Craniofacial Histology - Muscular System

Front 1

Organization of the Muscular System

Back 1

There are about 600 human skeletal muscles
Muscles are organized and named by:
shapes of muscles
actions of muscles
innervation of muscles

Front 2

Muscle Names

Back 2

Nomina Anatomica is the officially recognized system of Latin names used by anatomists.
Some English names for muscles are slight modifications of the Latin names.

Front 3

Functions of Muscles

Back 3

Movement, Control, Stability, Communication, Heat Production (85%)

Front 4

Connective Tissues of Muscle

Back 4

Epimysium - covers the whole muscle, blends into tendons and CT sheets called the deep fasciae that surrounds and separates muscles, Deep fascia grades into the superficial fascia (also called the hypodermis which contains various amounts of adipose between muscles and skin) contains blood vessels and nerves
Perimysium-layer of CT surrounding a fascicle (bundle of muscle cells), contains blood vessels and nerves
Endomysium- thin layer of areolar CT surrounding each muscle cell (muscle cell = muscle fiber), contains capillaries and nerves

Front 5

Superficial Fascia and Deep Fascia

Back 5

Superficial Fascia (hypodermis): found bw skin and muscles adipose tissue with vessels and nerves
Deep Fascia (epimysium): found around and between muscles
contains neurovascular bundles

Front 6

Back 6

red = individual muscle w/ fascicles
yellow outer= superficial fascia (hypodermis)
yellow w/ red & blue circle = neurovascular bundle
white = deep fascia (epimysium)

Front 7

Back 7

slide 9 lecture 7
know: endomysium (thin white collagen fibers)
perimysium
Facicles

Front 8

General Parts of a Skeletal Muscle

Back 8

Origin: attach to the more stationary end of a muscle
Belly: thick, middle region of a muscle
Insertion: attachment to the more mobile end of muscle

Example: biceps brachii origin is scapula and insertion is radius

Front 9

Muscle Attachments

Back 9

Connective tissue fibers of a muscle merge with the connective tissue of bone (periosteum).
Tendons & Aponeuroses

Front 10

Tendons

Back 10

merge with the bone periosteum and they are connected by extremely strong Perforating Fibers (Sharpey’s fibers). Stress will tear the tendon before pulling the tendon loose from either muscle or bone

Front 11

Aponeuroses

Back 11

are flat sheet-like tendons as under the scalp, palm, foot and other areas that attach muscle to the collagen fibers of the dermis.
example: palmaris longus tendon fans out to become the palmar aponeurosis

Front 12

Skeletal Muscle Shapes

Back 12

Fusiform Muscles: thick in middle and tapered at ends, biceps brachii m.
Convergent Muscle: broad at origin and tapering to a narrower insertion, pectoralis major m.
Parallel Muscles: long, uniform,parallel fascicles
shorten more than other muscles, rectus abdominis m.
Circular muscles: act as sphincters, ring around body openings, orbicularis oris m. and orbicularis occuli m.
Pennate muscles: fascicles insert obliquely on a tendon
unipennate, bipennate or multipennate, palmar interosseus m., rectus femoris m., deltoid m.

Front 13

Coordinated Muscle Actions

Back 13

Agonist: the Prime Mover produces most of the force
Synergist: aids the agonist stabilizes the nearby joint
modifies the direction of movement that occurs
Antagonist: opposes the prime mover prevents excessive movement and injury
Fixator: prevents movement of the bone that the prime mover is attached to

Front 14

Muscle Actions during Elbow Flexion

Back 14

Agonist = biceps brachii m.
Synergist = brachialis m.
Antagonist = triceps brachii m.
Fixator = muscle that holds the origin bone firmly in place such as rhomboideus major m. holds the scapula

Front 15

Intrinsic and Extrinsic Muscles

Back 15

Intrinsic muscles are entirely contained (both origin and insertion) within a region such as the hand like the palmar interosseous m.
Extrinsic muscles move the fingers but origin is outside of the hand like the flexor digitorum profundus m.

Front 16

Skeletal Muscle Innervation

Back 16

Skeletal muscles are activated by motor neurons
Motor Neurons branch out of the central nervous system from the skull (cranial nerves) and the spine (spinal nerves)
Cranial nerves arising from the brain exit the skull through foramina and are numbered I to XII
Spinal nerves arising from the spinal cord exit the vertebral column through intervertebral foramina

Front 17

Afferent Innervation
Efferent Innervation

Back 17

Afferent: sensory info from senses to brain
Efferent: motor somatic, outgoing to skeletal muscle
*autonomic, outgoing to glands, cardiac muscle, and smooth