Anatomy of Back and Trunk Muscles

Questions and Answers

Which cranial nerve is responsible for innervating the trapezius muscle?

Cranial nerve X

Cranial nerve III

Cranial nerve VII

Cranial nerve XI (correct)

What roots contribute to the formation of the femoral nerve?

L2-L5

L2-L4 (correct)

L1-L4

L1-L3

What is the primary function of most peripheral nerves in the extremities?

They are solely responsible for motor functions.

They only carry sensory information.

They typically have both sensory and motor fibers. (correct)

They act only as relay pathways between the spinal cord and muscles.

Which of the following is true regarding nerve plexuses?

The brachial plexus receives input from spinal nerves C5-T1. Signup and view all the answers

What key factor should a physical therapist understand regarding nerve injuries?

Distinguishing between spinal and peripheral nerve injuries is crucial. Signup and view all the answers

How do the sensory and motor fibers of a peripheral nerve typically behave as they approach their targets?

They become separated. Signup and view all the answers

What is the primary role of the myotomes in relation to peripheral nerves?

They represent the motor distributions of peripheral nerves. Signup and view all the answers

Which trunk muscles are innervated by branches of the brachial plexus?

Pectoralis major and latissimus dorsi Signup and view all the answers

What type of cartilage is primarily found in the external ear and epiglottis?

Elastic cartilage Signup and view all the answers

Which of the following joint classifications includes synarthroses?

Fibrous joints Signup and view all the answers

What type of cartilage is most resistant to compression and tension?

Fibrocartilage Signup and view all the answers

Which type of joint allows for three degrees of freedom?

Triaxial joint Signup and view all the answers

What mechanism primarily provides nutrition to cartilage?

Diffusion Signup and view all the answers

Which classification includes synovial joints that allow for gliding movement?

Plane joints Signup and view all the answers

What type of cartilage is present in growth plates during ossification?

Primary cartilaginous cartilage Signup and view all the answers

Which term describes the joint type characterized by the presence of fibrocartilage pads?

Secondary cartilaginous joints Signup and view all the answers

Which layer of the skin is primarily composed of dense irregular connective tissue?

Dermis Signup and view all the answers

What type of skin is characterized as thick and hairless?

Thick hairless (glabrous) skin Signup and view all the answers

Which of the following is NOT a function of the integumentary system?

Movement Signup and view all the answers

Which component of the integumentary system is primarily responsible for excretion?

Sweat glands Signup and view all the answers

Which part of the skeleton includes the cranium and vertebral column?

Axial Skeleton Signup and view all the answers

What is one of the primary components of the hypodermis?

Loose connective tissue Signup and view all the answers

Which of the following bones is part of the appendicular skeleton?

Humerus Signup and view all the answers

What process involves the turnover of cells and initiation of immune responses within the integumentary system?

Immune defense Signup and view all the answers

Which type of movement is characterized by sliding or gliding between joint surfaces?

Gliding/sliding Signup and view all the answers

What feature of a joint surface affects the types of movement allowed?

Type of curvature Signup and view all the answers

Which type of muscle is primarily responsible for movement and is under voluntary control?

Skeletal muscle Signup and view all the answers

What is the primary function of cardiac muscle?

Pump blood Signup and view all the answers

Which classification of skeletal muscle has a feather-like appearance?

Pennate Signup and view all the answers

What type of muscle is found in the linings of glands and blood vessels and operates involuntarily?

Smooth muscle Signup and view all the answers

Which of the following is an example of a multipennate muscle?

Deltoid Signup and view all the answers

What does a motor unit consist of?

A motor neuron and all muscle fibers it innervates Signup and view all the answers

What does a dermatome specifically refer to?

The area of skin innervated by a single spinal nerve root Signup and view all the answers

How do spinal nerves contribute to peripheral nerves in the trunk?

Many peripheral nerves are continuations of anterior primary rami of spinal nerves Signup and view all the answers

What is a myotome, and why is it significant for physical therapy?

A group of muscles innervated by a specific spinal nerve root, crucial for muscle function Signup and view all the answers

Where are the cell bodies for peripheral sensory nerves located?

In the dorsal root ganglia Signup and view all the answers

What type of information is primarily conveyed by the dorsal root fibers?

Pain and temperature sensations from skin Signup and view all the answers

Which of the following statements about skeletal muscle innervation is accurate?

It occurs via impulses from anterior horn cells through ventral roots Signup and view all the answers

Which nerves contribute to the innervation of abdominal muscles?

Lumbar plexus nerves such as iliohypogastric and ilioinguinal Signup and view all the answers

What is the primary distinction between dermatomal distribution and sensory distribution of an individual peripheral nerve?

Dermatomes are specific to spinal nerve roots while peripheral nerve distributions vary significantly Signup and view all the answers

Study Notes

Nervous System Innervation

Intrinsic back muscles are primarily innervated by posterior primary rami (PPRs); few have specific names.
Trunk muscles like pectoralis major and latissimus dorsi are innervated by the brachial plexus; trapezius receives innervation from cranial nerve XI.
Peripheral nerves arise from nerve plexuses and typically receive inputs from multiple anterior primary rami (APRs).
Example: The femoral nerve serves the anterior thigh, receiving contributions from L2-L4 APRs, which also supply other nerves like the obturator.
Most peripheral nerves carry both sensory and motor fibers; these fibers can separate as they approach targets.
Dermatomes represent skin areas innervated by single spinal nerve roots, while sensory distributions differ among individual peripheral nerves.
Myotomes refer to muscle groups innervated by specific spinal nerves, and understanding these is crucial for physical therapy (PT).

Nerve Plexuses

Plexuses are networks formed from APRs of spinal nerve roots in specific regions.
The brachial plexus derives inputs from C5-T1, producing five primary terminal branches and numerous smaller branches.

Relevance to Physical Therapy

Injuries can affect spinal and peripheral nerves, requiring PTs to differentiate injuries based on the location of damage.
A thorough understanding of spinal and peripheral nerve organization and function is essential for effective assessment and intervention in PT.

Sensory Innervation

Sensory information travels along fibers from peripheral receptors (skin, muscles, joints) entering the spinal cord via the dorsal root.
Cell bodies for peripheral sensory nerves are located in specific ganglia.
Review of dermatomal distributions is important for ongoing applications in the PT field.

Motor Innervation

Skeletal muscle receives motor signals from anterior horn cells via ventral roots through to spinal and peripheral nerves.
Knowledge of myotomes is essential for identifying which muscles are innervated by specific spinal nerve roots.

Spinal Nerves vs Named Peripheral Nerves

Peripheral nerves consist of spinal nerve components; trunk nerves often simply continue from spinal APRs.
Named peripheral nerves from the lumbar plexus (e.g., iliohypogastric, ilioinguinal) also innervate abdominal muscles and skin.

Integumentary System Overview

Comprises skin, hair, nails, sweat and sebaceous glands, subcutaneous fat, deep fascia, and mucous membranes.
Skin types include thin hairy skin (most of the body) and thick hairless (glabrous) skin (palms, soles of feet).

Functions of the Integumentary System

Protection against abrasions, chemicals, UV rays, and fluid loss; immune defense through cell turnover and barrier to microorganisms.
Thermoregulation via sweat and blood flow; insulation through subcutaneous fat; sensory communication; vitamin D synthesis; and excretion via sweat.

Layers of the Skin

Epidermis composed of stratified squamous keratinized epithelium for protection.
Dermis mainly consists of dense irregular connective tissue.
Hypodermis features loose connective tissue, often adipose, mediating skin mobility, acting as a shock absorber and thermal insulator.

Skeletal System Overview

Axial skeleton includes cranium, vertebral column, ribs, and sternum; vertebral composition includes cervical, thoracic, lumbar, sacral, and coccygeal categories.
Appendicular skeleton encompasses limbs and girdles.
Bone functions include protection, support, movement, blood cell formation, and salt storage.

Types of Bone and Cartilage

Types of cartilage include strong, load-bearing fibrocartilage and elastic cartilage, which provides flexibility.
Most cartilage is avascular and relies on diffusion for nutrition; perichondrium provides vascular and lymphatic supply.

Arthrology and Joint Classification

Joints classified as fixed (e.g., sutures) and movable (e.g., synovial joints like hinge, pivot).
Movable joints can be further categorized into uniaxial, biaxial, and triaxial, affecting the movements allowed (gliding, angular, rolling).

Muscular System Overview

Muscle types include skeletal (voluntary), smooth (involuntary, non-striated), and cardiac (involuntary, striated).
Function classification for skeletal muscle encompasses movement, heat production, postural control, and protection.
Motor units consist of a motor neuron and its innervated muscle fibers, with architecture varying across muscle types (e.g., pennate, fusiform).

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Description

Explore the intricate anatomy of muscles that contribute to the movement of the back and upper extremities. This quiz delves into the innervation of intrinsic back muscles and connection to cranial nerves. Test your knowledge of key muscle groups and their innervation pathways.