Chapter 11: Axial Musculature

Endomysium

wraps individual muscle fibers

Perimysium

surrounds fascicles (bindles of cells/fibers)

Epimysium

surrounds entire muscle

Fascia

a band or sheet of fibrous connective tissue that covers, supports, and separates muscle

fusiform muscles

Thick in the middle and tapers at the end

parallel muscles

Uniform width with aligned fascicles

Triangular (convergent) muscles

Broad at one end and narrow at the other

Pennate Muscles

feather shaped

Circular muscles (sphincters)

form rings around body openings

example of fusiform muscle

biceps brachii

example of parallel muscle

rectus abdominis

example of triangular (convergent) muscle

pectoralis major

example of unipennate muscle

palmar interosseous

example of bipennate muscle

rectus femoris

example of multipennate muscle

deltoid

example of circular muscle

orbicularis oculi

Compartments

Spaces enclosed by fasciae that contain one or more functionally related muscles, nerves and blood vessels

Fasciae

Intermuscular septa

Compartments in upper limbs

Anterior and posterior compartments

Compartments in lower limbs

Anterior, lateral, posterior deep and posterior superficial

direct (fleshy) attachment

Close association with bone and connection with collagen fibers

indirect attachment

Via tendon attaching muscle to bone and connects to periosteum and matrix

Aponeurosis

a broad, sheetlike tendon

Dermal attachments

Muscles that attach to the dermis of skin (facial muscles)

Intrinsic

Both origin and insertion contained within a particular region

Example of intrinsic muscle

O within hand and I within hand

Extrinsic

Acts upon a designated region but has its origin elsewhere

Example of extrinsic muscle

O in forearm and I within hand

Action

Effect produced by a muscle and produced or prevents movement

Prime mover (agnoist)

Produced main force of action

Synergist

Aids prime mover and may stabilize joint

Antagonist

Opposes prime mover

Antagonistic pair

act on opposite sides of joint

Fixator

Prevents bone movement

How are muscles named

Size, Shape, Location, Number of heads, Orientation of the fibers, and action

Example of size

brevis = short

Example of shape

teres = round

Example of location

Branchii = of the arm

Example of number of heads

Biceps = two heads

Example of orientation of the fibers

Rectus = straight

example of action

flexor = a muscle that flexes

Muscle innervation

Describes which nerve stimulates the muscle

Spinal nerves

Arise from spinal cord and innervate muscles below the neck

Cranial nerves

Emerge from brainstem and innervate muscles of the head and neck

Muscles of facial expression

Frontalis, orbicularis oculi, orbicularis oris, zygomaticus major, zygomaticus minor and risorius

Frontalis

elevates eyebrows

Orbicularis oculi

Closes eyes

Orbicularis oris

closes lips

Zygomaticus major and minor

raise corners of mouth for smile

Risorius

expresses horror or fake smile

Genioglossus

Protrudes tongue or moves it to one side if used unilaterally

Hyoglossus

depresses tongue

Styloglossus

Pulls tongue up and back

Muscles of the tounge

Genioglossus, hyoglossus and styloglossus

Muscles of chewing

Temporalis, masseter, medial pterygoid and lateral pterygoid

Temporalis

elevates and retracts mandible

masseter

elevates mandible

medial pterygoid

Elevate mandible and move it sideways

Lateral pterygoid

Depresses manidble and moves it sideways

Muscles of the neck

Digastric, sternohyoid and sternothyroid

Digastric

depresses mandible

Sternohyoid

depresses hyoid

Sternothyroid

depresses larynx

suprahyoid muscles

digastric, stylohyoid, mylohyoid, geniohyoid

Infrahyoid

omohyoid, sternohyoid, sternothyroid, thyrohyoid

Sternocleidomastoid

Rotates head to side when unilaterally active, draws head forward when bilaterally active

Neck flexors

SCM and scalene group

Trapezius

Extends the neck

Neck extensors

Trapezius, splenius group and semispinalis group

Muscles of respiration

Diaphragm

Diaphragm

Prime mover of inspiration

Muscles of anterior abdominal wall

Rectus abdominis and transverse abdominal

Rectus abdominis

Flexes waist

Transverse abdominal

Compresses abdominal contents

rectus sheath

Aponeurosis of transverse abdominals, internal obliques and external obliques

Rectus muscles

Lie within sheath

external oblique

compresses abdomen (superficial)

internal oblique

flexes and rotates vertebral column (middle layer)

Transverse abdominal

compresses abdominal wall, laterally rotates waist (deep layer)

linea alba

midline tendinous seam joining the abdominal muscles

Peritoneum

membrane that lines the abdominal cavity

Parts of aponeurosis

transverse abdominal, internal oblique and external oblique

Rectus sheath

fibrous sheath formed by aponeuroses of abdominal muscles

Linea semilunaris

Two layers from rectus sheath join to form a vertical line of aponeurosis

inguinal ligament

ligament extending from pubic bone to anterior superior iliac spine, forming lower border of abdomen

Muscles of vertebral column

Erector spinae, multifidus and quadratus lumborum

Erector spinae

straightens spine

Multifidus

Stabilizes adjacent vertebrae

Quadratus lumborum

aids respiration by stabilizing the diaphragm and rib 12

Muscles of pelvic floor

Ischiocavernosus, external anal sphincter, levator ani group, piriformis

Ischiocavernosus

maintains erection of the penis or clitoris by compressing deep structures of the organ and forcing blood forward into its body

External anal sphincter

Retains feces in rectum

Levator ani group

iliococcygeus, pubococcygeus, puborectalis

Piriformis

Pear-shaped muscle that laterally rotates and abducts thigh