for blood draws (venipuncture) due to its superficial location?

    <p>Median cubital vein (A)</p> Signup and view all the answers

    Which of these is NOT a branch of the thoracoacromial artery?

    <p>Subscapular (D)</p> Signup and view all the answers

    Which of the following structures does NOT pass through the cubital fossa?

    <p>Ulnar nerve (C)</p> Signup and view all the answers

    What is the mnemonic for remembering the boundaries of the cubital fossa?

    <p>My Brother Ruins Drinks (A)</p> Signup and view all the answers

    Which artery gives rise to the posterior circumflex humeral artery?

    <p>Axillary artery (D)</p> Signup and view all the answers

    Which nerve is NOT primarily affected in Erb's palsy?

    <p>Ulnar (D)</p> Signup and view all the answers

    A patient with a brachial plexus injury presents with a 'claw hand' deformity. Which nerve roots are most likely affected?

    <p>C8-T1 (C)</p> Signup and view all the answers

    Which nerve primarily innervates the deltoid muscle, which is responsible for shoulder abduction?

    <p>C5 spinal nerve (B)</p> Signup and view all the answers

    Which movement would you NOT expect to find impaired in a patient with a radial nerve injury?

    <p>Forearm supination (B)</p> Signup and view all the answers

    During a bicep curl, what type of contraction is the bicep brachii undergoing as the arm flexes?

    <p>Concentric contraction (A)</p> Signup and view all the answers

    A patient presents with their arm adducted, medially rotated, elbow extended and their forearm pronated, suggestive of what condition?

    <p>Erb's palsy (B)</p> Signup and view all the answers

    Which muscle group is primarily affected by an injury to the ulnar nerve?

    <p>Intrinsic hand muscles (A)</p> Signup and view all the answers

    The superior margin (roof) of the intervertebral foramen is formed by which structure?

    <p>The inferior vertebral notch of the vertebra above (D)</p> Signup and view all the answers

    Which of the following is NOT a type of synovial joint?

    <p>Suture joint (D)</p> Signup and view all the answers

    A patient has a nerve impingement due to an intervertebral disc protrusion at the level of L4. Which nerve root is most likely affected?

    <p>L5 nerve root (C)</p> Signup and view all the answers

    Which of the following actions is NOT limited by the anterior longitudinal ligament of the vertebral column?

    <p>Flexion (C)</p> Signup and view all the answers

    Compression of which space would most likely result in axillary nerve and posterior circumflex humeral artery pathology?

    <p>Quadrangular space (B)</p> Signup and view all the answers

    Which of the following is NOT located within the spinal cord?

    <p>Rami (C)</p> Signup and view all the answers

    Which structure forms the medial boundary of the axilla?

    <p>Serratus anterior, ribs 1-4, intercostal muscles (A)</p> Signup and view all the answers

    The posterior cord of the brachial plexus is formed by the:

    <p>Posterior divisions of all three trunks (A)</p> Signup and view all the answers

    What structures form the apex (inlet) of the axilla?

    <p>Clavicle, 1st rib, Scapula (C)</p> Signup and view all the answers

    Which of the following is NOT a major nerve derived from the brachial plexus?

    <p>Phrenic (A)</p> Signup and view all the answers

    Which trunks combine to form the lateral cord?

    <p>Upper and middle trunks (D)</p> Signup and view all the answers

    Which of the following structures forms the base (floor) of the axilla?

    <p>Skin, axillary fascia (B)</p> Signup and view all the answers

    The anterior divisions of the brachial plexus primarily supply:

    <p>Flexor muscles (A)</p> Signup and view all the answers

    Which of these is a primary action of the latissimus dorsi muscle?

    <p>Extending, adducting, and rotating the humerus medially (A)</p> Signup and view all the answers

    What forms the anterior wall of the axilla?

    <p>Pectoralis major, pectoralis minor, clavipectoral fascia (D)</p> Signup and view all the answers

    The nerve supply for the rhomboid major and minor muscles is primarily from which nerve?

    <p>Dorsal scapular nerve (C4-C5) (D)</p> Signup and view all the answers

    Which of the following describes the location of the vertebral artery and vein?

    <p>Through the vertebral foramen (A)</p> Signup and view all the answers

    What is the insertion point for the trapezius muscle?

    <p>Lateral third of the clavicle, acromion, and spine of the scapula (D)</p> Signup and view all the answers

    Which bone does the sacral vertebra articulate with?

    <p>Pelvis (A)</p> Signup and view all the answers

    What is the main function of the pectoralis minor muscle?

    <p>Stabilizes the scapula by drawing it inferiorly and anteriorly (A)</p> Signup and view all the answers

    What is the main action of the levator scapulae muscle?

    <p>Elevates the scapula and tilts the glenoid cavity inferiorly (D)</p> Signup and view all the answers

    Which type of vertebra has the largest and strongest bodies, designed to keep the weight of the upper body?

    <p>Lumbar (B)</p> Signup and view all the answers

    Which nerve(s) supply the flexor digitorum profundus muscle?

    <p>Ulnar nerve and anterior interosseous nerve (D)</p> Signup and view all the answers

    What is the most commonly dislocated carpal bone?

    <p>Lunate (C)</p> Signup and view all the answers

    Which of the following is a common cause of lunate dislocation?

    <p>High-energy trauma such as a fall on an outstretched hand (A)</p> Signup and view all the answers

    A patient presents with pain, swelling, and limited motion in the wrist following a fall. Which injury is most likely if a carpal bone is dislocated?

    <p>Lunate dislocation (A)</p> Signup and view all the answers

    What is the pathophysiology behind nursemaid's elbow?

    <p>Subluxation of the radial head (A)</p> Signup and view all the answers

    What is the typical mechanism of injury for a Colles' fracture?

    <p>Fall onto an outstretched hand with the wrist extended (C)</p> Signup and view all the answers

    What is a common symptom of an anterior dislocation of the glenohumeral joint?

    <p>Visible deformity of the shoulder (D)</p> Signup and view all the answers

    A child is brought to the clinic holding their arm bent with the forearm turned inward and refuses to use that arm. What is the most likely diagnosis?

    <p>Nursemaid's elbow (A)</p> Signup and view all the answers

    Study Notes

    Myotomes and Dermatomes

    • Myotome: A group of muscles controlled by a single spinal nerve.
    • C5 myotome involves muscles in the upper arm, controlled by the C5 spinal nerve.
    • These muscles include deltoids, infraspinatus, biceps brachii, and brachioradialis.
    • The C5 myotome is responsible for shoulder abduction, external rotation, and elbow flexion.

    Isometric and Isotonic Contractions

    • Isometric Contraction: Muscle length remains constant while tension increases. No movement occurs.
    • Concentric Contraction: Muscle shortens during contraction, such as lifting a weight.
    • Eccentric Contraction: Muscle lengthens under tension, such as lowering a weight.

    Intervertebral Foramina

    • The superior margin of an intervertebral foramen is formed by the inferior vertebral notch of the vertebra above.
    • The anterior margin is formed by the intervertebral disc between vertebral bodies.
    • The inferior margin is the superior vertebral notch of the vertebra below.
    • The posterior margin is the zygapophysial (facet) joint of the adjacent vertebrae.
    • Each pedicle contains superior and inferior vertebral notches.

    Planes of the Body

    • Sagittal Plane: Divides the body into left and right halves.
    • Midsagittal (Median) Plane: Divides the body into equal left and right halves.
    • Frontal (Coronal) Plane: Divides the body into front and back parts.
    • Transverse (Horizontal) Plane: Divides the body into upper and lower parts.

    Types of Joints

    • Fibrous Joints: Connected by dense connective tissue; little to no movement (skull sutures).
    • Cartilaginous Joints: Connected by cartilage; limited movement (symphyses, synchondroses).
    • Synovial Joints: Freely movable joints with a synovial cavity; six types.

    Six Types of Synovial Joints

    • Plane (Gliding) Joints: Allow sliding movements (intercarpal joints).
    • Hinge Joints: Permit flexion and extension (elbow, knee).
    • Pivot Joints: Allow rotational movement (atlantoaxial joint).
    • Condyloid (Ellipsoidal) Joints: Permit movement in two planes (wrist joint).
    • Saddle Joints: Allow movement in two planes with greater freedom (thumb carpometacarpal joint).
    • Ball-and-Socket Joints: Permit movement in multiple planes (shoulder and hip joints).

    Ligaments of the Vertebral Column

    • Anterior Longitudinal Ligament: Prevents hyper-extension.
    • Posterior Longitudinal Ligament: Prevents hyper-flexion.
    • Ligamenta Flava: Connects laminae; maintains upright posture.
    • Interspinous Ligaments: Connect spinous processes; limit flexion.
    • Supraspinous Ligament: Connects tips of spinous processes; limits flexion.
    • Intertransverse Ligaments: Connect transverse processes; limit lateral flexion.

    Spinal Cord

    • The spinal cord ends at the L1-L2 vertebrae in adults.

    • The dorsal root contains sensory fibers.

    • The ventral root contains motor fibers.

    • Spinal nerves exiting the spinal column branch out into rami.

      • Dorsal rami: innervate deep back muscle and skin on the back.
      • Ventral rami: form plexuses that innervate limbs and the anterior trunk.

    Spinal Tap (Lumbar Puncture)

    • Position: Between L3-L4 or L4-L5 vertebrae.
    • Landmark: Iliac crest aligns with L4 vertebra.

    Spinal Nerves and Intervertebral Foramina

    • Spinal nerves exit the spinal cord, branching into anterior and posterior rami.
    • The anterior rami enter the intervertebral foramina.

    Characteristic Features of Vertebrae

    • The vertebral column has 33 vertebrae (7 cervical, 12 thoracic, 5 lumbar, 5 sacral, 4 coccygeal).
    • The cervical vertebrae are the smallest and possess transverse foramina.
    • Thoracic vertebrae have facets for the ribs.
    • Lumbar vertebrae have large, kidney-shaped bodies.
    • Sacrum and coccyx are formed by fused vertebrae.

    Myotomes and Dermatomes: One Below Rule

    • A herniation at a disc typically affects the nerve root below the herniated disc.

    Specific Muscles, Bones, and Injuries

    • Information about specific muscles, spinal nerves, or injuries (e.g., nursemaid's elbow, brachial plexus injury) is dispersed throughout the notes and needs further investigation.

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    Anatomy Exam 1 Study Guide PDF

    Description

    This quiz explores the concepts of myotomes and dermatomes, focusing on the C5 myotome and its associated muscles. It also covers the types of muscle contractions, including isometric, concentric, and eccentric. Test your knowledge of spinal nerve functions and muscle mechanics.

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