A&P 1: Axial & Appendicular Muscles

Tendon

Attaches the muscle to bone, skin, or another muscle

Typically thick, cordlike

Aponeurosis

Tendon formed as thin, flattened sheet

Origin

Less movable attachment

Typically proximal or inferior

Insertion

More movable attachment

Typically distal or superior

Circular muscle

Concentric fascicles around opnening

Sphincter; contraction decreases opening diameter

Parallel muscle

Parallel fascicles along long axis, sometimes cylindrical with expanded central region (belly, gaster) which increases in diameter during shortening

High endurance, but not strong

E.g. rectus abdomins, biceps brachii

Convergent muscle

Widespread fascicles converging to common attachment (tendon, tendinous sheet or raphe); often triangular/fan-shaped

Versatile but less force than parallel when all contracting

Raphe

Slender band of collagen fibers (seam)

Pennate muscle

Feather-shaped arrangement with fascicles at same oblique angle to tendon; may have one or more tendons

Does not move as far as parallel due to angle but generates more tension/force relative to size

Unipennate

Pennate muscle with fascicles on the same side

E.g. extensor digitorum

Bipennate

Pennate muscle with fascicles on both sides; most common type

E.g. interosseous muscles (meta carpal)

Multipennate

Pennate muscle with branches; each branch has fascicles on both sides

E.g. deltoid

Agonist

Prime mover

Antagonist

Action opposes prime mover for speed control, smoothness to sabilize movement

Synergist

Assists prime mover often at start of movement or assists antagonist preventing joint movement for stability (fixator)

Muscle action

Adductor, abductor, flexor, extensor, pronator

Body region

Oris, cervicis, brachial, policis, gluteal, femoris, hallucis, anterior, posterior, superior, inferior, superficialis, profundis

Muscle attachment

Naming based on major bone(s)/bone region

Fiber orientation

Rectus, oblique, orbicularis

Muscle shape

Deltoid, quadratus, trapezius, longus, brevis

Muscle size

Major, minor, maximus, medius, minimus

Number of muscle heads

Biceps, triceps, quadriceps

Occipitofrontalis

Forms epicranius with epicranial aponeurosis; galea aponeurotica

Frontal belly raises eyebrows, moves scalp

Occipital belly retracts scalp

Nasalis

Flares nostril

Compresses nose bridge, elevates nostril corners

Procerus

Wrinkes/moves nose

Buccinator

Chewing muscle for compressing cheek to hold food

Depressor anguli oris

Frown muscle, draws mouth corners inferior/lateral

Depressor labii interioris

Draws lower lip inferiorly

Smile muscles

Levator anguli oris (draw superior/lateral)

Zygomaticus major & minor (elevate)

Mentalis

Pout muscle; protrudes lower lip

Orbicularis oris

Kiss muscle; purses lips

Risorius

Draws lips laterally; tenses lips

Corrugator supercilii

Furrows brow

Blink muscles

Levator palpebrae superioris (raises upper lid)

Orbicularis oculi (opens, closes, squints)

Extraocular muscles

Attach to sclera (outer white surface) with four rectus muscles forming tendinous ring in orbit:

Medial for adduction, lateral for abduction, inferior to look down, superior to look up; both superior and inferior move medially to look at nose

Elevation/depression and turning via inferior and superior (through trochlea) oblique attached posteriorly

Mastication

Action of temporalis (elevate, retract), masseter (elevate, protract), medial (+elevate) & lateral pterygoid (protract, lateral motion)

Gleniglossus

Protract tongue

Sytloglossus

Elevate, retract tongue

Hyoglossus

Depress, retract tongue

Palatoglossus

Elevate posterior tongue

Palate muscles

Levator veli palatini (elevate)

Tensor veli palatini (tense, open auditory tube for swallow/yawn)

Pharyngeal constrictors

Constrict in sequence to force bolus into esophagus

Super, middle, inferior

Laryngeal elevators

Palatopharyngeus, salopinopharyngeus, stylopharyngeus elevate pharnx/larygnx

Suprahyoid

Floor of the mouth mucles elevating hyoid bone during swallowing, speaking

Formed by digastric, geniohyoid, mylohyoid, stylohyoid

Digastric

Suprahyoid muscle which lifts hyoid and depresses mandible

2 bellies with tendon in fibrous loop

Mylohyoid

Connects hyoid to mental spines of mandible

Mylohyoid

Muscular floor of mouth, broad and flat with v shape

Stylohyoid

Elevates hyoid bone to elongate floor of oral cavity during swallowing

Infrahyoid muscles

Depress hyoid bone/larynx

Omohyoid, sternohyoid, sternothyroid , thryohyoid

Omohyoid

Scapula to hyoid for depression/fixation

Sternohyoid

Sternum to hyoid for depression

Sternothyroid

Sternum to thyroid cartilage for thyroid cartilage depression, hyoid fixation for return to position after swallowing

Deep to sternohyoid

Thyrohyoid

Thyroid cartilage to hyoid for depressing bone, elevating cartilage

Depresses head/neck muscles arising from vertebral column

Sternocleidomastoid

Flex the neck

Thick, cordlike muscle from sternum to clavicle to mastoid process

Bilateral contraction flexes neck, unilateral contraction tilts head

Scalene muscles

Anterior, middle and posterior muscles working with sternocleidomastoid to flex neck

Also elevate first and second ribs during forced respiration when neck is fixed

Trapezius

Posterior neck muscle moving posterior girdle and extending neck

Splenius capitis, splenius cervicis, longissimus capitis

Bilaterally contract to extend neck

Unilaterally contract to rotate head to same side

Suboccipital muscles

Rotates head to same side (obliquus capitis superior & inferior) and extend head and neck (rectus capitis posterior major & minor)

Erector spinae

Iliocostalis, longissimus and spinalis muscles; maintain posture/erect stance

Bilateral contraction to extend vertebral column

Unilateral contraction for lateral flexion toward that side

Iliocostalis group

Attach iliac crests to ribs (angles or cervical tranverse process); most lateral of erector spinae

Cervical, thoracic and thumbar parts

Longissimus group

Attach to transverse process; medial to iliocostalis group

Capitis, thoracic and thumbar parts

Spinalis group

Attaches to spinous process; most medial erector spinae group

Transversospinalis muscles

Muscle group deep to erector spinae which connects and stabilizes vertebrae

Bilateral action: extend vertebral column

Unilateral action: rotates vertebral colum to opposite side

Multifidus, rotatores, and semispinalis group

Quadratus lumborum muscles

Lumbar muscles for vetebral column extension (bilateral contraction) and lateral flexion (unilateral contraction)

Serratus posterior

Posterior thorax muscles; elevate ribs 2-5 (superior) and depress ribs 8-12 (inferior) during forced inspiration (superior) and expiration (inferior)

External intercostals

Extend inferomedially from superior to adjacent inferior rib to elevate and increase transverse thoracic dimensions for inspiration

Internal intercostals

FIbers perpendicular to external intercostals and deep

Depress ribs during forced expiration

Transversus thoracsis

Extends across inner thoracic cage attaching to ribs 2-6 to help depress ribs during forced expiration

Diaphragm

Internal dome-shaped muscle with fibers converging from margins toward central tendon

Contraction pulls tendon inferiorly toward abdominal cavity to enlarge thoracic cavity

Forms partition between thoracic & abdominal cavities; most important breathing muscle

Exteranl obique

Inferomedially directed muscles along lateral abdominal wall forming anterior aponeurosis

Bilateral: flexes vertebral column, compresses abdominal wall (forced expiration)

Unilateral: lateral flexion, opposite side rotation

Inguinal ligament

Inferior edge of external oblique aponeurosis; thickened cordlike structure from anterior superior iliac spine to pubic tubercle

Internal oblique

Projects superomedially at right angles to external oblique forming aponeurosis anteriorly.

Bilateral: flexes vertebral column, compresses abdominal wall (forced expiration)

Unilateral: lateral flexion, same side rotation

Transverse abdoimnis

Extends transversly across abdomen with anterior aponeurosis to compress abdominal wall (forced expiration)

Rectus abdominis

Long, straplike muscle extending the vertical length of the abteromedial abdominal wall between sternum and pubic symphysis.

4 segments partitioned by 3 tendinous intersections enclosed in rectus sheaths formed by oblique and transverse aponeuroses

Linea alba

Fibrous strip connecting left and right rectus sheath

Pelvic diaphragm

Floor of pelvic cavity formed by 3 layers of fuscles/fasciae extending from ischium and pubis of ossa coxae accross pelvic outlet to sacrum and coccyx to support pelvic viscera

Perineum

diamond-shaped region between lower appendages marked by pubic symphysis (anterior), coccyx (posterior), ischial tuberosities (lateral)

Urogenital triangle

External genitalia and uretrha

Bulbospongiosus (male or female), ischiocavernosus (m/f erection assist), superficial & deep transverse perineal, external urethral sphincter

Anterior pectoral girdle

Formed by pectoralis minor, serratus anterior, subclavius

Pectoralis minor

Depresses & protracts scapula

Serratus anterior

Large, flat, fan-shaped muscle between ribs & medial scapula border

Protracts scapula, rotates glenoid cavity, stabilizes scapula

Subclavius

Extends from clavicle to first rib

Stabilizes and depresses clavicle

Levator scapulae

Connects transverses processes of cervical vertebrae to superior angle of scapula

Elevates scapula and inferiorly rotates

Rhomboid

Parallel bands (major, minor) deep to trapezius directed inferolaterally from vertebrae to scapula to help elevate and retract (adduct) the scapula (stand up straight) and inferiorly rotate scapula

Trapezius

Large, diamond-shaped muscle from skull and vertebral column to scapula and clavicle to elevate, superiorly rotate, retract, or depress scapula depending on which fibers contract

Latissimus dorsi

Broad, triangular muscle on inferior back; swimmer’s muscle

Arm extension and adduction agonist; also medially rotates arm

Pectoralis major

Large, thick, fan-shaped muscle covering superior thorax

Flexes, adducts and medially rotates arm

Deltoid

Thick, powerful muscle forming rounded contour of shoulder.

Anterior fibers flex & medially rotate arm

Middle (lateral) fibers abduct arm

Posterior fibers extend and laterally rotate arm

Coracobrachialis

Synergyst to pectoralis major in flexion and adduction of arm

Teres major

Synergist for latissimus dorsi extending, adducting, medially rotating arm

Rotator cuff muscles

Subscapularis, supraspinatus, infraspinatus, teres minor

Provide strength & stability to glenohumeral joint attaching humerus, scapula

Subscapularis

Wind up rotator cuff muscle

Medial arm rotation agonist

Supraspinatus

Starts pitch execution by fully abducting arm

Infraspinatus, teres minor

Slow down pitching arm to complete movement; adduct arm, agonist for lateral rotation

Compartments

Organization of limb muscles with deep fascia surrounding muscles separated by intermuscular septa (dense connective tissue)

Contains functionally related skeletal muscles, associated nerves, blood vessels

Anterior arm compartment

Arm flexor compartment with elbow flexors

Brachial artery, muscolocutaneous nerve supply biceps brachii, brachialis, brachioradialis

Biceps brachii

Large 2-headed muscle that flexes and supinates forearm and weakly flexes humerus

Principal elbow flexor

Brachialis

Most powerful elbow flexor; deep to biceps

Brachioradialis

Flexes forearm at elbow along with biceps brachii and brachialis