Anatomy Lab Practical 1

Skin

Skin Information

Epidermis over dermis; subcutis lies deep to the skin.

Skin Function

Barrier, sensation, protection, and temperature regulation.

Hair coat

Hair coat Info

Keratinized hair shafts arise from follicles in the dermis.

Hair coat Function

Insulation and protection.

Compound hair coat

Compound hair coat Info

Several hairs emerge through a common follicular opening; coarse primary hairs accompany finer secondary hairs.

Compound hair coat Function

Combines protective guard hairs with insulating undercoat.

Tactile hairs (vibrissae)

Tactile hairs (vibrissae) Info

Specialized large hairs with richly innervated follicular sinus complexes, especially on face.

Tactile hairs (vibrissae) Function

Detect contact and nearby objects.

Superficial fascia (subcutaneous tissue; hypodermis)

Superficial fascia (subcutaneous tissue; hypodermis) Info

Loose connective tissue and variable fat beneath dermis; contains superficial vessels, nerves, and cutaneous muscles.

Superficial fascia (subcutaneous tissue; hypodermis) Function

Permits skin mobility, cushions, and stores energy.

Deep fascia

Deep fascia Info

Dense connective tissue investing muscles and forming compartments and septa.

Deep fascia Function

Supports muscle groups and transmits force.

Cutaneous trunci muscle

Cutaneous trunci muscle Origin

Superficial fascia of the trunk; broad sheet rather than a single focal bony origin.

Cutaneous trunci muscle Insertion

Axillary and proximal brachial fascia.

Cutaneous trunci muscle Action

Twitches the skin in the cutaneous trunci reflex.

Cutaneous trunci muscle Innervation

Lateral thoracic nerve.

Cutaneous omobrachial muscle Origin

Superficial fascia over the shoulder and brachium.

Cutaneous omobrachial muscle Insertion

Adjacent skin and superficial fascia.

Cutaneous omobrachial muscle Action

Moves the skin over the shoulder and arm.

Cutaneous omobrachial muscle Innervation

Axillary nerve.

Interdigital skin

Interdigital skin Info

Skin between digits, including the web spaces.

Interdigital skin Function

Flexible barrier; inspect for foreign bodies and inflammation.

Claw wall (unguis)

Claw wall (unguis) Info

Hard keratin shell over distal phalanx and claw bed.

Claw wall (unguis) Function

Protects the distal digit and provides traction.

Claw tip (distal free edge/apex)

Claw tip (distal free edge/apex) Info

Unattached distal end of the claw wall beyond its supporting bed.

Claw tip (distal free edge/apex) Function

Traction and wear surface; trimming must avoid vascular living tissues.

Claw fold (periungual fold)

Claw fold (periungual fold) Info

Skin fold surrounding proximal and lateral base of claw.

Claw fold (periungual fold) Function

Protects the emerging claw and its growth region.

Carpal pad

Carpal pad Info

Hairless keratinized pad on caudal distal forelimb near carpus.

Carpal pad Function

Additional traction during braking; usually not weight bearing in normal stance.

Metacarpal pad

Metacarpal pad Info

Large central palmar forepaw pad; thick epidermis over fibroelastic fatty tissue.

Metacarpal pad Function

Weight bearing, shock absorption, and traction.

Digital pads

Digital pads Info

Palmar or plantar cushions associated with individual digits.

Digital pads Function

Protect digits and distribute loading.

Nasal planum

Nasal planum Info

Hairless modified skin of external nose.

Nasal planum Function

Protection and tactile sensation; receives moisture from nearby secretions.

Lips and oral commissure

Lips and oral commissure Info

Lips combine external skin, muscle, and oral mucosa; commissure is the junction at the mouth corner.

Lips and oral commissure Function

Retain food and protect oral opening; facial nerve controls labial muscles and trigeminal branches provide sensation.

Eyelids

Eyelids Info

Mobile skin folds with conjunctiva internally and tarsal glands in their margins.

Eyelids Function

Protect cornea and spread tear film; facial nerve closes lids, oculomotor nerve elevates upper lid, trigeminal branches carry sensation.

External ear (pinna)

External ear (pinna) Info

Skin-covered elastic auricular cartilage directing sound toward the external acoustic meatus.

External ear (pinna) Function

Sound collection and communication; auricular muscles are supplied by facial nerve.

Cutaneous marginal pouch of external ear (Henry's pocket)

Cutaneous marginal pouch of external ear (Henry's pocket) Info

Fold or pouch along the caudolateral margin of pinna.

Cutaneous marginal pouch of external ear (Henry's pocket) Function

Normal identification landmark; specific function is not established.

Superficial Pectoral

Superficial Pectoral

Superficial Pectoral Origin

First two sternebrae and median fibrous raphe; lab manual also allows part of the third sternebra.

Superficial Pectoral Insertion

Entire crest of the greater tubercle of the humerus.

Superficial Pectoral Action

Adducts the free limb; prevents abduction during weight bearing.

Superficial Pectoral Innervation

Cranial pectoral nerves, ventral rami C7–C8.

Deep Pectoral

Deep Pectoral

Deep Pectoral Origin

Ventral sternum, median raphe, and associated abdominal fascia.

Deep Pectoral Insertion

Lesser and greater tubercles of the humerus.

Deep Pectoral Action

Adducts and retracts the free limb; draws the trunk forward and extends the shoulder when the advanced limb is fixed.

Deep Pectoral Innervation

Caudal pectoral nerves, principally C8–T1.

Brachiocephalicus

Clavicular intersection of brachiocephalicus

Brachiocephalicus and clavicular intersection Origin

Clavicular intersection is the fibrous junction between cleidobrachialis and cleidocephalicus; it contains a clavicular vestige in the dog.

Brachiocephalicus and clavicular intersection Insertion

Cleidobrachialis attaches to the humeral crest; cleidocephalicus attaches to the mastoid process and middorsal cervical raphe.

Brachiocephalicus and clavicular intersection Action

Advances the limb and extends the shoulder; with the limb fixed, bends the head and neck to the side.

Brachiocephalicus and clavicular intersection Innervation

Brachial part: brachiocephalic nerve from cervical ventral rami; cephalic part: accessory nerve and cervical branches.

Omotransversarius

Omotransversarius Origin

Wing of the atlas.

Omotransversarius Insertion

Distal scapular spine and acromion.

Omotransversarius Action

Advances the limb; bends the neck laterally with the limb fixed.

Omotransversarius Innervation

Accessory nerve. Dyce lists scapula as origin and atlas as insertion; attachments are the same.

Trapezius

Trapezius Origin

Cervical part: median neck raphe; thoracic part: supraspinous ligament over cranial thoracic vertebrae, approximately T1–T9.

Trapezius Insertion

Scapular spine.

Trapezius Action

Elevates and abducts the limb; cervical and thoracic portions move the scapula cranially and caudally, respectively.

Trapezius Innervation

Accessory nerve.

Rhomboideus

Rhomboideus capitis (yellow), cervicis (blue), thoracis (red)

Rhomboideus Origin

Capitis: nuchal crest; Cervicis: neck raphe; Thoracis: cranial thoracic spinous processes and supraspinous ligament.

Rhomboideus Insertion

Dorsal border and adjacent medial surface of the scapula.

Rhomboideus Action

Elevates the limb and holds the scapula against the thorax.

Rhomboideus Innervation

Cervical and thoracic spinal nerve branches; Dyce canine Table 16.2 specifies ventral branches.

Latissimus dorsi

Latissimus dorsi Origin

Thoracolumbar fascia over caudal thoracic and lumbar vertebrae; attachments to caudal ribs.